MEMOIRS OF THE PEABODY MUSEUM OF NATURAL HISTORYVOLUME III,

1

A.R1

A REVISIONth<
orf tne

CERATOPSIA
OR HORNED DINOSAURSBY

RICHARD SWANN LULL
STERLING PROFESSOR OF PALEONTOLOGYAND DIRECTOR OF PEABODY MUSEUM,YALE UNIVERSITYLVXETNEW HAVEN, CONN.
*933

MEMOIRS OF THE PEABODY MUSEUM OF NATURAL HISTORYYALE UNIVERSITY
VolumeI.

America.

A Monograph on the Extinct Toothed Birds of North
By Othniel Charles Marsh. Pp. i-ix, 1-201, pis. 1-34,

text

1-40.

Odontornithes:

figs.

Museum.

VolumeII.

Part

Brachiospongidae

1.

To

1880.

:

A Memoir on a Group of Silurian Sponges.

By Charles Emerson Beecher.

Pp. 1-28, pis. 1-6, text figs. 1-4.

To be obtained from the Peabody Museum.

1889.

Volume III.

Pp. i-xvi, 1-171, pis. 1-32, text figs. 1-62.

son.

from the Yale University Press,

obtained

Price $1.

By George Gaylord Simp-

American Mesozoic Mammalia.

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A Remarkable Ground Sloth.

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1-3.

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To be obtained

from the Yale University Press, New Haven, Conn.
PartA Revision of the Ceratopsia or Horned Dinosaurs.

3.

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1933.

Price $5

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Part

1.

be

i-xii,

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I-XVII,

By

text figs.

from the Peabody Museum.

The Merycoidodontidae, an Extinct Group of Ruminant
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Pt 3

•

A REVISION
OF THECERATOPSIA OR HORNED DINOSAURSiand as I prophesied, there was"So I prophesied as I was commanded:and the bones came together, bone to his
a noise, and behold a shaking,bone.

"And when 1 beheld, lo, the sinews and the flesh

came up upcm them,

there was no breath in them."and the skin covered them above: but

Ezekiel XXXVII, 7, 8.

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MEMOIRS OF THE PEABODY MUSEUM OF NATURAL HISTORYVOLUME III, PART 3

A REVISIONof th<GERATOPSIA
OR HORNED DINOSAURSBY

RICHARD SWANN LULL
STERLING PROFESSOR OF PALEONTOLOGYAND DIRECTOR OF PEABODY MUSEUM,YALE UNIVERSITYLVX ET

cHntt
a'ipm
VERITAS

NEW HAVEN, CONN.
!933

PUBLISHED ON THE

OTHN1EL CHARLES MARSH PUBLICATION FUND
PEABODY MUSEUM OF YALE UNIVERSITY

THE TUTTLE, MOREHOUSE & TAYLOR COMPANY

NEW HAVEN, CONNECTICUT'CONTENTS
Page

Introduction'.

3

History of discovery

3

Resume of discoveries prior to 1907
Recent discoveries

Geologic distribution
9

Geographic distribution
Alberta9

Saskatchewan

13

Montana13

North Dakota

14South Dakota

14

Wyoming1^

Colorado

16

New Mexico

'°

Texas

'

MexicoI**

1"South America

1°

Mongolia
BritishColumbia

1°(footprints)

Alphabetical list of genera and species

19

Ecology, habits and manner of life

20
^U

Environment

21

Feeding habits

22

Methods of combat
Progressive evolutionary changes and phylogeny

24

General morphology

10

Monoclones (Centrosaurus)

flexusAxial skeleton

30

Skull

RostralPremaxillary

32
32

Nasal

LacrvmalMaxillary
t
Jugal
i

'

33

33

CONTENTS

viii
General morphology—Cont.
Page

Skull— Cont.
Squamosal

33

Parietal

34

Crest

34

Palatal aspect

35

Lower jaw

37

Predentary

37

Hyoid

37

Vertebral column

39

Coalesced cervicals

39

Cervical IV

40

Cervicals

V and VI

40
41

Cervical VII

41

Cervical VIII

Cervical42

IX

Dorsal vertebrae

42

Dorsal VI

43

Dorsal IX

44

Dorsal XI

46

Sacrum46

Caudals

49
50

Appendicular skeleton

Coracoid50

Scapula51

Sternum

51

Humerus

53

Ulna

55

Radius

55

Manus

56

Ilium

:

57

Pubis

57

Ischium

58

Femur

59

Tibia

60

Fibula

61

Pes

62

Mounted specimens

64

Integument,

66

Chasmosaurus

66

Skull

66

Vertebral column

68

Integument

69

Brain and special sense organs

71

CONTENTS

IX

Page

Systematic description of genera and species'

Family Protoceratopsidae

74

Genus Protoceratops'

Protoceratops andrewsi

7R

Genus Leptoceratops
Leptoceratops

4

'

'°

gracilis

Q

1

Family Ceratopsidae

Genus Monoclones (Judith River phase)
8?
oiMonoclonius crassus°->

Monoclonius recurvicornis

0-2

Monoclonius sphenocerus
8^iMonoclonius dawsoni
Sub-genus Centrosaurus (Belly River phase)

Monoclonius (Centrosaurus) apertus
Monoclonius (Centrosaurus)

flexusMonoclonius (Centrosaurus) nasicornus

Monoclonius (Centrosaurus)

cutleri

87

Genus Styracosaurus

87•

Styracosaurus albertensis

90

Styracosaurus ovatus

Genus Eoceratops
Eoceratops canadensis

92

Genus Chasmosaurus
Chasmosaurus

belli

94"

Chasmosaurus brevirostns

Chasmosaurus

94

kaiseni

96

Genus Ceratops^
Ceratops montanus

96

....

97

Genus Brachyceratops
Brachyceratops montanensis
A

102

..

Genus Anchiceratops
Anchiceratops ornatus
•

i

()4

Anchiceratops longirostris
a

•

•

106

Genus Arrhinoceratops
Arrhinoceratops brachyops

108

Genus Pentaceratops
Pentaceratops sternbergii

Pentaceratops fenestratus^
Genus Triceratops•

Triceratops horridus

Triceratops prorsus
Triceratops brevicornus

Triceratops serratus

11 +

—
CONTENTSx

Systematic description of genera and species—Cont.

Cont.

"a e

Triceratops flabellatus

121

Genus Triceratops

8

**•*•

Triceratops elatus

Triceratops calicornis

123

Triceratops obtusus

125

Triceratops (Diceratops)

hatcheri"Inadequate" species
Triceratops alticorms
Triceratops sulcatus•

Triceratops maximus

126
12°

1AO

1
l

^°
?Q7
*

1

Of)

1

Genus Torosaurus
Torosaurus latus

1J "
1

09

Torosaurus gladius

Bibliography
Description of Plates (even pages only)

Index

133

140-170

I.

ILLUSTRATIONS

x ii
FigurePage

1.

Table showing stratigraphic sequence2.

Ceratopsia

7

localities

113.

Phylogeny of the Ceratopsia

4.

Skull of Monoclonius

5.

Skull of Monoclonius (Centrosaurus)

6.

Hyoid of Triceratops serratus

38

7.

Cervicals I, II, III of Monoclonius (Centrosaurus) flexus

39

8.

Cervicals

V and VI of Monoclonius (Centrosaurus) flexus

41

9.

Cervical IX of Monoclonius (Centrosaurus) flexus

42

10.

Dorsal II of Monoclonius (Centrosaurus) flexus

42

11.

Cervical IX of Monoclonius (Centrosaurus) nasicornus

43

12.

Dorsal II of Monoclonius (Centrosaurus) nasicornus

43

13.

Dorsal VI of Monoclonius (Centrosaurus) flexus

43

14.

Dorsal IX of Monoclonius (Centrosaurus) flexus

44

15.

Dorsal IX of Monoclonius (Centrosaurus) nasicornus

45

16.

Dorsal XI of Monoclonius (Centrosaurus) flexus

46

7.

Sacrum and ilia of Monoclonius (Centrosaurus) flexus, dorsal view

47

18.

Sacrum and ilia of Monoclonius (Centrosaurus) flexus, ventral view

49
50

1

28

(Centrosaurus) flexus, lateral view
flexus, palatal

31

view

36

19.

Scapula and coracoid of Monoclonius (Centrosaurus) flexus

20.

Sternals of Monoclonius (Centrosaurus) flexus

52

21.

Humerus of Monoclonius (Centrosaurus) flexus

53

22.

Ulna of Monoclonius (Centrosaurus) flexus

54

23.

Radius of Monoclonius (Centrosaurus) flexus

55

24.

Fore foot, anterior view of Monoclonius (Centrosaurus) flexus

56

25.

Fore foot, lateral view of Monoclonius (Centrosaurus) flexus

56

26.

Pubis and ischium of Monoclonius (Centrosaurus) flexus

58

27.

Femur of Monoclonius (Centrosaurus) flexus

59

28.

Tibia and fibula of Monoclonius (Centrosaurus) flexus

61

29.

Hind foot, anterior view of Monoclonius (Centrosaurus) flexus

62

30.

Skull of31.

Skull of Triceratops, sagittal section, showing brain cavity

72

32.

Skull of Protoceratops andrewsi, lateral view

75

77

67

Chasmosaurus belli, palatal view

33.

Skull of Protoceratops andrewsi, dorsal view

34.

Anterior cervicals of Protoceratops

80

35.

Anterior cervicals of Leptoceratops

80

36.

Pubis of Protoceratops

80

37.

Pubis of Leptoceratops

38.

Skull of39.

Skull of80
95

Chasmosaurus kaiseni, lateral view

40.

P entaceratops sternbergii, lateral view
Skeleton of P entaceratops fenestratus, lateral view

41.

Skull of Triceratops obtusus, lateral view

126

42.

Squamosal of Torosaurus latus, ventral view

131

109
1

12

™

^
INTRODUCTION
The Ceratopsia Monograph published in 1907 summarized our knowledge of this interestinggroup of dinosaurs up to about 1905, when the manuscript was completed. It was largely the workof John Bell Hatcher, who actually collected much of the material upon which the monograph was
based.
He utilized also the brief papers, mainly generic and specific descriptions, which had
appeared from time to rime under the authorship of Othniel C. Marsh, as well as the lithographic
plates and other illustrations which had been prepared under Professor Marsh's direction in anticipation of the monograph which the latter had planned to write.
It was fitting, therefore, that thenames of Hatcher and Marsh should appear as co-authors of the completed work. When Mr.
Hatcher died in 1904, several important sections still remained to be finished, including those on
the phylogeny, taxonomy, distribution, habits, and environment of the Ceratopsia.
He had said
that only two weeks more of work on the manuscript were needed, but no notes or other writings
regarding the unfinished sections could be found among his effects, and therefore, Professor Osborn,
who had succeeded Marsh as the Vertebrate Paleontologist of the United States Geological Survey,
assigned to the present author the task of completing the manuscript and seeing it through the press.
Since that time more material has come to light, largely from the older formations, such as the
Belly River and Edmonton of Canada and the Cretaceous of Mongolia, and while new species havebeen described from these formations, the time seems ripe once more to coordinate and amplify ourknowledge of this amazing group in the light of these discoveries. Some problems of generic
identity cannot even now be solved in view of the inadequacy of material, especially that from theJudith River of Montana upon which the genera Monoclonius Cope and Ceratops Marsh werebased; thus, it cannot now be determined definitely whether or not these genera are synonymouswith the better known Belly River forms of equivalent age.
Only more extended and detailed
collecting of plesiotypes in the Judith River formation can solve these problems in any degree of
finality.
Enough is known, however, to warrant this study.
The research upon which this publication is based was rendered possible primarily through theresearch funds granted to the Sterling Chair of Paleontology at Yale University, which not only
made possible the travel incident to the study of widely separated collections, but also provided fora research assistant to aid in the work.
I very deeply appreciate the generous aid given by the various museums and especially by theseveral individuals connected with each of them, all of whom were exceedingly generous of freeaccess to the collections as well as of personal aid and advice.
especial acknowledgments are
due to Mr. Charles W. Gilmore of the United States National Museum for facilities for study, forphotographs and other illustrations, and for the reading and friendly criticism of the manuscript. I
am also deeply indebted to Messrs. Barnum Brown and Walter Granger of the American Museumof Natural History for generous aid on several occasions as well as for extraordinary privileges inconnection with the rich collections of ceratopsian material. Several photographs were especiallytaken and others freely furnished for this work. To the authorities of Yale University I am
grateful for providing funds for the purchase of the Monoclonius (Centrosaurus) skeleton whichforms the basis of our morphologic work and restoration, and to the members of the Peabody
Museum staff who aided in the preparation, and in rendering permanent the results of our labors.
Two of the Canadian Museums have shown the friendliest courtesy, the Royal Ontario Museumof Palaeontology, in Toronto, through Professor Parks, and the National Museum of Canada, inOttawa, through Messrs. Kindle and Charles M. Sternberg, who granted not only access to the colThe latter institution also
lections but the use of several photographs which adorn this volume.
aided us in securing through exchange a fine skull of Chasmosaurus belli, and gave the privilege of
publishing the interesting restoration of that genus by L. S. Russell.
gratitude is also due to President C. C. O'Harra of the South Dakota State School ofMines for measurements and photographs of his Triceratops skull, to Mr. H. H. Lane of the

My

My

2

THE CERATOPSIA

University of Kansas for information concerning the Triceratops skull there, and to Mr. E. S. Riggsof the Field Museum of Natural History and Mr. F. W. Kohler of the Carnegie Museum for similaraid, as well as to the Field Museum itself for the privilege of reproducing Charles W. Knight's
mural of Protoceratofs, which forms the frontispiece. Mr. J. A. Allan of the University of Alberta
has kindly furnished the photograph of Chasmosaurus reproduced in Plate VII B.
Messrs. T. W. Stanton and L. S. Russell furnished valuable information regarding stratigraphy, and Mr. Roy L. Moodie graciously diagnosed and described the diseased squamosal of

Torosaurus.
Miss Clara M. LeVene has edited the memoir, and Miss Nelda E. Wright, Research Assistant,
has aided most efficiently in every way, preparing all of the text figures, with one or two exceptions,and seeing the manuscript through the press.

HISTORY OF DISCOVERY
A brief resume of discoveries prior to 1907 should be given, although set forth in detail in the
Ceratopsia

Monograph.

Horned dinosaurs were first found in North America in 1855, when Dr. F. V. Hayden made ageological reconnaissance on the Upper Missouri, around the mouth of the Judith River in Montana.
The material then collected, among which was a characteristic bi-fanged tooth subsequently referredto

Monoclonius, was described by Dr. Joseph Leidy in 1856 and 1859.

In 1872, the form later

described by Prof. E. D. Cope as Agathaumas sylvestris was discovered by Prof. F. B. Meek at Black
Buttes Station on the Union Pacific Railroad 52 miles east of Green River, Wyoming. Cope himDuring the summer
self visited the locality the same year and secured the remainder of the type.
of 1 873, Cope also discovered, somewhere in Colorado, the extremely fragmentary material which hecalled Polyonax mortuarius. This is clearly ceratopsian, but Hatcher considered it so undiagnostic
that he rejected the genus and species as a nomen nudum, founded upon an insufficient type. Hatcher
further considered it possible that some of the material collected by Dr. G. M. Dawson on Milk

River, British America (? Alberta), should be referred to the Ceratopsia, although Cope himself
referred it to the trachodont Hadrosaurus.
In 1876, Professor Cope, assisted by the veteran collector Charles H. Sternberg, explored theJudith River badlands of the Upper Missouri in Montana. Much of the resultant material was
It includes, nevertheless, the type of the ceratopagain too fragmentary for precise identification.
sian Monoclonius crassus, as well as other specimens referable either to Monoclones or an allied
genus, and described in 1877. In 1890, after Marsh had made known the principal characters of

the Ceratopsia from abundant material collected by Hatcher in Wyoming and Montana, Cope wasable to describe three additional species from his Judith River collections. They were Monoclonius
recurvicornis,

M. sphenocerus, and M. fissus.

In 1887 Marsh described Bison alticornis, based upon a pair of horn cores found by Dr. George
wasL. Cannon in the Denver beds on Green Mountain Creek, near Denver, Colorado. The form
afterward,
years
three
or
For
two
subsequently referred to Ceratops, now Triceratops alticornis.
Cannon, George H. Eldridge, and Whitman Cross continued to find fragmentary ceratopsians in theThis material has not yet revealed its true identity.
Hatcher's own collecting under Professor Marsh's direction began in 1888 when he made colCeratops montanus.
lections in the Judith River badlands, securing among other things the type of
Wyoming,
Niobrara
County),He then went to the eastern part of Converse County (now called
Guernseyby theA.
Charles
where he was shown a massive horn core found on the ranch of Mr.
securedandreturned
Hatcherranch foreman, Mr. Edmund B. Wilson. The next summer, Mr.

Denver and Arapahoe beds, near Denver.

as the type ofthe remainder of the skull, which became his "skull number one," later known
inthis famous
exploration
Triceratops horridus; it was also the beginning of his highly successful
than
32 complete
Niobrara County locality, extending from 1889 to 1892, which yielded no fewer
species ofthetypes of most ofor partial ceratopsian skulls and other skeletal material, including the
now either in the United
Triceratops, two of Torosaurus, and one of Diceratops. All of these are
States National Museum or in the Yale Peabody Museum.
Another famous locality was in the region of the Milk, Red Deer, and Belly rivers of Alberta,
long known to contain dinosaurian remains. The systematic exploration of

Canada, which wereand continued during the years 1898 andthis region was begun in 1897 by Lawrence M. Lambe
Finally, in 1902, an American

Museum party consisting of Messrs. Barnum Brown and R. S.

skull now in the American
Lull collected in Hell Creek, Montana, in Lance strata, a large Triceratops

Museum.

;

THE CERATOPSIA

RECENT DISCOVERIES
Since the publication of the Ceratopsia Monograph in 1907, an amazing amount of ceratopsianmaterial has come to light, as the subsequent pages will show. This has added little to our knowledge of the younger Lance forms, such as Tricemtops, other than to show the remarkable range of

But of the older forms, where fragmentary material only was
variation within the so-called species.
in several instances, more or less complete skeletons withskullsand,known, we now have perfect
Perhaps the most outstanding explorer of all iscovering.
occasional impressions of the external

Barnum Brown of the American Museum, whose remarkable skill both in discovery and exhumation has enriched our collections amazingly, especially by forms derived from the Belly River beds

Then that noted family of collectors, the Sternbergs, should be mentioned, headed by
the veteran Charles H., and ably seconded by his several sons, Charles M., George, and Levi. Theyof Alberta.

have worked collectively and individually, and some of the most remarkable of ceratopsians whichadorn the museums, not only in America but also abroad, are due to their indefatigable labor andCharles W. Gilmore of the United States National Museum, while working largely onskill.
other forms of bygone life, has also added some notable ceratopsians to that museum's collections.
Space will not permit a detailed account of the work of these collectors in the field, but some ofthe outstanding expeditions should be mentioned, of which Brown's expeditions to the Red DeerRiver region stand first. As we have seen, the exploration of this area was begun by Lawrence M.
Lambe of the Geological Survey of Canada, but, as is frequently true of collecting in a virgin field,
the material secured was extremely fragmentary ; nevertheless, it gave to science indications of an
extraordinary fauna. About 1908, a ranchman, John C. Wagner, who lived at Tolman, Alberta,
called Mr. Brown's attention to the profusion of dinosaur bones along the Red Deer River, and forseven seasons, including his initial visit in 1909, Brown explored the region with surprising results,
bringing to light not only horned dinosaurs but trachodons, carnivores, and other dinosaurs as well.
Owing to the peculiar conditions a more or less navigable stream flowing through the land of his
Mr. Brown found that his work could best be done by boat. Accordingly, he and his
exploration
assistants went to the town of Red Deer where the Calgary-Edmonton Railway crosses the river,and there built a scow, 30 by 12 feet, with a 22-foot sweep at either end for navigating it. Uponthis they pitched their tent and stored their impedimenta, and then set forth on a current that averaged some four miles an hour, with placid areas interspersed by occasional rapids. On this craft
the party lived, and from it they prospected, mooring ship when conditions were good and exploring not only the canyon walls but all of the tributary valleys as well, and storing the collected
At the end of the season when the weather
fossils on board until the boat was practically full.
became too cold for effective work, the craft was hauled out, materials stored, and on the comingof the second season she was recommissioned to continue from the point where she ceased theyear before. A canoe and an outboard motor boat added to the efficiency of the fleet.
This same method was afterward (1912-1916) used with admirable results by Sternberg andThe
his sons while working for the Canadian Survey under the direction of Lawrence M. Lambe.
preparation and description of this material was well under way when it was halted by Lambe's
sudden illness and death. Charles M. Sternberg is continuing to do effective work both in collecting and research but there is great opportunity for further trained workers in Canadian paleontology when conditions shall warrant it.
Mr. Sternberg senior has written two interesting books 1 which, aside from their value ashuman documents, recount in detail the collecting of some of the most remarkable of ceratopsianmaterial such as the two mounted chasmosaurs, PI. XIV, B; the skull of Styracosaurus, PI. VIII
the Pentaceratops material from New Mexico, both at the American Museum, PI. V, B, and at
Upsala, Sweden, Fig. 40} as well as other type and otherwise interesting specimens.

—

Sternberg, C. H., 1909, 1932.

—

HISTORY OF DISCOVERY

5Charles W. Gilmore of the United States National Museum explored for horned dinosaurs
especially in the Blackfeet Indian Reservation in northwestern Montana in 191.1. Here, exposuresof the Two Medicine formation were found along the Milk River near the Canadian boundary. The
collection was small, but of great interest since it contained several specimens of the only adolescentceratopsian found in America, the type of Brachyceratops (PI. IX, B), as well as other recognizable
also collected here the type of Styracosaurus ovatus.
material.
The discovery of Pro toe era tops in Mongolia by the American Museum expedition of 1922 underHe

Andrews and Granger has opened a new chapter in ceratopsian history, for it gives not only the firstrecord of the group outside the limits of North America, but also for the first time an ontogenetic
record of a ceratopsian genus. The collection includes eggs and all stages of growth from the newly
hatched young to the old adults. Several skeletons and no fewer than 73 skulls were included in
the finds.

The principal desideratum from the standpoint of ceratopsian study would be further exploraMontana for the purpose of securing additional material to clarify our conception of the early Cope and Marsh genera, Monoclonius and Cera/ops, oftion in the Judith River formation of northern

which our knowledge is so very imperfect owing to the fragmentary condition of the types. Anotherregion deserving more exploration is New Mexico, which is sure to yield ceratopsians other than
Pentaceratops, a genus which, with one authentic and another doubtful species, represents all that weknow of the southern horned dinosaurs.

GEOLOGIC DISTRIBUTION(Fig. 1)The known Ceratopsoidea, both of North America and of Asia, are confined to the Upper
Cretaceous (Senonian and Danian of European usage), and thus far have been found in non-marine
strata only.
In North America, they extend through several horizons, from the Belly River where
they appear abruptly, to the very close of the Lance formation where, with equal abruptness, they
disappear.

am indebted to Doctors L. S. Russell

1of the Geological Survey of Canada and T. W.
Survey for information concerning the correlation ofUnited States and Canadian horizons. The statements derived independently from these two highauthorities entirely agree, and from the tables of correlation that they furnished, the combined one
here published (Fig. 1 ) has been made.
In Alberta, two principal horizons have produced Ceratopsia. The first is the Belly River, inwhich the fossils are restricted to the Pale or uppermost beds of the series. Then, after an interval
represented by the marine Bearpaw formation, these animals reappear in the Edmonton, above which
there is no record of their occurrence in Alberta.
In Glacier County, Montana, the Ceratopsia-bearing horizon is the Two Medicine, the equivalent of the Belly River series of Alberta; but here again these dinosaurs, of which only a very
few have been found, are known from the upper part alone. In central Montana, the Judith River,
equivalent again to the upper half of the Two Medicine and to the Pale and Foremost beds of the
Belly River series, has produced ceratopsians whose closest equivalents taxonomically seem to lie
among those of the Belly River, although with curious morphological differences which will be
discussed, p. 27.
Ceratopsia from the Judith River are ill known, due largely to pioneer collectThey do not seem to being, nor is their precise stratigraphic position within the formation clear.
limited to any part of the horizon as in the Belly River series, according to available evidence.
Above the Judith River comes a longer interval of marine deposition than in Alberta, for the nonmarine Lance (Hell Creek beds) is separated from the Judith River by both the Bearpaw and theFox Hills formation, hence such annectant genera as those found in the Edmonton are entirely
I

Stanton1of the United States Geologicalabsent.

Niobrara County, Wyoming, contains the classic Lance locality, the so-called "Ceratops beds"of Marsh, out of which have come almost all of the principal types of the latest of the ceratopsians,

Triceratops, Diceratops, and Torosaurus.

The last genus, so far as we know, is found nowhere else.

In the Denver Basin of Colorado, the formations equivalent in time to the earlier Ceratopsiabearing horizons are all marine, and hence it is only in the uppermost Cretaceous, in the Denverand Arapahoe beds, correlated with the Lance, that a few horned dinosaurs have been found, which
are the generic equivalents of those of Wyoming and Montana.
A new locality, the Ceratopsia of which were unknown at the time of the publication of the
Ceratopsia Monograph, lies in San Juan County, New Mexico. Here the non-marine formations
are late in Cretaceous time and, as our table shows, are homotaxial with the Edmonton of Alberta
and with the Lance of Montana and Wyoming. Of these, the Fruitland and Kirtland, equivalent
to the Edmonton, have been the most productive, revealing a genus, Pentaceratops, which is morphologically older than Triceratops or Torosaurus but younger than the Belly River ceratopsians.
Some material is also recorded as possibly from the Ojo Alamo; but one cannot be sure either of2
the generic identity or of the stratigraphic reference, for the term Ojo Alamo is said to have been

1

Letters to the author, 1933.

2

Brown, B., 1910.

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THE CERATOPSIAgoriginally used to include the Kirtland and Fruitland as well.
or Ojotion Trkeratop itself, its reference to the McDermott

Were we to identify without quesAlamo as now restricted would beother than the several recognizable
expected, but all of the ceratopsian material from the Southwest
reference.
generic
Pentaceratofs specimens is too fragmentary for certainty ofhas its nearest taxonomic equivformation,
The Mongolian Protoceratofs from the Dja-doch-ta
value without further
correlationhasalent in Leftoceratofs of the Edmonton. Whether this one fact

evidence is open to question.
The geological sequence of the ceratopsian species is as follows:

Judith River Formation

Fruitland and Kirtland Formation

Ceratofs montanus

Pentaceratofs sternbergii

Monoclonius crassus
Monoclonius recurvicornis
Monoclonius sfhenocerus

Pentaceratofs fenestratus

Belly River Formation

Lance Formation

Chasmosaurus belli
Chasmosaurus kaheni
Chasmosaurus brev'irostris
Monoclonius dawsoni
Monoclonius (Centrosaurus) afertus
Monoclonius (C) flexus
Monoclonius (C.) cutleri
Monoclonius (C.) nasicornus

Torosaurus gladius

Eoceratofs canadensis
Styracosaurus albertensis

Triceratofs (Diceratofs) hatcheri

T orosaurus latus
Triceratofs alticornis
Triceratofs brevicornus
Triceratofs calicornis

Triceratofs elatus
Triceratofs flabellatus

Triceratofs galeus
Triceratofs horridus
Triceratofs maximus

Two Medicine Formation

Triceratofs obtusus

Brachy ceratofs montanensis

Triceratofs frorsus

Styracosaurus ovatus

Triceratofs serratus

Triceratofs sulcatus

Edmonton Formation
Anchiceratofs ornatus
Anchiceratofs longirostrisArrhinoceratofs brachyofs
Leftoceratofs gracilis

Dja-doch-ta Formation, Mongolia
Protoceratofs andrewsi

GEOGRAPHIC DISTRIBUTION

1(Fig. 2)

The remains of Ceratopsia have been found in at least two continents, Asia and North America,and possibly in South America. So far, only one genus and species has been unearthed in Asia,
while the remainder of the species have been located in North America, in a broad belt along thesouth.
eastern slope of the Rocky Mountains, running from Alberta in the north to Mexico in thecompletegaveainpublished
Lull,
and
1907,
Marsh,
Hatcher,
The Ceratopsia Monograph byfound. Since that date, however, alist of all localities where horned dinosaurs had hitherto beenwith certain of those alreadytogether
which,
number of additional regions have been discovered
forms.
interesting
andknown, have produced an amazing number of new
A list of all geographic localities from which Ceratopsia have been collected or reported is asfollows:

New Mexico

Alberta

Saskatchewan

Texas

Montana

MexicoSouth America
Mongolia
British Columbia (footprints)

North Dakota
South Dakota

Wyoming
Colorado

These will be discussed in the order mentioned.

ALBERTAThe Red Deer River region of Alberta has proved a wonderful field for ceratopsian discoveries,
first exploredno fewer than five new genera having been recognized since 1910. This country was
expeditions
bylargelyby Lambe in 1897, 1898, and 1901. Since that time, it has been reworked
AmericanandtheToronto,from the Geological Survey of Canada, the Royal Ontario Museum of
formadistinct
fromtwoMuseum of Natural History. In vertical sequence, the fossils have come
than
are
older
beds
Stratigraphically, the Belly Rivertions, the Edmonton and Belly River series.
Hills.
the Edmonton, and separated from the latter by the marine Pierre and Fox

From the Edmonton formation on Red Deer River (Locality 1, on map of North America,
Fig. 2), the following specimens have been obtained:

Anchkeratop oruatus, type, No. 5251 A.M.N.H., skull paratype, No. 5259 A.M.N.H., frontal
Collected by the American Museum ofhorns, part of skull; No. 5273 A.M.N.H., skull.
Natural History in 1912, 7 miles below Tolman.
Anchkeratop ornatus, left half of posterior portion of skull, collected by G. F. Sternberg in 1916,
This specimen is now at Ottawa.
l l 2 miles southwest of Morrin.
;/

Anchkeratop ornatus, skull, collected by the Royal Ontario Museum in 1931, 6 miles west and 3
miles north of Munson on the west side of the river.
Anchkeratop ornatus, skull, collected by the Royal Ontario

Museum in 1922, 6 miles west ofMorrin.

.

.

Anchkeratop longirostris, type, No. 8535 Geol. Surv. Canada, skull without lower jaws, collectedby C. M. Sternberg in 1924, 12 miles northwest of Morrin.
1Compiled by N. E. Wright.

.

THE CERATOPSIA

10Anchiceratops longirostris, No. 8538 G.S.C., complete skeleton except skull, collected by C. M.
Sternberg in 1925, lYi miles southwest of Rumsey. Mounted in the National Museum of
Canada.
Arrhinoceratops brachyops, skull, type No. 5135 R.O.M., collected by the Royal Ontario Museumin 1923, 6 miles west and 3 miles north of Munson, on the west side of the river.
Arrhinoceratofs brachyops, skull, collected by the Royal Ontario Museum in 1931, 6 miles west of
Munson on the west side of the river.
Centrosaurus, No. 5263

A.M.N.H., scapula.

A.M.N.H., squamosal;

No. 5265 A.M.N.H., lower jaw;

Collected by the American

No. 5267

Museum of Natural History in 1912, 3-10

miles below Tolman, on both banks of the river.

5244 A.M.N.H., brain case; No. 5246 A.M.N.H., frontal horn; No. 5260
A.M.N.H., maxillae and vertebrae. Collected by the American Museum of Natural History
in 1912, 3-10 miles below Tolman on both banks of the river.

Ceratopsian, No.

Ceratopsian, incomplete skull, collected by C.

M. Sternberg of the Geological Survey of Canada in

1925, southwest of Morrin.
Leptoceratops gracilis, type, No. 5205 A.M.N.H., incomplete skeleton, collected by the American
Museum of Natural History in 1910, 3 miles above Tolman, 190 feet above the river on theleft bank.

From the Belly River formation on the Red Deer River (Loc. 2, Fig. 2), we have the following material:

Centrosaurus apertus, type, No. 971 G.S.C., parietal crest, collected by Lambe in 1901, on the westside of Red Deer River, between Berry Creek and Dead Lodge Canyon.
Centrosaurus apertus, skull, collected by the Royal Ontario Museum in 1926, 2 miles south of Steveville, on the west side of the river.

Centrosaurus apertus, skull, less snout and part of crest, collected by C. M. Sternberg in 1919, fromIn the Carnegie Museum atthe south side of the west branch of Little Sandhill Creek.
Pittsburgh.

Centrosaurus apertus, No. 348 G.S.C., skull with lower jaws, collected by C. H. Sternberg in 1914,
Mounted in the Nationalat the lower end of Dead Lodge Canyon, 1 5 miles east of Steveville.
Museum of Canada.
Centrosaurus apertus, No. 347 G.S.C., skull without lower jaws, collected by C. H. Sternberg in
1913, at Denhart Ferry, about 1 5 miles below Steveville. In the National Museum of Canada.
Centrosaurus apertus, skull less nasals, maxillae, and most of face, collected by C. M. Sternberg in
1921, 1 mile east of Denhart Ferry. In the National Museum of Canada.

/

Centrosaurus sp., skull without crest or lower jaws, collected by C. H. Sternberg in 1914, 2 l 2 miles
below Denhart Ferry. In the National Museum of Canada.
Centrosaurus sp., complete skull without lower jaws, collected by C. M. Sternberg in 1917, lj^
miles south of the mouth of Little Sandhill Creek. In the National Museum of Canada.
Centrosaurus apertus, No. 4519 R.O.M., skull and part of skeleton, collected by the Royal Ontario

Museum in 1919, from Section 9, Township 21, Range 11.
Centrosaurus apertus, frill, collected by the Royal Ontario Museum in 1921, from Section 9, Township 2 1 , Range

1

1

Centrosaurus sp., skull and part of skeleton, collected in 1930 by the Royal Ontario Museum fromthe northwest quarter of Section 9, Township 21, Range 1 1.
Monoclonius nasicornus, skull with dentary and few bones of skeleton, collected by C. M. Sternberg
In the National Museumin 1917, \]/2 miles south of the mouth of Little Sandhill Creek.
of Canada.
Chasmosaurus kaiseni, type, No. 5401 A.M.N.H., skull, collected by the American
Natural History in 1913, 12 miles below Steveville in Township 21, Range 11.

Museum ofcr>«.

-e-




o

CLRATOPSIA
LOCALITIES

Flc.

2.— Geographical distribution of the Ceratopsia in North America.

»

/j

^*

•

Numbered localities described in the text.

THE CERATOPSIA

12

Chasmosaurus belli, No. 5402 A.M.N.H., skull with jaw and parts of skeleton, collected in 1913 by
the American Museum of Natural History, in Township 2 1 Range 1 2, about 1 mile below
Steveville, on the left bank of the river.
Chasmosaurus belli, No. 5499, R.O.M., skull and complete skeleton, collected by the Royal Ontario
Museum in 1926, 2 miles south of Steveville on the southeast side of the river. Mounted.
Chasmosaurus brevirostris, type, No. 5436, R.O.M., skull and part of skeleton, collected by the Royal
Ontario Museum in 1926, 3 miles south of Steveville on the west side of the river.
Chasmosaurus belli, paratype, No. 2245 G.S.C., skull and most of skeleton, collected by C. H. SternMounted in the National Museum of Canada.
berg in 1913, 3 l 2 miles south of Steveville.
mostof skeleton, collected by C. H. Sternberg inandChasmosaurus belli, No. 2280 G.S.C., skull,/

1
Mounted in the National
miles southeast of the mouth of Little Sandhill Creek.
1914, I /?,Museum of Canada.
Chasmosaurus belli, type, No. 491 G.S.C., parietal, collected by L. M. Lambe in 1898, on theeast side of the river, below the mouth of Berry Creek.
Chasmosaurus sp., skull and lower jaws, and a few bones of the skeleton, collected by C. M. Sternberg in 1928 on the west side of the river, 3 miles south of Steveville. In the National

Museum of Canada.
Chasmosaurus belli, No. 2016 Y.P.M., skull without lower jaws, collected by C. M. Sternberg in
1919, on the south side of the west branch of Little Sandhill Creek, 60 feet below the overlying
Pierre shales. At Yale Peabody Museum.
Chasmosaurus belli, skull, collected by the Royal Ontario Museum in 1930, on the southwest side
(Sent to Buenos Aires.)of the river 6 miles north of Denhart.
Chasmosaurus sp., dentaries, maxillae, nose, right side of face nearly to orbits, and part of skeleton,
collected by C. M. Sternberg in 1919 about 3 miles south of the mouth of Little Sandhill Creek.
In the National Museum of Canada.
Chasmosaurus sp., 2 incomplete skulls, collected by C. H. Sternberg in 1915 from the lower end of
Dead Lodge Canyon about 1 5 miles east of Steveville. In the National Museum of Canada.
Ceratopsian, No. 5407 A.M.N.H., orbital horns; No. 5408 A.M.N.H., vertebrae; No. 5410
A.M.N.H., ilium; No. 5415 A.M.N.H., maxilla and jaw; No. 5416 A.M.N.H., jaw. Collected in 1913 by the American Museum of Natural History about 1 mile below Stevevilleon the left bank of the river.
Ceratopsian, No. 5422 A.M.N.H., skull and parts of skeleton; No. 5425 A.M.N.H., skull; No.
5437 A.M.N.H., skull; No. 5439 A.M.N.H., brain case; No. 5342 A.M.N.H., fragmentary skull. The last was collected in 1914, the remaining specimens in 1913, all from the banksof Sand Creek about 12 miles below Steveville.
Ceratopsian, No. 5374 A.M.N.H., frill of skull, collected by the American Museum of Natural
History in 1915 from the "East Fork" of Sand Creek, about 12 miles below Steveville.
Eoceratops canadensis, type, No. 1254 G.S.C., skull, collected by Lambe in 1901 on the east side of
the river, a short distance below the mouth of Berry Creek.
Chasmosaurus, No. 40 University of Alberta, nearly complete skull, collected by G. F. Sternberg in
1920, 2 miles southeast and 1 mile east of the mouth of Sand Creek.
Monoclonius flexus, type, No. 5239 A.M.N.H., skull, collected in 1912 about 1 mile below Steveville on the left bank of the river.
Monoclonius dawsoni, type, No. 1 173 G.S.C., fragmentary skull, collected by Lambe in 1901 on theriver, between Berry Creek and Dead Lodge Canyon.
Monoclonius, No. 5442 A.M.N.H., skull, collected in 1913 about 30 miles below Steveville, near
the junction of the Pierre and Belly River formations (Section 15, Township 22).
Monoclonius crassus, central portion of crest, collected by C. M. Sternberg in 1917, 3 miles southwest of the mouth of Little Sandhill Creek. In the National Museum of Canada.
Monoclonius flexus, No. 5341 A.M.N.H. (No. 2015 Y.P.M.), skull and skeleton collected by theAmerican Museum of Natural History in 1914, about 2 miles from the mouth of Sand Creek,
12 miles below Steveville. Mounted in the Yale Peabody Museum.

GEOGRAPHIC DISTRIBUTION

13

Monoclonius cutleri, type, No. 5427 A.M.N.H., posterior half of skeleton, collected in 1913 near
the mouth of Sand Creek about 12 miles below Stevcville.
Monoclonius sp., No. 5429 A.M.N.H., skull; No. 5430 A.M.N.H., part of skeleton; No. 5443
A.M.N.H., ulna; all collected in 1913 by the American Museum of Natural Iwtory, all
the banks of Sand Creek about 12 miles below Stevcville.
Monoclonius uasicomus, type, No. 5351 A.M.N. H., skeleton, collected in 1914 by the American
Museum of Natural History, along Sand Creek, about 12 miles below Stevcville.
Monoclonius, No. 5377 A.M.N.H., skull and jaws, collected by the American Museum of Natural
History in 1915, on the "East Fork" of Sand Creek, about 12 miles below Stevcville.
Monoclonius, No. 5372 A.M.N.H., skeleton without skull and jaws, collected by the American
Museum of Natural History in 1915 on the "Middle Fork" of Sand Creek, 12 miles below
I

Steveville.

Monoclonius nasicomus, No. 8897 U.S.N. M., skull, collected by C. H. and L. Sternberg in 1917,
from Dead Lodge Canyon, 8 miles below Steveville.
Chasmosaurus (?), No. 5656 A.M.N.H., back of skull, frill including squamosals, collected by C. I.
Sternberg in 1 9 1 7, on Sand Creek.
Styracosaurus albertensis, type, No. 344 G.S.C., skull without lower jaws, collected by C. H. Sternberg in 1913, about 1
miles southeast of Denhart Ferry. Mounted in the National Museumof Canada.
1^

SASKATCHEWAN
The Lance formation in southern Saskatchewan has yielded two specimens of Trie cramps, collected by C. M. Sternberg of the Canadian Geological Survey in 1929. The exact locality of the first
specimen (Loc. 3, Fig. 2), which consisted of the posterior half of the skull, was 8 miles southwest

The second individual included the posterior twoof Eastend, in the lower Ravenscrag formation.
thirds of the skull and was found on the east side of Rocky Creek, south of Wood Mountain plateau(Loc. 4, Fig. 2).

MONTANA
Ceratopsia remains have been found in six different localities in Montana. The first (Loc. 5,
Fig. 2) is situated on the north side of Milk River, in the Blackfeet Indian Reservation, in GlacierCounty. This is the locality for the type of Brachyceratops montanensis, No. 7951 U.S.N.M., consisting of a considerable portion of a disarticulated skull; also for the paratypes, No. 7952, consistingof a rostral and portions of the premaxillaries, No. 7953, which includes a sacrum, complete pelvis,
and articulated caudal series of 45 vertebrae, and No. 7957, consisting of several tarsals and metaThese were collected by Gilmore in 1913, from the Two Medicine formation.
tarsals.

was found the type of Styracosaurus ovatus, No. 11,869 U.S.N. M.,
which consists of the posterior portion of the frill and numerous detached fragments. This specimen was collected by G. F. Sternberg in 1928. At the same time and place, he collected also alarge nasal horn, recurved forward like that of Monoclonius flexus, parts of a skull, 2 ulnae, a tibia,
scapula, coracoid, predentary, some ribs, and vertebrae. This material is catalogued as No. 12,745

At the same

locality

U.S.N.M.
In 1916, Messrs. Brown, Kaisen, and Johnson of the American Museum collected from thisregion a skeleton of Leploceratops, No. 5464 A.M.N.H., consisting of part of the skull, vertebra]
column including sacrum, pelvis, femora, tibiae, and foot bones. The exact locality was 3 miles westof Buffalo Lake, and 45 miles west of Sweetgrass, in the St. Mary formation.
The second Montana locality (Loc. 6, Fig. 2) is on Cow Creek, about 10 miles above the confluence of that stream with the Missouri River, in beds belonging to the Judith River formation.
The following specimens have been found there:

Ceratops montanus, type, No. 241 1 U.S.N.M., consisting of an
frontal horn cores, collected by Hatcher in 1888.

occipital

condyle and a pair ofj

THE CERATOPSIA

4

Monoclonius sfhenocerus, type, No. 3989 A.M.N.H., consisting of nasals and left premaxillary, collected by C. H. Sternberg, on Missouri River near Cow Island, in 1876.
Monoclonius recurvicomis, type, No. 3999 A.M.N.H., portions of skull, including frontal and nasal
horn cores, discovered by Cope in 1876, on the north side of Missouri River nearly opposite themouth of Dog Creek.
Monoclonius crassus, type, No. 3998 A.M.N.H., teeth?, sacrum, anterior dorsals, and parietal;
No. 3997 A.M.N.H., prefrontal and postfrontal with brow horn. Collected by Cope in 1876,
opposite the mouth of Dog Creek.

Another important locality (Loc. 7, Fig. 2) is along the canyon of Hell Creek, about 30 miles
above the mouth of Milk River, in the northern part of Dawson County. The following specimens
were found here in the Lance formation:

AmericanTriceratofs serratus, No. 970 A.M.N.H., skull, collected by Brown and Lull of thefroma tribuHell
Creekseparating
Museum party of 1902, on the extreme point of the divide
River.
Missouritary which entered it from the west about 1 5 miles from theTriceratofs brevicornus (?), two skulls found by W. H. Utterback of the Carnegie Museum, Pittsburgh, in 1 904, near Hell Creek.
Triceratofs frorsus (?), skull with recurved nasal horn, collected from Hell Creek by F. B. Loomis
Amherst College Collection.
in 1929.
pelvis andTriceratofs, No. 5033 A.M.N.H., 2 cervicals, 14 dorsals, 17 caudals, 28 ribs,

sacrum, right hind limb and foot, and left femur; No. 5039, lower jaw; No. 5045, coossified
These were obtained by Brown and Kaisen in 1909, 16 miles southeast
cervical vertebrae.
of Lismas.

Mounted skeleton.

Triceratofs maximus, type, No. 5040 A.M.N.H., 8 free vertebrae and 2 cervical ribs.
P. C. Kaisen in 1909, 20 miles south of Lismas.

Collected by

2
The fourth Montana locality (Loc. 8, Fig. 2) is the one referred to by Hatcher on Willow

Creek, about 13 miles north of Musselshell postoffice. In the same paper, Hatcher also reports
having seen ceratopsian material on the west side of the Big Horn River, between Fort Custer andCuster station (Loc. 9, Fig. 2).
Locality 10 (Fig. 2) is in the Chalk Butte region, between Powderville and Ekalaka. Here,E. S. Riggs of the Field Museum, Chicago, found a skull of Triceratofs horridus (No. 12,003), andThese fossils wereassociated with it were various skeletal parts and several pairs of horn cores.
formation.
Lance
included in the

NORTH DAKOTA
In the Little Missouri Badlands, in southern Billings County, A. G. Leonard collected in
1908, "various parts of the Cretaceous dinosaur Triceratofs, 2 or more individuals being present;
The material was identified by Mr. C. W. Gilmore. It is frominsufficient for specific diagnosis."
the Lance formation (Loc. 23, Fig. 2).

SOUTH DAKOTA
Both are in the Lancein the northeast
County,Harding
Hills,
Pine
Short
the
Locality 11 (Fig. 2) is information.
skull of theTriceratofs
yielded
a
It
has
1
E.
Range
quarter of Section 35, Township 17 N.,
Rapid City.
Mines,
of
SchoolState
DakotaSouth
271
The specimen is No. P
species horridus.
3
Gidley.
byidentified
been
have
skullsTriceratofs
From the same general locality, fragments of

Two localities in South Dakota have produced ceratopsian remains.

2
3

Hatcher, J. B. 1896, p. 118.
Gidley, J. W., 1916, U. S. Geol. Surv., Bull. 627, p. 24.

i,i

OGRAPHIC DISTMBl

I

ION

15

Locality 12 (Fig. 2) is in the neighborhood of Watauga, Township 23 N., Range 21 E. Ceratopsian material collected here in 1922 by Philip Reinheimer consisted of "a considerable part of a
The
The latter were not less than three feet in length.
skull, having the horns i]uite complete.
There were also various
frill had been eroded out and lay in many fragments upon the surface."skeletal parts that were quite disassociated.

4

WYOMING
Locality 13 (Fig. 2) is in the Big Horn Basin. Triceratofs bones were found here and identi5
Hatcher also reports having seen ceratopsian material along the eastern
by C. W. Gilmore.
flank of the Big Horn Mountains, about 40 miles south of Buffalo.
Locality 14 (Fig. 2) comprises a large part of Niobrara County, formerly part of Converse
County. This has been the most fruitful of all ceratopsian localities. Most of the collecting wasdone before 1907 by Hatcher, and by C. H. Sternberg, the account of which has been related indetail by Lull in the first monograph. However, a list of the specimens follows:
fied

K90.
Triceratofs obtusus, type, No. 4720 U.S.N. M., portion of skull, collected by Hatcher in
U.S.N.M.;
No.
U.S.N.M.;
4708
skull;No.
5741
U.S.N.M.,
No.
1201
Triceratofs elatus, type,1

No. 2100 U.S.N. M.; No. 1829 Y.P.M. These were all collected by Hatcher.
Triceratofs elalus, No. 5116 A.M.N.H., skull (on mounted skeleton), collected by C. H. Sternberg.
Triceratofs brevicomus, type, No. 1834 Y.P.M., skull with lower jaw, a complete series of presacralvertebrae, a number of ribs, and portions of the pelvis; possibly, No. 1832 Y.P.M. both collected by Hatcher, Utterback, Sullins, and Bostwick in 1891.
Triceratofs "ingens" (now referred to horridus), No. 1828 Y.P.M., skull, collected by Hatcher in,

1891.
Triceratofs calicomis, type, No. 4928 U.S.N. M., skull, and portion of skeleton, collected by Hatcher
in 1889.
Triceratofs horridus, type, No. 1820 Y.P.M., the greater portion of a skull, with portions of thelower jaws, collected by Hatcher in 1889.
Triceratofs flabellatus, type, No. 1821 Y.P.M., a nearly complete but disarticulated skull associatedwith several vertebrae, and a few limb bones, collected by J. B. Hatcher in 1888.
Triceratofs frorsus, type, No. 1822 Y.P.M., a nearly complete skull with lower jaw and six anteriorcervicals, collected by Hatcher in

1889;

No. 1205 U.S.N.M.

Triceratofs serratus, type, No. 1823 Y.P.M., skull with lower jaw, collected by E. C. Beecher in

No. 2416 U.S.N.M.
No. 4276 U.S.N.M., fragmentary skull, and vertebrae, collected by
Hatcher in 1890; No. 4286 U.S.N.M.; No. 1208 U.S.N.M.
Triceratofs, found near Schneider Creek, Niobrara County, by C. H. Sternberg in 1908, and sent to
1889;'Triceratofs sulcatus, type,the British Museum.
Triceratofs undetermined, No. 1836 Y.P.M.;

U.S.N.M.; No. 5738 U.S.N.M.;
U.S.N.M.; 1833 Y.P.M.

No. 1837 Y.P.M.; No. 1838 Y.P.M.; No. 2124
No. 5740 U.S.N.M.; No. 6679 U.S.N.M.; No. 7239

Triceratofs, tooth, identified by Gilmore, found in Section 30, Township 39 N., Range 62 W.
Collected
Triceratofs (Diceratofs) hatcheri, type, No. 2412 U.S.N.M., skull without lower jaw.
7by Hatcher in 1891.
Torosaurus latus, type, No. 1830 Y.P.M., skull without lower jaw, collected by Catcher in 1891.
Torosaurus gladius, type, No. 1831 Y.P.M., skull without lower jaw, collected by Hatcher in 1891.
1

4

6

Letter from J. D. Figgins, 1932.

U. S. Geol. Surv., Bull. 656, 1917, p. 28.
Op. cit., p. 118.
7
U. S. Geol. Surv., Bull. 471, 1910, p. 483.

8

THE CERATOPSIA

16

side of the
Locality 15 (Fig. 2) is situated south of the Seminole Mountains, on the west
Here, inSteele.
Fort
below
miles
and
40
stream,that
North Platte River, about one mile fromribs,
vertebrae,skull,
the
parts
of
of
consistingmaterial
1888, Hatcher found considerable ceratopsianrenderastocondition
decomposedandfragmentaryand other portions of the skeleton, all in such
In the same general locality, from the Medicine Bow formation of
their determination impossible.
ceratopsians but not
the Hanna Basin, Carbon County, there have been found bones belonging to thealong both sides
exposedisbestformationThissufficiently diagnostic for generic determination.
River.
of the North Platte River, at the mouth of the Medicine Bow
In the Ferris formation of the Hanna Basin, there were obtained "indeterminable fragments ofTrkeratops."
ceratopsians, and a few specimens that have been identified by C. W. Gilmore as
to theRiver,
eastward
Platteformation "is best exposed from the old Ferris ranch, on NorthThe

8

top of the hill north of 'Middle Ditch' at its junction with 'Big Ditch'."Locality 16 (Fig. 2) is in Sweetwater County in southwestern Wyoming, not far from Blackdiscovered the
Buttes station on the Union Pacific Railroad. It was here, in 1 872, that F. B. Meek
about
16 vertebrae, thetype of Agathaumas sylvestris (No. 4000 A.M.N.H.) which consists ofsacrum, the right ilium, and fragments of ribs.

COLORADO
Locality 17 (Fig. 2) is on Green Mountain Creek, near Denver. It was here that George L.
Cannon found a pair of supraorbital horn cores in 1887, first described by Marsh as Bison altkornis,
Frombut later referred to Ceratops and finally to Trkeratops altkornis, type, No. 4739 U.S.N. M.
numconsiderable
collectedaEldridge
andCross
Messrs.
Brighton,near
locality,
generalthe same
core
horn
nasal
also
a
There
was
U.S.N.
6530
M.
No.
No.
1871,
bones
dinosaurber of fragmentary
U.S.N.
M.
No.
2410
galeus,Trkeratops
of
type
the
described by Marsh as
In 1931, a U. S. Geological Survey party collected what is probably ceratopsian material fromthe Dawson arkose, east side Section 9, Township 14 S., Range 62 W. (Loc. 18, Fig. 2).

NEW MEXICONew Mexico has given us some of the most recent finds.
County.

Locality 19 (Fig. 2) is in San Juan

The following material has been discovered there:

Pentaceratops sp., No. 12,002 U.S.N.M., a left squamosal, found by G. F. Sternberg in 1929, inthe southwest quarter section, Township 24, Range 1 3 W.
Ceratops (?), No. 8604 U.S.N. M., the median bar of a fenestrated ceratopsian dinosaur, collected by
Reeside and Clark, ?>y2 miles southwest of Kimbetoh, near the south side of Section 4, Township 22 N., Range 10 W., in the Kirtland formation.
Ceratops (?), Considerable portion of a right squamosal, collected in the southeast corner of SecW., in the Kirtland formation.
tion 4, Township 22 N., Range 1
Monoclonius (?), No. 5798 A.M.N.H., part of a supraorbital horn; and small sections of charac-

From the Ojo Alamo sandstone.
teristic squamosal bones, not collected.
Monoclonius (?), No. 7347 U.S.N. M., coossified atlas, axis, third and fourth cervical vertebrae, considerable portions of several dorsal and caudal vertebrae, parts of two pubes, and fragments
miles south of Sanof other bones, collected in the Fruitland formation in Amarillo Canyon,
Juan River, and 2 l 2 miles east of Chaco River.
Monoclonius (?), No. 8359 U.S.N.M., proximal portion of an ischium, found in the uppermost
part of the Kirtland shale, about 4 miles west of Farmington, 34 mile east of Mesa Point, and
1

/

1

8

mile south of San Juan River.

Bowen, C. F., 1918, p. 230.

GEOGRAPHIC DISTRIBUTION

17

Pentaceratops^ No. 12,743 U.S.N. M., supraorbital horn and parts ol squamosal, collected by <> F.
Sternberg in 1929, from the Kirtland formation, in S. \Y. J4, Township 24 N., Range 12 W.,

San Juan County.
Pentaceratops sternbergn\ type, No. 6325 A.M.N.H., skull and skeleton (skeleton discarded), collected by C. H. Sternberg in 1922, 9 miles northeast of Tsaya, from the Fruitland formation.
Pentaceratops st embergit, No. 1624 A.M.N.H., skull with half of frill gone, collected by C. H.
Sternberg in 1923, from the Fruitland formation near Tsaya.
B) skeleton almost complete, lower
Pentaceratops fenestratus, types, (A) skull, without lower jaw;
H.
Sternberg
discovered
by
C.
in
mile
jaw;
south of Kimbetoh wash, on the south
1921,
KirtlandMyers
Creek,
intheshales.
branch of
The material is now at 'psala, Sweden. Sent
materialwere
twopiecesof a squamosal and part of a parietal Pentaceratops]
along with thiswhich were found on the south branch of Meyers Creek, 4 miles above Cattle Ranch, and also
from the Kirtland formation. There was also included the lower part of a squamosal, thedistal part of a quadrate, and the proximal part of a supraorbital horn about 35 cm. long.
These latter bones were found in the Fruitland shales, by C. H. Sternberg, on the south sideof Alamo Wash, 3 miles above Hunter's store.
(

1

I

(

Pentaceratops, No. 1625 A.M.N.H., rear part of crest, collected by C.
land formation in 1924.

)

H. Sternberg in the Fruit-

Ceratopsian, No. 1622 A.M.N.H., skull, from the Fruitland shales, near Tsaya, collected by C. H.

Sternberg in 1922.

The following ceratopsian material is in the U. S. National Museum:
Ceratopsian, a fragmentary skull, collected in Barrel Spring Arroyo, about 1 mile southwest of Ojo
9Alamo store in the Ojo Alamo sandstone.
10on the north side of Barrel
Ceratopsian, fragments of teeth, found in the Ojo Alamo sandstone,

Spring Arroyo, about 1 mile south of Ojo Alamo store.
Ceratopsian, fragments of a ceratopsian frill, not determinable, found on the north side of Barrellmiles southwest of Ojo Alamo store, in the Ojo Alamo sandstone.
Spring Arroyo, about \ /zCeratopsian, fragments of a frill, found on the north side of Barrel Spring Arroyo, 1 34 miles southeast of Ojo Alamo store, in the Ojo Alamo sandstone.
Ceratopsian, fragments discovered by J. H. Gardner of the U. S. Geological Survey in 1908, near
the head of Coal Creek, 1 mile southeast of Ojo Alamo.
Ceratopsian, teeth, found in 1915 on the north side of Barrel Spring Arroyo, ]/i mile west of thewagon road from Ojo Alamo, in the Ojo Alamo sandstone.
Locality 20 (Fig. 2) is situated in the Red Beds of the Rio Grande region, at Elephant Butte.
The only record of Ceratopsia from here is of some Trkeratops bones, consisting of a few frag11
mentary vertebrae identified by J. W. Gidley.

TEXAS
Locality 21 (Fig. 2)

isin theBig Bend of the Rio Grande, near the Chisos Mountains.

In

the Upper Cretaceous Rattlesnake beds exposed here there was discovered the lower extremity of a12
as ceratopsian, but considered by the author as scarcely
tibia, which was identified by Willistonsufficient for

determination.

However, it is indicated as a possible locality.

"Gilmore, C. W., 1919, p. 65.
10 Gilmore, C. W., 1916,
pp. 286-287.
11

12

Jour. Geol., 1907, Vol. XV, p. 57.
Williston, S. W., in Udden, J. A., 1907.

THE CERATOPSIA

18

MEXICO
Locality 22 (Fig. 2) is in the state of Coahuila, north of Movano but south of the railroad running north from Soledad. The ceratopsian material found here consists of a right squamosal, a large
It
and a small caudal vertebra, a large section of a femur, and two undetermined fragments.
was discovered by E. Haarmann in the Soledad layers, which he regards as contemporaneous with
the Lance.

13

Preserved in the University of Berlin.

SOUTH AMERICA
14

In 1918, A. Tapia disVon Huene gives us a possible ceratopsian locality in South America.
covered a part of a mandible which Von Huene ascribes to the Ceratopsia under the name of Notoceratofs bonarelli.

It

was found in the dinosaur layer, north of the outlet of Chico River, in the

The stratigraphical level is
The actual specimen, however, seems too fragmentary for definite

southeast angle of Lake Colhue Huapi, district of Chubut, Argentine.

below the upper marine Senonian.
determination.

MONGOLIA
The genus Protoceratops, found in Mongolia, presents the most complete fossil series of allfrom egg to adult and old age. The type specimen, No. 6251

stages of a reptile's existence,

A.M.N.H., was found in 1922 by Walter Granger and party, on the Kwei-wa-ting trail east of
Artsa Bogdo, in the Gobi desert, Mongolia, Lat. 44° N., Long. 1 04° E. The horizon is the Cretaceous Shamo series, Dja-doch-ta formation. Since that time the locality has yielded about 80 specimens, many of them in almost perfect preservation of skull and skeleton, and grading from the verysmall and youthful animals to the old adults.

BRITISH COLUMBIA
During the summer of 1930, C. M. Sternberg collected from the Peace River Canyon in British
Columbia a number of dinosaur tracks which correspond exceedingly well in size, posture, length ofstride, and morphology, with the known anatomy of some of the Ceratopsia, Monoclonius (CentroIt seems possible, therefore, that the Ceratopsia had inhabited this region.
saurus), for instance.
markedtime discrepancy. The horizon of the tracks is correlated with the
There is, however, alower Blairmore of about middle Lower Cretaceous age. The exact location of the footprints is in
the "Peace River Canyon, north side, about 1 2 miles upstream from Gething's mine, on a stratum
216 feet above Grant seam, Gething member of Bullhead Mountain formation."
15
The type, No. 8556 G.S.C., consists of a plaster cast of six tracks (two manus and two pes ofthe left side and one each from the right side), and has been called Tetrapodosaurus borealis, as/
1

described by C.

13
14

M. Sternberg. 10

See Janensch, W., 1926, pp. 192-197.

Huene, F. von., 1929, pp. 147-149.
Original could not be removed from the locality.
10
Sternberg, C. M., 1932, pp. 73-74.
15

ALPHABETICAL LIST OF GENERA AND SPECIESFor convenient reference, there is given below an alphabetical list of genera and species, withthe author and date of original description, the horizon from which they came, and the page and plateof their description or illustration in this memoir.

Anchiceratofi longirostris, Sternberg 1929, Edmonton, p. 104, PI. X; Text fig. 3.
ornatus, Brown 1914, Edmonton, p. 103, PI. XI.

Arrhinoceratops brachyops, Parks 1925, Edmonton, p. 106, PL XII; Text fig. 3.

Bracks'err at'ops montanensis, Gilmore 1914, Two Medicine, p. 97, PL IX, B.
Ceratops montanus, Marsh 1888, Judith River, p. 96.

Chasmosaurus belli, Lambe 1902, Belly River, p. 92, Pis. VI; XIV, B; XVII; Text figs. 3, 30.
brevirostris, nov. sp., Belly River, p. 94, PL VII, A.
kaisetii, Brown 1933, Belly River, p. 94, PL V, A; VII, B; Text figs. 3, 38.
Eoceratops canadensis, Lambe 1915, Belly River, p. 91.
Leptoceratops gracilis,

Brown 1914, Edmonton, p. 78, Text figs. 35, 37.

Monoclonius crassus, Cope 1876, Judith River, p. 82.
dawsoni, Lambe 1902, Belly River, p. 83.
recurvicornis, Cope 1889, Judith River, p. 83.
sphenocerus, Cope 1889, Judith River, p. 83.
(Centrosaurus) apertus, Lambe 1904, Belly River, p. 84.

Brown 1917, Belly River, p. 87, PL III, B.
Brown 1914, Belly River, p. 86, Pis. II, III, A; Text figs. 3-5, 7-10, 13-14, 16-29.
nasicornus, Brown 1917, Belly River, p. 86, PL IX, A; Text figs. 11, 12, 15.

cutleri,

flexus,Wiman 1930, Kirtland, p. Ill, Text fig. 40.
stemberga, Osborn 1923, Fruitland, p. 108, PL V, B; Text figs. 3, 39.

Pentaceratops jenestratus,

Protoceratops andrewsi, Granger and Gregory 1923, Dja-doch-ta,

1913, Belly River, p. 87, PL VIII;
ovatus, Gilmore 1930, Two Medicine, p. 90.

Styracosaurus albertensis, Lambep.

Torosaurus gladius, Marsh 1891, Lance, p. 132, PL XVI; Text fig. 3.
lotus, Marsh 1891, Lance, p. 130, PL XV; Text figs. 3, 42.

Marsh 1887, Denver, p. 128.
Hatcher
1905, Lance, p. 119, Text fig. 3.
brevicornus,
calicornh, Marsh 1898, Lance, p. 123, Text fig. 3.
elatus, Marsh 1891, Lance, p. 122, PL XIV, A; Text fig. 3.
flabellatus, Marsh 1889, Lance, p. 121.
(Diceratofs) hatcheri, Lull 1905, Lance, p. 126, Text fig. 3.
horridus, Marsh 1889, Lance, p. 116, PL XIII; Text fig. 3.
maximus, Brown 1933, Lance, p. 129.
obtusus, Marsh 1898, Lance, p. 125, Text figs. 3, 41.
prorsus, Marsh 1890, Lance, p. 117, Text fig. 3.
serratus, Marsh 1890, Lance, p. 120, Text fig. 6.
sulcatus, Marsh 1890, Lance, p. 128.

Triceratops alticornis,

74, Pis.

I,

Text fig. 3.

IV; Text figs. 32-34, 36.

ECOLOGY, HABITS AND MANNER OF LIFEENVIRONMENTOne should visualize the known habitat of the horned dinosaurs in North America as a great
belt of lowlying lands along the western border of a vast inland sea,

now the Gulf of Mexico into northern Alberta and Saskatchewan.

which extended from what isWhen these creatures first appear,in middle late Cretaceous, this sea had already dwindled from its former extent, and by Lance time,1

according to Schuchert's maps, was merely a narrow vestige confined exclusively to the limits of theUnited States. To the west of the bordering lands, the great uplift of the Rocky Mountains was
already in process of formation; the so-called Laramide revolution, which produced it, also brought
The great area
about, at the close of the Age of Reptiles, the final drainage of the epeiric sea.
wherein the dinosaurs dwelt was for the most part so near the sea level that very slight vertical movements would either submerge it beneath the sea or drain it wholly or in part, thus producing attimes a rapid change from land to shallow-water or marine conditions over relatively large areas.
This would account for the alternation of marine and non-marine strata and the consequent occaThe actual habitat has been
sional breaks in the continuity of the record of ceratopsian history.
likened to such a region as the Florida Everglades, a vast swamp drained by small interlacing
There must have been areas of firmer
streams the course of which was continually changing.
ground, for not all of the associated dinosaurs were adapted to swamp conditions. The entire region,
swamp and drier areas, must have been covered with abundant plant life of an essentially modern
The names of the
aspect, and of sufficient profusion to form, in places, extensive beds of coal.
2
ferns, sequoia and other conifers, the gingko, and of deciduous trees,
recorded plants are familiar
the poplar, beech, elm, sycamore, maple, willow, and oak. In addition to these forest trees there
must have been an abundant underbrush and actual swamp vegetation. With the exception of thepalms and sequoia, all of these plant genera now thrive in the vicinity of New Haven, and do notnecessarily imply a tropical, but perhaps a warm temperate climate with more equable conditions
the year round than in present-day Connecticut, for great reptiles could hardly survive a New
England winter. The contrast of conditions in the same geographical area then and now is striking, for where vast swamps and deltas and heavily forested lowland formerly prevailed, there is
now a great plateau, semi-arid to desert in character. The events which have produced this alteration of environment, largely elevation and consequent climatic change, erosion, and deposition, andwhich have made the area untenable to dinosaurian life, are among the fundamental causes of thepassing of a great race.
There was a curious repetition of conditions at the close of the Jurassic and toward the end of
the Cretaceous; for both periods saw the wide extent of what has been called the amphibious-aquatic
environment and its peopling by dinosaurian forms. But in the Jurassic, the great amphibious andswamp-dwelling dinosaurs were the saurischian sauropods, such as the gigantic Brontosaurus, while3
in the Cretaceous, with one apparent exception, these had entirely passed away, at all events in the
Northern Hemisphere, and their place was filled by Ornithischia, especially unarmored trachodons
and Ceratopsia. Very comparable physical and climatic changes seem to have caused the final
extinction of each of these amphibious assemblages.
But the question of the origin of these Cretaceous forms arises, for, as Matthew has shown, neither the trachodons nor the ceratopsians had theirinitial evolution under such conditions and in such a habitat as that in which we find them, a factwhich may account, in part at any rate, for the abrupt appearance, especially of the latter. Matthew
says, "These Cretaceous giants .... appear to have evolved, not from amphibious or aquatic dino-—

1

C, and Dunbar, C, 1933, p. 348, PI. 31, maps 2, 3.
Knowlton, F. H., 1930.
3
Gilmore, C. W., 1922, A.

2Schuchert,

HVBITS AND MANNER OF LIFE
saurs of the Jura, but, in partat least,from small andlittle21

known forms, o| more upland adapta

don, which had been much more highly specialized for dry land life than any ol the Jurassic swamp
dwellers, and had readapted themselves to the forest and swamp environment of the later Creta
H As heritages from this upland phase ill their evolutionary history, Matthew stresses particuceous.'
larly the efficient grinding dentition and the compact feet with depressed hoofs, which characterizeboth the trachodons and ceratopsians, for these characters when found in modern mammals are
As further evidence for this upland stage, he cites theespecially associated with an upland habitat.
rarity of very young animals among the thousands of dinosaurs which have been unearthed in the
In Protoceroto-ps, all stages from the egg to the old adult are known, but in
America I know of but a single form which can really be called adolescent and that is Gilmore'sHence,
Brac/iycenirops* All of the rest are fully adult, although not all are aged individuals.
Matthew argues that the laying of eggs or bringing forth of young was done elsewhere than in theadult environment, probably in the upland regions where the periods of infancy and adolescence werepassed, the creatures coming to the swamps on maturity when increasing size made the amphibious
principal quarries.

environment more suitable. It is well known that many animals today return periodically to theirown birthplace to produce their offspring, but the final significance lies in the fact that the breedingor egg-laying place would be presumptively the ancestral habitat of the race.
While the trachodons, with their webbed feet and laterally compressed swimming tail, arcclearly splendidly adapted to an amphibious life, fully as much so as a modern crocodile, I cannot
see any character or group of characters in the ceratopsians which can be interpreted as in any sense
aquatic in their adaptation. On the contrary, the low-carried head with the nostrils near the ground,cumbersome limbs, and the relatively short tail as compared with that of other dinosaurs, all
Swampy areas, where the ground was sufficiently firm to bear
point to a terrestrial manner of life.
their weight without miring, and perhaps an occasional water hole would be visited but never the
I would visualize their manner of life as somewhat similar to that ofactual aquatic environment.
a modern browsing rhinoceros, which they resemble superficially in a number of ways, but I doubt
whether submergence would be desirable either for coolness or for ridding the body of parasites, formodern reptiles bask in a scorching heat and it is difficult to imagine ticks or insect pests having
any effect on the thoroughly protected hide of a ceratopsian.

the

FEEDING HABITS
There is no ambiguity about the mouth armament of a ceratopsian. It is clearly that of an
herbivorous animal and is not in any sense fitted for the rending of prey. Anteriorly, there is alaterally compressed beak, while in the rear of the mouth, there is a splendid battery of successional
teeth comparable to those of the trachodons; although the individual teeth are larger, and consequently fewer in number, and their mode of succession is different, they are fully as efficient. There
powerful muscular cheeks, formed
is evidence that the masticating area of the jaws was enclosed bylargely of the masseter muscles, and the well -developed coronoid points to equally powerful temporalmuscles. Altogether, the mouth, with its activating tissues, was fully as efficient as that of a modern
rhinoceros, with this advantage, that the endless succession of teeth gave no limit to the expecta-

modern mammal whose permanent teeth,
The jaw movement was a vertical or chopping one through antion of life as compared with the very definite limit of aonce worn out, cannot be replenished.

arc the center of which lay in the articulation, with no indication either of lateral sway or of fore
and aft motion; and the teeth met, not as in a modern ungulate with the horizontal surface of thecrowns in contact, but shearing past each other so that the occluding surfaces were vertical, on the
They were in effect like two converging pairinside of the lower teeth and outside of the upper.
shears, one on either side of the mouth. Hence their mastication was not a grinding one, but a shear-

4
5

Matthew, W. D., 1915, p. 278.
Gilmorc, C. W., 1922, B.

THE CERATOPSIA

22

ing and chopping one, which is one reason for the need of muscular cheeks to retain within thewell-developed mobile
mouth that portion of the food which would fall outside the teeth.
tongue is also a necessary part of the buccal mechanism. The form of the muzzle varied somewhatA

degree of lateral compression, being very narrow and deep in Monoclonius, but broader andshallower in Chasmosaurus. Whether this indicates a difference of food and the manner of its prehension it is difficult to say. There is no marked specific distinction in the teeth themselves otherthan of size and a small variation in the number of vertical rows.
6
Tait and Brown have given us a vivid picture of a feeding ceratopsian, derived not only from astudy of the mouth, but also from that of the ball and socket articulation of the skull and neck andOf course, a ball and socket joint is a unithe length of the unprotected area of the spinal cord.
versal one in the mechanical sense, but whether it implied a ninety-degree rotation of the skull on
They say, "From its bodily configuraits long axis, which their picture calls for, I seriously doubt.
tion .... it must have attacked the plants and plant stems near their base, and the wedge-shaped
in itsbeak .... was no doubt the instrument employed in seizing these stems. Tricerato-ps is possessed offorward projecting horns, and it is conceivable that these may also have been used as an accessory
mechanism in the process of food collecting.
"Throwing its beak laterally towards the cluster of vegetation, in which position it could seize
and grip vertically growing objects, it picked, let us say, one of these stems, the recurved beak closNext with violence it wrenched the selected stem
ing either lightly or firmly around the column.
A nasal horn such as Monoclonius possesses may have played some part."
towards the open
7
I agree with Nopsca that the horns of the Ceratopsia could have had little or no part in foodgetting, but were offensive and defensive weapons, and I do not see why, with its great weight andwidespread fore limbs, a horned dinosaur could not have ridden down the stems of desirable vegetaThis seems to me far moretion, in addition to that within easy reach, exactly as does a moose.
consonant with structural limitations than the remarkable cervical gymnastics postulated by Tait and

Brown (see p. 73).

METHODS OF COMBATThat the ceratopsians were pugnacious animals is attested first by their possession of horns andneck shield, and secondly by the injuries which they carried, such as puncture wounds and broken
horns, all of which were premortem. These are in addition to the manifestations of bone tumors or(See Torosaurus latus, Fig. 42 and PI. XV, which shows a puncture wound above
other disease.
and in front of the right orbit, visible in the plate, in addition to the diseased condition of the rightsquamosal.)

Nopsca stresses the heavy, broad-gauged position of the fore feet in contrast with the more
movable hind limbs. This permitted a freer rotation about the fore limbs, the creature swinging
the stern over to present the head to the enemy, rather than moving laterally the more cumbersome forward part. What it strove to do, I imagine, was to charge the enemy head on, and at
the same time protect its own flank from attack. The long, more or less erect nose horn of Monoclonius must have implied a somewhat different mode of attack from that of Triceratofs with its shortnasal and long brow horns. The variation in curvature of the latter in the various species which
possessed them implies either that some of the difference is due to postmortem conditions or that8

the individual tactics varied. The reinforcement of the skull, together with the powerful musculaThere is neverture of neck and shoulder, indicates a very decided survival value in these horns.
any evidence of immensely long spinous processes in the anterior dorsal vertebrae of these animals,——

however, such as certain horned mammals the bison, titanotheres and rhinoceroses possess. The
great extent of the crest, together with the mechanical advantage of increased leverage of the head
may have offset this in the ceratopsians.
67J., and Brown, B., 1928.
Nopsca, F., 1929, A, pp. 69-70.

8Op. cit.

Tait,HABITS \M> MANNER OF LIFE

23

On the defensive side, there is the crest itself, especially the squamosal area which would receive
the brunt of the attack, and the thickened and highly rugOSC upper and anterior rim ol the orbit, which
was for the protection of the eye. I cannot think of the eye as protruding, as latcher believed, andhence the vision must have been limited to a lateral held with a blind area immediately in front, as
1

with the sperm whale.
One has to consider not only combats with rival males but protection against such carnivorous
enemies as Gorgosaurus of Belly River time and, above all, the huge Tyratmosaurus of the Lance.
That the menace of these beasts of prey was real is attested by the facts that little or no sexual distinction is provable among ceratopsians and that apparently both males and females of a species
possessed both the horns and crest in equal degree.

PROGRESSIVE EVOLUTIONARY CHANGES AND PHYLOGENY(Fig. 3)

The recorded evolutionary history of the Ceratopsoidea opens abruptly, with several highlyinteresting early chapters not yet revealed, for when these grotesque animals appear in our records

they are already ceratopsians with the essential features established. Not only so, but their differentiation into at least three phyletic lines has already been brought about.
The Protoceratopsidae end where they begin, for the two isolated genera, Protoceratops andLeptoceratops, each with its single known species, tell all we know of the group. With them there
is no recorded phylogeny.
The Ceratopsidae, on the other hand, while established as such at their initial appearance, donevertheless show a very considerable series of changes, some of which are common to all phyla,
others peculiar to one or more.
It is necessary, therefore, to give a "synopsis of preceding chapters," the details of which must be derived from comparative morphology and the known evolutionary trend of later forms, for the actual record of these chapters is as yet undiscovered. I should
derive the Ceratopsia from some unarmored stock of ornithischian dinosaurs, probably bipedal ingait, although among those already discovered we know of none which could be considered
ancestral, even in the structural sense.
The unrecorded changes have to do with the secondary assumption of the quadrupedal posture
and with the increasing power of the fore limbs to carry the growing weight of the anterior part ofThe
the body, although the fore limbs never assume the rectigrade posture of the hind limbs.
increase in size of the head is correlated with a shortening of the neck and loss of motion, due toThethe condition of coossified immobility on the part of the three anterior cervical vertebrae.
postpubis shortens to a vestige and, on the part of the Ceratopsidae, the elongated ischia become
curved downward, and the upper border of the ilium reflected so that the blade becomes horizontal
as in certain of the Stegosauria.
The skull becomes more or less wedge-shaped when viewed from above, and in front of thelaterally compressed premaxillaries there appears an additional bone, the rostral, which forms the
opposing element to the predentary and, like the latter, is sheathed in a prehensile beak. The
ancestral form was provided with premaxillary teeth, which persist in the Protoceratopsidae, but are
lost in the Ceratopsidae.

The crest is composed of the squamosals and a median element which is variously interpreted,but is called here the parietal, and which is fenestrated on either side of the midline. The mannerof origin of the fenestrae is clearly indicated in the genus Chasmosaurus, although not so evident inother contemporary genera, and it may possibly have arisen independently in more than one way.
In Chasmosaurus, the squamosals are elongated and the median element consists of a keel-like,longitudinal portion, at the hinder end of which a transverse bar is extended to meet the end ofeither squamosal.
Ancestrally, therefore, the outer limit of the fenestra must have been thesquamosal. At the anterior end of the fenestra, behind the supratemporal openings, a plate ofbone extends laterally to join the squamosal near its anterior end, and from these transverse portions of the parietal, branches developed forward and backward, as the case may be, extending along
the squamosal until they met in an overlapping suture which, at any rate in Chasmosaurus, failed tofuse and in one case failed to meet. This now excludes the fenestra from contact with the squamosaland the aperture thus formed is persistent throughout the recorded history of the phylum. The
other type of aperture, which disappears in evolution, seems to be merely a fenestration or perforation of the broad, plate-like parietals, and is associated with squamosals of short or intermediate
length, for in the first records of this type, in Protoceratofs, Monoclonius, or Centrosaurus, thefenestrae are some distance from the squamosals (toward the midline), with thin margins, somewhat variable in extent, even between the two of the same crest. There is no sign of sutural unionin thebone forming the outer margin.

1\

OLUTIONARY SUMMARY25

its
In the chameleon, the crest is Formed by the middle parietal bar reinforced from below atorpostpostfrontal
theHere, the parietal broadens out to meetanterior end by the supraoccipital.
The
orbital, which in turn articulates with the jugal below, and the squamosa] below and behind.
bar,parietalthus
latter bone, passing backward, arches inward until it meets the hinder end of theenclosing an opening interpreted as the supratemporal fossa, but equivalent in position to the parietal

In the latter, the supratemporal fossa is separated from the fenestra by
a transverse portion o( the parietal, but the two apertures may once have been confluent before thefenestra of the Ceratopsia.

formation of the transverse portion, which in all large fenestrated forms still lies below the levelof the remainder of the crest and forms the area for the origin of the temporal muscles.
In the Protoceratopsidae, a sagittal crest indicates that the origin of the temporal muscles overlay the greater part if not all of the dorsal surface of the parietal portion of the frill. In the Ceratopsidae, there are definite but limited areas in the wake of the supratemporal fossae which received
the origin of this muscle. Thus, the frill had a dual function, mechanical and protective, for it formed
the origin of the temporal muscles of the jaws on the upper aspect, while below it served for theinsertion of the several neck muscles which wielded the head.

It also formed a protective buckler toguard the otherwise unprotected portion of the spinal cord from the point of its emergence from theforamen magnum until it disappeared beneath the neural arch of the axis, a distance of several inches.
Other vital portions of the neck, such as arteries and veins, were afforded protection as well.
Initially, the formation of the frill was analogous to that of the chameleon; but whether the sameelements enter into its formation in each instance is a matter of debate.
The dorsal surface of the cranium, while unmodified in the Protoceratopsidae, even in the adult,
that found inis altered in the Ceratopsidae through the formation of a false roofing analogous tocase proper.
brain
and
the
bones
roofingthebetweenthe Chelonia, and inclosing spacious sinuses
development
yetits
horns,
supraorbitaloftheThis is doubtless correlated with the evolution
seems to have anticipated that of the horns, for it is well established, although not perfected, ingenera in which these horns may be in an incipient stage, such as in some species of Chasmosaums
and in Styracosaurus. Another peculiar feature which is the outgrowth of this false roofing is thepostfrontal fontanelle which lies in the midline of the dorsal aspect of the cranium, just above theThis forms an opening into the sinuses from without and waslevel of the supratemporal fossae.

supposed by Marsh to be the pineal foramen. This it clearly is not, for it does not communicate
with the endocranial space, but what function it actually served we do not know. When I gave
the name of postfrontal fontanelle to it, I supposed that its presence was temporary and that it always
closed over completely with age. But I find this is not true, for in but a single instance known tome, that of the type of Trkeratofs prorsus, is the closure complete. Moreover, there are always, so
far as I know, two canals which radiate outward and backward from the fontanelle and of which
This would seem to imply some sort of function,
vestiges are discernible even in the prorsus skull.
but not that of the emission of bloodvessels on the surface of the crest, for the vascular impressions
emerge from the supratemporal fossae, but are not apparent until the margin of the smooth area forthe origin of the temporal muscle is reached, where they are few and deep, ramifying into a countless
1

number as they disperse over the crest.

Hay in speaking of the postfrontal fontanelle says, "Probably in all cases this postfrontal
foramen divides below into two, one for each side," as Hatcher describes in Torosaurus latus. "Itseems perfectly clear that the foramen in question represents the supratemporal fossae of the alligaThe bone rising up and dividing the fossa into two, either at the
tor and of various other reptiles.
surface or deeper down, will almost certainly be found to be the true parietal. Through the enormous thickening of the postfrontals four parietals] the parietal has been crowded from the upper surface of the skull of Trkeratofs and the two supratemporal fossae have been pushed into one at the2
midline."But we recognize the supratemporal fossae as present and functional. Perhaps the canallike depressions radiating from the postfrontal fontanelle represent old lines of communication
1

2

Hatcher, Marsh, Lull, 1907, p. 24 (footnote).
Hay, O. P., 1909, pp. 97-98.

THE CERATOPSIA

26

between the fontanelle and the supratemporal fossae which at one time were confluent, and Hay was
At all events, the fontanelle and its canals represent a vestigial structure thepartially correct.
apparently lost. Compare this area in Styracosaurus, PI. VIII.
which
was
function ofAnother characteristic feature is the series of separate ossifications, one, the epijugal, at thelower end of either jugal, and a series, to which the name epoccipitals is applied, around the peripheryof the crest.

The Protoceratopsidae possessed the former, but apparently not the latter.

In the first-

appearing genera of the Ceratopsidae the epoccipitals are also present, and while seemingly absent
in some later forms I seriously doubt whether they actually were missing during the lifetime of theanimal, except perhaps in Torosaurus.
Of horns, the Protoceratopsidae possess none at all, for in the many skulls of Protoceratops
Leptoceratops, on the other hand,itself there is not the slightest indication of their presence.

while agreeing with Protoceratops in all essential details, except in the crest, is based upon so incomplete a skull that the areas where brow horns would naturally arise are missing, but the nasals arepresent and show no trace of a nasal horn. The inference is that the two genera agreed in hornlessness as in other ways.
present.

In the Ceratopsidae, horns are a very characteristic feature and are invariably

The Belly River and Judith River genera had already developed the nasal horn;in fact,

Styracosaurus has the largest one on record, with Monoclonius or Centrosaurus a close second.
That of Chasmosaurus, however, is much smaller. Almost the entire progressive development of
Of the brow
the nasal horn, therefore, lies within the unrecorded part of ceratopsian evolution.
horns, this is not true, for while Chasmosaurus kaiseni and Ceratops montanus possess fairly large
ones, they are as a rule in an extremely rudimentary state in most species of each of the several
genera which appear at the beginning of our record, especially in the Belly River series. This completes the tale of the missing chapters.
The actual recorded evolution, aside from the increase in size together with the mechanicaladjustments of the skeleton necessary to carry the increasing weight, lies mainly in the head andmore particularly in the horns and crest. As to size, the recorded increase in the over-all length is
not very great. The length of the Yale Monoclonius (Centrosaurus) is 17 feet 4 inches, measured
on the curve, and of the Washington Triceratops, 23 feet 6 inches; the larger Chasmosaurus at
Ottawa is about 1 6 feet long, while Torosaurus, another long-crested form, probably did not exceed

21 feet.

Of the skull alone, that of Centrosaurus is 4 feet 6 inches, Triceratops 8 feet 2 inches,

Chasmosaurus about 5 feet, and Torosaurus gladius, as restored, 8 feet 10 inches (although themuzzle, which in the restoration looks disproportionally short, may have brought the actual length
The living weight of a horned dinosaur has never been accurately estimated, but
to over 9 feet).
the percentage of increase can be roughly calculated, that of Triceratops over Centrosaurus being
about one third.

The nasal horn seems to have reached its maximum size by Belly River time, for no subsequent
short squamosal form, such as Triceratops, has a proportionately longer horn than Centrosaurus, andIn this phylum, therefore, the recorded
in several species it is much reduced, even to elimination.

evolution of this horn is entirely retrogressive. In the long squamosal phylum, however, the nasal
horn of Chasmosaurus is not as large as that of its Fruitland successor Pentaceratops, but in
Torosaurus the horn has diminished so that in this phylum if we are correct in assuming thisgeneric sequence
the trend is first progressive and then retrogressive, the culmination occurring——

at a later date than in the other phylum.

Another interesting feature in connection with the nasal horn is its apparent shifting forwardin evolution, and here the rate of movement is approximately equal in both phyla, for in Belly Rivergenera it lies above the posterior limit of the nares, while in those from the Lance, it is over theanterior limit; the position of those of the Edmonton Anchiceratops and the Fruitland Pentaceratops
This shifting forward of the nasal horn results in a lengthening of theis more or less intermediate.
face, especially in the long-crested phylum.

The brow horns are always progressive in their evolution, regardless of phyla. In Belly River
time they are incipient, sometimes a mere rugosity above the orbit, again a short pyramidal horn
seemingly, sometimes at least, originating in a separate ossification which may be lost in macera-

I

VOLUTION \KY SUMMARY

27

Very rarely, as in Chasmosaurus kaiseni and Cera/ops montanus,
The subsequent forms are all well endowed with brow
arc those horns of even moderate length.
horns although these are not always equally long, as in Trkeratops brewcornus and Triceratops
alticornis by way of contrast; nevertheless, there is no evidence of retrogression.
There is a tendency in Belly River genera, but notably in the short-crested Centrosaurus andStyracosanrus, toward the development of peculiar horn-like excrescences around the periphery of
the parietal. The former genus may be ancestral to such later Ceratopsia as Triceratops, the latter
At all events, these excrescences disappear with the Belly River-Two
I think died without issue.
Medicine forms, for all of the Lance types are conservative in the ornamentation of the crest, if
such it was. If, as I think, these growths were due to a sort of acromegalic response to the chemical
environment, the altering of conditions might lead to a more normal racial health and hence theirtion as in the type of Styracosanrus.

disappearance.
ceratops of theWith the long-squamosal types, the height of this ornamentation occurs in AnchiEdmonton, lessens but is still apparent in the Fruitland Pentaceratops, but in Toro-saurus of the Lance the crest is bereft of all appendages. Thus, in two details, in the length of thenasal horn, but not its position, and in the ornamentation of the posterior part of the crest, the longsquamosal phylum lags behind that of the short-crested types.
The closure of the parietal fenestrae is foreshadowed in the Belly River types and complete
never disappear.
in the Lance in the short-crested phyla, while in the long-crested types the fenestrae

Anchiceratops, although with comparatively long squamosals, has relatively small fenestrae. It may
be a precocious side line culminating in the Edmonton, although it is undoubtedly related to the

Chasmosaurus-Pentaceratops-Torosaurus line.
The long crests seem to have been less closely invested in the horny covering than were thethat the crest in
short crests, if one may judge by the vascular impressions. Although, if this means
hada singularly
have
must
creaturesthemusculature,body
the former was not free of the dorsal
there was apersistedfenestrae
when
the
that
contrary,
immobile head. It would seem, on the
peripherytheatperhaps
exceptbelow,
and
above
both
crest
thicker, more fleshy covering over thehas deepfenestrae,
the
close
tendency
to
with
its
Anchiceratops,
in Chasmosaurus and Pentaceratops.
impressions
vascular impressions in spite of its phyletic relationship. The variable extent of vascularextentto whichtheaccurately
more
indicatetoseems
on the under side in the closely invested crests
the crest is free from the body.
As an outcome of the present study,

have attempted to present graphically, in Figure 3, cerThey are in no sense final,
tain conclusions in regard to the phyletic sequence of the Ceratopsidae.
due perhaps to misinterimperfect,
is
which
sheet
and the figure is to be regarded merely as a trial
record.
theofpretation, but more, I hope, to the incompleteness
The two main phyletic lines, which may be of sub-family rank, are distinguished principally byform of the crest, specifically in the length of the squamosal and its reaction upon the crest, and byItheeither the persistence or closure of the parietal fenestrae.
The long-crested line, with persistent fenestrae, begins with the Belly River Chasmosaurus, of
Chasmosaurus belli is the most generalized form, while Chasmosaurus kaiseni is progressivewhichwith belli of thethe development of its brow horns, although it may be an actual contemporary
but this genus,
Anchiceratops;
rudimentary horns. In the Edmonton, this phylum is represented by
Fruitland
homotaxialofthewhile showing certain characters comparable to those of Pentaceratops
inthe high
especiallyline,
Kirtland formations, seems to depart from the main evolutionaryinanddegree of vascular impressions on both surfaces of the crest, and in the tendency toward the diminuAccording to available evidence, it seems to represent an abortive side line
tion of the fenestrae.
which left no descendants. This is not true of Pentaceratops, however, for the typical species sternother than of size
its predeces-

hergii could be the lineal descendant of Chasmosaurus kaiseni with little alteration,and the more abundant vascularity of the squamosal. It is far removed in space from

Arrhinoceratops,
sors and descendants, but otherwise fits into its place in the sequence admirably.
formwith vascularalso of the Edmonton, presents certain difficulties. It is clearly a long-squamosalancestral tobeIt may prove toimpressions on either side of the crest and rather small fenestrae.
Triceratops of the short-crested

phylum and the resemblance is rather close, especially between

EVOLUTIONARY SUMMARY

29

Arrhinoceratops and the Triceratops species obtUSUS and hatcher), in which the nasal horn is reduced.

The closing member of this phylum is Torosanrus, which again fulfills the requirements in being justwhat one would be led to expect from the evolutionary trend established by its predecessorIt
strange that this genus should be so rare, with but two recognizable specimens found within a mile ofeach other at the very summit of the Niobrara County Lance. The contemporary Triceratops, on
the other hand, is represented by hundreds of individuals' of which comparatively few were.

icollectable.

The initial short-crested form is Monoclonius (Centrosaurus), from the Judith River and Belly
River formations, which may be the beginning of the entire line culminating in Triceratops, but the
sub-genus Centrosaurus itself, with the high degree of ornamentation at the rear of the crest, seems
too specialized.
It may well be that the true ancestry lies in the ill-known forms of Monoclonius
or even Ceratops of the Judith River which seem to be more conservative in this regard. The continuity through the Edmonton is not good, for A rrhinoceratops is the only known possibility and theobjections to its inclusion in this phylum have already been given.
Styracosaurus, with the riotous
processes around the rear of the crest, is clearly derivable from the Monoclonius stock but not fromany of the known forms, all of which are apparently too nearly contemporaneous.
Triceratops isevidently a polyphyletic genus, and I have shown at least three descent lines, or rather groupings,
within the genus.
Of these, perhaps the most conservative is the prorsus-brevkornus-horridus
phylum. The sequence, as I have shown it, is not actual, for the type of horridus is next to thelowermost of the Niobrara County series, although, if I am correct in referring the giant skull sometimes known as Triceratops "ingens" (No. 1828 Y.P.M.) to this species, it persisted until near theclose of the Lance record.
As the skulls are arranged, they show progressive increase in size,
and reduction of the nasal horn. Of the elatus-calicomis group, the elatus type is somewhat theolder, but here again elatus has a long vertical distribution and the single ca/icoruis specimen may
be merely a variant from the type, but actually conspecific.
The great brow horns and curiouslyreduced nasal horn are the most outstanding features of this group. T. obtusus, with the nose hornnearly vestigial, is at the very beginning of the Niobrara County sequence; T. (Diceratops) hatcheri
is two-thirds of the way up.
Whether obtusus was actually ancestral to hatcheri is questionable, but
except for smaller size, the latter seems to be the embodiment of the obtusus evolutionary trend.

Brown

reports

500

in theHell Creek region alone.

1933, A, p. 2.

GENERAL MORPHOLOGY
1
Mr. Hatcher's study of the osteology of Triceratops leaves little to be desired. There havebeen, however, a few new elements discovered since his time, such as the hyoid, sternal, and sclerotic
In addition, studies have been made of theplates, which will be discussed in their proper place.

cranial musculature and a good deal of argument has arisen concerning the homologies of certain
elements in the skull. Hatcher also discussed in such detail as was then possible the skeleton of

Cope's type of Monoclonius crassus. Because of the abundance and perfection of material which
has come to light in the Red Deer region of Alberta, including at least seven nearly complete skeletons representing four genera and two geological horizons, it is now deemed wise to describe anew
the morphology of the genus Monoclonius {Centrosaurus), basing the description on the skeleton at
Yale, recently purchased from the American Museum of Natural History (No. 2015 Y.P.M.).

MONOCLONIUS (CENTROSAURUS) FLEXUS

2

Brown

The animal was much smaller than Triceratops and the limb bones, especially, lack the robustness of that genus, although aside from the skull the skeletal elements are otherwise quite similar.

AXIAL SKELETONSKULLThe skull (Fig. 4) of the Yale specimen resembles that of the type of Centrosaurus flexus
Brown, differing only in minor details such as having two forwardly directed processes over theparietal fenestrae instead of but one, and in the nearer approach of the inwardly curved hook-likeprocesses at the rear of the crest. These are shown to be matters of individual variation and apparently have little or no specific value.
3
speaksIn Brown's description of C. flexus the following points are noted for comparison:
This
true
at
genus.
wasofthespecies
described
than
in
any
other
longerof the nasal horn being

He

that time, but his subsequently described C. nasicornus has a longer one although straight rather thancurved forward. The nasal horn in the C. flexus type is described as ovate in section at the base withthe broad end of the oval toward the rear, with which the Yale specimen agrees.
The horn arises from the nasals at their mid-length in both specimens so that its center lies
This is a character common to all early genera, in
directly above the posterior border of the nares.

Lance in which the horn lies over the anterior rim of the nares. In
C. flexus the horn curves forward; in Monoclonius dawsoni Lambe it curves backward with about
the same degree of curvature, while in M. sphenocerus Cope and C. nasicornus Brown it is straightand erect.
The supraorbital horns are rudimentary as compared with those of Triceratops. They are considerably larger than in Monoclonius dawsoni, and in both the type of C. flexus and the Yale specicontrast with those of themen they are asymmetrical, that of the left side being in each skull considerably higher than the right.
In the Yale specimen the left horn core is triangular, viewed from without, with a flattened outer
On the right side there is only a rough, rounded area where
face, and less rugose than in the type.
the horn should be. Brown thinks it possible that the horns may have been derived from separate
centers of ossification and that the right one has been lost, leaving only the rugose elevated portion
In the type of Styracosaurus albertensis (PI.
of the postfrontal forming its base of attachment.
VIII, B) in the Ottawa museum there are distinct sutural surfaces showing where the horn cores
1

Hatcher, Marsh, Lull, 1907, Chapter III.
For the sake of simplicity, during this chapter on morphology the term Centrosaurus will be used for all Belly River
species under the genus Monoclonius.
2

3

Brown, B., 1914, B.

THK SKULL

31

would h.u c been attached were they present.

This is apparently true also of a Chasmosaurus skull in
the Yale collection, but not in either Centrosaurus skull under discussion.
Hatcher states that inTriceratofs the supraorbital horns are simple outgrowths of the postfrontals, whereas the nasal horn,like the rostral, predentary, epoccipitals,

and epijugals, is to be considered a dermal or epidermal
But no known Triceratofs skull is individually young enough to prove the point, forthe supraorbital horns are so large that coalescence with the postfrontals must have occurred at a very
early age if they arose from separate centers of ossification.
Brown expresses doubt as to whether
the supraorbital cores bore a horny sheath in the rudimentary stage of their development in Centrosaurus.
But judging from the abundance of vascular impressions, especially on the crest of older
ossification.

Y. P.M. 2015

Fie. 4.

—an, angular;/,

prefrontal;

n, nasal;'anterior process of crest;

opening;po, postfrontal;

squamosal;

horn;h, supraorbital

nar, narial

maxillary;sj,

Left lateral view of skull of Monoclonius (C entrosaurus)

ap,

/,

/'/,

ar,

articular;

preorbital fossa;

nk, nasal horn core;

0,

c,

«'//,

orbit;

pp, posterior process of crest;

flc.xtts,

atcoronoid process;infratemporalp, parietal;q,quadrate;

Museum,Yale Peabodyd, dentary;

e,

T

s

epoccipital;

natural size.
»/,

epijugal;mx, maxillary;
pd, predentary; />/, parietal fenestra; pmx, prefossa;

y;',

/',

jugal;

quadratojugal/,;

Iacrymal;r,

rostral;.<,;,surangul.ir;

teeth.

individuals, the entire head except for muscle areas must have been clothed with a close-fitting rehorny in texture. It is reasonable to assume that the areasof the horns were likewise so covered, and that, as in the horned lizard P/irynnsoDia, corneous horntant integument, leathery if not actuallylikeprominences may actually have preceded rather than followed the development of an osseoushorn core.

RostralThis bone is essentially as in Triceratofs except for its smaller size relative to the entire face.

The ascending process does not rise so high on the nose in Centrosaurus, and as a consequence theposterior margin of the rostral is straighter. The highly rugose and pitted character of the bone ischaracteristic of all ceratopsians. The muzzle of Centrosaurus is relatively deeper than in Triceratofs
and much deeper and shorter than in the contemporary Chasmosaurus.

THE CERATOPSIA

32

Premaxillary
divides the externalThis forms in a broad, smooth, vertical plate, the osseous septum, which
The septum differs from that ofAbove it meets an equivalent portion of the nasals.
nares.
4
This verticalall Lance genera.
Triceratops in being thinner and in lacking the fenestration found in
plate

is

called the?

septomaxillary by

Von Huene in his description of the skull of Triceratofs.
premaxillanes proper.

There is in no instance known to me any indication of suture between it and thethan is represented
Here, again, however, the suture may have become obliterated at an earlier age
montanensis
Brachyceratops
by any known skull. One would expect to find it in the very youthfulMuseum in which the cranial eletype, as well as in the skull of Triceratops flabellatus in the Yalements are practically all isolated from each other, but the latter does not show it.
nose, withthe premaxillary is convex and broadened out to form the front of theAnteriorly,

process is overlapped lateran ascending process reaching nearly to the base of the nasal horn. This
which together with the latterally and posteriorly by a downwardly curved process of the nasal
is strongly convex
forms the convex profile of the nose. The lower margin of the premaxillary
margin is
downward, as viewed laterally, in all Centrosaurus specimens, while in Triceratops thismore nearly straight. The surface of this portion of the bone is smooth. The posterior process ofrelatively deeper and lessthe premaxillary, which is included between the nasals and maxillary, is
In some Centroconsiderably.
vary
however,
extent,
and
form
Its
slender than in Triceratops.
it is widely
othersinauthors),offoramen(lacrymal
fossa
preorbital
thesaurus skulls it reaches
whether
althoughvariationtosubjectalso
islacrymalthewithcontactIts
separated from the fossa.
YaleandAmericantheinskulls
two
C.
the
fexus
In
clear.
notof specific value isor not this ismuseums there is such contact, but in the Ottawa one there is not, nor in the type of C. nasicornus,
showswhile the skull of Centrosaurus apertus No. 4519 R.O.M., which is very similar to nasicornus,
other
In
horn.
nasal
curvedforwardly
sharp
with
a
does skull No. 348 G.S.C.

such contact, as
three skulls
words, the ascending process of the premaxillary meets the lacrymal in two out of
nasal
directed
forwardly
the
one
with
in
and
nasicornus,
identified as C. fiexus, and in one skull ofskull.
one
in
fexus
and
horn. The bones fail to meet in one nasicornus

Nasal

The nasal of Centrosaurus is of very different proportions from that of Triceratops, due in partlies over the posterior rather
to the position of the erectly arising nasal horn which, as we have seen,
to the horn relathan the anterior margin of the nares. This makes the portion of the nasals anterior
the anterior
half
nearlyform
nasalsthetively longer in the present genus. Thus, in Centrosaurus,
Triceratops
ofnasals
the
horn,
the
Posteriortoprofile of the muzzle, in Triceratops, little, if any.
nasalsare also
theCentrosaurus,inOn account of the depth of the face
are relatively longer.
divided,and areare
Centrosaurus
deeper than in Triceratops. Anterior to the horn, the nasals intrue ofnotapparently
is
which
separated by the anterior ascending process of the premaxillaries,
the
from
right
the
separating
Posterior to the horn, on the other hand, the suture
Triceratops.
theTriceratops,Instudied.
left nasal is obsolete and not discernible in any skull which I haveindividuals insuture is, as a rule, clearly visible to the extreme posterior end except in very old
thus form theCentrosaurus
which practically all of the sutures have been obliterated. The nasals in
where
they meethorns,
top and sides of the nose to about halfway between the nasal and supraorbitalThus theface.
the prefrontals above and the lacrymals (and ? preorbitals) on the side of thereachthe prebounding of the nasals is comparable to that in Triceratops, except that they neverexcludemay
premaxillary
orbital fossa. The variable extent of the posterior ascending process of the

R.O.M.
the nasal from contact with the maxillary as in the C. fexus type skull and the No. 4519
and No. 348 G.S.C. skulls. In the C. nasicornus type, on the other hand, the contact between nasal
This fenestration is not present in all Triceratofs skulls, which leads to the supposition that it may
the thin septum.
normally present in the living animal, but is merely an accidental post-mortem perforation through4

not have been

THE SKULL

33

In Centrosaurus as we have seen, the nasal forms part of the septum separating the anterior nares. The extent of this septum area varies in the different Cenlrosaurus skulls.
In Triceratops, the nasals have no part in the nasal septum.

and maxillary occurs.

Lacrymal/'C^*

The lacrymal is, comparatively, of about the same size as in Triceratops, but differs from the^.
latter in being sometimes bounded anteriorly by the posterior process of the premaxillary.
isBelow,

iM^

bounded by the jugal and maxillary, and above, by the nasal and prefrontal.

MaxillaryThis element has the same form and limitations as in Triceratops.

It

contains alveolar grooves

for about 31 teeth, and on its inner face has a corresponding number of nutritive foramina in a hori-

The preorbital fossa is included within the maxillary though generally at the upper
The maxillary is bounded in front and above by the premaxillary, above by the lacrymal

zontal row.
border.

and jugal, behind by the jugal, and on the roof of the mouth by the premaxillary, palatine, andpterygoid.

Jugal

The form of this bone differs markedly from that in Triceratops, being broader and more
rectangular, whereas in the latter the outer aspect of the bone is somewhat T-shaped. The area
which overlaps the quadratojugal is much broader in Centrosaurus. Externally, the jugal is boundedby the maxillary and lacrymal, in front and above, and posteriorly by the postfrontal (postorbital)and squamosal. The epi jugal is borne on the lower outer corner of the jugal as in all ceratopsians.
Posteriorly, the infratemporal fossa is entirely surrounded by the jugal and squamosal, the quadratojugal not forming the lower border as it does in Triceratops. The jugal of Centrosaurus covers
over more of the quadratojugal-quadrate complex than in Triceratops, when viewed squarely fromwithout.

Squamosal
This is a most characteristic bone in the Ceratopsia, concerning which there has been little or noIts form and development are of generic value.
The squamosal of Centrosaurus is roughly quadrangular with the Jong axis running obliquely downward and backward. Its upper forward margin articulates with the postfrontal. Anteriorly, it
meets the jugal, posteriorly the parietal. The outer free margin sends forward a short process
which forms part of the lower border of the infratemporal fossa and unites with the jugal andquadrato-jugal. The anterior free border of the squamosal, together with the quadrate complex,
forms a deep notch behind which the border of the squamosal is continued to form the lateral marginof the crest. This part of the border has five prominences which orginally bore the epoccipital bones,of which two only are preserved on the right side and none on the left, where the margin is broken.
In this specimen the remaining epoccipitals are fully coossified with the squamosal. In the typespecimen of C. fexus there are three on the right side, one of which is represented by the base only.
These squamosal epoccipitals in the type are much smaller than are those borne on the parietals,
whereas in the Yale specimen they are nearly equal in size. The number of prominences is one
greater in the type and the emarginations between them are not so deep. I find five to be the usual
number of squamosal epoccipitals, not only in Centrosaurus but in Styracosaurus also. In Anchiceratops the number is six, while in Triceratops it is generally six with the seventh overlapping thesquamoso-parietal suture.
In long-squamosal forms, like Chasniosaurus, the number is naturally
greater, and averages nine.
discussion, as all authorities agree as to its identity.

v

-

u

THE CERATOPSIA

34

Vascular impressions are present but not very numerous on the upper surface of the squamosalin this adult specimen. This is true also of the type of C. flexus.

Parietal
About two-thirds of the area of the crest is formed by the coalesced parietals. Each incloses a
These have much the same extent in alllarge fenestra with a thin, somewhat variable margin.
never complete in any Centrosaurus skullpractically
however,is,marginThe
Centrosaurus skulls.
The right fenestra of the Yalethin.
extremely
been
have
must
edges
ultimate
as preserved, for its
specimen is materially smaller than the left, although the width of the bone on the outer side is thesame in each instance. The left fenestra is somewhat ovoid, with the apex pointing to the rear, andthere is an angular prominence in the middle of the anterior margin, but slightly indicated on theright side. The bony edges may in life have merged into a cartilaginous or membranous sheet which
covered the aperture, the evolutionary tendency in this Monodonius-T riceratofs phylum being
toward the final closure of the fenestra by bone, as opposed to its persistence in the Chasmosaurus-

T orosaurus group.
The supratemporal fossae are large, and open directly backward, due to the overgrowth of thefalse roofing of the skull. They are bounded by the postfrontals in front and above, and the parietals
In the rear of each there is a smooth area, depressed below the level of the postfrontal and squamosal bones, which must have formed the place of origin of the temporal muscles.
facial bones to the coronoid process
The latter ran obliquely forward and downward beneath the
5
Lull
on
the musculature of the ceratopsianThis is true of all Ceratopsia (seeof the lower jaw.
fossae to deploy on the dorsal
supratemporalskull). Bloodvessels also doubtless emerged from the
not toward the middle of thebutsurface of the crest, especially on the anterior and outer portions,

within and behind.

crest.

The central portion of the parietals between the muscular depressions and the fenestrae forms
portiona thickened bar, convex above and to a less extent concave below, which supports the medianofportionmarginal
into
theof the crest. Posteriorly, this bar increases in thickness and widens out
the crest, thus forming the inner and posterior margins of the fenestrae. It terminates between thehook-like posterior processes.
The free outer margin of the parietals bore four epoccipital bones on either side, the curious
inwardly curved hook-like processes constituting a fifth pair, if indeed they are homologous with theepoccipitals.

In several Centrosaurus skulls, notably in the one in Ottawa (No. 348 G.S.C., which I would
marginal end ofalso refer to C. flexus), there is a triangular bone filling a corresponding gap at thetwo
the squamosal-parietal suture. This also seems to be in the nature of an epoccipital, or possibly
Triceratops.
fused together, and corresponds to the epoccipital which overlies the end of this suture in
In the Yale skull this element is not in evidence, but the space where it may have been is present in
the type of the species (No. 5239
epoccipitals as the Yale specimen.

A.M.N.H.).

The latter has the same numberof parietal

Crest

The crest or frill differs from that of Triceratofs in several important details. Its general form
from the rear the squamosals form a smaller poris more highly arched transversely when viewed;

there are large fenestrae through the central parietal bone; and normallyposterior
there are two pairs of curious processes arising from the rear of the crest. Of these, theforcurving
other,
each
towardpoint
andcrest,
two are small and hook-like, lie in the plane of the
The
area
form.
in
variablebutoccurrenceintoward their tip. These are seemingly constanttion of the entire area;wardof the crest which lies between

5Lull, R. S., 1908, pp.

388-389.

them is smooth and rounded.

The larger anterior processes areTHE SKULL

35

variable in occurrence as well as in form.
ifcwus has but one, that on the left side.

Generally, there are two, but the type of Centrosaurus
In Lambe's type of Centrosaurus apertus, the right process

only is preserved. This was detached at the time of Lambe's first description and, as it was an
unknown element, he very naturally mistook it for a nasal horn and so described it. Later, it was
fitted into place.
The Yale specimen has the normal two anterior processes. These arise from therear bar of the crest on its dorsal aspect and project forward and slightly downward over the fcnestrae.
They taper to a point, are somewhat curved, and are irregularly grooved or sulcated on their
upper surface. Where the right process is missing in the type, the point where it would normally
have arisen is smooth and shows no evidence of former attachment.
Brown speaks of theseprocesses as being of the nature of the ossified tendons which occur in this group of dinosaurs. The
fractured end of these processes does not seem to bear this out.
Compared with sections of thenasal horn core, the structure revealed is essentially the same, cancellous bone within and a denser
outer layer. In the nasal horn are occasional larger canals which doubtless contained bloodvessels,
for the vascular grooves on the outer surface begin abruptly proximally, branching distally as though
the bloodvessels carrying nourishment to the horny sheath penetrated from within the bone outward,
there to run their course in the external grooves. These are not apparent in the processes, but this is
the only histological difference which I can discern. On the other hand, ossified tendons from thedorsal region of Triceratops brevicornus type (No. 1834 Y.P.M.) are of a very different character,far denser and with a more or less fibrous outer surface.
Brown also suggests that the forwardly
directed processes may have been for muscular attachment. If so, I cannot see what muscles these
could have been, especially as the ends of the processes point downward toward the two large fenestrae through which no known muscle could have passed.
Nor is their direction right for a possible
prolongation of the temporal muscles, which have been shown to have their origin on the upper surface of the crest just behind the supratemporal openings and, passing through the latter, to go downward and forward within the jugals to be inserted into the coronoid process of the jaws.
These processes constitute a sub-generic character, although as we have seen, their degree ofdevelopment varies with the individual, and the forward processes may be asymmetrical to theextent of total absence of one, or possibly both.

Palatal Aspect

The Yale skull (Fig. 5), while admirably preserved on the whole, is somewhat obscure in theregion of the occiput, especially in the lack of clarity of the sutural limitation of the various elements.

The narrowness of the Centrosaurus skull is especially marked in contrast to its contemporary,
Chasmosaurus. Anteriorly, the rostral is well preserved, together with the maxillaries and theircontained teeth, the last somewhat of a rarity especially in the various skulls of Triceratops known toscience.

The precise limitation of the individual teeth is at present obscure, so that the number may

not be told with exactness.

There seem to be about 31 vertical rows, as compared with 35 in thetype of C. fiexus.

The teeth of Centrosaurus are described by Brown as differing from those of Triceratops in thatthe central carina of the enameled crown in the middle rows is relatively higher and the outer curvature of the rows consequently greater.

The rostral, seen from below, is V-shaped, and the sharp, cutting edge is prolonged backward by
the downwardly curved margins of the premaxillaries, although the actual edge is here somewhat
rounded.

No trace of the rod-like vomers is present, although, as Brown says, they must have been

These elements are so extremely fragile that they are preserved in
One case is that of Triceratops serratus No. 970 in theAmerican Museum of Natural History, and the other a skull of Chasmosaurus at Yale (see Fig. 29).

similar to those of Triceratops.

but two ceratopsian skulls so far as I know.

In the C. flexus type the maxillaries are notched for articulation with the anterior ends of the missing
vomers. Were they present, the latter would form "a long narrow bridge dividing the space between•Lull, R. S., 1903, PI. LIX, and Hatcher, Marsh, Lull, 1907, Fig. 26.

THE CERATOPSIA

36

Fig. 5.

—

Palatal view of the skull of Monoclonius (Centrosaurus) flexus,

bo, basioccipital;

dyle;

bs,

f, parietal;q, quadrate;basisphenoid;e,epoccipitals;

ff, parietal fenestra;

qj, quadratojugal;

r,

J>1,

rostral;exo, exoccipital;palatine;

fmx, premaxillary;so, supraoccipital;

1/8 natural size,

mx, maxillary;sq, squamosal ;af, anterior process of crest;

nar, narial vacuity;oc, occipitalff, posterior process of crest;/, teeth;
vo, vomer.

ft,

con-

pterygoid;

the maxillaries into two large vacuities as in Triceratops."'' The region of the palatines and pterygoids is defective, as they seem to be entirely lacking in our skull, but in the type specimen they

resemble those of Triceratops.

The basi- and exoccipitals, together with the condyle, are fairly well preserved, but are deficient in the clarity of their outlines.

This is especially true of the limitations of the supraoccipital.

From the ventral aspect of the skull of the Yale specimen, the exoccipitals appear as wing-like
7

Brown, B., 1914, B, p. 557.

THE SKULL

37

posteriorly by aprocesses extending outward and backward from the occipital condyle, and bounded
posterior tolatter.
Just
thelengthof
thealong
midway
about
wing
wing
to
from
suture crossing(secFig. 5).
supraoccipitaltheHatcherandMarshcalled
by
bone
small
the exoccipitals is a

Beyond this the parietal extends to the posterior end of the crest, at first broad and concave, but
Brown interprets these structures differently, making the supraoccipital
flattening toward the rear.
magnum, the wings of the exoccipitals, and a line drawn transversely
foramena bone bounded by the
between the expansions of the exoccipitals. Behind this is his small parietal, with what he terms thepostfrontal (our parietal) forming the remainder of the middle portion of the crest. Our nomenclathe foramenture, however, is based on the following points: the apparent lack of a suture acrossshouldparietal
the
that
held
been
alwayshas
itfurthermore,magnum defining an extra bone here;
not
do.
does
parietalso-called
Brown'sform part of the roof of the brain case, which

Lower Jaw
(Fig. 4)

The jaws in Centrosaurus are more slender and less massive than in Triceratops.
there is a

Posteriorly,

morehigh coronoid process which curves forward toward its summit into a hook-like processusual,
marked in M. sphetweerus than in the Yale specimen. The main portion of the mandible, as
toextendingsplenial
surface of which is a large
is formed by the dentary, on the lower and innerrising
to
bone
of
plate
the hinder end of the mandible. Externally, the angular forms a triangularlarger than in
about half the depth of the mandible, exclusive of the coronoid, hence relatively
margin of the jaw except
Triceratops prorsus. Above this lies the surangular, which forms the rearlimits arewhere it meets the articular below. The articular is well developed although its external
are two
There
Externally, the modeling of the jaw is characteristic.
not very clearly defined.
the
much
is
upper one
longitudinal hollows, separated by a rounded horizontal ridge. Of these, thewellimpressions,deeper and runs within the coronoid process toward the rear of the jaw. Vascular
are only
shown along the inferior margin of the dentary and angular in the M. sphenocerus type,animal. This is in harmony with
faintly indicated in the Yale specimen, evidently that of a younger
not possess a lower jaw.
the general surface of the skulls as well. The type of C. flexus does

Predentary

The upper
detail.
This bone in Centrosaurus resembles that of Triceratops except for one
Centrosaurus
in Triceratops, but insurface which is defined by two longitudinal ridges is horizontal
resembles the rostral in its
predentary45°.
theExternally,
about
of
an
angle
is inclined outward at
vascular surface.

Hyoid(Fig. 6)

Marsh in

The final preparation of the wonderfully preserved type skull of Triceratops serratus
Museum of Yale University has brought to light a bone hitherto unknown among thethe Peabody
horned dinosaurs and rarely observed in the entire dinosaurian order.
jaw, opposite
The hyoid, if such it is, lies nearly in situ alongside of the right ramus of the lower
as to form a nearly complete
It is of very peculiar form, being sharply curved so
its hinder end.
with the main massthin, blade-like expansion set at an angle of about 35
semicircle, and having a

The general form, seen from below, is shown in Figure 6, together with its position
pair, the articulating[surface being at
relative to the adjacent jaw. The bone is evidently one of aof the bone

moderately sharp edge but is slightly
the end opposite the blade. This articular surface thins out to aIt
the median line of the head.
beyondleftthetowardextends
As it lies, the boneroughenedWith
displaced.
90°
actuallythanratherofangle
anthroughseems, however, to have been rotatedTHE CERATOPSIA

38

the conjectural position of the pair of hyoids relative to the jaws, it will be seen that the bones
If so, the latter must
enclose a space within which the vocal apparatus may have been situated.
have been very large, implying on the part of these animals a voice commensurate with their bulk
and judging from their armament general aggressiveness.
The curved body of the bone, which is unlike any other that I have seen, is provisionally referred——to the basihyal and may constitute half of the first branchial arch.

Fig. 6.

—Hyoidof Triceratop serratus,

No. 1823 Y.P.M.,

y natural2

size,d, dentary;h,hyoid;a,anterior;

f, posterior.

Compared with the so-called thyrohyals of Centrosaurus, the two elements have nothing incommon other than being in each instance portions of the hyoid complex which can be known in its
entirety only through future discovery.

Hyoid elements in the skull of Centrosaurus afertus No. 4519 R.O.M. have been described"Both these elements were discovered in the present specimen with theiranterior ends touching the internal surface of the maxillaries near their posterior extremities, andThe bones are long and slender, the rightthe posterior ends almost meeting in the midline.
measuring 168 mm. and the left (slightly broken anteriorly) 162 mm. in length. The anterior end
outwards.
is somewhat expanded, the upper surface flattish and the posterior end inflected slightly
The under surface is more convex in its anterior portion and this convexity rises into a distinct ridge
near the outer side of the bone less than half way down. This ridge crosses the bone diagonally andby Parks

8

as follows:

terminates on the inner edge at the posterior extremity, thus giving a twisted appearance to the bonewhen viewed from the ventral side. The width at midlength is 1 6 to 18 mm. and the thickness(dorso-ventral) about 12 mm." These bones are comparable to the thyrohyal preserved in a Camp9
The chief difference seems to lie in a decided curvature in thetosaurus skull, No. 1887 Y.P.M.
Camptosaurus bone. Doubtless these bones were homologous elements ; they cannot have been thesame as the peculiar hyoid of Triceratops.

89Parks, W. A., 1921, p. 57.
Gilmore, C. W., 1909, p. 224, PL 9.

THE VERTEBRAL COLUMN
VI R

1

1

39

URAL COLUMN

The vertebral formula agrees with that of Triceratops in that there are 21

presacraland 10In Centrosaurus the number of caudals has been determined by Brown 10 to be 46.
The exact number is apparently unknown in Triceratops. Of the presacrals 7 have heretofore been
described as cervicals and 14 as dorsals. To this Brown takes exception, however, claiming 9 as
belonging to the cervical series and 12 to the dorsal. His arguments will be discussed later.
sacral vertebrae.

Vertebral Formulae

Triceratofs

Centrosaurus

Anchiceratop
Brachyceratop
Protoceratop
Chasmosaurus
Pentaceratop

Cervicals

Dorsals

Sacrals

Caudals

Total

7-9
7-9
7-9

14-12
14-12
14-12

10

45 ?

10

76
77

8

14 ?

6

7?

13

7-8

7-9
7-9

14-12
14-12

10

46
38
50
45
45

10

28+

?

10

67
78
72
76
59

+

Coalesced Cervicals(Fig. 7)

Centrosaurus conforms with the rule in the Ceratopsia, in having the three anterior cervicals
Each of these vertebrae bears a neural arch and the second and third

coalesced into a single mass.

Fig. 7.
of axis;/,—Anterior cervicals of Monoclonius (Centrosaurus) flexus, J4 natural size,intervertebral foramen;
facet;
if,p, posterior zygapophysis;h, capitulara,r,anterior;rib;s,f, posterior;

as,

spine

spine of third cervical;

tubercular facet.

a spine which as in Triceratops is bent sharply backward.

The axial and third spines, although fusedthroughout, are distinctly defined in the distal half, and their summits are broadened transversely.
In the Yale Centrosaurus the neural arch of the atlas arises as a rather heavy plate a little
forward of the center; in Triceratops it is seemingly lighter and arises farther back. The upper
outline of the neural spines is lost, but the intervertebral foramen between the axis and the third
10

Brown, B., 1917, p. 289.

THE CERATOPSIA

40

vertebra is elliptical in shape and is relatively longer and lower as

form in Triceratofs.

compared with its nearly circular
.

,.

.,

11
apparently dividContrary to the descriptions of Marsh and Hatcher, Lull recognized a sutureof three. To
insteadvertebrae
coalescedfour
described
hewhich
ing the atlas, on the strength ofMuseumAmericaninthespecimens
Monoclones
four
that
the
this Brown takes exception, claiming
markedclearly
divisionsvertebral
three
only
show
Triceratofs,
collections, and also a specimen ofagreement
with
also
in
am
now
spines.
I
andarches,neuralby the point of union of the vertebrae,
in
not
only
visiblemarkingissuturalthe
Nevertheless,
Marsh and Hatcher as well as with Brown.
beensughasIt
specimen.
Centrosaurus
Yale
the
in
the Triceratofs frorsus type at Yale, but also
which would thengested that the portion of the atlas in front of this suture may represent a proatlas,

accepted three.
not increase the number of vertebrae in the coossified part beyond the generally
practically indismatrix
withfilled
it
is
end,
as
The neural canal cannot be traced at its anteriorHerethe canal has aclear.
outlineisthe
Posteriorly, however,tinguishable from the bone.
triangular section, broader at the base than on either side.
The articular face for the reception of the occipital condyle is a hemispherical cup, practically

There is little if any flattening above or below until near the
In Triceratofs there is a dispoint where the axis and atlas meet, where the former is flattened.
not evident, or very
tinct, median, fore and aft groove on the inferior face of the axis which iscircular in outline, as in Triceratofs.

Laterally, the lower half of the centra of the axis
slightly so at the anterior end, in Centrosaurus.
and third cervical in Centrosaurus is constricted, much more so than in the axis of Triceratofs, cervical
The junction of the second and third is narrower below than in
III in each being more alike.
12
are slight
Triceratofs, and, if one may judge from Hatcher's figure, than in M. crassus also. There
Monoclonius
prominences on either side of the atlas in the Yale specimen suggestive of those in

no real evidence of an atlar rib such as Hatcher assumes for the latter. These
prominences, or at any rate the inferior ones, are lacking in the Triceratofs frorsus type, which is
crassus, but thereisexceptionally well preserved.
The posterior face of the centrum of the third cervical is concave in the Yale Centrosaurus andcrassus, according to Hatcher,its transverse diameter exceeds the vertical, the reverse being true in M.

although, as he says, the proportions have been much altered by crushing.
Cervicals I-III of the Yale Centrosaurus as well as of a specimen of Centrosaurus afertus,
4519
Toronto, are very different in general appearance from those of the M. crassus type,No.
inthe greater elevation of the neural spines, the fore and aft length of the third cervical,
especiallyand the general proportions of the entire mass.

Cervical IV

As it is now preserved, the centrum is opisthocoelous with the anterior face flat, the posterior
one concave.

The anterior aspect is almost pentagonal, but the ventral angle fades out posteriorly.

The lateral sides are concave. Part of the right rib is present, consisting of both capitulum andtuberculum. The cervicals differ only slightly from those of Triceratofs, except for size.

Cervicals V and VI
Cervicals V and VI (Fig. 8), evidently pathologic, are coossified, with no visible sign of division
between the centra. The neural arches are, however, normally distinct. The centra have a flattened

lower aspect and no decided constriction on their lateral faces. The articular face of the fifth ishexagonal while the posterior face of the sixth, as preserved, is nearly quadrangular.

11

12

Marsh, Lull, 1907, p. 47.
Hatcher, Marsh, Lull, 1907, Fig. 78.

Lull, R. S., in Hatcher,THE VERTEBRAL COLUMN

41

az

Fie. 8.

—az, anterior
Cervicals V and VI, coalesced (pathologic), of Monoclonius (Centrosaurus) fiexus, ]4 natural size,/, tubercular facet.
/, neural spine of 5th cervical;

zygapophysis ; h, capitular facet; fz, posterior zygapophysis;

Measurements of Cervicals
IV
68.6 mm.

THE CERATOPSIA

42

Cervical IX(Fig. 9)IX corresponds more nearly to Hatcher's figure. In this bone the centrum is stillbiconcave, with the sides more deeply constricted than in M. crassus. The centrum is more evenly
Cervicalrounded, lacking the flattened lower surface seen in cervical VIII.

The neural canal is still large

az

Y.PM. 20J5

az, anterior
natural size,
Cervical IX of Monoclonius (Centrosaurus) fiexus. Left lateral, and anterior views, Y\
s, neural spine; t, tubercular facet.
zygapophysis;
posteriorcanal;
neuraln,fz,
zygapophysis; d, diapophysis;

Yic. 9.

and somewhat triangular in section except for a rounded apex. The capitular facet is hardly
diapophysis.
but is still borne on the centrum, while the distinct tubercular facet lies at the end of thevisibleDorsal Vertebrae

One marked peculiarity of the dorsal vertebrae (Fig. 10) of this specimen, which may be amore backward slant of the spinous processes as compared either with
M. crassus or C. naskomus (Figs. 11, 12) in which they are more nearly erect. This_ involves thein dorsal VI
entire neural arch and becomes more marked in the posterior vertebrae, especially

specific character,

is

the

In the Yale specimen the lateral constrictions are also deeper. The diapophyses aretriangular in section, with the base of the triangle uppermost and the other sides concave.
(see Fig. 13).

K P.M. 2015

Fig. 10.

—

zygapophysis;
spine;/,

anterior
Dorsal II of Monoclonius {Centrosaurus) flexus. Left lateral, and anterior views, /i natural size, az,zygapophysis; /, neurald, diapophysis; h, capitular facet; n, neural canal; f, pleurocoele; fz, posterior

tubercular facet.

lTHE VF.RTEBRAL COLUMN

4.3

az

az

h
AM.NM.555l

Fig.

1

1.

—Rightaspect of cervical(Centrosaurus)

clonkts

nasicornus,

J4/,cloniusnatural size.

az, anterior zygapophysis; h, capitular facet;spine;Fig.

IX of Mono/,

12.

—Right{Centrosaurus)

aspect of dorsal 11 of

nasicornus,

az, anterior zygapophysis;

neuralof succeeding vertebra;

tubercular facet.

/,d, diapophysis;
/,

size.

zygapophysisaz', anteriorfz, posterior zygapophysis;
tubercular facet.

facet;

Mono-

natural}4h, capitularneural spine;

Dorsal VI(Fig. 13)This vertebra differs greatly from that figured by Hatcher as a posterior median dorsal vertebra
constrictedof M. crassus. The centrum has flattened articular faces but, viewed laterally, is deeply
facet
is now on
capitular
and in addition has deep pleurocoeles in the upper half of each side. The

az

Y.P.M 2015az,
Anterior and right lateral views, 34 natural size,
Dorsal VI of Monoclones (Centrosaurus) fiexus.
zygapophysis;
posteriorpleurocoelc;
canal;fz,
f,anterior zygapophysis; d, diapophysis; h, capitular facet; n, neural/, tubercular facet.
s, neural spine;

F, r

.

1

3

THE CERATOPSIA

44

The latter is strong and well develnarrow, but of considerable fore and aft extent, and slightly

a level with the zygapophysis at the base of the diapophysis.

oped, and the spinous process

is

flat,

expanded distally. The lateral aspect of the bone is peculiar as the entire complex of processes arises
above or behind the pedicels in marked contrast to any other Centrosaurus species. The zygapophyses
are large and strongly buttressed while the neural canal is much smaller than in cervical VIII, so
that behind the brachial enlargement the spinal cord was slender, in fact very slender for an animalof this size. In Monoclontus crassus the equivalent vertebra is more erect and lacks the backward
offset and angulation of the processes.
The zygapophyses are confluent as in M. crassus. The neuralarch is higher than in presacral VIII and is somewhat constricted above the neural canal.
In itsanterior aspect the Yale vertebra resembles that of M. crassus but differs markedly when viewed fromthe side.

Height of centrum, anterior face

Measurements of Dorsal VI
M. crassas
No. 3998 A.M.N.H. 16
97.0 mm.

Width of centrum, anterior face
Length of centrum

Width across pedicels
Vertical height over all

Width across diapophyses
Length of spinous process
Neural canal height, anterior end
Neural canal width, anterior end
Length over zygapophyses(Figs. 14, 15)

In this vertebra the centrum is somewhat wedge-shaped, when viewed from the side (possibly
due in part to crushing, although otherwise there is no evidence of it). The anterior face is nearlyplane (but the rim is partly eroded), the posterior face concave. Lateral pleurocoeles are present in

5

THE Yl'RTF.KRAL COLUMN45

the upper part of the centrum. The zygapophyses arc confluent, the anterior pair forming a V-shapcd
1'hc posterior sulfates arc smaller and nearlysurface which looks upward and somewhat backward.
horizontal, with a slight division between the two halves, which look slightly outward as well as
downward. The diapophyses are broad fore and aft and flattened. The capitular facet, one-third of
the way out on the anterior border, is buttressed by the prezygapophysis.

The tubercular facet is

az

Y\ G

.

1

5.

—Rightlateralphysis;terminal.

view of dorsal IX of Monoclones (Centrosaurus) nasicomus, J4 natural size,
A, capitular facet;fz, posterior zygapophysis;s,neural spine;/,az, anterior

zygapo-tubercular facet.

The spinous process arises behind the pedicel so that its anterior edge is about over theposterior margin of the neural arch. It is flattened and its antero-posterior diameter is nearly twice
median ridge rises from the
The thickness of each is about equal.
that of the diapophyses.
neural canal to the junction of the zygapophyses. In this, as in the general form of the latter, theA

and the depth of the lateral pleurocoeles, the19vertebra differs markedly from that of M. crassus figured by Hatcher.
offset to the rear of the base of the spinous process,Measurements of Dorsal IX
Centrum, length at top
Centrum, width of anterior faceCentrum, height of anterior face10

71.0 mm.
97.5
7°.

Width over diapophyses
Width over capitular facets

244.0

Length of spinous process

166.0

Neural canal, height of anterior end
Neural canal, width of anterior end

25.0

Hatcher, Marsh, Lull, 1907, Fig. 79.

114.4

13.0

;

THE CERATOPSIA

46

Dorsal XI(Fig. 16)This vertebra shows the following characteristics: centrum constricted at mid-length; pleuroanterior face nearly plane, posterior one deeply concave; prezygapophyseal facets
confluent and nearly horizontal; postzygapophyseal facets forming an angle of 90° with each other.
The latter are well below the former, and well behind the centrum as in the preceding vertebrae.
The capitular facets are situated about one-third of the way out on the anterior edge of the zygapophyses. From them a groove extends outward on the anterior edge to the end of the diapophysis forcontact with the rib.
The spinous process is plain, slightly tapering, and slanting well backward.

coeles fairly deep;

Y.P.M. 2015

Fig.

16.

—

Dorsalanterior zygapophysis;s,neural spine;t,

XI of Monoclonius (Centrosaurus)d,diapophysis;//,

capitular facet;

flexus.

az,
Anterior and right lateral views, Y\ natural size,
fz, posterior zygapophysisf, pleurocoele;n, neural canal;

tubercular facet.

Compared with Triceratofs, the vertebra in question differs in the shape of the centrum, when viewed
from the end, that in Centrosaurus being more nearly circular and that in Triceratofs somewhat
pear-shaped. In Triceratofs there is less slope to the neural arch and spinous process. The general
proportions of the zygapophyses and spinous process are somewhat similar, but the surface for conThetact with the rib between capitular and tubercular facets is much less marked in Triceratofs.
latter has no pleurocoele.

Measurements of Dorsal XI
Centrum, length at top
Centrum, width of anterior faceCentrum, height of anterior face

67.5 mm.
100.0

Width over diapophyses
Width over capitular facets

253.0
115.0

Length of spinous process

140.0

Neural canal, height of anterior end
XTirj
Neural canal, width of anterior end

16.0) .„..
in 5i C ill preserved outline
Ay
)

,

•

,

78.0

,

,

.

Sacrum(Fig. 17)

The sacrum in Centrosaurus, as in all of the later Ceratopsia, consists of ten coalesced vertebrae.
The spinous

To these is added a dorso-sacral, coossified with the sacrum above but free below.

processes, including that of the dorso-sacral, have become fused into a solid bar, the original limits ofTHF VFRTFRRAL COLUMN

47

the individual processes being for the most part indistinguishable in the present condition of the Yale
specimen. The spinous processes are low and their superior margin is essentially straight throughout
the first five sacrals, beyond which the individual summits are restored in such a way as to give a

saw-tooth outline, as viewed from the side. Whether or not this restoration is correct is difficult todetermine, for in the C. nasicornus sacrum the spines are entirely obscured by the ossified tendons;

Y.P.M. 2015

F, c

i7_

—Sacrum and

ilia

of

Monoclonius (Centrosaurui)

flexus.

Dorsal view,ax, anterior zygapophysis of dorso-sacral vertebra;•/£

natural size,d, diapophysis;

il,a, anterior;f, posterior;

ilium.

and in C. cutleri the posterior
In the Yale specimen, the zygapophyses and spinous process of
The zygapophyses are well indicated only
the last sacral are distinct, the latter being isolated.
fortheprezygapophyses of the dorso-sacral, they
exceptotherwise,sacrals;two
last
between theslightly
upward (from the horizontal) from theslopediapophysesThe
fused.
are thoroughlyIV, and least at X. The diapophyses
highestat
sacral
being
of
slope
angle
the
outward,neural archand the anterior edge is deflectedfollowing
immediately
than
the
two
heavierareof the dorso-sacraland flat, but reach the bladearerathernarrowIII
andsacralsofDiapophyses
sharply downward.
below to meet the pubic
heavily
buttressed
and
wider
III
is
sacralofthat
whereasof the ilium,from the third sacral
Triceratops
ariseswhichinparapophysis,thebuttressislowerpeduncle. This
fusedwith the diapophysis
and
is
not
backward,
deflected
thesecond,isagainstalthough bearing also
secondsacralandsweeps backward
from
the
arise
seems
to
parapophysis
theabove. In Centrosaurus,
Contrary
Triceratops,
para- andIII.
tosacralcentrumoftheoppositepeduncleisso that the pubic
agrees
with
the
Yale
specimenincrassus
type
of
M.
The
sacrals
III-IX.
indiapophyses are fusedbaracetabular
which
abuts
against
the
form
the
III-VIofparapophyses
Dia- andthis respect.
acetabulum, agreeing with Tricerato-ps. The parapophyses in the rear of the acetabular bar are thinin theM. crassus type the summits of the spines are broken away;

summits are separate, but in line.

THE CERATOPSIA

4g

buttresses of bone which, together with the diapophyses,of them meet the ilium except those of sacral X.

form a T- or L-shaped cross section.

All

The sacrum of C. cutleri type differs from that of the Yale specimen mainly in the forward

dorso-sacral is a slender boneextension of the ilia in front of the sacrum. In both, the rib of theribs in C. cutlen also
fused with the under side of the blade of the ilium near its anterior end; theseshow that the ilia incurve forward much more than they do in the Yale specimen, which seems to
do notdiapophyses of sacral
both specimens are essentially complete. In the Yale specimen thepelvesbetweenthemeet the ilia, in C. cutleri they do, as seen from below. The visible differences
preservationis
To what extent they are due toof the Yale Centrosaurus and C. cutleri are slight.
areperhaps sexual variations, andnot clear. They are otherwise perhaps accountable as individual,
value.
hardly of specificX

Measurements of the Pelvis
C. flexus Y.P.M.

C. nasicornus

Length of entire sacrum over zygapophyses, including dorso-sacral

840 mm.

800 mm.

Width over anterior diapophyses
Width over diapophyses of IV
Width over diapophyses of VII
Width over diapophyses of X
Width across ilia, anterior end
Width across ilia, over ischiac peduncle
Width across ilia, posterior end

252
237
276
226
75i
630

Length of right ilium, as preserved
Length of left ilium, as preserved
Length often sacral centra

960
968

1060

™3
322

Width across acetabular bar at pubic peduncle
Length of ilium in C. cutleri (estimated from photograph )

~~

1 1

24

18) that the dorso-sacral is clearly differentiated from the sacrum
separated from sacral I by atproper, for here the centrum is free from the following ones, being
centra, although the line
sacraltennormally
There areleast 1 6 mm. of matrix at its lower margin.
present condition of theintheindicatedof demarcation between the ninth and tenth is not clearly
Yale specimen. In the C. cutleri type all are distinct.
The centrum of the dorso-sacral is constricted medially but possesses no pleurocoeles. Ventrally
and aft. The parapophyses are distinctly indicated and are
it is flattened and but slightly concave fore
coossified with the
fused with the horizontally flattened diapophyses which, at their distal ends, areproximally abutwhich
In addition, the dorso-sacral bears a pair of slender, slightly curved ribs
ilia.
these ribs
Distally
line.
against the slightly dilated end of the parapophyses, with which they are in
marginof thecurve slightly forward and unite with the ilia below and a little behind the anteriorthe
tip isthe ilium, but
as preserved. On the left side, the rib extends to the outer margin of
It is only from below (Fig.

lattercentra of sacrals I-III
not present and may have jutted slightly beyond the limit of the ilium. The
Numbers V-VII areare broad, and flattened inferiorly, being somewhat trihedral in cross section.
Sacrals VIII-X widen again, the median constricdistinctly narrower and are constricted medially.
III is a deep median groovetion disappearing in the last. Beginning about the middle of centrum
but can still be seen at the
however,
out,
fades
soon
It
IV.
part
of
anterior
which is deepest in the
II and extends the entire
centrumwithbeginsgroovethisTriceratofs
In
union of VI and VII.
markedin the Yale Centrosaurus.
most
also
it
is
where
II-IV,
inwidestlength of the sacrum, being
ninth,
the inferior surface ofwiththeterminating
andfourththewithcommencing

In M. crassus,
marked at the junctions
the sacrum is broad and shows a median shallow groove somewhat moreand M. crassus^
Triceratofs
both
from
differs
therefore,
specimen,Yale
Theof the several centra.
The C. cutleri
shorter.
noticeablyiswhichgroove,medianventralin the fore and aft limits of thetype is more like M. crassus in this respect.

THE VERTEBRAL COLUMN49

The heavy parapophyses which support the pubic peduncle arise on the side of centrum II, butbear equally on II and III in the form of a triangular web of bone which covers the entire length
The second, third, and fourth parapophyses arise at the junctions of centra IIIof each vertebra.
The second and third sweep backward to join the acetabular bar while the fourth
to VI inclusive.
buttresses the ischiac peduncle and is perpendicular to the axis of the sacrum.

This is especially true

Y.P.M20I5

Fig. 18.
terior;r,—Sacrum andacb, acetabulum;

iliaof Monoclonius {Centrosaurus) flexus.

ds, dorso-sacral vertebra;

rib of dorso-sacral vertebra;/'/.ilium;

Ventral view,if, ischiac

peduncle;% naturalsize,

far, parapophysis ;a,anterior;

f, pos-ff, pubic peduncle;

I-X, sacral vertebrae.

of the right half of the sacrum, as Figure 18 shows. In all of this, the Yale specimen agrees essenIn the last, the form of the first
tially with M. crassus and to a less extent with Triceratofs.
parapophyses differs in that they arise almost entirely from centrum II and do not have the tri-

angular shape as seen from below, being more nearly cylindrical and somewhat dilated distally. The
parapophyses of V to VII in Centrosaurus arise opposite the junctions of centra VI to IX. Number V
Number VI is somewhat
is narrow fore and aft and forms a triangular buttress to the diapophysis.
Parapophyses of VII to IX are broadened
less deep but wider, while number VII is the widest.
arises apparently in the middle of the centrum instead
distally and fuse with the ilia. That of sacral
This is in agreement withof at the junction with the one before, and does not reach the ilium.
Trkeratops. The acetabular bar, formed by the fusion of parapophyses 1 to IV, unites with theilium, but with a distinct suture, and forms part of the acetabulum. Both pubic and ischiac peduncles

X

are thus formed in part by the sacral and in part by the iliac elements.

Caudals
Except for a few proximal vertebrae and other scattered centra, the caudal series and theirchevrons in the Yale specimen of Centrosaurus have been restored from the type of C. nasicornus of
the American Museum. Brown's description of the latter follows: "The caudal series is completeTHE CERATOPSIA

50

of the anterior caudals
and is composed of 46 vertebrae including the minute terminal centrum. 23
The centra and spines of the caudal series decrease in size uniformly
bear transverse processes.
not have a spine. The
from the last sacral vertebra down to the 45th. The 46th apparently does
than high, slightly cupped on the anterior
centra of the last 12 caudals are proportionately longer
these last 12 vertebrae are likeend with a corresponding ball on the posterior end and the spines ofwise elongated anteroposteriorly.
20of the corresponding chevrons."

The spines in the caudal series are in height equal to the length

APPENDICULAR SKELETONCORACOID(Fig. 19)that the transverse diameter isBoth coracoids are present, the left being somewhat crushed sonormally. In the Yale specimen the coracoids are notlessened and the bone is more concave thanolder individual such as the Monoclonius crassus type
an
in
be
would
the scapulae as they
fused with

Monoclonius (Cen/rosaurus) fiexus, 1/6 natural size,
FlG- 19 —External view of right scapula and coracoid ofs, scapula.
cf, coracoid foramen; g, glenoid fossa;
20 Brown, B.,
1917, p. 289.

c,coracoid;

THE SCAPULA
figured by Hatcher.

21

51

There, the fusion is complete although the suture is still visible.

The form

01 both coracoids and scapulae in the two species is very similar and the size approximately the same.

The external surface of the coracoid is somewhat coin ex except toward the scapular surface andwhere the bone thickens rapidly and as a consequence becomes concave.
The outline agrees with that of M. crassus, having thesame posterior hook-like process. Hatcher describes the coracoid foramen as midway between theanterior and posterior borders, directly opposite the point where the coraco-scapular suture joins the
glenoid surface.
Internally, the foramen opens at the coraco-scapular suture.
Externally, thecoracoid of the Yale specimen agrees; internally, however, the right coracoid (restored) shows theforamen about 20 mm. away from the suture. The left coracoid is more in agreement and is probably
the more correct. There is no essential disagreement with Centrosaurus nasicornus.
that of the glenoid fossa,

The internal surface is concave throughout.

Scapula(Fig. 19)

The scapulae agree with Hatcher's description of M. crassus. The external surface is convex
longitudinally, although tending to straighten toward the distal end.
The inner surface, concave
longitudinally, is deeply so transversely, especially at the proximal third.
Hatcher says that thecoraco-scapular suture just about bisects the glenoid fossa; with our specimen the greater part of
the fossa is formed by the scapula, the lesser by the coracoid. The scapula dilates at the fossa, andis heavy at the proximal end, thinning out at the distal end of the blade.
There is in each case aslightly rugose area just above the glenoid fossa

from which a low (Hatcher says prominent 22 )ridge extends obliquely outward toward the anterior edge at the distal end.
In Triceratops, thisridge arises in the same manner, but curves at about one-third of its length in such a way that it

terminates at the middle of the distal end of the blade instead of toward its anterior edge. The
scapula of the contemporary Chasmosaurus agrees with that of Centrosaurus in this respect, whereas
the ridge in the Edmonton genus Anchiceratops does not reach the anterior border and tends toward
the condition found in Triceratops, thus showing an evolutionary trend.

Dimensions
C. flexus Y.P.M.

Coracoid

365 mm.
217

Antero-posterior diameterTransverse diameter

M. crassus
336 mm.
176

Coraco-scapula
Over-all length

810

840

Sternum
Additional morphological data concerning Triceratops, learned since the writing of the CeraMonograph, include but three items, the sternal plates, a hyoid element and the complete

topsiaThe first were actually made known before the publication of the Monograph but the descripOur knowledge of these elements is based upon the discovery of apes.

tion of them was not included.

very imperfect Triceratops skeleton, without skull, found by the American Museum of Natural
History expedition of 1902 in the Hell Creek region of Montana, about a mile from the locality
23of the T. serratus skull (No. 970 A.M.N.H.) described by the author
in 1903.
21

22
23

Hatcher, Marsh, Lull, 1907, Fig. 84.
Hatcher, Marsh, Lull, 1907, p. 79.
Lull, R. S., 1903.

THE CERATOPSIA

52

24

These sternal plates have been figured and described by Brown.
They "are paired, elongate,
and symmetrical except where distorted by crushing. One end terminates in a point which is
restricted and enlarged with the rough portion most extensive on the visceral surface, and stands
away from the body of the plate. The opposite end is thickened and rugose at the outer angle but
thins rapidly toward the inner border which is very thin and nearly straight.
The outer border isthickened, smooth and slightly concave. The ventral surface or outside of the plate is convex transversely while the dorsal or visceral surface is concave. Both are smooth. A deep incision on thevisceral surface near the broad end of each plate may represent a foramen or a deep ligamentous
attachment." Apparently "the pointed end extended forward with the enlarged point attached tothe terminal curved portion of the coracoid.

When placed thus with the thin inner borders meeta.

Y.P.M. 2075

Fig. 20.

—

Sternals of Monoclonius {Centrosaurus) flexus.

Ventral view, 1/6 natural size,a,anterior;-p,posterior.

ing in the median line the width of the body cavity is determined at this point and the position of
the coracoids is approximately fixed. ...
In the Jurassic Dinosaurs, Brontosaurus, Morosaurus
and Di-plodocus, the sternal plates were firmly united in the median line by cartilage as indicated by
the long straight rugose inner border. But Triceratops presents an entirely different type of sternumin which the median borders of the sternals as well as the body of the plate are extremely thin and notcoossified.

clavicle.".

The deep anterior emargination of these plates indicates the presence of an interSubsequent, very complete ceratopsian skeletons have not, however, disclosed this ele.

.

ment. "The external third of the plate is thick and formed its chief strength, while the uniformly
smooth surface shows that there was no lateral attachment of cartilaginous ribs as in the Ratitae.
This rib attachment was clearly formed at the posterior end of the plate, probably direct without the intervention of a xiphisternum, for the thick posterior end seems subdivided as for rib
attachments."

The two sternal bones of Centrosaurus flexus (No. 2015 Y.P.M.) (Fig. 20) do not appear to
be mates, as they differ so markedly in contour, and in color and general appearance, doubtless as
The left, which is much the shorter of the two, retains
apparently more of the original form, as there is little restoration on it. To what extent its outline
a result of conditions of preservation.

eroded away can not be determined. It is in essential agreement with the sternal in Triceratops
and in C. nasicomus except for an emargination of the inner border, where the bone is extremely thinand may therefore have lost some of its former extent. The right, however, is relatively longer andnarrower and lacks the emargination, so that in this latter respect it is in closer agreement with
Brown's figures. It resembles that of C. cutleri except that the distal end is not so wide.
is24

Brown, B., 1906, pp. 297-300

1

THE FORK I.IMH AND FOOT53

The sternals of 67. naskonius, according to Brown,"'' consist "of two broad flat plates, each plate
having a thick external border and a thin internal border for articulation with its mate. The anterior
1

end is thickened on the external border for articulation with the process of the coracoid, while thedistal end is thick and shows on the ventral surface indentures for the attachment of the cartilaginous
These indentures are not recognizable in the Yale specimen. "The dorsal surface of eachribs."
plate is flat and the ventral surface is marked by a low ridge that extends from the proximal to the
There was probably no intermediate cartilaginous element."
distal end near the outer border.
Dimensions of Sternals

Lengthratofs

67. flexus

C. nasicornus

67. cutleri

No. 2015 Y.P.M.

No. 5351

No. 5427

No. 97

left

right

A.M.N.H.

A.M.N.H.

A.M.N.H.

318 mm.

354 nun

330 mm.

450 mm.

580 mm.

129
159

107
140

110
160

110
180

Greatest width

Proximal end
Distal end ....

220
(at middle)

Y.P.M. 2015

Fro. 21.

—

Left humerus of

Monoclones (Cen/rosaurus)d, deltoid ridge;

h,

head;

r,

flexus.

radial crest;

A, external view; B, internal view;
condyle; tic, ulnar condyle.

1/6 naturalsize.

re, radial

Humerus(Fig. 21)
restoration,
Both humeri in the Yale specimen are comparatively well preserved, with little
withessentiallyagreeshumerusleft
though the right one is somewhat distorted by crushing. The
25

Brown, B., 1917, p. 292.

THE CERATOPSIA

54

a heavy bone with a very
Hatcher's description of that of Monoclonius crassus™ The humerus is
more than halfway
extends
andcrest
radialprominent deltoid ridge which is continued into the
distinct apparquite
rugosity
separatebears
atoward the distal end. In Triceratofs the radial crest
combine moretwotheCentrosaurus
includingently from the deltoid ridge, whereas in Monoclonius
eminence
hemisphericalalmostsmall,or less into the deltoid ridge. The head is a comparatively
tothe shaftanglesright
atbackward
which lies within the median half of the proximal end and looks
In thisposition.
inhorizontal
been nearlyof the bone, so that the humerus during life must have
head
the
which
in
Triceratofs
that ofrespect it agrees with that of Chasmosaurus, but differs fromshoulderoftheangulation
normalseems to merge into the summit of the bone, implying that thewas greater than a right angle.
of the head or the
Another crest comparable to the deltoid ridge lies on the extensor side
Distally,
the trochlear end
humerus but continues little more than half as far as does the former.
again there isHerethe more prominent.
of the humerus is well developed, the radial condyle being
habitual.
indication that extreme flexion of the elbow joint wasunder discussion and that of M. crassus
humerusthebetweendistinction
any
There is little iffrom Triceratofs in its greater slenderexcept that the latter seems more robust. It differs markedly
end.
proximaltheofconformation
ness and especially in the
Dimensions of Humerus

M. crassus

C flexus.

No. 2015 Y.P.M.
left

585 mm180

LengthWidth across radial crest-

Least width of shaft

Width across trochlear end

195

Length of deltoid ridge and radial crest

275

A

B

—

,

THE FORE LIMB AND FOOT

55

Ulna
(Fig. 22)

The general character of the ulna is not unlike that of Triceratops except that it is much lessrobust, and the olecranon process, as preserved, is much less pronounced, occupying little more than
one-third the total length of the bone, whereas in Triceratops, measured in the same way, it is about
one-half. The ulna of Centrosaurus has a somewhat curved shaft, flattened distally. As preserved,
there is a longitudinal hollow on the inner face and a corresponding low ridge on the outer face which
disappears in the distal third of the bone. Proximally, this ridge culminates in a high crest which,

together with the anterior margin of the bone, bounds a deep depression to receive the proximal endof the radius. The olecranon seems to be defective as it does not begin to show the massiveness ofthat of Triceratops, either relatively or actually.

Dimensions of Ulna
C. flexus Y.P.M.

,

Length over all

—

left

right

C. nasicornus

437 mm.

457 mm.

450 mm.

Greatest width'56

Proximal end
Distal end

96-5

Radius(Fig. 23)

Both radii are fairly well preserved, especially the left. The radius is a slender, slightly curvedbone dilating proximally to form the humeral facet, the superior aspect of which is concave to receive
somewhat flattened. At mid-shaft, on
the radial condyle of the humerus. Distally, the radius isareas occur for muscle attachment.
roughened
Severalsection.
inthe other hand, it is trihedral

Y.PH 2013

Fig.

23.— Left radius of Monoclonius (Centrosaurus) flexus.
extremity;f, proximal

A, posterior view;d, distal extremity.

B, anterior view, 1/6 natural size.

THE CERATOPSIA

56

Dimensions of Radius
345 mm.

Length over all
Greatest proximal width

83

Greatest distal width

99

Manus
(Figs. 24, 25)

The left manus is almost entire, including the two carpalia, only five phalanges being missing
The right manus, on the contrary, contains but two actual bones.

and these have been restored.

The bones of the manus differ very little from those described by Brown for C. nasicornus.
Distally, the metacarpals are rugose, implying, as Brown has said, considerable cartilage there
as well as in the wrist, where but two small osseous

elements were apparently present.

These evi-££^.

YPM.2015

24.

Fig.

—

Anterior view ofleft

Motwclonius {Centrosaurus) flexus, 1/6c,carpals;

m, metacarpal;

fore

foot

of

natural size.

x
f -f*-> phalanges;

I-V,

—

Lateral view of left fore foot ofFig. 25.
Motwclonius (Centrosaurus) flexus, 1/6 natural size.
c,carpals;

m, metacarpal;

second phalanx;

digits.

1

f ,

first

phalanx;f,digits ///, IV, V.

dently pertained to the distal row of carpalia. Of these the larger has more or less smooth
one-half the bulk
surfaces, otherwise it is deeply pitted and irregular. The lesser carpal has about2
the larger
manus
of
the
restoration
Brown'sInofbone.
nodulea highly irregularof the latterofspecimen
In
the
III.
over
smallertheIV,metacarpal
carpal lies over the proximal end ofsitu,
inarticulatedbones
skeletal
the
all
with
found
Anchiceratofs in the Ottawa museum, which wascorroborates
the carpalia correspond both in number and position to those of Centrosaurus, whichIV, thecarpalrepresents
probablylargerThe
Brown's description of what and where they were.
opposite—

smaller carpal III.
As the measurements show, the manus of the two specimens, C. nasicornus and C. flexus (Yale),average about the same size.
The phalangeal formula was 2, 3, 4, 3, 2. Flattened ungual phalanges were borne on digits
in bearing the
I-III, those of IV and V being reduced to nodules only, but digit IV must have aided
enclosed in awas
footentireThe
extent.
creature's weight and perhaps also digit V to a lesser
protruded indigitshoofedthree
theelephant,
weight-absorbing cushion although, unlike that of an.

front as our restoration (PI. II), based in part on footprints, shows.

28

Brown, B., 1917, PI. XII.

C. nasicormt'

THE CERATOPSIA

58

Fig. 26.

—Righti,pubis and ischium of Monoclonius (Centrosaurus) flexus, viewed from the inner surface, 1/6 natural size.
facet for articulation with pubis; ff, postpubis.
il, facet for articulation with ilium;f, pubis; fb,

ischium;

Ischium(Fig. 26)

The proximal halves of both ischia are present in the Yale specimen, with clean-cut breaks.
As preserved, they seem to agree more nearly with C.

cutleriand Monoclonius crassus

in being

In the latter, the shaft, viewed from the side, has an almost uniform
distally,
whereas in C. cutleri the bone is straighter until the extreme end
curve, increasing somewhat
straighter than in C. nasicornus.

reached, when the curve is very marked and the end dilated, recalling the hammerhead-like ter30
Chasmosaurus (PI. XIV, B), as
mination seen in the crested trachodons of the Belly River.
is more like Triceratofs
nasicornusC.
while
mounted in Ottawa, also possesses this type of ischia,
to the several
belongingischiathebetween
Proximally, there is little distinctionin this respect.

isCentrosaurus species.

The surface for articulation with the pubis is smaller and lighter than thecontinued into a rugose area on the outer aspect of the bone.
corresponding rugosity on the outer aspect of the pubis.

iliac

facet,

whichisThere is a

Dimensions of Ischium
C. flexus Y.P.M.

250.0 mm.
35.0

Width across proximal end
Least diameter of shaft

peduncle to end (measured on curve), estimated30

C. nasicornus

mm.

mm.

57.5

Greatest diameter of shaft
Iliac

C. cutleri

....

770.0

800.0

740.0

This feature Nopsca (1929 B) considered indicative of the male sex, those which did not possess it being females.

Unfortunately for his argument, however, all known specimens of the Lance genus Trachodon would be females!

THF. HIND LIMB AND FOOT

59

A

V
/v

/,,

/

Y.P.M.2015

OCp, c< 27.

—Left femur(V,of Monocloniui (Centroiaurui) fiexus.

inner condyle;of, outercondyle;r,

A, internal view; B, external view, 1/6 natural size.
/", 4th trochanter.
/' lesser trochanter;h, head;great trochanter;

Femur(Fig. 27)

The left femur in the Yale specimen is entire, but quite badly crushed from side to side,
The head is also eroded, so that its dimensions do not equal thoseespecially at the distal end.
Hatcher figures butof the right. The latter has the great trochanter and the distal end restored.
does not describe the femur of M. crassus, for he found none among the bones corresponding to
Cope's original description, as they are too long and, according to Hatcher, out of proportion to
the tibia."

The femur of the Yale specimen resembles the figure of M. crassus except that it appears to beThis may be due in part to the fact that the two bones are crushed differ-

relatively more slender.
31

Judging from Hatcher's
tibia :: 7.4 6.
i.e., femur::

figures(1907, Fig. 86), however, the proportions are about the same as in C. naskornus

THE CERATOPSIA

60

ently, the first from side to side, the second from front to rear.

In Centrosaurus cutleri, Brown

32

describes the femur as "flattened but the general form is well preserved, displaying a long, straight
The lesser
shaft with a large head that rises slightly above the level of the great trochanter.
slightly
below its
terminates
cleft
and
trochanter is separated from the great trochanter by a narrowsummit. The fourth trochanter is a faint elevated ridge about six inches long that terminates a little
below the middle of the shaft. The distal end of the femur curves inward from the line of the
shaft and the inner condyle appears to be larger than the outer condyle, a condition which if true
The crushed femora in the type specimen of C. nasicornus fail to settleis the reverse of Triceratops.
In the Yale femora the agreement with C. cutleri is essential except that the shaft is notthis point."
flattened and the fourth trochanter seems to be lower down than in C. cutleri. The length of eachIn the femur under discussion, that is,is about the same as is the ratio of femoral to tibial length.
the left, the inner condyle is eroded and crushed in such a way that the outer one is much the larger,
agreeing with Triceratops but the reverse of Brown's description of C. cutleri, whereas in the rightfemur the restorers have made the inner condyle the larger, agreeing with C. cutleri. Which ofthese is correct is not apparent.

Dimensions of Femur

Outside length from top of great trochanter to bottom of external condyle
Girth, mid-shaft

Width, mid-shaft
Fore and aft diameter of shaft
Width of proximal end
Width, fore and aft fat great trochanter)
Width, fore and aft (at external condyle)

C. flexus Y.P.M.

C. nasicornus

C. cutleri

M. crassus

789 mm.
320

740 mm.

800 mm.

713 mm.

85
97.5

180
167
189

Tibia
(Fig. 28)

The tibia differs from that of Triceratops in being more slender throughout, and having relaIn both genera the distal end of the tibia is widened transversely,
Apparently lacking in
there being no antero-posterior increase in the dimensions of the bone.
and Anchiceratops
Chasmosaurus,
Triceratops, the calcaneum seems to be present in Centrosaurus,
bones cover the
two
these
although not always distinguishable from the astragalus. Between them,
In Triceratops, on the other hand, the calentire distal end of the tibia in these earlier genera.

tively less expansion at the ends.

caneum has either been replaced by, or absorbed into, a heavy, downwardly directed process of the
below thetibia comparable to that of the inner side but, unlike the former, descending somewhat
Hatcherlevel of the astragalus, with which it is in close contact on the latter's external side. This,33"may be regarded as having performed the same functions as did the external malleolus or
says,
distal end of the fibula in the mammalia."
The proportionate lengths of tibia and femur vary with the species. In Triceratops prorsus(mounted specimen in U. S. Nat. Mus.) the femur is half again as long as the tibia. In Centrosaurus
nasicornus and Monoclonius crassus the tibia is relatively longer, while in C. cutleri^ and the Yale
specimen of C. flexus the proportions are similar to those of Triceratops. Brown believes this rela34
however, would consider such variative size to be of at least specific value in this family; Nopsca,
form an additional point ofproportions
thesesexual.
In
any
case,
to
be
indicated
heretion as is
type of C. cutleri.
theformingskeleton
specimenpartial
Yale
and
the
the
betweensimilarity
32
33
34

Brown, B., 1917, p. 304.
Hatcher, Marsh, Lull, 1907, p. 62.
Nopsca, F., 1929, B.

THE HIND 1.IMH AND FOOT61

-F

Y.PM. 2015

ddFig. 28.
natural
ic,

size,

—

Left

f,

inner condyle;tibia

proximalandfibula ofextremity;oc, outer condyle;

Monoclonius (Centrosaurus)d,t,distalextremity;a,flexus.

astragalus;A, anterior view; B, posterior view; 1/6
fibula;cc, cnemi.il crest;
calcaneum
/,

c,

;

tibia.

Fibula(Fig. 28)

The fibula is a long, slender bone with a more or less cylindrical shaft and flattened, dilated
is somewhat lessextremities which lie in planes at right angles to each other. The over-all lengththan that of the tibia, although the proximal end rises above the articular face of the latter. Proximally, the fibula lies against the outer rear surface of the tibia; distally, against the outer front
surface.

The shaft of the bone, aside from a certain

The distal end articulates with the calcaneum.

the rear, and distally
torsion, is curved toward either end in the reverse direction, proximally toward
toward the front.
Dimensions of Tibia and Fibula

Total length of tibia including astragalus..

C. flexus Y.P.M.

C. cutleri

C. nasicornus

M. crassus

552 mm.

500 mm.

600 mm.

538 mm.

460

560

505

527

Length of fibula

Width of tibia
Proximal end
Mid-shaft
Distal end

222

35 Estimatedfrom Cope's figure.

230"

93

220

Width of fibula
Proximal end
Mid-shaft
Distal end

.

54
34
82

184"

THE CERATOPSIA

62

Pes
elements have been discovered, two in the proximal
Of the tarsalia in the Ceratopsia, but four36

row the astragalus and calcaneum, and two in the distal row of which the larger represents tarsal
Hatcher knew only the astragalus among the tarsalia, although he assumed that others wereIV.
present. His description of the astragalus of Tricerato-ps was brief; he says, "It was closely appliedand early became coossified with the tibia, covering over the internal two-thirds of the distal extremity
In Centrosaurus, on the other hand, the astragalus covered about three-fourths of
The astragalus is thick, with a convex distal surface and a concave proximal
is thin and rises higher on the surface of the tibia than does the thicker
borderposteriorone. The
ascending process, as in certain other groups of dinosaurs.
no
is
There
margin.
anteriorof that bone."the end of the tibia.

Y.PM. 2015

F, G- 29.

—

Anterior view of left hind foot of Monoclottius (Centrosaurus) flexus, 1/6 natural size,
15phalanges; digits I-V; t, tarsals.
p -?

m, metatarsal;,

The calcaneum is a much smaller bone which in the Yale specimen is so closely fused with thesomewhat theIt hasastragalus that its presence as a separate element would hardly be detected.
form of the astragalus but does not rise so high on the posterior surface of the tibia. Between them,
articulathese two bones cover the entire distal end of the tibia and form a very perfect surface forthetion with the remainder of the tarsus which, however, must have been largely cartilaginous, as
Of the distal tarsalia thesmall distal tarsals do not begin to complete this segment of the limb.
The position of the other islarger, according to Brown, articulated with the fourth metatarsal.

doubtful; possibly it lay above metatarsal III.

The left foot (Fig. 29) is practically entire in the Yale specimen, only the fifth metatarsal
and the first and fourth ungual phalanges being artificial. Four functional digits are present, all
The fifth digit isof which are provided with ungual phalanges, as against three in the manus.
the phalangeal
Thus,
only.
metatarsal
of
the
part
proximalrepresented
by
the
and
is
vestigial
formula is 2, 3, 4, 5, 0, which is normal for a predentate dinosaur.
Metatarsal I is short, heavy, and rather irregular, the proximal end somewhat triangular, butwith one of the angles rounded. The articular surface is slightly concave. There is a rugose area

36

See, however, p. 69, Chasmosaurus.

THE HIND LIMB AND FOOTon the flattened external face of the bone.

63

The distal end is expanded, with the outer aspect concave

quadrangular and turned to look somewhat outward as
The first digit could not have borne
proximal end is elongated anteroIV.
thanlittlelongerThe1
isa1
Metatarsal
much if any weight.
somewhat rounded, with aposterior
andtheparallel,andflattened
posteriorly, the lateral sides
facet
is slightly concave as in 1.
proximalThe
metatarsal
I.
that
of
slightly rugose area opposing
The shaft is fairly straight,
convexantero-posteriorly.
facet
distalThe distal end is dilated, with thein the vertical plane.

The

articular faceisthough the digit divaricated away from the axis of the foot.

but tapering fore and aft.
Metatarsal III, evidently the axial one, is the longest. The proximal end is flattened on the
inner side, rounded more or less externally except where it makes contact with metatarsal IV. The
shaft is slightly curved, with the concave side outermost. The shaft is thickest antero-posteriorly at
the proximal end and widens somewhat transversely distally but not as much as in C. nasicomus.

The bone is somewhat rugose on the proximal half of the inner face.
Metatarsal IV is broadly expanded proximally, and has a flattened shaft, with a distinct keelon the outer face of the distal half. The rear of the shaft is concave, the front only slightly so.
There is a triangular, flattened area on the interior aspect for contact with the third metatarsal,
which is half as long again.
Metatarsal V is vestigial and about two-thirds the length of metatarsal I. The proximal end iscomparatively large and ovate and the shaft laterally compressed, the antero-posterior diameter being
three or four times as great as the transverse. The distal end is small and rounded, without trace ofThis bone bore no phalanges and served no other function than to increase thearticular facet.
lateral diameter of the metatarsus and thus to aid indirectly in supporting the creature's weight.
The phalanges exhibit nothing unusual. The proximal one of digit I is nearly twice as long as
wide, but all of the others are wider than long, except the unguals, which are depressed, spade-like
The circumference of the restored
bones. The general pose of both manus and pes is digitigrade.
foot, with the sole pad, is about 1360 mm., that of the hand is 1090 mm., which makes the plantar
area of the pes roughly nearly twice that of the manus and presumably gives an approximation of
the relative weight borne by each.

Dimensions of Pes

1
Length of metatarsal
Length of metatarsal II
Length of metatarsal III
Length of metatarsal IV
Length of metatarsal V
1-1
Length of phalanx
1-2
Length of phalanx
Length of phalanx II-l
Length of phalanx II-2
Length of phalanx II-3
Length of phalanx III-l
Length of phalanx III-2
Length of phalanx III-3
Length of phalanx III-4
Length of phalanx IV-1
Length of phalanx IV-2
Length of phalanx IV-3
Length of phalanx IV-4
Length of phalanx IV-5

C. nasicomus

C. cutleri

123 mm.
180

103 mm.

215
160
77
101

97

69
46
93

60
37
35
80
54
35
32
23
69

87 Artificial.
88

Is

it

not more probable that thisisIII-4?

It

would seem so from the photograph.

C. flexus Y.P.M.

THE CERATOPSIA

64

MOUNTED SPECIMENS
Two specimens of Centrosaurus have been mounted in their entirety, both of which were collected by Barnum Brown.

Of these the first is the type of Centrosaurus nasicomus at the American

Museum, and the second is the specimen which forms the basis of the morphological section of thismemoir, Centrosaurus flexus, at Yale.
C. nasicomus is a slab mount exposing the right side of the skeleton in the posture in which it
was found. C. flexus, on the other hand, is a "plastic mount," that is, the skeleton is fully articulated and may be viewed from the left side, while the right has been clothed with a syntheticallyconstructed restoration of the animal in the flesh.

The American Museum mount (PL IX, A) is admirably executed, but the pose is that ofdeath rather than of life, as though the creature were lying on its side with the neck flexed dorsad
much more than when living. The pelvic elements are also somewhat displaced, as the ischia aremuch too near the tail to allow for the posterior outlets of the body. The feet, of course, are not
39
As Brown says, it "differs in several important features from the Marshin their normal position.
reconstruction of Trkeratofs and from the composite Trkeratofs skeleton mounted in the National

Museum.
"The body is shorter and deeper in the posterior dorsal region, while the feet are more digitigrade with toes turning out, the axis of the manus through digit II and the axis of the pes between
digits II

and III.

"A Trkeratofs skeleton in the American Museum [PI. XIV, A] determines the general construction to have been essentially the same in the two genera and the skeletal structure in Monoclonius may be considered as typical of the family Ceratopsia."
The Yale specimen, as mounted (PI. II), differs from that at the American Museum in several
particulars which may be in part matters of interpretation and in part due to specific and individual
variation.

As has been shown, not only are the usual three anterior cervicals fused into a solid

mass, but as a result of some pathologic condition the centra of the fifth and sixth vertebrae are also
coossified. The latter seem to indicate that the centra cannot have been spaced apart to the extent
shown in the New York mount, which precludes the possibility of the strong dorsad flexion of theThis flexion is often seen in recent as well as in prehistoric animals as a result ofHence the neck of the Yale
specimen is nearly straight, with the centra spaced much more nearly together. The curious backward offsetting of the neural arch in the vertebrae of the back in this specimen has resulted in acertain obliquity of the vertebral centra of this region which may or may not be correct. The sacrum
has been given a more nearly horizontal pose and the tail as a result does not droop at its base,which, together with the position of the ischia, gives ample clearance as compared with the American
Museum specimen. The anterior long rib (cervical VIII) has a curious reversed curve. This has
evidently been placed at the posterior end of the series in the specimen at New York. The characterof the proximal end of this rib, however, determines its position, in addition to which the actual posterior one is in position, fused with the ilium, both in the Yale specimen and in the Centrosaurus
The penultimate rib in both of the latter specimens is highly peculiar as it has acutleri type.
remarkable backward curve extending through nearly half a circle. This is not shown in the typeIt wasof C. nasicomus or in any of the other six ceratopsian skeletons which have been mounted.
neck during life.

postmortem contraction of the ligaments and muscles of the neck.

evidently a specific character.
In placing the feet, reference was made to what may well have been ceratopsian footprints dis40
covered by C. M. Sternberg on Peace River, British Columbia, in strata correlated with the lower
Blairmore of middle Lower Cretaceous age. These footprints, which are those of a quadruped, as
opposed to the associated tridactyl bipedal tracks, and which Sternberg calls Tetrapodosaurus
borealis, agree in character, in length of stride, and in width of trackway with our conception of such

30

40

Brown, B., 1917, p. 300.
Sternberg, C. M., 1932, p. 74, PI. V, Fig. 8.

Mor\TF.n srr.ciMi'.xs

65

an animal as Centrostmrus. They were made by a digitigrade form and exhibit the correct numberof digits. The rear pad-Jike part of the foot, however, did not make a full impression, which isunderstandable, as the toes would dig into the sand somewhat more deeply at the end of the stepwhen the heel of the font wis lilted from the ground. At the same time the fore foot, which may
have toed in at first, would be brought into line with the hind foot. The animal is therefore posedwith an easy stride, with the elbows flexed and bowed outward, and the humerus nearly horizontal.
The hind limb, on the other hand, was nearly straight, with a slight flexing of the knee at the
beginning of the stride, before the weight was fully borne. All four feet are on the ground although
the several feet probably struck the ground at slightly different intervals. The normal stride musthave been slow, the body swaying in front to bring the weight toward the hand that bore it when theother one was lifted. One imagines the foot movement to have been somewhat shuffling, as with amodern elephant, the feet never rising far above the ground. In charging, the movement must havebeen more rapid, but only for a short distance.
The head was probably carried low, with the muzzle near the ground. This was determined inpart by the articulation of the cervicals, which do not indicate a great deal of intervertebral play, andin part by the direction of the pedunculate occipital condyle, the axis of which must have been
carried normally in line with that of the three coalesced anterior cervicals.
This is also in harmony
with the findings of Tait and Brown based upon the position of the horizontal semicircular canal
41

Anchtceratops.
A further discussion of this problem will be found under the section on the
Brain and Special Sense Organs, p. 73. The jaws in our specimen have been set somewhat agape.
inOn the right side the flesh (PI. II, B) of the animal has been restored. The original modeling was done synthetically, the muscles, especially those of the limbs, being built on from within
outward although, as the completed restoration is in the form of a shell, only such as determine
the outer contour of the muscular system are preserved.
In accordance with my former practice,not only is the entire right side of the head, body, and tail covered by flesh but that of both right andleft limbs as well, in so far as the latter may be seen from the right aspect.
Thus, when viewed
squarely from the right, one gets a complete silhouette of flesh, no bone being visible, while fromthe left the entire skeleton may be seen, including the inside of the right limbs and the outside ofthe left.

4 "'In restoring the musculature, reference was made to the very careful studies on "The Pelvic
Musculature of Ornithischian Dinosaurs" by Alfred S. Romer,4" as well as to papers on the myology
44of the chameleon and the iguana by St. George Mivart,
together with some dissection of a young
alligator.

The processes at the rear of the crest in this genus were a problem.

Brown, in his publishedwould require a very considerable thickness of subcutaneous tissue, muscular or otherwise, and which is out of harmony withthe bloodvessel impressions on the surface of the crest, since the latter imply a close-fitting, resistantinvestiture.
We have therefore deemed it wise to show these as processes sheathed like the horns,
without trying to solve the question of their possible utility. Of course, the horny covering musthave overlain the parietal fenestrae, the presence of which is indicated by a slightly depressed area.
In restoring the mouth, we compared the beak and bones of a loggerhead turtle with the rostraland predentary of Centrosaurus. With the remainder of the mouth we have varied somewhat frommy previous ceratopsian restorations, in which the gape was limited to the prehensile part only, themasticating portion being covered by integument to retain the food in the mouth. But the integument of the face was horny and resistant, and would be either creased and folded over opposite thetooth row when the mouth was closed or, as in the Crocodilia, the gape would apparently extend
to the articulation of the jaws.
The crocodiles show, when the mouth is open, certain muscular softdrawing,41

4 ''encloses them in the general integument of the crest, which

Tait, J., and Brown, B., 1928.

4J

Note.

43

Romer, A. S., 1927.

44

Mivart, St. G., 1867, 1870.

4

The photograph of the right or flesh side of the animal has been reversed in the plate, for ease of comparison.

'Brown, B., 1917, PI. XIV.

THE CERATOPSIA

66

gape. Fromparts at the rear on either side, extending a short distance in front of the limit of thethatthe muscularbut
Ceratopsia,
true
of
the
would
be
thing
same
the
that
idea
this we conceived thepouches,cheek
serve,
not
as
and
so
tooth
row
the
limit
of
anterior
thetoforwardarea would extend

which Hatcher thought might have existed, but merely to retain the chopped food that would otherin mastiwise be lost out of the mouth. Incidentally, these are the masseter muscles which also serve41
themselves.
bones
of
the
jaws
on
the
indication
abundant
there
iscation and for which'

Integument
In restoring the external surface, recourse was had to a cast of the skin impression of Chasmosaurus received from the National Museum of Canada at Ottawa, and more particularly to the skinwhich is preserved with the type of Centrosaurus cutleri (PI. Ill, B) in the American Museum.
From the latter dies were cut which could be applied to the soft outer layer of plasteline, leaving a
positive imprint comparable to that of the hide itself. The integumentary impression, as preservedin the C. cutleri over the flank and over the lower end of the femur, consisted of "small polygonal
tubercles and large round tubercles, all low and of the same height. The small tubercles are five or
six-sided, close set together and do not grade in size up to the larger, round ones as they do in

The large tubercles are defined by a circumscribing groove and are
Ceratops [Chasmosaurus].
uniformly round; they were disposed in rows over a part, probably the ventral surface of the47
The disposition of these larger tubercles elsewhere is a matter of conjecture and we havebody."
Thethem
in more or less regular rows over the entire animal with the exception of the face.
shown
.

.

.

wrinkling of the inelastic skin has been suggested by various modern reptiles.

CHASMOSAURUS
While a number of skulls of this interesting genus are known in several museums, three skeleThe last has not as yet been
tons also have been mounted, two in Ottawa, and one in Toronto.
described or figured, and while it is a praiseworthy attempt, many of the bones themselves, especiallythe posterior presacral vertebrae, are so badly distorted by crushing that they could not be articulated48

on the other hand, are much
more normal and give a very accurate idea of the general morphology of the skeleton, especially aswith one another.

The Ottawa specimens (described by Sternberg),

each one supplies supplementary information which the other lacks. The two animals are approximately the same size, though varying slightly in proportions, as the measurements show.
The two skeletons (PI. XIV, B) stand side by side, one being No. 2245 G.S.C., collected in

1913, and the other No. 2280 G.S.C., collected in 1914. The former is of especial interest in that49
in 1914, the partial skull
constitutes the paratype of Chasmosaurus belli as described by Lambeitbeing figured at that time.

SKULL
The skull of Chasmosaurus departs very widely from that of both Centrosaurus and Trkeratops,
and resembles that of Torosaurus in the character of the crest. The entire skull is longer and wider
but less deep than that of a Centrosaurus, although the over-all length of the two animals is nearly
the same, e.g., C. flexus (Y.P.M.) 17 feet 8 inches, Chasmosaurus (No. 2280 G.S.C) 16 feet 3 inches.
The muzzle in front of the nasal horn is notably longer and shallower, and the same is true of thelow, flat, crest. The latter is broadly quadrangular, with very long squamosals, longer than in any
genus other than Pentaceratofs and Torosaurus. The fenestrae are correspondingly large. The
epoccipitals are normal, and there are no enlarged spine-like processes as in the contemporaneous
46 Lull, R. S.,
1908, p. 389.
47 Brown, B.,

1917, p. 305.

48

Sternberg, C. M., 1927.

49

Lambe, L. M., 1914, B, Pis. XIX-XX.

CH XSMOSU'RUS MORPHOLOGY

Fig. 30.

—

Skull of Chasmosaurus belli, palatal view, y$ natural size,

exo, exoccipital;

maxillary;pterygoid

ft,

61

;',

jugal;;

bo, basioccipital; bs, basisphenoid; e, epoccipitals;
condyle; ^.parietal; />/, parietal fenestra; pi, palatine; pnx, prc/, tooth;vo, vomer.
qj, quadratojugal; r, rostral; sq, squamosal

mx, maxillary;j,quadrate;oc, occipital;THE CERATOPSIA

68

Centrosaurus or Styracosaurus. Chasmosaurus differs further from both of these genera in having a
low nasal horn which may be curved backward. The supraorbital horns, on the other hand, may be
more prominent, although extremely variable, ranging from practically nothing (see PI. VI) to aremarkable pair of Cerat ops-like horns in a specimen in the American Museum (Chasmosaurus
These last arise close together,kaiseni Brown, No. 5401 A.M.N. H., see PL V, A and Fig. 38).
In this specimen, the nasal horn apparently
flare outward, and curve strongly forward and upward.
skull
consists of three elements, one of which may represent the espinasal, whereas in a companion
supra(No. 5402 A.M.N.H.) the nasal horn is more prominent, and without sutures, while theorbitals are small, and trihedral in section, with a rounded outer face. All of these horns have deep
vascular impressions. The skulls, except for certain minor variations, are quite similar and are cerAt the American Museum, the skull, No. 5401,
tainly generically, but not specifically, identical.
with small nasal and large supraorbital horns, has been considered a male, the other, with larger

This so-called male skull has supraorbitals not unlike thetype of Ceratops montanus from the Judith River beds, which consists of supraorbital horns only,with no other diagnostic parts of the skull preserved. It is the only Chasmosaurus skull known inwhich there is the least correspondence between the two genera, which in itself is not sufficient evidence for their synonymy. This will be further emphasized in the discussion on genera and species

nasal and smaller supraorbitals, a female.

(see p. 94).

Reverting to the crest once more (Fig. 30), the large fenestrae lie entirely within the central
element (parietal), which is reduced to a rather slender bar of bone between them and a yet more
slender portion between fenestra and squamosal on either side. A peculiar feature is an overlapping
suture in this lateral bar, about mid-length of the fenestra. This apparently is not a suture between
two separate cranial elements, but seems to represent the place of contact of two progressive processesof the same bone, one of which developed backward laterally to enclose the opening, the other for50
A large epoccipitalward from the transverse posterior bar to meet, but not fuse with, the first.
limit of thetheposterior
justbehindaccentuates each postero-lateral angle of the crest and liesinthe
Yale andSometimes,assquamosal. The form of the posterior bar of the parietal varies.
to formmay
curvedsoasbeAmerican Museum specimens, it is more or less straight across, again it
squamosals
Thea distinct emargination at the midline as in the Ottawa skull, No. 2280 (see p. 93).
are long, extending nearly to the posterior corner of the crest, being three or four times longer thanwide. The inner border is thickened and rounded and the outer slightly crenulated, bearing seven
Between the outer and inner margins the after part of the squamosal is
to nine epoccipital bones.
depressed, and differs from most of the dorsal surface of the skull in possessing no vascular grooves,another point of similarity with the crest of Torosaurus. There are, however, vascular impressions on
the surface of the parietal element in Chasmosaurus which, together with the possession of epoccipiThetals, distinguish it from Torosaurus, in which the entire crest, except the anterior end, is smooth.
epijugals are prominent.

VERTEBRAL COLUMN
The vertebral column is comparable to that of Centrosaurus except for the sudden increase in theheight of the neural arches and spines posterior to the crest, i.e., beyond the tenth presacral vertebra.
Both have twenty-one presacral vertebrae ; the sacrum has the usual ten vertebrae, in four of which(the second to fifth) the parapophyses or sacral ribs coalesce distally to form the acetabular bar as inCentrosaurus; behind these are four other fused centra whose transverse processes do not meet theilium.

The anterior fused sacral also has free diapophyses.

The spinous process of sacral I isisolated, those of II to VI are fused into a continuous plate, while those ofagain.

Vll to X are isolated

The sacral ribs all seem to spring from the point of union of adjacent centra, whereas inCentrosaurus the last arises from the middle of its centrum.
50

2016 Y.P.M., these processes do not meet, hence a portion of the outer margin offormed by the squamosal (see Torosaurus gladius, p. 132). This appeared in the course of further preparationof the skull, subsequent to the drawing of the figure.
In the skull of Chasmosaurus No.

the fenestraisCHASMOSAURUS MORPHOLOGY69

The caudals seem to have a lighter neural arch than in thai of Monoi lonhu figured by
The spinous processes are fairl) tall, with a gentle decrease, as in Centrosourus.

Ilatcher."

The shafts of the posterior cervical ribs are quite straight, more so than in Centrosourus, in
In Chasmowhich the first long rib, borne on presacral VIII, has a curious reversed curve.
process
is in line
tubercular
the
end,
in
that
proximalpeculiar
at
the
first
ribs
very
are
sjurus, thedistancesome
turnarisesincapitular,
which
the
above
high
elevatediswith the straight shaft andbelow, and projects at right angles to the axis of the rib. The result is that in attempting to articutuberculum could not possibly meet the diapophysis of the vertebra unless the shaft
were thrown outward at an utterly impossible angle. The posterior ribs are slender and well arched
and the capitular process does not form the right angle with the shaft as in the anterior ribs but ismore as in Centrosourus. When articulated with the diapophyses of the vertebrae, the posterior
Thus, theribs are thrown outward in such a way as to give a flat back and broad abdominal cavity.
alwaysarealmostribs
But
theregion.
abdominal
narrow
chest
and
broad
mounted skeletons have alate the rib, thesubject to postmortem deformation and the diapophyses in the fossil may be bent upward or downward, thus materially altering the shape of the body from that which it possessed in life. The Yale
Centrosourus, as mounted, presents a very different appearance, as it is somewhat slab-sided and not

One cannot, however, trust too implicitly the curvature of theat all broad in the abdominal region.

ribs in their present condition.

The last presacral ribs in Chasmosourus differ from those of Centro-

The posterior one curves outward and downward, passing beneath, but apparently not fusing
with, the ilium. The penultimate rib is much longer and heavier than the last, and curves forwardsourus.

and outward to clear the anterior end of the ilium, according to description, although passing beneath
Thence it curves backward and slightly inward. At mid-length, this rib
it in No. 2280 G.S.C.
thickens and bears a flattened rugosity on its hinder margin for attachment with the anterior end of
the pubis. These posterior ribs all lack the decided backward sweep seen in Centrosourus cutleri andthe Yale specimen of C. fle.xus.
The only other distinction of note lies in the tarsus where there are three distal tarsalia, but thismay be due to preserval rather than a real distinction from Centrosaurus in which but two are known.
One peculiarity seen both in the Toronto specimen and in one of the Ottawa animals lies in theproximal end of the humerus, which has not only the large deltoid crest, but a corresponding one on
With the head of the humerus in articulation, this posterior crest
the opposite side of the bone.
impinges against the ribs in such a way that the upper arm could not be swayed backward without
There seems to be something
either a fracture of the ribs or a displacement of the shoulder.
mechanically wrong about either the skeletons or the way they are mounted. This difficulty did
not appear in posing the Yale specimen of Centrosaurus, in which the posterior crest is smaller andof a different shape.

It isquite evident that the coracoids are placedmuch too far apart in both

Ottawa specimens, a point which Mr. Sternberg concedes.

INTEGUMENT
A portion of the integument'" was preserved with the skeleton, No. 2245 G.S.C. The section,measuring about \ 2 x 3 feet, lay over the pelvic arch and right flank, and extended from a point
nor far from the median line. There is no evidence of bony plates in the skin. The surface wasspaced fromarranged in irregular, longitudinal rows andcovered with "large round plates
distinctly
differentiatedalwaysarenot
two to four inches apart. They vary considerably in size andfrom the larger polygonal tubercles either in size or shape. The large plates, one of which is two
and one-fourth inches in diameter, were low, flat, circular, and are defined by a circumscribing groove.
The edges of many of the larger polygonal tubercles as well as the large round plates hacrinkled appearance due to short grooves placed at right angles to, and ending at the edge of theplates.
Closely surrounding these large plates are smaller polygonal tubercles giving the appearance

/
l

.

"

32

.

Hatcher, M.irsh, Lull, 1907, Fig. 81.

Lambc, L. M., 1914, A, PI. XIV.

.

.

.

.

THE CERATOPSIA

70
of a rosette.

The intervening spaces were filled with polygonal, tubercle-like, non-imbricating scales

smaller size
In g eneral th e large round plates decrease in size from the dorsal
surfacejofr the body downward over the femur and ischium though the generalarrangement seems to be the^"u-same."A very interesting flesh restoration of Chasmosaurus by L. S. Russell is shown on Plate XVII.
Measurements of Chasmosaurus(From Sternberg 1927, converted into mm.)
No. 2245
Total length of skeleton
Greatest length of skull

Length, occipital condyle to back of crest
Greatest breadth of crest
Greatest length of fenestrae

Greatest breadth of fenestrae (at center)
Anterior end of rostrum to center of skull between orbits

Depth of skull taken just back of nasal horn core, including dentary
Length of mandible including predentary
Length of brow horn from upper rim of orbit
Length of vertebral column measured along tops of spines
Length of presacral vertebrae measured along center of centra
Length of sacrum
Length of tail measured along centra
Height of skeleton at pelvis:
Height of skeleton at first dorsal [eighth cervical?]Length of ilium
Length of ischium
Length of femur
Length of tibia
Length of fibula
Length of scapula
Greatest length of coracoid

Length of sternum
Length of humerus
Length of ulna
Length of radius

BRAIN AND SPECIAL SENSE ORGANS
The ceratopsian brain is known in at least five excellent instances, four of which are from theskulls of Triceratops and one

from Anchiceratops.

Descriptions and figures have been published asfollows:

N flaielUtus, No. 1821 Y.P.M., Ceratopsia Monograph, Fig. 31, p. 37, Fig. 33, p. 38
2416 U.S.N. M., Ceratopsia Monograph, Fig. 32, p. 37, Fig. 34, p. 39
Triceratops sp., No. 5740 U.S.N. M., Gflmore 1919 B, Fig^. 1; this Memoir, Fig. 31
Triceratops sidcatus, No. 4286 U.S.N.M., brain not figured
Anchiceratops omatus, No. 5259 A.M.N.H., Brown 1914, Pis. XXXIV, XXXV; this Memoir, PI. XITriceratops serratus, No.

Hatcher says that the brain, compared with the size of the skull, is smaller in the Ceratopsia
than in any other known group of vertebrates. This is due in part to the great expansion of the skull
beyond the limits of the actual cranium, especially the crest and facial region. In proportion to thecranium alone, the brain size compares favorably with that of other dinosaurs, and in actual size
considerably exceeds that of a stegosaur of equivalent body bulk. In S/egosaurus, there are marked
dilatations of the neural canal in the spinal column; a huge one in the sacrum, at least twenty times
the size of the cranial cavity, and a lesser one in the brachial region of the thorax. In Triceratops,these dilatations, while present, are by no means so marked, for the tail, which was innervated largely
from the sacral nerve mass, is a much smaller organ relatively and had not the offensive anddefensive functions in the Ceratopsia which are usually attributed to that of S/egosaurus.
From comparisons with studies by Dendy 1 on the mid-section of the skull and brain of Spheno2
don, Osborn concludes that "The intracranial cavity in Tyrannosaurus corresponds with the outersurface and foldings of the dura mater and is thus merely a cast of the outer envelope of the brain,

which gives us little idea either of the form or size of the brain itself. The reasonable inference isthat the intracranial cast of Tyrannosaurus greatly exceeds and possibly doubles in cubic capacity theactual brain which was formerly contained within it.
"In Sphenodon the cubic capacity of the dura mater envelope appears to be double that of thegives us a means of measuring the size of the dura
brain itself. Thus the cast of Tyrannosaurus
mater envelope. It displaces 530 cubic centimeters of water. If the brain proper bore the same proportion to the dura mater envelope as that of Sphenodon, the bulk of the brain of Tyrannosaurus
may be estimated at 250 cubic centimeters. The brain proper was extremely small in comparison
with the enormous size of the body."
I find that the brain cast of Triceratops serratus displaces 300 cubic centimeters of water, which,according to Osborn's conclusions, would give an estimated volume for the actual brain of not morethan 150 cubic centimeters. This, I imagine, would give much the same ratio of brain to body bulk.

.

.

Triceratops and Tyrannosaurus were actual competitors in the same environment, so that their nervous and hence psychic requirements would be much the same, but far lessthan those of a large ungulate and its competitive carnivore, today.
The endocranial casts of both Tyrannosaurus and Triceratops, but more especially of Anchiceratops (PI. XI), show certain protrusions on the superior and lateral aspects which do not represent
cranial nerves but membranous extensions of the dura mater into corresponding depressions in theendocranial wall. There is no evidence that the actual brain bore such appendages; they seem torepresent spaces for the passage of bloodvessels for cerebral nourishment.
In the ceratopsian brain, the olfactory lobe is large, and the olfactory nerve emerges in theyoung T. fabellatus skull from a single median foramen which, in the types of T horridus andprorsus, is divided into two by a median bony partition. But the skulls of horridus and prorsus are

as in Tyrannosaurus.

.

'Dendv, A., 1911.
2
Osborn, H. F., 1912, p. 21.

THE CERATOPSIA

72

both fully ossified specimens, while that of flabellatus is very young, so that the partition may still
have been cartilaginous. One assumes that the olfactory nerves themselves were always paired andthat the sense of smell was amply developed. The cerebrum, on the other hand, was small in proportion to the bulk of the brain as a whole, which gives evidence of an extremely low grade of intelligence, compared with mammalian standards. The cerebellum is relatively large and is followed bya distinct constriction of the mass, as viewed from above, the cranial cavity expanding again for
the reception of the enlarged medulla oblongata. In the region of the constriction lay the otic mass,
including the semicircular canals, which are beautifully preserved in the Anchiceratops specimen

O.so

Fig. 31.

—

Y% natural size.
occipital

Left side of longitudinal section of skull, showing brain cavity of Triceratofs, from No. 5740 U.S.N.M., about
B. oc.fr., basioccipital process; car, foramen for left carotid artery; D.so., anterior end of dermo-supra-[parietal] ;pin., pinealF., posterior portion of frontal;

foramen[?]i[exoccipital] ;v,

fi'-f-ypituitary fossa;

Mx., maxillary; Oc, occipital condyle;P/.f.,

postfrontal;

pf.f.f.,postfrontal

P., parietal

fontanelle;[supraoccipital];S.oc, supraoccipitalforamina for exit of supposed veins; /, //, ///, IV, V, VI, VII, VIII, IX, X, XII, foramina for exit of(Figure and legend after Gilmore.)

cephalic nerves of corresponding numbers.

XI).

(PI.

The foramina for the emission of the cerebral nerves are large and clearly defined, but

in the interpretation of some of them Brown, Hatcher, and Gilmore differed, nor am I able to comeBrown's interpretations for Anchiceratops, as indicated in theto any more definite conclusions.

legend of PL XI, are the latest and most acceptable.
One innovation in the brain cast of a Trachodon, as well as in that of the Anchiceratops describedby Brown, is the demonstration of the semi-circular canals, the seat of the organ of equilibration.
3"These canals," according to Brown, "have the normal reptilian position and open freely from one
to the other with distinct ampullae at the origin, but the horizontal is much shorter and smaller thaneither the anterior or posterior divisions."
3

Brown, B., 1914, A, pp. 546-547.

The cochlea if present was not preserved.

Something

1

BRAIN AND SPECIAL SENSE ORGANS

73

form ol B Cochlea must have been present for the perception of sound, luit it would not have
had the degree of development seen in the birds and mammals.
Reverting to the semi-circular
canals once more, it is interesting to note that the plane of the horizontal one with reference to thelongitudinal axis of the skull has been considered as evidence for the static carriage of the head withmuzzle pointed somewhat downward near the ground, a position which we had previously determined as correct upon evidence afforded by the occipital condyle and the fused anterior ccrvicals, thelong axes of which should he in line. The comparatively large extent of the circular or angular
sweep of the vertical canals, as opposed to those of the horizontal ones, has been taken as an index
of the extent of accelerated movement habitually carried out by the animal in the plane and in the
directed sense of the canal itself. The conclusion is, therefore, "that Anchiceratops vigorously swung4
its head about a vertical axis to a far less extent than about horizontal axes."
But A>i, hii rratops,
with well developed vascular impressions on the underside of the crest, must have had the latterlargely free of the neck musculature and the head was, therefore, capable of freer rotational movement than Cetitrosaurus, for instance, which we necessarily restored with the crest, except for the
periphery, in contact with the underlying muscles (PI. II, B).
In Centrosaurus, freedom ofrotational movement seems to have been very limited.
Another interesting detail of the nervous system which has been alluded to previously is
the lack of bony protection for the spinal cord from its exit from the foramen magnum to its
entrance into the enclosed neural canal of the axis, a distance, according to Tait and Brown, of at
least
Moreover, the plane of the occiput slopes away from that ofinches in a large Triceratops.
the beginning of the neural arch, the one sloping from below upward and backward, the other,
upward and forward, so that the upper surface of the spinal cord was free of bone restriction to agreater extent than the lower. All this is taken by Tait and Brown as further evidence for marked
rotational movement of the skull on its longitudinal axis, necessitated by the laterally compressed
form of the prehensile beak and its use in severing vertically growing stalks of vegetation such as tallferns, cycads, Equisetae, and other elevated and luxuriantly crowned plants which formed the creature's
food.
But the Ceratopsia lived during a time of modernized flora and it is not necessary to imagine
their dietary restriction to plants of so primitive a character. Frankly, I do not believe that the head
was ever rotated to such an extent that "like a hen viewing a hawk, they looked upwards with therupper eye" and thus were enabled to grasp with their recurved beak the bases of vertically growing
stems and bring the foliage down from above.
Hatcher," in speaking of the sense organs of the Ceratopsia, says that the large comparative
size of the olfactory lobe and the foramina for the exit of the olfactory nerves, as well as that of
the orbits, and the ample dimensions of the optic foramina, imply that both the sense of smell andthat of sight were well developed. He thought, however, that from the structure of the skull in theauditory region and the small size of the foramen through which the auditory nerve may have had
And, as he says, perhaps this deficiency in hearing
its exit the sense of hearing was extremely dull.
may have hastened to some extent at least the extinction of the group. In the Anchkeratofs brain
case, while the cochlea could not be explored, there is, nevertheless, little evidence of deficiency of
the auditory apparatus, nor am I inclined to accept Hatcher's conclusion in the matter, especially his
Triceratops and Torosourm lived
final suggestion that this difficulty may have hastened extinction.
It is not necesto the very close of the Mesozoic, when the wholesale reptilian extinctions occurred.
sary to find any specific cause of racial death which would apply to Ceratopsia alone, for that death
was indiscriminate among reptiles and not restricted solely to the ceratopsians.
Even though the sense of hearing was somewhat dull as compared with that of modern grazing mammals, I imagine the noise of approaching danger was proportionately loud; for there wereno stealthy beasts of prey of sufficient prowess to menace a Triceratops in his prime.
in the

1

1

'

4

22.
Tait, J., .in J Broun, B., 1928, pp. 2'Op. cit., p. 23.
Hatcher, M.rsh, Lull, 1907, pp. 38-39.
,

r
1

—

SYSTEMATIC DESCRIPTION OF GENERA AND SPECIES
1
The classification of the Ceratopsia, as modified from Williston, may be stated as follows:

Class

—

Reptilia—

Diapsida
Super-order Archosauria

Sub-class

—
—

Order

Ornithischia—

Sub-order

Ceratopsia——

FamilyProtoceratopsidae
Genera Protoceratops, Leptoceratops
Family 2 Ceratopsidae
Genera Anchiceratops, Arrhinoceratops, Brachyceratops,
Chasmosaurus, Ceratops, Eoceratops, Monoclo1

nius (Centrosaurus), Pentaceratops, Styracosaurus, TriceratopSy Torosaurus.

Family PROTOCERATOPSIDAE Granger and Gregory3

The family characters are as follows:" primitive, small ceratopsians, with a hornless skull;with-out secondary skull roof above the frontals; no epoccipital bones; well developed crest with sagittal
ridge and persistent parietal fenestrae; premaxillaries with teeth; cheek teeth arranged in a verticalseries of not more than two developed at one time, roots simple not bifid; fore limb slender, manus

much smaller and shorter than pes, the latter elongate with compressed unguals; ilium with blade
but slightly inclined outward to the sagittal plane, not reflected or produced laterally above thefemur; prepubic process relatively small, not expanded vertically; femur with large fourth
trochanter, femur shorter than tibia; midcaudal vertebrae with very long spines.
Genus PROTOCERATOPS Granger and Gregory 3
Protoceratops andrewsi Granger and Gregory 3
Pis. I, IV;

Text Figs. 32-34, 36

Holotype: No. 6251, A.M.N.H., a skull, lacking the occiput. Much other material has subsequently been found,consisting of several skeletons and no fewer than seventy-three skulls, ranging in age from the newly hatchedyoung to the senescent.
Horizon: Cretaceous; Shamo series, Dja-doch-ta formation.
Locality: On the Kwei-wa-ting trail, east of Artsa Bogdo, Gobi Desert, Mongolia (Lat. 44°N., Long. 104°E.)
Collector: Walter Granger and party, Sept. 2, 1922.

The original description is as follows: "The skull (A.M.N.H. No. 6251) is hornless and far
smaller than that of any known ceratopsian or ankylosaur, being only about 160 mm. in lengthfrom the anterior end of the premaxilla to the posterior border of the jugal. As seen from above,it is broadly triangular, with a pointed apex and wide lateral crests, the latter composed chiefly of
the backward-and-downwardly expanded jugals. The greatest width of the skull across the posteriorborders of the jugals is about 190 mm., while the depth of the jugal below the middle of the orbit
1

Williston, S. W., 1925.

2

Revised from Gregory and Mook, 1925, p. 4-.
Granger, W., and Gregory, W. K., 1923, pp. 1-9.

3

PROTOCERATOPS ANDREWS
is 4-3IS

mm. The orbits are very large (50 mm. in anteroposterior length), not surmounted by supra-

orbitalbones or horns.

Parts of the anterior and lateralThe postorbitaJ squamosa] bar is narrow.

borders of the supratemporal fenestra as preserved indicate that the fenestra was large and that theThe
occipital roof was very delicate and not produced as far backward as in later Ceratopsia.
squamosal broadly overlapped the enlarged jugal and was produced posterosuperiorly but was not
greatly enlarged. The pineal foramen is small or absent. The single preorbital fossae are far larger
than in other predentates.
bone, which is broken

off;

The premaxillae were very large and probably supported a large rostral
the premaxillae and nasals approach the ceratopsian type and the sameand the quadrates. The quadratojugal lies on theis true of the pterygoids, the internal nares,
posterior surface of the quadrate.

"The mandible has on each side a straight row of about nine relatively large and long-crowned
teeth, worn on their buccal sides and set far inward toward the midline. The remains of the lower

1
A.M.N.H. 6408—

Left lateral view of skull of Protoceratop andrezvsi, Y\ natural size, an, angular; ar, articular; c, coronoid;J, dentary; /, frontal; if, preorbital fossa; iff, infratemporal fossa; /, jugal; /, lacrymal; mx, maxillary; //, nasal; nar,parietal fenestra; pus, premaxillaryp), postnarial opening; o, orbit; />, parietal; /<;, palpebral
fd, predentary;
Fig. 32.

squamosal;/,

pf, prefrontal;p, premaxillary teeth

;

ff,

;

frontal (postorbital) ;;q,quadrate;qj, quadratojugal;r,rostral;sa,surangular; sq,

teeth.

molar crowns suggest the three-pointed lower molars of ceratopsians, rather than the spatulate,many-cusped teeth of ankylosaurs and of European Acanthopholidae. The anteroposterior measurement of the four teeth ... is 28 mm. The last tooth preserved has its tip about 13 mm. above thealveolus. The first four teeth are represented by their alveoli. The diastema from the first alveolus
to the predentary bone was about 1+ mm. in length. The strong coronoid process rises from the denThe predentary bone is well developed and has a pair of long inferior
tary at a gentle slope.
processes, one on either side of the midline.

"... The true Ceratopsia, [Ceratopsidae] hitherto unknown below the Upper Cretaceous ofAmerica, are all far larger than Protoceratops; all of them have horns; the crest is much expanded
above and behind the occiput; there are epoccipital and supraorbital bones; and the orbit is small,placed high up and bounded by a wide postorbital bar. The preorbital fossa is reduced to a small
slit.

"As Protoceratops presents the opposite of these characters, it may prove necessary to erect fornewit a new suborder (Protoceratopsia) but we prefer at present to regard it only as the type of aand probably primitive family, the Protoceratopsidae, characterized by the lack of horns, the verylarge size of the orbits, and the narrowness of the postorbital-squamosal bar."
Protoceratops skull No. 6408 A.M.N.H. (Figs. 32, 33), figured by Gregory and Mook in 1925,
and described as a small, young adult skull, possibly a female, may be taken as a plesiotype. Uponthis the following observations were made: The muzzle is deep and laterally compressed, with a welldeveloped rostral bone bearing vascular impressions. There are abundant nutritive foramina scatteredover the facial bones. The premaxillaries lack the sculpturing of the typical ceratopsians and form

THE CERATOPSIA

16

premaxbut a small portion of the inferior margin of the jaws. There is no septum formed of theusual,As
Ceratopsidae.
inthepresentitisalthoughnares,
theillaries and nasals partially dividing
rostralofthelimitsthebetweenmuzzleoftheprofilethehowever, the premaxillaries enter into
and the nasals. An unusual feature among Ceratopsia, found elsewhere only in Leptoceratops, is thepossession of a pair of cylindrical teeth in close mutual contact on either side of the muzzle just behind
The nares are elongated ellipses with their long axes directed upward andthe rostral border.
backward at an angle of about 45° from the perpendicular.
The maxillaries, together with the jugals, are the largest bones of the face. They are roughly

triangular in form, being bounded in front by the premaxillaries, above by the lacrymals, and for avery brief space by a downwardly projecting process of the nasals. Posteriorly, the maxillaries arebounded by the jugals and pterygoids. Inferiorly, there is an unusually long, edentulous margin
before the tooth row is reached. The number of dental alveoli is 13 to 15, and, because there are

but two horizontal rows of successional teeth, there is no such deep alveolar groove as that seen in
the later ceratopsians. The preorbital fossa forms a not very deep depression on the side of the face,
and includes within its area about equal moieties of the maxillary and lacrymal bones. The actualforamen (lacrymal foramen of authors) is much smaller and lies within the lacrymo-maxillary suture.
This fossa is reduced to a narrow slit in the later ceratopsians. Mr. Granger thinks it may havelodged a facial gland, possibly hedonic, like those found within either ramus of the lower jaws inThis is, however, a matter of pure conjecture, and the gland would of necessity
the Crocodilia.
become practically vestigial in later forms. What then would be its utility? The foramen is apparently the vestige of the preorbital opening, large in saurischian dinosaurs, but always reduced in the
Ornithischia.

The nasal bones meet in a median suture throughout, without the customary fusion seen in mostAnterior to the nares there is a slender process which meets an ascending process of thepremaxillary. There is the suggestion of a prominence about mid-length of the nasals, with a concentration of the grain of the bone toward it, seemingly foreshadowing the coming of a nasal horn.

later genera.

There is a median longitudinal depression on the nose, reaching back beyond the limits of the frontals
The nasals are bounded by the premaxin specimen No. 6408, but less pronounced in No. 6429.
maxillaries,
of varying width, followed bywiththecontact
an
area
of
with
below,
illaries in front andarticulate with the frontal
hinder
end,
they
their
At
bones.
prefrontal
andthat with the lacrymal
bones.

.

The complex of bones surrounding the orbit has been subject to varied interpretation.

.

It is

generally assumed that the true frontals, as discrete bones, do not appear on the surface of the skull
One would expect toin the later ceratopsians in which the secondary roofing has been developed.
which
the secondary roofingin
Leptoceratops,
inprobablyandfind them, however, in Protoceratops,

should interpret the pair of bones lying between the orbits on the dorsal surface of
this skull as frontals, flanked in front and behind the orbit by the prefrontals and postfrontals
respectively, the "freely articulating palpebral bones" of Gregory and Mook representing the supraThe prefrontal lies above the lacrymal, the suture between them being clearly visible inorbitals.
the skull under discussion. They form the anterosuperior border of the orbit except where excluded
therefrom by the palpebral bones. Above and anteriorly, the prefrontals are bounded by the nasals,
and posteriorly by the frontals which form the superior orbital border. Nowhere is the rim of theorbit thickened as in later ceratopsians, for this is a defensive modification concomitant with the development of horns. The postfrontal bones bound the orbit on the rear and articulate in turn with thefrontals above, the squamosals behind, and the jugals below. Near the junction with the postfrontals,
the frontals become somewhat roughened, and over the suture, especially on the right side of theskull, there appears once more a decided prominence suggestive of the brow horn yet to come. Thereis no trace of the pineal foramen nor of the pseudo-pineal fontanelle which is seen only in forms withthe secondary roofing and may disappear even in them, as in the type of Triceratops prorsus. The
absence of the true pineal foramen casts doubt upon Gilmore's interpretation of an aperture in theroof of the actual brain case of Triceratops* below the secondary roofing. (See p. 72, Fig. 31.)isincomplete.

4I

Gilmore, C. W., 1919, B, p. 107, Fig.

1.

PROTOCERA TOPS ANDREWS!

77

The lacryma] is an irregular-shaped bone forming the anterior limit of the orbit and containing
The Lacryma] is bounded by the nasal and prefrontal above,
the upper half of the preorbital fossa.
below and in front. The preorbitallacrymal)andbelow,
maxillaryandbehindthethe jugal
foramen lies in the mid-length of its inferior border.
The jugal is one of the largest bones of the skull. It is roughly quadrangular, with the
It is bounded in front by the maxillary and lacrymal, above by thelongest axis nearly horizontal.
process
above the infratemporal fossa which meets the squamosal. Within,postorbital, and has a longand quadrate. In skull No. 6429 A.M.N.H., a horizontal
quadratojugal
the jugal bears upon theridge divides the posterior part of the jugal into an upper and lower portion. The rear lower partof the jugal flares outward very strongly in some skulls of Protoceratops (sec PI. I), suggesting(—

Dorsal view of skull of Protoceratofs andrewsi, ]/\ natural size. /, frontal; itf, infratemporal fossa; ;', jugal;
mx, maxillary; «, nasal; nar, narial opening; o, orbit; p, parietal; fa, palpebral; ff, parietal fenestra; fmx,

Fig. 33.

/.lacrymal;

premaxillary;fo, postfrontal; prj, prefrontal;

qj,

quadratojugal;r,rostral;sq,squamosal;

s/f,supratemporal

fossa.

somewhat the jugal horns of Pentacerato-ps. There is no trace, however, of an epi jugal bone,
although the surface of the jugal is in places somewhat rugose and pitted.
The postfrontal (postorbital) is bounded by the prefrontal and the supratemporal fossa above,
the rear of the orbit and the squamosal laterally, and the jugal below.
The crest is composed of the usual three elements of which the unpaired median one is gener-

The skull of Protoceratops, with its primitive simplicity,
affords the best of evidence for this interpretation. In this, Gregory and Mook agree. The lateralelements are of course the squamosals; concerning these, opinion is undivided. The latter bones lie
ally considered as the fused parietals.

on their outer anterior margins. Anteriorly, thesquamosal articulates with the postfrontal and the extended process of the jugal, while its lower
margin meets the quadratojugal and quadrate, which combine to form the infratemporal arcade and,
together with the jugal and squamosal, enclose the very large infratemporal fossa. The squamosals
The parietal bones are broadly expanded,bear slight vascular impressions on the outer surface.
completely surround the large, slightly irregular fenestrae, and form the periphery of the crest
beyond the limits of the squamosals. They are peculiar in having the midline raised into a pronounced sagittal crest. Anteriorly, their surface, together with that of part of each squamosal, dips
below the general level of the surface of the crest, especially in the wake of the supratemporal fossae.
Such depressed areas are always present in varying degree among Ceratopsia, especially in Chasmosaurus, but never to the relative extent seen in Protoceratops. They seem to be the areas of origin of
the temporal muscles which, passing downward and slightly forward beneath the postfrontal andjugal bones, were finally inserted into the coronoid process of the jaw and served to actuate thatpowerful member. Here the pull is more directly upward than in later Ceratopsia and as a consequence the coronoid process of the jaw has a different shape from that of Triceratops or Monoclonins
in

their usual position

bounding the(Centrosaurus), for instance.

parietals

THE CERATOPSIA-g

The rear of the skull exhibits the usual ceratopsian complex— a spherical condyle, heavy

basi-

The
processes which abut against the pterygoids.
occipital region, and two forwardly directed
the
than
in
extentverticalgreaterpterygoids are typically ceratopsian, but have an immensely
muchdilateso
notvertically and do
Ceratopsidae. The exoccipitals are widespread but are narrowis not in evidence as it is in Trkeratops
groovepterygoidThelatter.
the
in
as
end
toward their outervertical ridge
suture between the parietals and occipital complex is clear, crossing theserratus.

The(Centrosaums). As usual, one
above the foramen magnum at its mid-height, as in Monoclonius
cannot determine the limits between the supra- and exoccipitals.
The lower jaw is extremely hollow and must have possessed a large splenial which is not now
There is a row of 12 to 13 large nutritive foramina on the inside of the dentary, one
in evidence.
corresponding series of 13 to 15 on the inner side of theat the base of each vertical tooth row, and alarge. The coronoid seems to lack the forwardly turnedaresurangularandThe angularmaxillary.

slightly in the direction of thehook-like summit characteristic of later ceratopsians, but is grooved
above,
37.)p.
temporal muscle pull. (SeeThe outer surface of both mandible and maxilla bears ridges limiting the masseter muscle.
not distensible
Between the latter and the teeth were hollows which formed deep but probably
of foodretentionforthemerelyare
These
Trkeratops.
forcheek pouches, as Hatcher suggested
storage.
for
sense
in
no
were
They
lost.
be
otherwise
which, falling outside of the teeth, would
Monoclonius
Below the masseter ridge the mandible has a flattened outer surface more suggestive of
profilekeel-likewithapointed,sharplyispredentary
than of Trkeratops. The{Centrosaums)

The shape of the various sutures of skull and jaws varies in the two specimens, No. 6408 andNo. 6429 A.M.N.H.
As but one species of Protoceratops is known, it is impossible as yet to determine what

specific as opposed to the generic characters.

The

generic

relationshipisnearestto

Leptoceratops

distinctions from Brachyceratops are much more marked.

are theIhe
the American forms.
(See contrast of Leptoceratops andamong

Brachyceratops, p. 79.)

Genus LEPTOCERATOPS Brown
Leptoceratops gracilis Brown

5

Text Figs. 35, 37
and jaws, including nasals, maxillaries, portions of the orbital
splenial; a series of articulated caudal vertebrae; a comborder, back part of crest, dentary, predentary, andHolotype-

No 5205 A.M.N.H.;

parts of skull

plete fore limb and parts of hind limbs.
Horizon: Edmonton Cretaceous, about 400 feet above the Pierre.
bank of the Red Deer River, Alberta.
Locality: Three miles above Tolman, on the east
expedition of 1910.
History
NaturalofMuseumCollector: American"Skeleton small. Skull short and deep,smooth;Crest with a high thin sagittal ridge, posterior border of crest
without nasal horn.
Dentary massive,
single-rooted.
squamosal extending to extreme posterior border of crest. Teeth
symphysis. Preto
extendinglargesplenial
teeth;
offifteenrows
short and deep, with less thancarpals ossified,hoofs;
interminating
III
and
II
I,
digitswithdentary long and narrow. Manus
Tail longlarge.
comparatively
trochanter
fourthwithstraight,
ulnare and radiale large. Femur
chevrons."
longandand deep, with high slender spines
Kaisen, andAnother fine specimen of Leptoceratops has come to light, collected by Brown,
Lake,
Buffalo
of
west
miles
formation,
Mary
3
St.
Tohnson in 1916, from near the bottom of theskeleton,entirenearlyisaA.M.N.H.,
5464
numberMontana This specimen, which bears the
The left hind limb is represented by a femur, tibia
skull and the fore limbs.

The generic and specific characters are as follows:

except for most of the"'

Brown, B., 1914, C.

LEPTOCERATOPS GRACILIS

79

by the femur only. The caudals are intermittently present. Except for thehind feet, of which only a few phalanges are preserved, and parts of the skull, this specimen has
been restored completely from the type specimen, ;ind is to be mounted. Hence, it affords an admiWith Brachyceratops, on the otherrable basis for comparison with Protoceratoops, its nearest ally.

andfibula, the righthand, there is little basis for comparison;

nevertheless, as such comparison has been made, it is wellto discuss here the points of contrast.

The skull of Leptoceratops has little in common with Brachyceratops.
nasal horn composed of a right and a left element divided

The latter has a large

by suture, the entire structure, with the

exception of a small terminal ossicle, being a continuation of the nasal bones. In Leptoceratops, there
is no trace of a nasal horn, the nasals, wide at their posterior end, terminating in a point, with no
The supraorbital horns,
elevation of profile or other indication of even an incipient nasal horn.

which are present, though small, in Brachyceratops, are also presumably absent in Leptoceratops,
although of this there is no direct proof. Other skull details, available for comparison, lie in the
In Leptoceratops, the posterior median part of the crest (parietal) only
crest, mandible, and teeth.
that of Brachyceratops in the form of the hinder margin, which in the
differsfromIt
preserved.
isformer is straight, in the latter with a shallow reentrant angle. Leptoceratops has a rather high, thinsagittal ridge extending nearly to the posterior edge; Brachyceratops has none, although the midline
is somewhat elevated, with the undulating profile which is characteristic of several ceratopsian genera,
notably Monoclomus {crassus), and Triceratops. Judging from the position of the squamoso-parietal
suture, the squamosals in Leptoceratops must have extended to the rear of the crest; in Brachyceratops, the same evidence indicates that they were short, and terminated at about the middle of the
Finally, there is no evidence whatever of the presence of parietal fenestrae in thelateral margins.
preserved portion of the Leptoceratops crest. They were present, but apparently small, in Brachyceratops. This, however, may be only a difference of degree and not of kind, for all other Edmonton
The mandible and predentary
Ceratopsia possess these openings, and Leptoceratops may have.
differ markedly, those of Leptoceratops being short and deep, with an unusually large predentary inproportion to the dentary. In Brachyceratops, the mandible is slender and the predentary relatively
small, more as in normal ceratopsians. Alveoli in the premaxillary of Leptoceratops betray the presence of premaxillary teeth which certainly do not occur in Brachyceratops. Apparently, Leptoceratops has single-rooted teeth, those of Brachyceratops being probably of the regular ceratopsian bifanged
sort, although this cannot be verified.
Among skeletal contrasts there are marked differences in the ilia, pubes, ungual phalanges, andin the spines of the caudal vertebrae, all of which are typically ceratopsian in Brachyceratops anddiffer widely from those of Leptoceratops, in which these elements are highly diagnostic, as thecomparison with Protoceratops will show. On the whole, I see no indication whatever of relationshipbetween Brachyceratops and Leptoceratops, the latter being something very much apart from theremainder of the American Ceratopsia.
Mr. Brown has already stressed a number of points of comparison between Leptoceratops andProtoceratops, and the newly acquired skeleton, instead of showing distinctions, serves only to emphasize further likenesses which indicate real relationship between the genera even though they wereremotely removed from one another in space. Several instances of such discontinuous distribution
are known, however, notably the extant Tapirus, the surviving members of which, living as they doin Brazil and the Malay peninsula, are yet more remote.
So far as the skulls of Leptoceratops and Protoceratops can be compared, the similarities include
hornlessness, the presence of premaxillary teeth, the single-rooted character of the other teeth, anda general agreement of size on the part of some of the larger Protoceratops skulls. The lower jaws
agree somewhat in shortness and depth, but the form of the coronoid differs, as does the proportionate
size of the predentary bone, which is much the larger in Leptoceratops.
The parietals are alike in the possession of the sagittal crest, and in the comparatively straight
posterior border, but there the resemblance ceases, for the squamosal sutures are much farther apartin Protoceratops, where they form a wide angle of about 90° with each other, while in Leptoceratops
they are more nearly parallel, thus implying a short squamosal on the part of the former, and a longTHE CERATOPSIA

80

one on the part of the latter. The form of the squamosals has high diagnostic value in otherBut perhaps the most striking contrast lies in the very large parietal fenestrae inceratopsians.
Protoceratops, so large that there is merely a narrow band of bone between them and the rear of

AMNH 5464

Fig.

34.

—

Lateral view of anterior cervicals ofProtoceratofs anirewsi,
naturalsize.-

cervical;az,

No. 6417 A.M.N.H., J4

anteriorh, capitular facet;zygapophysis
if,offourthintervertebral fora-men;fz, posterior zygapophysis of fourth cervical;s, neural spine of axis;/, neural spine of third cervis", neural spine of fourth cervical;

cal;

t,

Fig.

3 5.

—

Lateral view of anterior cervicals of

Leftoceratofs, J4
if,natural size,h,capitular

facet;

fz, posterior zygapophysis
rib; s, neural spine of axis;

intervertebral foramen;of fourth cervical;r,/, neural spine of third cervical;s" , neural spine offourth cervical.

tubercular

facet.

The rather large portion of the Leftoceratofs parietal preserved shows no trace of fenestrae
at all, so that if fenestrae shall ultimately be found in Leptoceratops, they will be much smaller andthe crest.

farther forward, for the area where they occur in Protoceratops is here solid bone. This one element
is so distinctive that, however closely allied these forms may prove to be on other counts, their dis-

Fig.

36.

—Rightpubis of Protoceratofs andrewsi,

No. 6417 A.M.N.H., internal view,f, pubis;y natural size.
2

Fig.

37.

— Right

pubis of Leftoceratofs, internalview, J4 natural size,f, pubis;ff, postpubis.

ff, postpubis.

tinction is surely generic.

The general form of the skulls was probably quite different, as the much

longer nasals in Leptoceratops give further evidence.
Of the anterior cervicals, all are thoroughly coossified in Leptoceratops (Fig. 35), while in
the unmounted skeleton of Protoceratops (Fig. 34), No. 641 7 A.M.N.H., the atlas and axis are fully
fused, the axis and third cervical are coossified at the base of the centrum, but the zygapophyses are
distinct.
The spine of the axis is erect in both genera and not bent backward as in all other ceratopsians.
The caudal vertebrae are similar in the two genera, but otherwise unique among horned

LEPTOCERATOPS GRACILIS

81

dinosaurs in the possession of extremely long spines, especially in that area of the tail which lies
behind the greatly elongated ischia, as though each possessed a flattened, crested tail almost that ofamodern basilisk.

See, however, Knight's restoration of Protoceratops in the frontispiece.

The ilia are alike, and differ from those of other ceratopsians in that they lack the reflected
upper border which, in the latter, overhangs the acetabulum, making the blade of the ilium nearlyhorizontal instead of vertical. The ischia, long and straight, and the very peculiar pubes
Figs. 36,37), with relatively short prepubes, are also in agreement with each other to the exclusion of otherforms. Comparable also are the femora, with a large fourth trochanter, and a well-defined third
trochanter.
In each, the unguals are slender and compressed, more like those of Camftosaurus(

than of a more typical ceratopsian.

These many details of agreement point to a very close relationship on the part of the twogenera and a wide divergence from all other known members of the superfamily Ceratopsoidea. I see
no indication of ancestry on the part of Protoceratops; certainly Leptoceratops of the Edmonton,
which is later in time than all of the Belly River, Judith River, and Two Medicine genera, and contemporaneous with Anchiceratops and Arrhinoceratops, is debarred by time from actual ancestry of
any of them, and its characters are not such as would permit it to be even a structural ancestor of anyof the Lance forms.

Protoceratops and Leptoceratops, each with its single known species, belong to the same family
7
Protoceratopsidae proposed by Granger and Gregory, but denned by Gregory and Mook.
The

family characters lie in those details which both genera show in contrast to the Ceratopsidae, andinclude hornlessness, premaxillary teeth, single-rooted maxillary and mandibular teeth, and thepeculiarities of ilia, pubes, and caudals which I

have stressed.

Family CERATOPSIDAE Marsh

The characters of the family may be stated as follows: large; highly specialized skull bearinghorns; with secondary roofing above the frontals; crest generally with epoccipital bones; without
premaxillary teeth; cheek teeth with bifid roots; fore limb shorter than hind; blade of ilium
horizontal; prepubic process comparatively large and expanded vertically at the anterior end; fourth;

trochanter of femur nearly obsolete, femur longer than tibia;
and hoof-like; midcaudal vertebral spines not elongated.

unguals of manus and pes depressed

Genus MONOCLONIUS Cope (Judith River phase)

The type species of the genus Monoclonius is M. crassus, described by Cope in 1876, from the
They were
Judith River beds of Montana. Three other species were described later in 1889.
Because of the fragmentary character of the typefissus, M. recurvicornis, and M. sphenocerus.
material, the doubt of actual association of the various elements in single individuals or even species,
and the fact that homologous parts of the different types are rarely preserved, it is extremely difficult
The same is true
to define the genus in detail, and next to impossible to compare all the species.
of the species of Ceratops, as described by Marsh, which come from the same general horizon andM.

locality.

The several species from the Belly River formation which have been described by Brown as
Monoclonius belong to the genus originally described by Lambe as Centrosaurus, with the species
If the generic identity of Centrosaurus and Monoclonius is finally determined
apertus as the type.
without question, the latter takes precedence.

On the basis of present evidence, I am inclined toconsider Centrosaurus a local, Belly River phase of Monoclonius., possibly of sub-generic rank.
In the morphological chapter of this memoir the skeleton of Monoclonius {Centrosaurus) flexus"Granger, W., and Gregory, W. K., 1923, p. 4.
7
Gregory, W. K., and Mook, C. C, 1925, p. 4.

THE CERATOPSIA

82
atYale was used for a basis of description, and comparison was made in so far as possible with thetype of Monoclonius crassus Cope, as described in considerable detail by Hatcher in the Ceratopsia
monograph. So far as the skeleton was concerned, no differences other than of specific rank were
The chief
discernible; without the skull, however, generic identity is difficult of establishment.
distinctive characters of Monoclonius, as determined by Hatcher,8"are its small size, the diminutive
theshort,
broad,
and widely fenestrated parietals;
upward;pointing
directly
supraorbital horn coressquamosal
bordertheontheparietals
in the type."
indicatedbythe short squamosals, as
nasal
include
a
horn
core,
the
character of this element
so that
The type of M. crassus does notcannot be included in the generic description, as based upon that type. The horn of M. sphenocerus
is present, but is unassociated with a crest and therefore might as readily have pertained to a StyracoHence, one cannot prove fromsaurus, to which it has actually been referred (see beyond, p. 90).
the original material whether this type of horn was characteristic of Monoclonius or not.
The crest of M. crassus differs from that of Centrosaurus a-pertus in the presence of five prominences, forming a median row as in Triceratops, and in the lack of any indication of the four posterior
horn-like processes which are highly diagnostic of every Belly River specimen pertaining to Lambe's
genus, except that one or the other of the forwardly-directed pair may be missing, as in Brown'sM. (C.) flexus type, but never both so far as I can ascertain. On the other hand, their presence
has never been demonstrated on any Judith River specimen.
The long nasal horn and short brow horns; the short, deep muzzle; the saddle-shaped crest,with its short squamosals and widely fenestrated parietals, the latter with a smooth median bar; andthe two pairs of processes arising from the rear, an anterior sulcated pair (one of which may be undeveloped) projecting forward to overhang the fenestrae, and the posterior curved, hook-like pair,constitute the diagnostic characters of the sub-genus Centrosaurus.
The nasal horn presents little difficulty, as it is not demonstrably absent from Cope's type, but
the processes of the crest are, to my mind, a serious obstacle to the acceptance of generic identity, as
they are demonstrably absent in the type of the genus. Geographically, the two genera come fromareas at least 250 miles apart; stratigraphically, the Belly River and Judith River formations arestated to be equivalent (see chapter on distribution, p. 6).
Be that as it may, the predentate
dinosaurs from the two areas present a very different aspect, and this refers to the unarmoredtrachodons as well as to the ceratopsians; for the Belly River forms are often grotesque, such as thehelmeted dinosaurs culminating in the remarkable Parasaurolophus with the extreme backward extension of the skull, and Monoclonius {Centrosaurus) and Styracosaurus with equally remarkablespinescence. That this condition may be due to racial abnormality having its seat in the pituitary
gland, which, as is well known, does react to certain peculiar conditions of the physical or chemical
environment, may have been true. Nevertheless, the specializations to which such conditions giverise may be considered as having taxonomic value, whether generic or specific.
It cannot be that, as
Nopsca and others have argued, these distinctions are sexual, for that would mean permanent segregation of the sexes either geographically or in time, a manifest absurdity from the standpoint of
racial continuity.

Monoclonius crassus Cope 9
No. 3998 A.M.N.H.; incomplete median element of crest. The sacrum and other skeletal elements,
described in detail in the Ceratopsia Monograph, bear the same catalogue number as the holotype (No. 3998),

Holotype:

although sometimes with a query.

There are also a number of isolated vertebrae, with no record available

as to their associations although in sizeand general character they agree with the remainder of the skeleton.
No. 3997: prefrontal and postfrontal with brow horn, questionably referred to M. crassus.
Horizon Judith River formation.
Locality: Nearly opposite the mouth of Dog Creek on the north side of the Missouri River, Montana, in the same:

locality asM.

recurv'icornis.

Collector: E. D. Cope, 1876.
89Hatcher, Marsh, Lull, 1907, p. 70.
Cope, E. D., 1876, pp. 255-256.

MONOCLON1US RECURVICORNIS

83

Monoclonius recurvicornis Cope 10
Holotypc:

No. 3°' il1 A.M.N.H.; upper portion of

facialregionbearing both supraorbital

and nasal horns,

together with a fragment of the left jug.il, and part of the margin of the right squamosal with two epoccipitals.

Horizon: Judith River formation.
Locality:

The same as M. crassm.

Collector: E. D. Cope and party, 1876.

Except for the supraorbital horn of M. crassus, which does not belong to the holotype, there
homologous andtherefore, comparable.
Hence, specific distinction is not demonstrable.
There is a skull of Monoclonius {Centrosaurus) in Ottawa (No. 348 G.S.C.) in which the nasal
horn is quite similar to that of Cope's type in the degree of its forward curvature. The left browhorn is relatively nearly as large as in recurvicornis, but the right is much smaller, nor have either ofthem the same form as in recurvicornis. There the resemblance ceases, as the Ottawa specimen
shows no trace of a small horn-like prominence borne on the prefrontal on either side about midway
between the nasal and brow horns. Beyond this, comparison cannot be made.
are no parts of the skulls of M. crassus and M. recurvicornis preserved which are

Monoclonius sphenocerus Cope 11
Holotype: No. 3989 A.M.N.H.; nasal horn, nasal and left premaxillary.
Horizon: Judith River formation.
Locality:

On Missouri River, near Cow Island.

Collector: C.

H. Sternberg, 1876.

Here, again, no comparison can be made with homologous elements in M. crassus. This is not
M. recurvicornis and M. sphenocerus, for in each instance the nasal horn is present.
The two horns are very different in character, that of the species under discussion being straight, erect,
laterally compressed, and of great fore and aft diameter at the base, with a rapid diminution of thisdimension toward the tip. In recurvicornis, on the other hand, the basal section is more broadly
elliptical and the horn curves sharply forward.
Clearly, therefore, M. recurvicornis and M. sphenocerus are specifically distinct, but, unfortunately, neither species can be differentiated from M. crassus,
the type of the genus, which, in case of proved identity, would take precedence over either recurvicornis or sphenocerus, but which one cannot say.
So here the matter rests until more adequate
material is secured from the Judith River formation.
The comparison between the M. sphenocerus horn and that of Styracosaurus albertensis will
shortly be discussed and the relationship between them, which some have argued, dismissed as
unproved.
true, however, of(?)

Monoclonius dawsoni Lambe 12

No. 1173 G.S.C; parts of two skulls.
Horizon: Belly River formation.
Locality: Red Deer River, between Berry Creek and Dead Lodge Canyon, Alberta.
Holotype:Collector:

L. M. Lambe, 1901.

Mr. Lambe's description is as follows: "The remains of an apparently undescribed species ofthis genus, consisting of the skull of one individual

and the posterior crest of another, are of especial

The skull when found lay on its right side and although very much crushed, certain
parts of it supply definite information as to its structure and size. The two orbits, the right maxilla,interest.

a quadrate, and the occipital condyle were conspicuous and apparently in place, with a large posterior
10
11

12

Cope, E. D., 1889, p. 716.
Cope, E. D., 1889, pp. 716-717.

Lambe, L. M., 1902, pp. 57-63.

THE CERATOPSIA

84

Somewhat in advance of the orbits a horn core, of large size and apparently symmetrical form, occupied a position suggestive of a nasal origin, the nasal bones and thefrontals being probably represented by the fragments filling the space between the orbit and thecrest extending to the rear.

horn core ....

"The large posterior crest forms the back part of the skull above; its exact shape is fortunately[This crest, No. 971 G.S.C.
supplied by the admirably preserved specimen shown in outline, ....
13
was later made the type of the genus and species Centrosaurus apertus Lambe. ] The surface of thebone, above the orbit and from there inward for a short distance toward the median line of theskull, is moderately smooth and shows no trace of ahorn core."

The remainder of the description

pertains to the second crest.
It is unfortunate that the condition of the actual crest of this specimen rendered it incapable ofpreservation and that Mr. Lambe, instead of describing it in detail, should have turned to the otherSo far as the nasal horn is concerned, Lambe's firstcrest to complete his description of the species.
reference of the species to Monoclonius would be valid, although it is the only known specimen of

this genus in which the horn curves backward.

or forwardly curved.

In all the other Monoclonius skulls it is either erect

No other detail debars the type from Monoclonius except possibly the crest.

The known characters of the species M. dawsoni are as follows:14

nasal horn large, curved
margins to crest;
small,
smoothundulating
squamosals
backward;
statement
reducedorabsent.
If
thelastis true thefenestrae
greatlyepoccipitals absent; parietal
however,been
also
referredtoThis
species
has,
Centrosaurus.
form cannot be Monoclonius or
Two
Medicine
formation,althoughevidencetheBrachyceratops, a genus described by Gilmore fromThe nasal horns are very different, for in Brachyceratops it
for such inclusion is very inadequate.
was made up of two elements, one derived from each nasal bone and therefore separated in the
median plane, a juvenile character known in no other ceratopsian skull except Eoceratops canadensis.
A presumable element of agreement lies in the apparently small size of the parietal fenestrae and thegeneral form of the squamosals, with their undulating border and lack of epoccipital bones. The
shape of the orbit is somewhat similar in each form. The actual form of the crest which belonged
to the type skull, at present vaguely understood, will determine the generic status, and not until
another undoubted specimen is found can the real position be known. Tentatively, I would leavesupraorbital horns incipient;the form as Lambe originally named it.

Sub-genus CENTROSAURUS Lambe (Belly River phase)
1This sub-genus was founded upon a parietal crest first described by Lambe " in conjunction withThe latter consisted of an extremely fragmentary
the Belly River type of Monoclonius dawsoni.
Lambein
1901, but in such condition that the crest could not
skull, No. 1 173 G.S.C, discovered byNo.
971 G.S.C, was considered part of the type,
be preserved, so that the one under discussion,
although from a somewhat different locality and level, and was used in the original description;
no record was taken of the actual crest other than a rather vague, though measured, field sketch
16
From this sketch it is evident that Monoclonius dawsoni had
made before the parts were removed.
a different type of crest from that of Centrosaurus apertus and that Lambe was justified in erecting a
new genus for the inclusion of the latter. But the species of Centrosaurus are confused in the same
way as are those of Monoclonius, since in each genus the genoholotype is based on a crest only, whichcannot be compared with the same element in the types of the other species, because these types"Lambe, L. M., 1904, p. 81.
14
15

10

Lambe, L. M., 1915, p. 21.
Lambe, L. M., 1902, pp. 58-59, also Hatcher, Marsh, Lull, 1907, p. 89, Fig. 92.

May 30,1905, and published in the Ceratopsia Monograph, page 179,
in what he calls the Lower (primitive mammal) beds with
Eoceratofs canadensis; while Monoclonius dawsoni, No. 1173, is referred to the Middle beds, and Chasmosaurus belli toCentrosaurus afertus was collected on the west side of Red Deer River, July 26, 1901, while Monoclonius
the Upper.
In a letter to the present author dated

Mr. Lambe places the type of Centrosaurus afertus, No. 971,

dawsoni came from the east side, August

1

5of the same year.

MONOCLONIUS DAWSOM

85

Monoclonius), or the specific distinctions seem to lie in other parts of the skull,
the crests alone being spedficall) indistinguishable from the genoholotype, or from one another

do not possess a crest(

Lambe's original description stressed the curved, hook-like processes at the posterior
end of the saddle-shaped frill, hence Centrosaurus. He did not, however, recognize the forwardly
projecting process as such, for it was detached and hence mistaken for a rather peculiar nasal horn.
Later, it became evident that this horn fitted accurately on a fractured portion of the posterior parietal
The right one only is present, however, there being nobar, and it was then cemented into place.
That was later found to be of occasionalsign that the animal ever had possessed the left one.
occurrence (cf. Monoclonius (Centrosaurus) flexus type).
The sub-genus Centrosaurus is now known in its entirety, even to the hide (PI. Ill, B), and theUtrosmmu).

description of it appears in detail in the morphological portion of this memoir (pp. 30-66).

We have-already stressed the sub-generic characters in distinguishing Centrosaurus from Monoclonius ; but
the specific distinctions separating the various centrosaurs are not so clear, and seem to lie mainly
The named species are:in the character of the nasal horn, whether straight or forwardly curved.
Brown; and C. cutleri
nasicornus
Centrosaurus a perl us Lambe, genoholotype; C. flexus Brown; C.

Of these, C. nasicornus is based upon an entire skeleton with skull and jaws, all of a singleOf C. flexus, on the other hand, the type consists
individual, and is, therefore, entirely adequate.
Brown.

of a skull only, without the lower jaws, or other skeletal elements; while C. cutleri is based upon apartial skeleton with the merest fragments of skull which cannot be compared with the flexus or any
other skull. In other words, there is no assurance that these two species are distinct, as the types

Furthermore, the Yale specimen, again a single
contain no homologous parts for comparison.
individual, possesses a flexus skull while the skeleton is more suggestive of cutleri, as the descripthe
I am inclined, therefore, to consider C. cutleri as possibly invalid, which reduces
tions show.
species to three, or possibly two, since neither flexus nor nasicornus can be distinguished from apertus

on the basis of the crest alone.
Characters, shown by the skulls, which may be contrasted and are hence of specific value, areas follows:

The nasal horn is always well developed, much more so than in Chasmosaurus, and is either
The only variant known to me is in skull
erect as in nasicornus, or curved forward as in flexus.
No. 4519, at Toronto, in which it is erect but curves slightly backward toward the tip.
The brow horns are never large in the Belly River forms, except in Chasmosaurus kaiseni(PI. V, A). In Centrosaurus, they have the same degree of development as in the other chasmosaurs, and vary from mere rugosities over the orbits, as in nasicornus, to pointed, trihedral horns, ofwhich the height about equals the fore and aft diameter at the base, as in the Toronto specimen,
No. 4519, mentioned above. Strangely enough, in both the flexus type and that at Yale, as well as
thein a curious skull, No. 348, at Ottawa, one horn is developed to a much greater extent than isother and, through coincidence or otherwise, in each of the three it is the left which is the larger.
The forwardly directed processes at the rear of the crest may be straight or have varying degrees
An extreme instance is shown in the skull No. 348 referred to, in which the curvature
curvature.
of

The posterior processes of the crestof both the nasal horn and the processes reaches a maximum.
The crest isapart at the base.
in
theirdistanceaswellcurvature,
asofdegreetheirinalso varyinthe apertus
ratherflat
fromcurvature,transverse
degreeofinthevariesbut
saddle-shaped,
alwaysorientapart
to
the
in
may
be
due
skulls.
Thisofnumbergreater
curve
of
the
extremetype to the

The apertus crest was, I believe,tion of the specimens in their original position in the strata.
theirside when found, which, in eitheronliespecimens
most
of
the
whereasflat,
detached and lying
case, must influence the ultimate form of the fossil due to crushing.

It does not seem as though thisfeature can be of specific significance.
Finally, the muzzle, while always shortand deep as compared with thatin

Chasmosaurus,

nevertheless varies, especially in profile and in the degree of rugosity of the part immediately above
F.\treme curvature and rugosity is seen in the type of nasicornus, and also in specimen
the rostrum.

No. 8897 U.S.N.M., which agrees with the type in other details as well.

THE CERATOPSIA

86

On the basis of these details, I recognize two clearly defined species, flexus and nasicomus,
either of which

may be referable to the genoholotype apertus.

But in view of the paucity of thistype, it merely serves to establish the sub-genus as compared with Monoclonhis and not the species,

hence no reference of any other skull to this species can be made with any assurance at all. It is thecustom in the Canadian museums to label as apertus all exhibition specimens of Centrosaurus, theI shall try to allocate each to one or thecorrectness of which can neither be affirmed nor denied.
other of Brown's species, with the following results.

Monoclonius (Centrosaurus) flexus Brown 17
Pis. II, III;

Holotype: No. 5239 A.M.N.H.;
Horizon: Belly River formation.

Text Figs. 4, 5, 7-10, 13, 14, 16-29

skull.

About 1 mile below Steve ville, on the east bank of Red Deer River, Alberta.
American Museum expedition of 1912.
Plesiotype: No. 2015 Y.P.M.
Locality:

Collector:

Horizon: Belly River formation.
12 miles below Steveville, 2 miles from the mouth of Sand Creek, on the east bank.
Collector: American Museum expedition of 1914.
Locality:

The chief distinguishing character of this species lies in the nasal horn which is long andcurved forward.

To this species I would also refer skull No. 348 G.S.C., at Ottawa, although it departs fromthe definition in the extreme curvature of the nasal horn and anterior processes, and in the decided
rugosity of the premaxillary profile of the muzzle. These may be due in part, however, to age.

Skull No. 347, at Ottawa, agrees in the forward curvature of the nasal horn, but disagrees in the
rudimentary character of the brow horns, and in the straight anterior processes. This last detailcorresponds with the apertus type, beyond which comparison fails.

Monoclonius (Centrosaurus) nasicornus Brown 18PI.

IX, A; Text Figs. 11, 12, 15

Holotype: No. 5351 A.M.N. H.; a complete skeleton.
Horizon: Belly River formation.
Locality: North fork of Sand Creek, 12 miles below Steveville, Red Deer River, Alberta, Canada.
Collector:

American Museum expedition of 1914.

The skull characters of this type are as follows: Nasal horn erect, brow horns rudimentary,
being represented by a heavy rugosity above the orbits (whether or not the actual horn core was
detached in maceration can not be proved), crest processes moderately curved, muzzle deep, profile
very convex and rugose.
To this species, besides the holotype, No. 5351 A.M.N.H., I would refer the skull No. 8897
U.S.N. M. in which the nasal horn, so far as preserved, is erect, although restored by the collector,
C. H. Sternberg, as curving slightly forward. Otherwise, it conforms well with the type. Anotherskull, No. 4519 R.O.M., Toronto, agrees with the type in its erect nasal horn and rugose muzzle,
although the latter is not so extreme as in the type. The brow horns, on the contrary, do not correspond, as they are pointed and trihedral, being about as well developed as in any Centrosaurus.
17

18

Brown, B., 1914 B, pp. 549-5 58.
Brown, B., 1917, pp. 281-301.

;

MONOCLONIUS (CENTROSAURUS) CUTLER!

87

Monoclonius (Centrosaurus) cutleri Brown 10
Holotype:

J" A.M.N.H.;
No. 54posterior half of the skeleton,

ami a section of the epidermal impression over-

Lying the right lemur.

Horizon: Belly River formation.
Locality: North fork of Sand Creek, 12 miles below Stevcvillc, Red Deer River, Alberta, Canada.
Collector: American Museum expedition of 1913.

A few skeletal comparisons can also be made in the three specimens which are sufficiently complete, namely, the types of nasicornus and cutleri, and the

Yale specimen of flexus.

These contrasts

and,lie in the form of the ilia, ischia, sternal plates, femur-tibia ratio, curvature of the posterior ribsasdorsalsof
thein the Yale specimen, the curious backward offsetting of the neural arch and spinescompared with those of nasicornus (see Figs. 9-15).
Comparing the type specimens of nasicornus and cutleri, the following differences are observed:
The preserved vertebrae are a little larger in cutleri, but, according to Brown, of exactly the same
form as in nasicornus, no distinctions being seen in any part of the column. The sternal plates ofThecutleri are markedly longer, narrower proximally, and wider distally than in nasicornus.
anterior blade of the iliumismuch longer in cutleri than in nasicornus.

The ischium of cutleri islong and comparatively straight, with the distal end sharply decurved and expanded, in contrast to
the more even curve throughout in nasicornus. The femora are more than one and one-half times
the length of the tibiae in cutleri, and not over one-third longer in nasicornus, the ratios being 1 .60
A final detail is the remarkable curvature of the lastin the latter.
to 1 in the former, 1.32 to
dorsal rib through an arc of more than 180° in cutleri and in the Yale specimen, and not at all in
1nasicornus.

isThe skeleton belonging to the Yale specimen, which the skull characters determine to be flexus,
compromise between nasicornus and cutleri. The dorsal vertebrae differ in a marked

a curious

way from those of nasicornus in the offsetting of the neural arch and spines to the rear, as has been
In this they disagree with cutleri. The femur-tibia ratio in the Yale specimen, which
Unfortunately, the distal
is
1, is intermediate between that of nasicornus and cutleri.
elongationof the ilia is again interbut
thenasicornus,
after
been
restoredeachischiumhas
half ofoutline,resemblein the one cutleri,inimperfect
sternalplates,
the
two
last
of
all,
mediate. And
characterize
the Yale skeleton
featureswhich
distinctive
are
the
These
nasicornus.
and in the othermentioned.

as 1.43 to

but without the skull, one would hardly be justified in erecting a new species for its inclusion. The
feeling is quite strong, however, that were the skull of cutleri known, it would prove to resemble oneof those we have included under the species flexus.

Genus STYRACOSAURUS Lambe
Styracosaurus albertensis Lambe 20
PI. VIII
Holotype: No. 344 G.S.C.; skull without lower jaws.
Horizon: Belly River formation.
Locality: \ x 2 miles south of Denhart Ferry, Red Deer River, Alherta.
Collector: C. H. Sternberg, 1913.

/

Generic characters are as follows: "Skull massive, elongate, pointed in front, and greatly
extended behind to form a neck-frill with long, robust, tapering outgrowths projecting obliquely
backward and outward from its posterior border. Fontanelles of moderate size within the coalesced
Squamosals somewhat quadrangular and entering largely into the formation of the front
parietals.

rown,

I!.,

-" Lambe, L.

1917, pp. 301-306.
M., 1913, p. 109.

THE CERATOPSIA

88

part of the frill.
Postfrontal fontanelle large.
Supratemporal fossae opening widely behind.
Nasal horn-core large, upright, straight, rising from the back of the nasals. Supraorbital horn-core
incipient."

This is the most bizarre of all the ceratopsian genera, one in which the spines and processes
borne on the skull have run riot. The holotype of S. albertensis is preserved at Ottawa, and consistsof a splendid skull without the lower jaw, although an artificial mandible has been taken fromanother genus and modified to fit. The skull is entire, except for the following: part of the rostralbone, a little more than the distal half of the nasal horn core, and portions of the spines bordering theparietal part of the crest.
There is no reason to suppose that these restorations are other thancorrect, as they continue the contour of the elements to which they are attached.
The nasal horn core is heavy, with an elliptical cross-section and, as preserved, there is no
trace of axial curvature either forward or backward.
It is not quite erect, however, but inclines
slightly forward.
As with Monoclonius including Centrosaurus, the horn is slightly constricted at
the base before the vascular impressions begin.
The anterior margin of the horn lies just over theposterior limit of the nares as in Chasmosaurus, hence it lies relatively farther back than in
Monoclonius, wherein the middle of the horn core overlies the posterior margin of the nares. The
nasal extends but little behind the horn.
The supraorbital horns were incipient, and the actual ossifications were apparently lost duringmaceration, for a distinct but irregular facet is visible over the rear margin of each orbit. A second
specimen, mentioned by Lambe, shows the same condition. The premaxillaries are broadened out
below, but are deeply depressed and smooth in the narial area. The length and comparative shallowness of the muzzle recall Chasmosaurus rather than Monoclonius. The posterior limit of thepremaxillary is far removed from the lacrymal.
This was found to be a variable condition in
Monoclonius. The vestigial preorbital fossa (lacrymal foramen) lies, therefore, between the nasal
and maxillary only.
The jugal is deep, and not very extensive fore and aft. There is no indication of an epijugal.
The squamosal is short, as in Monoclonius, and bears five crenulations, but no separate epoccipitals.
The fused parietals form the bulk of the crest. The sutures between them and the frontals and post21
frontals are clearly defined on either side of and within the postfrontal fontanelle.
The orbit is broadly elliptical, the longitudinal axis lying upward and slightly backward, about
45° out of the perpendicular. The crest bears three pairs of large spike-like prominences and threepairs of small ones. There are some faint vascular impressions on the surface of the crest itself, butthey are many and deep on the processes. The posterior pair of large processes is divergent andslightly curved outward; they are not, however, complete throughout their entire length, so this isconjectural. The intermediate pair is straight and also diverges outward, but they are more perfect,
especially as the tip of the left one is preserved, so that there is little doubt of their correct restoration.
The forward pair, which again is slightly curved outward, underlies the intermediate pair alittle, at their base.
Here, again, there is some restoration, but it is evidently correct. Of the small
prominences, the hinder pair, which arises on the superior surface of the crest, is suggestive in position of the forwardly projecting processes on the crest of Monoclonius {Centrosaurus), while the pairon the lateral margins of the crest, just in front of the anterior large processes, is like those of
Monoclonius {Centrosaurus) in character but not in position, in that they show the same grooved orfluted surface.
In front of these processes on either parietal margin are two other prominences comparable to and probably homologous with epoccipitals, although again without sutural limitation.
Viewed from above, the crest gives the impression of having been pulled away from the frontal areaof the skull at the posterior limit of the fontanelle.
There is, however, no evidence of fracture. It

when viewed from the side, a flattened aspect unlike any other ceratopsian
except Torosaurus gladius as restored (see PL XVI). As Lambe says, 22 "In lateral aspect the skull

gives the entire skull,isdepressed and very long in contrast with its height.

21

Sternberg, C. M., 1927, A, p. 140.

"Lambe, L. M., 1913, p. 110.

The spike-shaped processes double the length

1

.

-I

\

RACOSAURUS VLBERTENSIS

89

which, without them, would compare favourably in relative size with the corresponding
expansion in later forms ot the Ceratopsia, such as TficeratOps, in which the orbit is hut slightly inadvance ot the mid-length ot the skull. Behind the nasal horn the upper outline is straight, thensomewhat depressed near the middle of the crest, finally rising to its highest point at the terminationof the [undermost process."
The parietal tenestrae are irregularly oval in outline, with their longer diameter extending
From anterior to posterior and slightly diverging outward. Anteriorly, they approach but do notreach the squamosal suture. Beneath the large nasal horn the nasals are massive, to withstand theheavy strains to which the use of the horn subjected them; a bulky transverse arch is formed by thedescending processes, which meet ascending processes from the premaxillaries, while in front, thenasals form a shallow, laterally compressed arch, which descends vertically in a sweeping curve tomeet the premaxillaries in advance of the narial openings, after the manner of a flying buttress.
The vertical nasal septum supports this arch from beneath and is, as in Monoclonius, contributed tojointly by both nasals and premaxillaries.
The septum is not fenestrated, agreeing again with
23
Monoclonius but in contrast to Triceratops.
The infratemporal arcade is formed by the quadrate,
quadratojugal, and a forward process of the squamosal. The last, together with the jugal, forms
the actual limits of the infratemporal fossa itself.
No skeletal elements attributable to Styracosaurus are known, but presumably, in size and proportions, the body and limbs were not unlike those of its contemporaries, Chasmosaurus andMonoclotiius ( Centrosaurus )of the trill,

Dimensions of the Skull(After Lambe 1913, but converted intomm.)

Maximum length of specimen from midway between the points of the back processes
Greatest breadth of same across the processes

1S61 mm.
1435

Length of squamosal from the posterior termination of its free edge to the back margin397

of the jugal

Breadth of same from its lowest point to the top of the squamoso-postfrontal suture
Length of nasal horn core as foundTransverse diameter of same, at breakLongitudinal diameter of same, at break

...

31

251
70
98
Ill

Transverse diameter of same, at baseLongitudinal diameter of same, at base
Length of nasal horn core as restored

162

552

Measurements Made from the Skull by R. S. Lull
From tip of rostral to rear of crest between processes, measured over the curve
From tip of rostral to tip of left rear process
Length of posterior left process
Length of intermediate left process
Length of anterior left process

1390 mm.
1970
550
500

390 (Calculated)
260
580
280
770
300

Nasal horn on rear margin, actual boneNasal horn on rear margin, as restored
Depth of premaxillary
Rostral to supraorbital horn suture

Width over orbits
Width over squamosals, on curve
Length of left parietal fenestra

1000
265

Width of left parietal fenestra

210

en

in

the several Tricerotofs specimens thispostmortem accident, as the septumisextremely thin.

isso variable a feature that the perforation

may be merely the result of

THE CERATOPSIA

90

Styracosaurus ovatus Gilmore 24
Hnlotype: No. 11,869 U.S.N.M.; posterior portion of the crest and numerous detached fragments.
Horizon: Two Medicine formation.
Locality: Milk River, Blackfeet Indian Reservation, Glacier County, Montana.
Collector: G. F. Sternberg, 1928.

This species conforms to the generic characters in so far as determinable from the extremely
meagre type, which consists of the posterior part of the crest bearing the four median processes
together with a detached fragment bearing another.
The original description follows: "The outstanding peculiarity of the skull of Styracosaurus
albert ensis is the large horn-like processes that project outward and backward from the posteriorborder of the frill. Somewhat similar processes are present on the frill before me. The two processes
forming the hindermost pair lack their tips but it is quite evident they were not as long as in the
Furthermore, these two horns are convergent as opposed to the divergent
Canadian specimen.
It would seem that if completely preserved the extremities of these twoprocesses in S. albertensis.
horns would nearly meet on the median line. Those of the next pair in advance are nearly as large
That there was a third pair is shown by
as the hinder pair but point outward more than backward.
the presence of a small lateral section of the frill, from the side of which a small, stubby process
projects outward. ...
If, as is apparent, this fragmentary part represents the third pair, theseprocesses have their origin considerably forward of the second pair as shown by the smooth, roundedborder between them. In S. albertensis these processes are relatively shorter, curved, and twinned
with the second pair at the base.
.

.

.

".
That large fontanelles were present on either side of a median bar as in S. albertensis isshown by the rapid thinning of the bone on the anterior borders on either side of the middle, andThis part of the median bar is broadly
also of the posterior portion of the bar which is preserved.
rounded transversely on the upper side but flattened beneath.
"The upper and lower surfaces of the frill parts are marked by the usual vascular grooves.
The horn-like processes are much flattened above and below and cross sections taken from almost
any part would be broadly ovate in cross section.".

.

Thus, the main distinctions of the present species from S. albertensis are: processes III arecloser at the base and converging instead of diverging toward their tip, and there is a wider separa-

In albertensis, the processes are in contact} in ovatus, a roundededged margin of crest lies between them, flat and sometimes slightly hollowed on the under side.
The presence of vascular impressions on the crest of ovatus in contrast to the smooth surface inalbertensis may be a matter of individual age, the former being the older, although somewhat moretion of processes I and II at the base.

recent in geologic time.

The type of Monoclonius sfhenocerus Cope, from the Judith River of Montana, which consistsof the nasal horn, nasals, and part of the left premaxillary, is quite suggestive of the corresponding

Of these, Lambe says, 25 "In Cope's species the nasal horn-core is farther
forward on the nasals, is proportionately shorter, and more laterally compressed, with a muchgreater antero-posterior diameter at the base. The nasals in front of the horn descend rapidly
part of S. albertensis.

downward, and the nasal opening is larger andplaced more under the horn."
As a matter of fact, the type of Monoclonius (Centrosaurus) nasicornus Brown is even more like

instead of rising conspicuously before they curve

Styracosaurus in this particular portion than is that of M. sfhenocerus.

The nasals in front of thehorn rise as in Styracosaurus, and agree in being highly rugose; the smaller nasal opening lies under
the anterior part of the horn, and the character of the horn itself agrees except for minor differences
which may be due in part to the manner in which the distal half of the Styracosaurus horn is
24
25

Gilmore, C. W., 1930, pp. 36-37, PI. 10, Figs.
Lambe, L. M., 1913, p. 115.

1, 2.

EOCERATOPS CAN \M N'SIS
restored.

91

M. {(.'.) nasicornus is not Styracosaurus^ for the crests, while possessing processes andshort squamosals, are otherwise totally different, as are the general proportions of the entire skull.

The two cannot be congeneric, and there is no more assurance that Styracosaurus albertensis andMonoclormu sphenocerus were. On the other hand, Styracosaurus, being a short squamosal form,lies nearer Monoclonius (Centrosaurus) in relationship than any other contemporary genus, evidently representing a highly aberrant offshoot of the same ancestral stock as that of Monoclonius.
Certainly, no known Lance genus or species gives any evidence of relationship.
The evolutionary
trend in Styracosaurus, as shown by the available material, seems to be toward a shortening, broadening, and straightening, together with a convergence, of the posterior processes.

Genus EOCERATOPS Lambe
Eoceratops canadensis Lambe 20
Holotypc:

Right squamosal, No. 1254a G.S.C.; the right posterior lateral extension of the parietal, No. 1254b;

the right postfrontal and prefrontal with the supraorbital horn core rising from the former bone, No. 1254d;

No. 1254c; the left dentary without teeth,
No. 1254e; and an anterior dorsal vertebra, No. 1254.
Horizon: Belly River formation.
Locality: On the east side of Red Deer River, Alberta, a short distance below the mouth of Berry Creek.
Collector: L. M. Lambe, 1901.
the right nasal including the right half of the nasal horn core,

Generic characters are: "Skull small, short, compact; supraorbital horn-core moderately large,
slender, overhanging the orbit, circular in cross section, tapering to a point and directed upward, andslightly inward and backward above; nasal abbreviated and deep; nasal horn-core short, contributed
to by the nasals and two separate, anterior ossifications; crest or neck-frill slightly longer than half

the total length of the head; squamosal broadly triangular, longer than broad, with a smooth,undulating outer border, without epoccipitals, forming the greater part of the crest laterally; fenestrae of the crest long, enclosed without by the squamosal, and behind by a slender parietal bar which

passes forward beneath the inner posterior border of the squamosal; dentary robust, with about
twenty-five vertical series of teeth."

The type material upon which the genus Eoceratops is based consists of several isolated bones,
pertaining to an immature individual, which might well account for such features as the absence ofand the character of the nasal horn core. Lambe's outline of the skull, with the shortand very deep muzzle, is highly conjectural except for the fact that a deep facial region generally
goes with a short broad squamosal. It is noteworthy that in the presence of so many nearly perfectskulls of the other Belly River genera, especially of Monoclonius (Centrosaurus) and Chasmosaurus,
this should be the only recognizable specimen referable to this genus.
The full understanding ofrelationships in this instance, as in that of Alonoclonius dawsoni and the Judith River genera, must
epoccipitals,

await further discovery.

The skull, as at present understood, differs from all other Belly River genera in the natureand position of the nasal horn core. The character may be partly juvenile, but the position overthe forward margin of the narial opening, instead of over the rear, separates it from Monoclonius(Centrosaurus), Chasmosaurus, and Styracosaurus, and likens it to the Lance Triceratops.
The form of the squamosal also resembles that in Triceratops. It is short like that of Monoclonius (Centrosaurus), but differs in being generally triangular instead of quadrangular, as in the

The long fenestra, apparently but partly enclosed by the parietal element, is suggesimperfectan
Chasmosaurus crest rather than of Monoclonius (Centrosaurus) in which thefenestrae are widely removed from the squamosal. The absence of epoccipital bones is not invariably diagnostic, since they are lacking in several Triceratops skulls, notably that on the mounted
skeleton at the American Museum, in which they have probably been lost through lack of coossification before fossilization.
latter genus.

tive of26

Lambe, L. M., 1915, pp. 1-25.

THE CERATOPSIA

92

Genus CHASMOSAURUS Lambe

The type of this genus, No. 491 G.S.C., is a portion of the crest consisting of the median bar
2
and part of the posterior transverse bar, first described by Lambe as Monoclonius belli. Becauseof Lambe's conviction that this genus was directly ancestral to the Lance genus Torosaurus, thename Protorosaurus was given to it in 191 4, 28 together with a detailed description based upon theplesiotype, which supplied all the necessary details except the anterior part of the skull, including
the muzzle and nasal horn. The first of these I find to be important in Chasmosaurus, the second
20
Later in the same year,
rather less so, although a principal diagnostic character in other genera.
a further description of this species was given, with the new generic name, Chasmosaurus, replacing
Protorosaurus, which was found to be preoccupied by H. v. Meyer for a genus of Permian reptiles.
The generic characters, as given by Lambe, 29 are as follows: "Skull large, broadly triangularin superior aspect, with a narrow, abbreviated facial portion, and a broad and greatly expanded
posterior crest ending squarely behind. Coalesced parietals forming a slender framework enclosing
large sub-triangular fontanelles.
Squamosals very long and narrow with a scalloped free border.
Supratemporal fossae of moderate
Epoccipitals present.
Supraorbital horn-cores small, upright.
Teethlarge, of the ceratopsian type.
Body
size.
Postfrontal fontanelle present. Jaws robust.
covered with non-imbricating, small plate-like, and smaller tubercle-like scales."The holotype of this genus, incomplete as it is, shows no specific characters; but, as in MonoThe plesiotype, on the other hand,clonius and Centrosaurus, serves only to establish the genus.
allows for an almost complete generic description and establishes the species belli as well. In spiteof the fact that the various skulls show considerable variation among themselves, two other species
seem to be definable, although in each instance based upon a single skull.
The contrasting specific characters lie in the brow horns, whether longer or shorter than thenasal horn, the former being the more progressive condition. The muzzle, whether long or short,seems also to be distinctive. The emargination of the posterior bar of the crest may prove to be
On thedistinctive; at present, it seems to be merely an individual, or possibly a sexual variation.
basis of these and certain minor distinctions, the following species may be defined.
'

Chasmosaurus belli Lambe 30
PI. VI, XIV, Bj

Text Fig. 30

No. 491 G.S.C.; parietal.
Horizon: Belly River. Upper (primitive mammal) beds.
Locality: On the east side of Red Deer River, below the mouth of Berry Creek, Alberta.
Collector: L. M. Lambe, 1898.
Plesiotype: No. 2245 G.S.C. (PI. XIV, B), consisting of a large part of the skull and skeleton now mounted at
Holotype:

Ottawa.
Horizon: Belly River formation.
Locality:On the east side of Red Deer River, a short distance below the mouth of Berry Creek.

Collector:

C. H. Sternberg, 1913.

The distinctive characters of this species are as

follows:

Brow horns short, trihedral, anderect; orbit elliptical, with long axis nearly horizontal; posterior bar of crest not emarginate

—

large

epoccipitals are present at the outer rear corners of the crest just behind the termination of thesquamosal, but there is none borne on the parietals; squamosals bearing seven or eight epoccipitals,
increasing progressively in size from front to rear. To these features, determinable from the plesiotype, may be added Nasal horn larger than the brow horns, although short and robust and muzzle
long and slender.
;

:

27

Lambe, L. M., 1902, pp. 66-67, PI. xx, Figs.
Lambe, L. M., 1914, A, pp. 131-132.
29
Lambe, L. M., 1914, B, pp. 149-15 5.
30
Lambe, L. M., 1902, pp. 66-67.
28

1, 2,

Text Fig. 20.

CHASMOSAURUS BBLL1

would add the companion skeleton, No. 2280
further representatives of this species,
VI); and No. 2016 Y.l/.M. The skull ofC. (PI. XIV, B) 5 skull No. 54(12 A. M.N. II. (PI.
which hears two more
2280, at Ottawa, differs in having a deepU emarginate posterior bar
axis
on either side of the midline. The orbit is more nearly circular, with the long
1

Vs

\

93

epoccipitals

more nearly vertical and the brow horns, especially the left, somewhat recurved. Skull No. 5402
more anteriorly
A. M.N.H. conforms, except that the brow horns slope forward and are somewhat
and hasemarginate,
not
crest
is
the
rear
of
The
type.
the
than
in
orbit
placed with relation to thebeing
rudimentary,
are
horns
brow
the
that
exceptagrees,also
specimenfour epoccipitals. The Yale
merely rugose areas above the orbit.
There is in the American Museum collection the partial skull of a chasmosaur, No. 5656
A.M.N. H., collected by C. H. Sternberg in 1917, from the Belly River horizon of Sand Creek,
Red Deer River, Alberta. The upper surface of the cranium, including the horns, and the muzzle
specimen is thathave been eroded away, but the crest is in a remarkable state of preservation. The
apparently
withandsutures
definedclearlywithof a young individual, about 80 per cent grown,
all ofthe epoccipitals preserved in situ.

The outstanding features of this skull are the deeply emarginate posterior bar, bearing two

together with a marked
large, sharply pointed epoccipitals on either side of the reentrant curve,
bear an epoccipital,present
at
notprominence just behind the terminus of the squamosal which doesparietals have theThein the position of the largest of these in an adult chasmosaur.

althoughthe squamosal.
usual overlapping suture on the outer border of the very large fenestrae just within
length of thethe
two-thirds
The latter bone is very short for Chasmosaurus, extending for aboutbear a longiand
The squamosals are deeply concave transversely as seen from above
parietal.
this stage ofatThere are four distinctly sutured epoccipitals
tudinal row of boss-like prominences.
jugal
growth on either squamosal, and the antero-external angle is acuminate. The outer end of theposterior
Vascular impressions are absent except on theis rounded, with no evidence of an epijugal.
crest resembles most nearly that of No. 2280 inThisepoccipitals.
on
the
and
parietals
bar of thepresence of the row
the Ottawa group (PI. XIV, B), the main distinctions, other than size, being theshort in No. 2280 asof bosses on the squamosal, its somewhat less relative length (although it is stillwith six squamosalcompared
four
as
No.
plesiotype,2245),
belli
compared with the Chasmosaurus
squamosal.
theofterminusthebehindjustepoccipitallarge
epoccipitals, and the absence of thethat theIn these two animals the differences may be due entirely to age, for it is conceivable
theHence,
them.
bearing
bones
of
the
lengthening
epoccipitals might increase in number with the
four
its
with
crest
emarginate
deeplyThe
conspecific.
two specimens seem without question to be
characters, distinguishingto six epoccipitals and the shorter squamosals may prove to be specificcrest is not emarginate
the
which
in
plesiotype,form from No. 2245, the Chasmosaurus belli
thisand the squamosals are relatively long.

On the other hand, these may be sex differences.

Sternberg'" who thinks that No. 2245

This

may have been a malewould accord with the idea of C. M.
and No. 2280 a female on the ground that, "it is common, among reptiles, for the female to beoflarger than the male," No. 2280 being somewhat the more robust. I have referred the question
question.
will
no
one
authority
the relative size of the sexes in reptiles to Raymond Ditmars whose
He writes as follows:*" "I have found, with the greater number of snakes, that the females areWith some species, this is so marked that the sexes can belarger and heavier than the males.
distinguished at a glance.
"Among the lizards, however, the reverse is generally the case. In fact, it may be fairly sate
more ornate."
to say that with the majority of the species, the males are a bit larger and certainly
seem that the analogy lies with the lizards if anywhere, so that on two counts the
It

would

specimen with greater robustness and greater ornamentation at the rear of the crest (No. 2280)
as well as theshould be considered the male. It is unfortunate that the muzzle and nasal horn,other animal,
or
the
one
lackinginelements,
theseforcontrasted,becannotischium,
distal end of thethem.
possessingone
thewere restored from-ternberg, C. M., 1927, B, p. 67.
letter of October 22, 1932.

THE CERATOPSIA

94

The chasmosaur skeleton in the Royal Ontario Museum, No. 5499, was also found by the
expedition of 1926, on the east side of Red Deer River, two miles south of Steveville, Alberta, andTherefore, it was 75 feet below the Chasmosaurus brevirostris
125 feet above the river level.
Whether this means 75 feet of intervening strata is not clear. This skeleton is, as yet, undeskull.
The skull has been partially
scribed, but varies from those in Ottawa in minor details only.
brevirostris,
but there detailed
suggestiveofrestored, and with a rather short muzzle somewhat
nearlycircular orbit
theresemblance ceases, for there are no brow horns, only the rugose area above
abruptly
truncated.
The nasal horn, on the other hand, is stout, straight, andas in the Yale skull.
The crest is deeply emarginate, the effect of which is heightened by the very large epoccipitals at
the postero-lateral corners of the crest. This skull and that on the skeleton No. 2280 at Ottawa,
show the deepest emargination, but otherwise, the resemblance is not very close. The value of thisIn view, however, of the high specialization of thecharacter in itself is difficult to determine.
entire crest, I should imagine that minor individual variations were common—no two

crests, in fact,

no two skulls, are ever exactly alike.
Chasmosaurus brevirostris, n. sp.
PI. VII,skull without

Holotype:

No. 5436 R.O.M., Toronto;

Horizon:Belly River formation.

Locality:On the west side of Red Deer River, Alberta,Alower jaws, the rear of the crest slightly restored.
three miles southwest of Steveville, along the railway

grade, at an elevation of 200 feet above the river.
Collector: University of Toronto expedition of 1926.

This specimen conforms to belli, except that the muzzle is very short and deep, more as in
Monoclonius, and the nasal horn is large and curves somewhat backward, although inclined forward
The brow horns are like the nasal but smaller. The last epoccipital on the squamosal isat the base.
markedly larger than in any other specimen, and the broadly elliptical orbit is almost vertical. The
There were nine epoccipitals
right epijugal is sharp and trihedral, like that of Pentaceratops.
borne on the squamosal.

Chasmosaurus kaiseni Brown 33
PI. V, A; Text Fig. 38
Holotype: No. 5401 A.M.N.H.; a splendidly preserved skull without lower jaws.
Horizon: Belly River formation.
Locality:

Collector:

About 12 miles below Steveville, on the Red Deer River, Alberta.
American Museum expedition of 1913.

The specific characters are as follows: Muzzle very long, terminating in a relatively small
Nasal horn of medium length, consisting apparently of three elements, one median,rostrum.

grooved on its posterior face, the others anterior and lateral to the first, the lateral ones being highly
rugose, and the entire horn unlike that of any other known chasmosaur brow horns very large fora Belly River ceratopsian, since those of no other skull, except Eoceratops canadensis and a chasmosaur to be described below, approach them in size. They rise above the anterior half of theorbit, curve outward, and sharply forward, then upward, and bear abundant vascular impressions.
The
It is these horns alone that show any approach of Chasmosaurus to Ceratops (see p. 97).
angle
at
an
backward
andupwardaxis
inclined
long
the
with
oval,
orbit is very large, and broadly;of 45°.

33

The rear of the crest is but slightly emarginate, with the usual large epoccipitals justBrown, B., 1933, B.

CH VSMOSAURUS KA1SEN1

95

Anteriorly, the squamosal is broad, with a pointed epoccipital at
The jugal is long, andthe antero-external corner. The jugal notch is deep, with parallel sides.
that of Pentaceratop,
resemblingthus
jugal,
epi
slopes backward and outward, with a long pointed
type.
as does a number of other details of this very interesting

behind the end of the squamosals.

lo-xw

^TV^

A.M.N.H. 5-

w

j~±^
w)

so

I

C \

^~N~^^ I nar

r^~^\

j

r

I

V
V

Fig.

38.—

/, prefrontal;

nasal;

Right lateral view of skull of Chasmosaurus kaiseni, holotype,h, supraorbital horn;

if,

preorbital fossa;

itf,

1/12 natural size,

infratemporal fossa;;',

jugal;/,e,^epijugal;
mx, maxillary; n,epoccipitals;

lacrymal;premaxiUary; fo, postfrontal;
nh, nasal horn; nar, narial opening; o, orbit; f, parietal; tf, parietal fenestra; fmx,
sq, squamosal.
r, rostral;
quadratojugal;
qj,

q, quadrate;

Dimensions
Greatest length, from tip of rostrum to outer angle of crest

Width of crest at posterior end of squamosals
Tip of rostrum to posterior end of nasal horn
Tip of rostrum to anterior edge of orbit
Tip of rostrum to posterior end of jugal
Height of orbit

Width of orbit

Brow horn, from rim of orbit to summit
Height of nasal horn above nares

1520 mm.
820
463
560
724
102
62
370
130

Chasmosaurus cf. C. kaiseni Brown
PI. VII, B

Specimen: No. 40, Univ. Alberta;
bones of the skeleton.
Horizon: Belly River formation.

anterior part of a skull to about one-third the length of the crest, and a few

Red Deer River, 2 miles southeast and 1 mile east of the mouth of Sand Creek, Alberta.
Collector: G. F. Sternberg, 1920.

Locality:in the museum of the University of
Yet another remarkable chasmosaur skull is preserved
34
who referred it, with a query, to theAlberta, Edmonton, and was briefly described by Gilmore,
adult; short,genus Eoceratofs Lambe. Gilmore's description stresses the following points: Fullybrow horns;
deep nasal region, small, upturned nasal horn; subcircular, tapering, slightly recurved
These are all featriangular squamosal having the dimensions of the type of Eoceratops canadensis.
34

Gilmore, C. W., 1923, pp. 51-52.

THE CERATOPSIA

96

Contrasts with Eoceratops are found in the inclination of the postorbitalhorns and the presence of epoccipitals, which are absent in Eocerato-ps. These are not significant points,tures found in Eoceratops.

but the longitudinally-divided nasal horn core of Eoceratops type, as distinguished from that of the
In comparison with Chasmosaurus, the epoccipitals and thepresent specimen, is of importance.
parietal fenestrae agree, but Gilmore thinks the squamosal too short, even if continued beyond the
Our figure shows, however, that the squamosal could be prolonged to agree withbroken end.
Chasmosaurus without lack of harmony with the preserved lines. With the rostral added, this skull
shows rather marked similarity with Chasmosaurus kaiseni. The muzzle is somewhat shorter, thenasal horn differs, and the brow horns are not so long, but the character of the jugal and theanterior margin of the squamosal defining the jugal notch are very similar, as well as the comparaGilmore's objection, on the ground of the small size of the skull, is hardly
tively long brow horns.
valid, for the specimen seems to be nearly as large as the type of kaiseni.

Dimensions(From Gilmore)
Greatest length of skull, estimated about
Greatest width of squamosal

Height of brow horn above superior border of orbit
Antero-posterior diameter of horn at base

Height of skull, from border of alveolus to tip of nasal horn, about1200 mm. 35
280
170
65
320

My identification would place this as a variant, possibly sexual, of Chasmosaurus kaiseni.
Genus CERATOPS MarshThis Judith River genus is based on so very inadequate material as to be undefinable. Four
species were described by Marsh, of which one, Ceratops paucidens, was based upon a left premaxillary and maxillary with its contained teeth. This Hatcher determined to belong to one of
the trachodons, and hence not ceratopsian at all. Another skull described as Ceratops horridus, wasafterward made the type of a new genus Triceratops, while the third, Ceratops alticornis, consisting of a pair of brow horns, from the Denver beds, was later removed to the genus Triceratops,
where it evidently belongs. Thus, only one is left, Ceratops montanus, which is the genoholotype.
Ceratops montanus Marsh 36
and a pair of supraorbital horn cores.

Holotype:

No. 2411 U.S.N.M.;

Horizon:

Judith River formation.

Locality:

Cow Creek, about 10 miles above the confluence of that stream with the Missouri River, Montana.

Collector:

J. B.

Hatcher,

occipital condyle,li

In addition to this scanty material, Marsh referred the squamosal, No. 4802 U.S.N.M., to thiswhile another, No. 2415 U.S.N.M., was also figured in the Ceratopsia Monograph and37
referred to C. tnontanus.
These are both short squamosals and might with equal, if not greater,
propriety, be referred to Monoclonius, for they are of the character of those borne by M. crassus, as
They give no aid whatever in defining the genus
the short sutural surface in the type shows.
with the type. The only known character, thereof
their
lack
of
association
Ceratops, because
actualspecies,fore, lies in thebrow horns themselves, which, in the absence of other skull features, are insufficient

to define the genus.

35

I. would estimate this at nearer 1 500 mm.
Marsh, O. C, 1888, pp. 4-77-478.
37
Hatcher, Marsh, Lull, 1907, PL HI, Figs.

3n

1,

2.

1

BRACHVCERATOPS MONTANEN3IS

97

The brow horns which constitute the type are large and, as reoriented by Hatcher, curve sharply
outward from their base, when viewed from in front. From the oblique rear, they are straight, but
The only possible comparisons with contemporary forms are with Monotaper rather abruptly.
clonius recurvicomis Cope, Eoceratops canadensis

which theLambe, and Chasmosaurus

only is Judith River, the others being Belly River forms.

firstkaiseni

Brown, ofIn the first of these, thebrow horns are much shorter, truncated, and erect, without axial curvature, hence differing decidedly
from the widely curved horns of Ceratops montanus. The comparison with Eoceratops canadensis is
88
They are nearly the same lengthnearer; in fact, Hatcher says the horns "are strikingly similar."in each species, that of Eoceratops being a little the shorter, but much more slender and backwardly
curved. These distinctions may be specific only. Comparison with Chasmosaurus kaiseni (see Fig.
38) also shows about the same degree of likeness and difference, the latter having to do with thegreater relative slenderness and curvature, for here the horns slope outward and forward at their
Fortunately, Chasmosaurus kaisenibase, and curve upward toward their summit in a single curve.
is founded upon a perfect skull, and its reference to Chasmosaurus is unquestioned on the basis of
the crest, but it and one other (No. 40, Univ. of Alberta (see p. 95)) are the only instances, in anyof the nine Chasmosaurus skulls known to me, in which long brow horns occur, all of the others, inwhich they are preserved, having rudimentary horns. One cannot, therefore, accept the synonymy
of Ceratops and Chasmosaurus on such slender evidence as this, especially as the latter is a well
Ceratops
defined genus, and from a different region, although perhaps of nearly equivalent age.
montanus comes from the summit of the Judith River series and may represent a more advanced
evolutionary stage of the same phylum as Chasmosaurus, but until more perfect diagnostic material,
including the entire crest, is collected from this horizon and locality, the status of Ceratops cannot be
solved.
The relationship between Monoclonius and Centrosaurus is more nearly proved, but theinferred assumption that if these genera are nearly related, Ceratops and Chasmosaurus must also
No fragment of a long squamosal, such as that of Chasmobe, is based upon no evidence whatever.
saurus, has come to light in the Judith River collections.

Genus BRACHYCERATOPS Gilmore
Brachyceratops montanensis Gilmore 39
PI. IX, B

Holotype:

No. 7951

U.S.N.M., considerable portionof a disarticulated skull with

which

is

provisionally asso-

fragmentary part of the crest and a right dentary and predentary.
Paratopes: No. 7952, U.S.N. M., rostral and portions of the premaxillaries; No. 7953, U.S.N. M., sacrum, pelvis,
articulated caudal series of 50 vertebrae, with which are provisionally associated dorsal vertebrae and ribs;
No. 7957, U.S.N. M., tibia, fibula, and partly articulated hind foot from the left side, consisting of an
ciated a

astragulus, calcaneum,and 2tarsals of the distalrow, 4 metatarsals and a portion of a

fifth,

and1

phalanges.

Horizon:Two Medicine formation.

N.E. /\ sec. 16, Township 37N., Range 8 W., Milk River, Blackfeet Indian Reservation, GlacierCounty, Montana.

Locality:

Collector: C.

lW. Gilmore, 1913.

The originaldescription of genericandspecific characters, as

emended by Gilmore, 40 is as[Note. The small size of the animal, Gilmore says, may befollows: "Typically of small size.
due to some extent to the immaturity of the individuals. I should say to a large extent, for the
impression one gets from the open sutures and general proportions is that of a creature not halfgrown. A very Monoclonius-Wke squamosal in the collection, which is nearly if not quite as large
38

Hatcher, Marsh, Lull, 1907, p. 102.
Gilmore, C. W., 1 9 1 4, pp. 1 - 1 0.
40 Gilmore,
C. W., 191 7, p. 7.
39

THE CERATOPSIA

98

as that of an adult Monoclonius, may possibly have pertained to a full-grown Brachyceratops. \Skullwith facial portion much abbreviated and deep vertically. Supraorbital horn cores small and firmly
united with postorbitals. Nasal horn core outgrowth from nasals, large, slightly recurved, laterallycompressed, and divided longitudinally by median suture. Frill with comparatively sharp medianapparently of small size, and entirely within the median element. Border of frill
scalloped but without separate marginal ossifications. Dentition as compared with Triceratops greatly
Ilium with greatly expanded anterior
reduced. Five digits in the pes, the fifth being vestigial.
blade that curves strongly outward."
The narial opening, Gilmore states, is situated "well forward and under the nasal horn." This
position is midway between that of the Belly River Ceratopsia and those of the Lance, for primitively
the horn arises over the posterior border of the nares; in the Edmonton forms, Arrhinoceratops andAnchiceratops, and in the contemporary Pentaceratops, it is over the opening itself, whereas in Triceratops it overlies the anterior margin. This is a progressive evolutionary change which is true ofcrest, fenestrae

all phyla.

Viewed laterally, in profile, the skull shows a great abbreviation of the facial portion, whencompared with the Lance genera. It is to this shortening that the generic name refers. This reduction of the face is also true of Chasmosaurus to an even greater degree, but there the similarity
between Brachyceratops and Chasmosaurus ends. The distance between the nasal horn and thesupraorbital horns is exceedingly short, due to the shortened nasal bones, the great fore and aftdevelopment of the nasal horn, and to the forward position over the orbits of the small supraorbitalhorns.

"An entirely new phase of nasal horn development and one which appears to be unique among
dinosaurs appears in the longitudinal separation of the horn core into two halves by the nasal suture.
The nasal horn itself appears to be an outgrowth from the nasal bones instead of having originated1from a separate center of ossification, as in the more specialized Triceratops"* [notably the types ofT. serratus and flabellatus, in each of which the sutures are well indicated and the horn ossification
The Eoceratops canadensis type from the Belly River also shows a suture separating notlost].

is42

forming theonly the nasal bones, but the horn as well. There is here, however, an epinasal
anterior portion of the horn, which is lacking in Brachyceratops, according to Gilmore, although his
figure indicates a small, separate ossicle on the summit of the left half of the horn, with a facet
indicating the former presence of one on the right. Whether these are homologues of the epinasalof Eoceratops, or the separate horn ossification as in Triceratops, or both, I am not sure. The latter

would seem probable.

The nasal horn is directed somewhat forward, but the curve of the posterior margin gives it a
The upper half bears vascular grooves.
The maxillaries are triangular in outline, with alveolar grooves for 20 vertical rows of teeth,

slightly recurved appearance.

±30 in Triceratops, 27 for Pentaceratops, and 35 for Monoclonius (Centrosaurus)
The small number of alveoli may again be due to the juvenile character of the specimen

as compared with
fiexus.

jaws elongate with growth, the teeth with their alveolar grooves would either have tois rather doubtful, or the number of rows would increase.
The dorsal aspect of the cranium is of interest. There is no trace of frontal bones, according
In most reptiles the frontal is interposed
to Gilmore, as the pre- and post-frontals are in contact.
between them, although the condition shown in Brachyceratops is found in all the Ceratopsia except
Protoceratops and possibly Leptoceratops.
The postorbital, which gives rise to the small supraorbital horn core, forms nearly one-half theborder of the orbit. It is separated from the postfrontal by a longitudinal suture which is elsewhere
unknown, even in Protoceratops. 43 Posteriorly, it overhangs the supratemporal fossa, while antefor, as theincrease in size, which,

41

Gilmore, C. W., 1917, p. 8.
Lambe, L. M., 1915, p. 6, PI. V, Fig. 1.
43
In all other Ceratopsia, the absence of this suture makes it impossible to distinguish the postorbital from the postfrontal elements, hence the two terms are considered synonymous.
42

BRACHYCKRATOPS MONTANENSIS

99

riorly, it shows a short suture for the small supraorbital bone which is missing.
The horn is situated44
on the extreme anterior end of the postorbital and not on the supraorbital at all. Gilmore doubts
the propriety of designating these horns as supraorbital, but as generally understood, the namerefers to their position above the eyes rather than to the element which bore them. The horn coreis low, with a summit obtusely rounded longitudinally but sharply
pointed transversely.
The
external surface is plane, the internal one strongly convex, and the antero-posterior diameter greatly
exceeds the transverse. The height of the horn above the orbit is 3 1 mm.
The crest is represented by the median elements from two individuals (No. 7950 and No. 7951
4
U.S.N. M.). For this median element Gilmore
accepts the designation dermosupraoccipital orinterparietal, after Von Huene.
It is united by suture with the anterior portion of the skull at the'and questionably with the parietals

postfrontal fontanelle, articulated with the postfrontals above(our supraoccipital) beneath.

The median part is sharply ridged except at the posterior extremity,

where it flattens into a thinner portion with an emarginate median border. Between the fenestrae themedian bar has a thickened triangular cross-section. The bone surrounding the frill fenestrae isvery thin, but it thickens toward the lateral free edges and posteriorly. The exact shape and extent
of the frill fenestrae cannot be determined from the available specimens; in fact, judging from
Gilmore's figure, there is only a small portion of the antero-internal margin of the right one which
can be determined at all. He is probably right in saying that they were comparatively small. In
this, as in the short squamosal, Brachyceratofs agrees more with Monoclonius than with Chasmosaurus.
There were no epoccipital bones on the margins of the frill, but a series of prominences oneither side of the median emargination give the periphery a scalloped effect comparable to that produced by the epoccipitals of Triceratops. Epoccipitals may have been present, however, and may
yet be demonstrated by the discovery of a more mature skull.
As Gilmore 4 rightly says, "The modifications found in the ceratopsian skull are greater perhaps
than in any other known group of reptiles, living or extinct.
The inclosed and compact nature of
the skull was of the greatest value as a means of protection, and it contrasts strongly with the open
structure of most other dinosaurian skulls. These modifications have led to a rearrangement of the
''

.

.

.

elements of the cranium, that until interpreted is as confusing as it is unusual.
"It now appears that the prefrontals and postfrontals, which in the normal reptilian cranium
are lateral to the parietals and frontals, have in the ceratopsian skull pushed upward and inward
4
above those bones, completely covering their dorsal aspect," although they are not in contact withthem because of the intervening frontal sinus.
.

.

.

'

Dimensions of Skull(After Gilmore)
Greatest length, about

Greatest breadth, estimatedLength of crest along median line
Height of nasal horn core above nares
Breadth between center of orbits
Postorbital horn cores at baseAnteroposterior diameterTransverse diameter
Horizontal diameter of orbit
Nasal horn core at baseAnteroposterior diameterTransverse diameter"Gilmore, C. W., 1917, p.
45

11.

Loo cit., p. 1.
48
Loo cit., pp. 17-18.
47
Our usage except* the parietal which forms the median element of the crest.
1

565 mm.
400
315
125
130

34
27
57
90
41

THE CERATOPSIA

100

There is nothing distinctive about the vertebrae of Brachyceratops. The sacrum is of interest,
however, as it is the most immature ceratopsian sacrum on record. "The sacrum in the paratype,
No. 7953, is represented by all the centra, portions of the neural processes of the posterior vertebrae,
The centra are all suturally united and in an adult individual
and numerous detached sacral ribs.
would doubtless be firmly coossified, as in other ceratopsians. The paratype has nine articulated
centra, of which the anterior six are regarded as true sacrals and the posterior two as true caudals.
The remaining intermediate vertebra between tail and sacrum constitutes a modified caudal thatfunctions to a certain extent as a sacral and can therefore be designated a sacrocaudal.
"The sacrum of the paratype, including the sacrodorsal and the sacrocaudal, had eight centra
48[This
with sutured articular ends whereas Monoclonius and Triceratops had ten such vertebrae.
is, however, a juvenile condition and not necessarily a generic distinction, for it is probable that atleast two more vertebrae would later be added to the sacral series, bringing the number up to the.

.

.

standard ten.]
".
its

.

.

The first sacral may be recognized at once by the great transverse breadth of the centrum,

flattened ventral surface, and the inferior position of the posterior articular facets for the second

The second sacral centrum is also distinguished from all others by the much greater
The centra of the remaining
breadth of the anterior as compared with the posterior extremity.
sacrals are of about equal dimensions, higher than wide, constricted medially, with slightly flattenedsacral rib ...

.

inferior surfaces.

"A second specimen (No. 8072, U.S.N. M.), however, shows centra that are broader than highand that have a shallow longitudinal depression on their inferior surfaces. The differences are inare decidedly
The first three vertebrae of the sacral region
all probability due to crushing.
ribs
are
borne
jointly
by all the centra.
Theheavier than any that succeed them. The sacral
second and strongest sacral rib of the series articulates jointly with the first and second dorsals[sacrals] low down on the sides of the centra, the inferior surface of the rib being on a level with
.

.

.

.

.

.

The succeeding ribs articulate with facets that are but little
the ventral surface of the sacrals.
below the level of the floor of the neural canal.
.

".

.

.

.

.

The few spinous processes are exceedingly short thin plates of bone with little transverse

thickening of their superior extremities. That these were united into a bony plate is indicated by adetached sacral process belonging to another individual (No. 8072, U.S.N. M.), which shows suturaledges fore and aft that continue to the top of the spine. The same condition prevails on the spineof the fifth sacral, ... so it would appear that this plate may have been continuous from the first to[The sacrum of Triceratops figured by Marsh, and now part of
the fifth, much as it is in Triceratops.
the mounted animal in the United States National Museum, is peculiar in that the first spinous
process is free, the second to fifth fused into a plate, and the remaining ones free; that of sacral VI

make a wide-angled notch between it and number five.

slants aft so as to(Centrosaurus), Fig. 17.]Compare Monoclonius

The relative shortness of the spines in Brachyceratops would at once dis-

[It is conceivable, however, that as a mechanicaladjustment to increasing weight the spinous processes would lengthen with age.]"As in Triceratops the spinal cord appears to have been only slightly enlarged in the anterior
sacral region. The diapophyses are comparatively weak and are given off on a horizontal plane from
Their inferior borders extend obliquely downthe neural arches, with thin ends directed forward.
ward and inward and present a narrow sutural edge for articulation with the upper and inner borders
Nearly all of the transverse processes are missing, but their point of origin, asof the sacral ribs.
."shown by the broken surfaces, is indicated
A complete series of caudal vertebrae, 50 in number, was discovered for the first time inBrachyceratops. Since then a complete series of 45 has been found in Protoceratops and of 38 in
Anchiceratops. Thus the number is greater than in any other ceratopsian genus, as evidenced either
by actual count or by estimate. "The greater number were found articulated, and such displacement as existed was so slight that there can be no question that they represent a consecutive

tinguish its sacrum from that of the former genus.

.

.

.

.

.

series.

.

.

.

"Gilmore, C. W., 1917, pp. 21-23.

.

.

.

.

BRACHYCF.RATOPS MONTANENS1S

its

101

"The centrum of the rirst or sacrocaudal ... is longer than wide and has an articular facet on
superoantero lateral angle for the articulation of the last sacral rib. The neural arch, although

1 he anterior
poorly preserved, indicates that the spine was distinct from the spines forward of it.
vertebrae.
sacralpreceding
in
all
not
coalesced,
as
also
are
differentiated,posteriorzygapophyses
and
well
below
arch
of
the
the
sides
off
from
are
given
secondfirst
andcaudals
The diapophyses on the.

.

.

the zygapophyses but above the neurocentral suture, but that on the fourth caudal is below that
suture." Thence backward to caudal 25 the diapophyses are borne on the centra of their respective
vertebrae, although bearing somewhat on the pedicels of the arch until the 20th is reached.

nothing particularly distinctive about either the pectoral arch or fore limb, except
perhaps the slenderness of the preserved elements. The coracoid and humerus are unknown as yet,which is also true of the carpus. A few phalanges of the manus are preserved.
The ilium is peculiar as compared with that of Monoclonius and Triceratops. It is not only
much smaller, but the transverse expansion of its anterior plate, the greater inclination outward of
the crenulated outer margin, and the differentiation of the thickened deflected border above the
The pubic
ischiac peduncle are all distinctive from described forms, including Pentaceratofs.
peduncle is rather slender, but the ischiac peduncle is relatively very heavy.

There

is

The dimensions of the left ilium of the paratype, No. 7953, U.S.N. M. are as follows:
362 mm.

Length over all

65

Width of anterior blade
Transverse width at center

37

Depth of posterior blade
Depth at center of acetabulum

51

The pubis is not unusual. The ischium is a long, slender, slightly curved bone with an expanded
proximal end which bears a heavy articulation for the proportionately massive pubic peduncle. The
bone compares in curvature with that of Monoclonius {Centrosaurus), and contrasts sharply withthat of Pentaceratofs and Triceratops.
The ratio of tibia to femur in Brachyceratops is as 1: 1.28; while in Triceratops it is 1: 1.59,
and in Monoclonius {Centrosaurus) 1: 1.43. That is, in the first, the femur is about one-quarter
longer than the tibia, in the others it is one-half longer. May this not be another juvenile character?
Dimensions

Femur (No. 7953)
Greatest length

337 mm.

Tibia (No. 7957)

268 mm.

Greatest width

Proximal end
Distal end
Least width of shaft

100
83
45

99 anteroposteriorly, estimated
30

There are two distal tarsals in addition to the astragalus and calcaneum. The former are "irreguThe largest
larly rounded discoidal elements with upper surfaces concave and lower convex.
to which it
III,metatarsal...
withsmallest
articulates with the proximal end of metatarsal II, themetatarsal
apposition
toinwhollywas found securely attached by matrix. The third tarsal was
.

.

.

IV.""

The metatarsals were four functional and one vestigial, as in Monoclonius {Centrosaurus), andthe general appearance of the entire foot is comparable.
The complete skeletal restoration of Brachyceratops (PI. IX, B), erected in the United States
National Museum in 1922, was the first attempt to mount one of the earlier Ceratopsia, and it is ahighly commendable result, viewed in the light of later finds. The skeleton is composite, with suchelements as were not present in the collection modeled preferably from Judith River forms.

u Loc. cit., p. 33.

The—
THE CERATOPSIA

102

animal from the end of the nose to the tip of the tail is about 6 feet 9 inches,
and its height at the hips, about 2 feet 4 inches. The number of presacral vertebrae was made tototal length of thecorrespond with that of Triceratops brevicornus type, at that time the only complete presacral series
known. As interpreted by Gilmore, this number was 22, as he seemingly followed Lull in interpreting the number of coalesced (anterior) cervicals as four, instead of the generally accepted three.
The number should be 21, cervicals 7-9, and dorsals 14-12, according as one interprets numbers 8
and 9. The number of sacrals is given as 6, and caudals as 50, making 78 in all, according toGilmore, or 77 with the corrected number of cervicals. This is exactly the same total as in Monoclonius (Centrosaurus), the latter having 4 more sacrals and 4 fewer caudals, which again may be
merely a matter of greater maturity.
Brachyceratops once more has but a single species montanensis, so that the specific characters,
as distinguished from the generic, are not definable, especially in light of the juvenile state of the
only known material.
The relationship of Brachyceratops with other genera is obscure. The form of the squamosal
places it nearest to Monoclonius, but Gilmore makesof highly diagnostic value in the Ceratopsia
the following points of contrast. He says that Brachyceratops has no epoccipital bones around themargin of the crest. However, this is negative evidence and should be evaluated as such, for at the
ontogenetic stage represented by the type material they would not be coossified, and hence would bereadily lost; and they may have been very much smaller than in a mature animal.
He says alsothat there are no hook-like processes on the posterior border of the parietals, but the anterior pair ofinvariably present in all known Centrothese is variable in occurrence and even the rear ones
Monoclonius
crassus.
The fenestrae of the crest aresaurus species—are missing in the generic type,
again
may
be expected in a somewhat later phylodecidedly smaller than in Monoclonius, but thisgenetic stage. The real distinction lies in the longitudinally divided nasal horn which is apparently
unique except for Eoceratops canadensis Lambe from the Belly River formation. Here, however,there is what has been called an epinasal on the anterior face of the nasal horn which finds noparallel in Brachyceratops, unless the small terminal ossicle which Gilmore figures as capping theleft of the paired bones is its homologue.
The brow horns in the two genera are totally different.
The species Monoclonius dawsoni Lambe has been referred to Brachyceratops by Lambe 50 but on
insufficient evidence, for the nasal horn is a large backwardly curved element without trace ofdivision into right and left halves except at its base and for a short distance upward into the horncore.
The other characters stressed by Lambe are the incipient supraorbital horn cores, small squamosal, smooth undulating border to the crest without epoccipitals, and greatly reduced openings in
the parietals, if they were present at all. The type of dawsoni was so ill preserved that it was not
all collected, and one has to depend upon Lambe's field sketch and personal description for the character of the crest.
It is, in other words, impossible to verify the specific description from the present
condition of the type, and its inclusion in the genus Brachyceratops is therefore unprovable.

——

Genus Anchiceratops Brown

The most distinctive generic characters of Anchiceratops (PI. X) lie in the crest, which is rectangular in form, with rather small fenestrae as compared with the area of the crest. Around therear margin are very large epoccipitals, six borne on the parietal,

and on the squamosals a large

The squamosals are long, but do not come sonear the end of the crest as is usual in Chasmosaurus. The latter also differs from Anchiceratops in
the much larger parietal fenestrae. In addition to the epoccipitals, there is a smaller pair of prominences arising from the midline at the rear of the parietals and diverging outward. Brown describes
these as knob-like, but they are somewhat flattened and curved so as to be convex upward.
The
posterior pair with others of the usual form and size.

degree of development of the horns is what one finds in all genera of this and succeeding geologicallevels, namely, large, curved brow horns and a much smaller nasal horn.
60 Lambe, L.

M., 1915, pp. 6-7.

ANCHICF.RATOPS ORNATUS

103

Anchkeratofs agrees most nearly with Pentaceratofs (PI. V, B) in the character of ornamentation at the rear of the crest, but differs from it in the relatively smaller parietal (enestrae, and in
the smaller and differently shaped nasal horn. With its contemporary, ArrhmocerotofS (PI. XII),The wide, flat crests are similar in theirin the Edmonton formation, there is even less agreement.
relatively small parietal fenestrae, and in the extent of vascular grooving on the under side; but
there are no great prominences, epoccipital or otherwise, at the rear of the ArrhmocerotofS crest,
which is extremely thin. The brow horns are somewhat alike, but the nasal horn in Arrhinoceratofs
If so, there was certainly a functional organ formed by the nasal
is supposed by Parks to be lacking.
bones that took its place, which in form was not unlike that of Anchkeratofs longirostris. The
muzzle of the latter is much longer and slenderer than in Arrhinoceratofs.
Two species of Anchkeratofs have been described, A. ornatus Brown, and A. longirostris Sternberg. Unfortunately, the material upon which the first is based lacks the anterior part of the skull,as there is very little preserved in front of the orbits, so that the long rostrum which gives its namemay have been equally characteristic of the other. The specific contrasts,
One of the chief distinctions between
foundin the remainder of the skull.
bemust
therefore,
can be in part the result of preswhichhorns,browthecurvatureoftheornatusisandlongirostrisforward, and then slightly outdecidedly
upward,curve
longirostris
of
for
those
sure deformation,
horns of the former are also
forward.
The
then
and
outwardcurve
ornatushorns
ward, while theto Sternberg's species

smaller and wider apart at their base, which may be sex or individual variation. The distinctions ofthecrest lie in the parietal fenestrae, which are proportionately much longer in longirostris, andwhole crest is thinner, with relatively smaller prominences.
The two type specimens were collected in approximately the same place and horizon, while ain thethird partial skull in the Royal Ontario Museum resembles longirostris more than ornatusof theabsencetheandin
crest,
thinner
extreme forward curvature of the horns and in the somewhat
never
to be
epoccipitals
isofabsence
But thelarge epoccipital at the rear end of the squamosal.
ifespeciallydeath,
after
skull
taken seriously as diagnostic because they are so readily lost from a
the individual is young.

The two species may be held tentatively, pending more perfect material of A. ornatus, which is
to age,the type of the genus, and must stand in any event. The variations of ceratopsian skulls duesex, or the individual are such that no two ever seem to agree.

Anchiceratops ornatus Brown"' 1
Holotype:
Paratype:horns missing.
No. 5251 A.M.N. H.; an incomplete skull, anterior end, and top of supraorbital
complete.
nearlyhorns
supraorbital
No. 5259 A.M.N.H.; brain case andHorizon: Edmonton formation.
7 miles below Tolman Ferry, Red Deer River, Alberta, Canada.
Collector: American Museum expedition of 1912.

Locality:"Skull large. Supraorbital
then forward. Crest
horns rising close together, massive at base and divergent, curving outward,
epoccipital bones; alarge
byornamented
borderles;
fontanellateralsmalllarge, thick and flat withintermediate inSquamosal
crest.
endofposterior
superior
onprocesses
knob-like

The generic and specific characters are stated to be as follows:

pair of shortlength between Monoclonius and Triceralofs.
".
The bone that forms the brain-case as well as that of the crest is unusually thick, withwide vascular grooves.
such surfaces as were not deeply embedded in muscle, furrowed byonthe upper surface is composedandoutlineinquadrilateral"The crest ... is broad, flat andand a median element,
distinct
suturally[squamosals]paired lateral bonesof three elements('parietals').
which is interpreted as the fused postfrontals
count".
The squamosal is elongate and terminates just in front of the third epoccipital bonebecannotextent
its
front
In
...
fontanelle.
ing from the rear, opposite the posterior border of the
.

.

.

.

51

.

.

;

.

Brown, B., 1914, A, pp.

5 39-548.

THE CERATOPSIA

104

determined above the free border but posteriorly it is well denned. The extreme anterior border isconcave and the angle formed by the two borders is produced into a sharp process followed by theepoccipital bones.

"The epoccipital bones are one of the most striking features of the skull.

They are extensive,

covering the margin of the crest completely, all firmly coossified to the underlying bone but withthe squamosal there are six, the anterior five about equal in size, the sixth
sutural union distinct.
Following these on each side are three epoccipitals equally of enormous size.
very much larger.

On

.

.

.

They are attached to the border of the postfrontals ('parietals') and directed backward and outward.
The surface is slightly roughened and they taper from the thick elongate base to the rounded point
and thin borders.
"Immediately above the base of the last epoccipital is a pair of massive, short, curved processes
suturally united to each other and in the type specimen not distinct from the postfrontals below.
andIn the skull of the young specimen, No. 5273, however, one of these processes was taken off
endinginoutward
curve
and
are
large
They
bone.
supportingthetosuturefound to be united byofMonoprocesses
hook-likefromtheposition
and
form
in
differslightly
short blunt points. Theyclones [Centrosaurus] but, as in that genus, probably served as attachment for muscles and were
not sheathed in horn" [see, however, p. 35].
Brown compares Anchiceratops with Styracosaurus albertensis, from the Belly River of Alberta,

which he says "resembles Anchiceratops in some respects and may have been its ancestor. In bothform
the crest is comparatively flat with [ep?] occipital bones unusually developed but in this later
ex
[ep?]
the
reducedandarefontanelles
lateralthe squamosals are progressively lengthened, theoccipitals are shortened.

The development of the supraorbital horns is also distinctive."

The fragmentary crest of Styracosaurus ovatus Gilmore, from the Two Medicine formation ofMontana, with its further shortened epoccipital spines, is still more like the posterior part of thecrest of Anchiceratops.

When one sees the entire skull of Anchiceratops, as in the type specimen of A. longirostrisof theSternberg, the resemblance to Styracosaurus is less marked, especially in the forward region
For the face and muzzle of Anchiceratops are elongated more as in Chasmosaurus, and theskull.
the long, nearlynasal horn is low, projects forward, and has a sharp dorsal edge, very different from
Styracosaurus.
erect horn of
52
Anchiceratops longirostris Sternberg

PI.
Holotype: No. 8535 G.S.C.; nearly complete

skull,

X

without lower jaws.

Horizon: Edmonton formation.
the same
12 miles northwest of Morrin, Red Deer River, Alberta, from approximately
A. ornatus.
Collector: C. M. Sternberg, 1924.

Locality:

localityasand slender
Sternberg's description adds the following points, some of which, like the very longof muzzle
type
same
thoughthenose, may be specific rather than generic characters. For instance,
(No.
genus
5436 Ct.
ordinarily prevails in Chasmosaurus, yet there is at least one skull of the

R.O.M. PI. VII, A), preserved at Toronto, in which the muzzle is shorter and deeper than usual.
And so it may have been with Anchiceratops where, in the only known specimen in which the anterior
specifically, topart of the skull is preserved, the latter is long and slender, yet it may have varied,a shorter, deeper, muzzle correlated with a shorter, wider, crest.
[PI. X, A] the skull [of A. longirostris]"Viewed from the side,
.

.

is

very long and flat, the

.

orbit
well in advance of the midline; the anterior naris is long and situated nearer to the
The rostral bone resembles that of Chasmosaurus and as in thatthan to the end of the beak.
of
the premaxillae.
largelymadeupgenus the beak is

orbit

is

.

.

.

.

52

Sternberg, C.

M„ 1929.

.

.

WCHICF.RATOI'S I.ONGIROSTRIS

105"The lui.uil /torn core ... is triangular in cross-section with the apex of the triangle above, andirpoints forward and upward.

Vascular grooves are not so well developed as on the brow horns,

but there is no doubt it carried a fair-sized horny sheath.
".
The orbit is moderately large and circular in outline.
.

.

.

.

.

"The broic horn cores ... are moderately large and circular in cross-section, except at the basewhere they are sub-triangular. They rise from the supero-posterior border of the orbits and continue upward, forward,

and slightly outward, thus differing from A. ornatus in which they curve

outward, then forward. They taper gradually to the tip, but are farther apart at the base and much
The horn cores bear well-defined, longitudinal, vascularsmaller than those of A. ornatus.
grooves.

.

.

.

frontal jontanelle is closed superiorly, due to the union of the [post] frontals,
This [post] frontal fontanelle opens
thus completing the secondary roof on the superior surface.
posteriorly, however, and, apparently, is larger than in A. ornatus.
"The supratemporal fossae do not appear to differ materially from those of A. ornatus. They

"The

[post].

.

.

open posteriorly, as in that species and in the genera Torosaurus and Triceratops.
The fontanelles are proportionately much
"The crest is large, rectangular, and quite flat.
arewhollywithin the parietals. The crest is relaspecies,
and,
that
A.
ornatusasinlonger than inmaximum
thickness of the crest, throughThe
fontanelles.
advanceofthetively thin, especially innotmorethan half this.
thicknessisaveragethethe posterior portions ... is 30 mm., but
thoroughly
fused with theareTheepoccipitals
so"The squamosals are long and narrow.
The
same is true
separateossifications.
thansquamosals that they appear as serrated edges rather
marked byareThe
squamosalsof the large epoccipitals on the posterior edge of the parietals.
vascular grooves both above and below.
"The parietals resemble those of A. ornatus., but are thinner, and the epoccipitals are muchthinner and smaller. As in A. ornatus, there is a pair of short, thick, hook-like processes, thoroughly
.

.

.

.

.

.

fused to the median posterior extremity of the superior surface of the parietals. On the superior
surface of the parietal, in advance of the fontanelle, there is an area in which the surface is lower
than the rest of the bone and quite smooth. This is a backward extension of the floor of the supra-

temporal fossa and the bone is very thin. Except for these areas in advance of the fontanelles theparietals are covered with vascular markings."

Dimensions of Type

(From Sternberg)
Length, tip of rostral to extremity of crest
Greatest breadth of skull (anterior portion of crest), as restored

Breadth of posterior portion of crest, including epoccipitals
Height of nasal horn core
Length from tip of rostral to anterior border of orbit
Length, anterior border of orbit to extremity of crest
Greatest depth of muzzle in front of nasal horn core
Distance between antero-external edges of orbital rims
Length of brow horn from superior border of orbit
Circumference of brow horn near base
Greatest diameter of orbit
Greatest diameter (fore and aft) of parietal fontanelles
Transverse diameter of parietal fontanelles
Occipital condyle to extremity of crest

1660 mm.
730
660
72

600
1060

220
260
310
255
110
280
150

860

The beautiful skeleton of Anchiceratops longirostris mounted at Ottawa (No. 8538, G.S.C.)
was found on the Red Deer River in the Edmonton formation, and except that it lacks a(PI. X, C)
skull,

iscomplete to the tip of the tail.

There were, however, a few diagnostic fragments of theAplaster skull
posterior portion of the crest which determined the genus and probably the species.
essentiallycorrect.
probability
is
in
all
which
longirostris
of
A.
from
the
type
has been modeled

THE CERATOPSIA

106

When found, the animal lay fully articulated on its right side, but as this was the better preserved, its position was reversed in mounting so that now the right aspect of the completed mountisexposed.

In size, it is somewhat smaller, curiously enough, than are either of its Belly River predecessors,
Chasmosaurus or Monoclonlus (Centrosaurus), but exceeds both in relative robustness, especially of
the ribs.

The lesser over-all length is due in part to the short tail.

This skeleton is as yet undescribed but a few notes taken by the author may be of interest.
The vertebral formula, except for the short tail, corresponds with that of the Belly Rivergenera. The eighth presacral bears the first long rib; the latter, and also the rib articulating with
the ninth vertebra, has a capitulum which bears upon the centrum of the vertebra as do the typicalThe sacrum, as restored, has low spines, equal in height, and separated from one
cervical ribs.
another by a slender line of matrix. Curiously enough, there are thirteen such spines. Whether
or not there are thirteen centra in the sacrum instead of the normal ten, one cannot at present tell.
The dorsal spines are also low although that of presacral XVIII is higher than the preceding one.
Not only are the caudals fewer than usual, numbering 38 as against 46 for Monoclonius (Centrosaurus), and 45 for Chasmosaurus, but the distal vertebrae are small, which accounts, in part, for thelesser over-all length.

The first chevron is light and is borne on caudal IV. The last six or seven vertebrae arewithout chevrons. The pubis articulates with the penultimate rib, and the last rib underlies the
These are points of agreement with Chasmosaurus. All of the dorsal
ribs seem heavy, due in part to the way the middle and after ones are swayed together as the specimen lies, so that they are in contact from rib number 12 to number 21. The posterior rib has a
decided curve backward, as it now lies. The ischia are curved as in Triceratofs, and meet in a shortsymphysis. The scapula is heavy, the distal end widening out, and the median longitudinal ridge
not approaching so near the anterior border distally as it does in the Belly River genera. It shows
an evolutionary trend toward the condition seen in Triceratofs. The humerus is heavy, with a very
pronounced deltoid ridge. The position of the head of the humerus is such that the angulation of
the fore limb in life was similar to that of the earlier forms. There is no crest on the rear of theproximal end of the humerus, as in Chasmosaurus, which makes one wonder whether the latter canbe correct (see p. 69). There is no mechanical difficulty in swaying the humerus backward as seems
The ulna has a very robust olecranon which
to be true of the mounted Chasmosaurus skeletons.
heightens the feeling of mechanical power in comparison with Chasmosaurus.
The pes, as preserved, shows no trace of the vestigial fifth digit seen in the Belly River forms.
This has apparently been lost from the specimen, as it is present in the mounted Triceratofs in the63
American Museum.

anterior part of the ilium.

Genus ARRHINOCERATOPS Parks
Arrhinoceratops brachyops Parks 54
PI. XII
Holotype: No. 5135 Ct. R.O.M.; nearly complete skull without lower jaw.
Horizon: Edmonton formation.
Locality: 3 miles above Bleriot Ferry, on the Red Deer River, Alberta.
Collector: University of Toronto Expedition of 1923.

The generic and specific characters are described as follows: "Supraorbital horn cores large,
directed outwards and forward; nasal horn core absent; facial region short; crest relatively large,
subquadrate, flat; squamosals long; parietals with oval fontanelles of moderate size; anterior
process of jugal unusually long."r' 3

Osborn, H. F., 1933, p. 12.

"Parks, W. A., 1925.

ARRHINOCF.RATOPS BRACHYOPS

107

Doctor Parks goes on to say: "The nasal horn core is apparently absent, but the nasal bone issharp above and somewhat rugose, suggesting that it may have carried a horny sheath. The nasal
bone rises very abruptly, posterior to the suture with the rostral, suggesting the condition thatmaintains in Triceratops prorsus, but there is no trace of a horn core nor of an epinasal; neither
does the surface of the bone indicate that a structure of this kind has been lost." There is, if anything, more of an indication of a nasal horn than in the type of Triceratops obtusus at the United
And the position of the horn-like area lies over the anterior margin ofStates National Museum.
the narial opening as in the Lance genus, not above the posterior margin as in all Belly River forms.
The face is characteristically short, resembling Chasmosaunis, and the crest is also typical, being
subquadrate in outline and very flat toward the rear. Herein it again resembles both ChasmoSOUTHS and the Lance Torosaurus, as it also does in the extremely elongate squamosals which, however, are relatively broader anteriorly than in either genus. The parietal fenestrae are smaller thanThe jugals are
in Chssmosaurus, and are narrower, though relatively longer, than in Torosaurus.

extremely long fore and aft, especially in their anterior process which overlaps the maxillary to aremarkable extent. This, as Parks says, makes the distance between the maxillary and the orbit
The infratemporal arcade is long and straight, which gives the infratemporal fossa
strikingly great.
a subtriangular shape, with a sharp apex and rounded base.
The supraorbital horn cores are stout, tapering sharply, circular in cross-section at their base

There are the usual vascular impressions
instead of being laterally compressed as in Torosaurus.
extending for about 250 mm. from thesulcation
longitudinaland, in addition, each bears a shallow
horn cores are rather close together atTherim.
tip downward, in line with the edge of the orbital
and then curve forward in a manner similar to those of theparatype of Anchiceratops ornatus described by Brown.
The crest, composed of the usual elements, squamosals and parietals, is subquadrangular, withsomewhat curved lateral and straight posterior margins. It is deeply marked by vascular impressions not only on its dorsal side, but over as great a part of the ventral aspect as in any other ceratopsian skull. The parietal fenestrae are elongated, and oval in shape. Another opening, doubtlesstheir base and flare strongly outwardof a pathologic nature, pierces the left squamosal.
The orbits are elliptical, with the long diameter directed upward and backward.

They almost

form and position very similar towhich the front margin of theinDiceratops
fromdifferingandobtusus,
Triceratopsofthe type
orbit.
thebisectdownward,
about
continued
ifhorn would,
Parks stresses the absence of sutures in the occipital condyle, the presence of which would indi"Nevertheless," he says, "it would be hazardous to concate that the exoccipitals form part of it.
entirely underlie the anterior half of the horn core, being both include that the condyle is composed of the basioccipital alone." I know of but twoinstances among
the horned dinosaurs in which any trace of these sutures is present, indicating the tripartite characterof this element. One is that of a detached condyle belonging to the type skull of Torosaurus gladius(No. 1831 Y.P.M.) figured by Hatcher in the Ceratopsia Monograph (Fig. 7), in which the sutures
are clearly visible on the articular surface; the other is the plesiotype of Triceratops elatus (No.
4805 U.S.N.M.) in which the sutures show at the fractured base but not on the surface. The
assumption is, however, that every ceratopsian condyle includes portions of both exoccipitals and thebasioccipital.

Quoting from Parks again, "The anterior tips of the nasals embrace the posterior end of thepremaxillaries

rostral," which, if true, is a very unusual occurrence, for generally, if not always, theAs usual, the nasals form a part of the bony
are interposed between the rostral and nasal bones.
nasals which
nasal septum though the greater portion is of premaxillary origin. That portion of theIt arises abruptly in front, forming a triangularfunctioned as a horn core is trihedral in shape.
convex ridgeface, while the two plane, sloping, lateral sides meet above in a sharp somewhat
and slightly
anterior
face
on
the
rugose
is
quite
bone
The
orbits.
tothehalfway
backward
extendingbutinvestment,
hornyclose-fitting
been
a
have
must
There
end.
anterior
the
side
at
left
so on theimpressions
vascular
deep,
for
the
supraorbitals,
in
the
horn
as
growing
progressively
hardly apresent in the latter are absent in the nasal region.

^THE CERATOPSIA

108

The epijugals are quite conspicuous, almost horn-like processes, very suggestive of those ofPentaceratops. The crests in the two genera are also somewhat alike, with elongate fenestrae. The
nasal horns, however, are very dissimilar.

That of Anchiceratofs, on the other hand, resembles the
The crests in these twonasal of Arrhinoceratops much more closely, even to the sharp upper edge.

genera are also somewhat similar except at the rear, for that of Arrhinoceratops lacks the epoccipitals
and the two knob-like prominences on the rear of the parietals. In proportions, Arrhinoceratofs
has a relatively short, deep muzzle while that of Anchiceratofs longirostris is elongate, as the nameimplies.

Measurements of Skull of Arrhinoceratops(After Parks)

Length, from tip of rostral to extremity of crest
Width, across tips of epijugals
Width, across posterior margin of crest
Width, across anterior end of crest

Maximum width of crest
Tip of rostral to occipital condyle
Occipital condyle to rear of crest

1520 mm.
700
830
834
1080
718
810

There is but one species, as but two specimens only are as yet referable to this genus, one ofwhich is unprepared, hence specific characters as distinguished from those of the genus cannot be
determined.

The relationship of Arrhinoceratofs to other genera is not evident.

Itbelongs to thegroup characterized by long squamosals, and on this basis alone would lie nearer the ChasmosaurusTorosaurus phylum than the Monoclonius-Triceratofs line in which the squamosal is either short orof medium length (see p. 27 and Fig. 3). This is in accordance with Doctor Parks' opinion.

Genus PENTACERATOPS Osborn
55
Pentaceratops sternbergii Osborn

PL V, B; Text Fig. 39
Holotype: No. 6325 A.M.N.H.; skull without lower jaw (skeleton discarded).
Horizon: Fruitland formation.
Locality: Nine miles northeast of Tsaya, New Mexico.
Collector:

C. H. Sternberg, 1922.

Generic characters are stated to be "One nasal horn, two prominent anteroverted postorbital
dermosupraoccipitalhorns, two lateral jugal osseous horns; with elongate narrow fontanelle in the
between thecharacterinintermediate
Borders of the crest moderately sculptured. Generally
crest.
type,
theTriceratofs
approaching
Eoceratops and Anchiceratofs types of skull, in size and proportion:

TorosaurusP
Osborn says further: "Comparing this skull with other specimens of ceratopsians, we observe
the following resemblances and differences.
"(1) The fontanelles are elongate, instead of circular as in Monoclonius and Torosaurus
in the large fontanelle resembling(Hatcher-Lull Monograph, 1907, PL II).
forward,"(2) The postorbital horns rise directly above the center of the orbit and curve gently
Lull
andby Hatchera different position and inclination from that observed in the types described{of. cit., PL V).

.

The skull of Pentaceratofs, when compared in profile with that of Diceratops and Irijugals. They project
ceratofs {of. cit., PL XLIV), shows that the lateral horns are borne upon the[op. cit., PL
brevicornus
Triceratofs
jugalsoftheonprominencesthanthemuch more widely"(3)

XLII].

The skull of Pentaceratops sternbergii ... is relatively more elongate than that of Tricera-

55 Osborn,

H. F., 1923.

PF.NTACFRATOPS STERN IU'.R< ill

109much more elongate than in Triceratops prorsus (cf. PL
In its dun
are more elongate than in that species.
XXXV) jmoreclosely(cf.
PI. XXVII)
resembles
serratus
Triceratops
proportions PenUKermtops sterniergii
tops brevicortms]

the fontanel les arc

both the rostrum and thefrillalthough it differs widely from this species in the three generic characters above noted, namely, thefontanel les, the jugal horns, and the postorbital horns.

A.M.N. H. 6325

Fig. 39.
jugal;/,—Left lateral view of skull of Pentaceratop sterttbergii, holotvpe, 1/14 natural size,h, supraorbital horn; if, preorbital fossa; it], infratemporal fossa; /', jugal;

prefrontal;

impression;m.\; maxillary;fmx, prcmaxillarv;>/,

nasal;po, postfrontal;

nar, narial opening;q, quadrate;r,

rostral;

tlh,

sq,

nasal

horn;

o,

orbit;/,e,epoccipitals;/,

lacrymal;parietal;/>/,ej, cpi-mi, muscle

parietalfenestra;squamosal.

"Considering the division of the Ceratopsia into two phyla {of. tit., p. 161), Pentaceratops seems
It may be an offshootto represent rather the Torosaurus phylum than the Triceratops phylum.
intermediate in geologic time between the Ceratopsia of the Judith River and Belly River formations
and the Torosaurus of the Lance of Converse County, Wyoming.
"Comparing this animal with the ceratopsians described since the appearance of the HatcherLull

Monograph of 1907 we make the following observations:"Belly River Formation
Styracosaurus Lambe, 1913, type S. albertensis
Protorosaurus (C hasmosaurus) Lambe, 1914, type Monoclonius belli Lambe'"Edmonton Formation
Anchiceralops Brown, 1914, type A. or nut us
Leptoceratops Brown, 1914, type L. gracilis"Two Medicine Formation
Brachyceratops Gilmore, 1914, type B. montanensis"Belly River Formation
Eoceratops Lambe, 1915, type E. canadensis

THE CERATOPSIA

110"After comparison with the above ceratopsians of Belly River, Two Medicine, Edmonton andLance age, this new genus and species appears to be distinct from all previously described genera.
It differs widely from Anchiceratops of the Edmonton with its ornate crest, yet it would appear tobelong to a geologic stage equivalent to the Edmonton. It differs widely in its elongate propor-

from Brachyceratops. It is naturally profoundly different from the older Belly River andTwo Medicine genera described by Lambe, Gilmore, and Brown, although it might be geologicallytions

successive to the Eoceratops canadensis of Lambe in the Belly River stage."
The "lateral jugal osseous horns" are not new structures as they are present in nearly all Ceratopsia,

and were named epijugals by Marsh.

Here, they have reached a remarkable degree of

elongation which distinguishes them from those of most genera. They are, however, very marked
in some specimens of Protoceratops, notably No. 6433, No. 6439, and No. 6467 A.M.N.H., aswell as in the type of Anchicerato-ps ornatus, No. 5251 A.M.N.H., and to a less extent in Chasmo-

saurus kaiseni, No. 5401

A.M.N.H., and in Arrhinoceratops brachyops type, No. 5135 Ct. R.O.M.

This character is, therefore, one of degree and not of kind.

This is true also of the nasal and supra-

orbital horns.

Osborn's statement that the fontanelles are much more elongate than in Triceratops prorsus isclearly a slip if he means the parietal fenestrae, for there are none in Triceratops prorsus or in any
other Triceratops species, a fact of which he is well aware.
Pentaceratops seems to resemble Chasmosaurus on the one hand, and Torosaurus on the other.
With the former, it agrees in the rather short face and longer muzzle, in the long squamosals andlarge fenestrae, and in the position of the nasal horn. It disagrees in the possession of long supra-

which in Chasmosaurus are very short, with two known exceptions that of Chasmosaurus kaiseni type skull No. 5401 A.M.N.H., and the specimen No. 40 Univ. of Alberta. Withorbital horns

Torosaurus, the differences are all the results of a probable evolutionary trend. The elongate crestand the short face are alike. The muzzle of Torosaurus was also probably somewhat elongated, but
as both of the known skulls are defective in this regard, an actual comparison cannot be made. The
fenestrae of Torosaurus are relatively smaller although still persistent, and the epoccipitals havedisappeared, while the epijugals are reduced. There is also a reduction of the nasal horn, which incommon with that of the contemporary Triceratops has shifted forward to lie over the anterior,
The base of each supraorbital horn in Toroinstead of the posterior, rim of the narial opening.
saurus extends further back in relation to the orbit, a tendency which is also seen in the Pentaceratops

specimen No. 1624 A.M.N.H.
The only point of agreement with Eoceratops that I can find is the position of the supraorbitalhorn immediately over the orbit. The shape of the horn is, however, very different. The squamosal of Eoceratops is rather short, a feature which would seem to debar it from a Pentaceratops
ancestry; also the position of the nasal horn in the two genera does not agree. Eoceratops certainly
cannot displace Chasmosaurus, its contemporary, as a probable ancestor of Pentaceratops.
With Anchiceratops also there is little agreement. The position of the supraorbital horn withreference to the orbit is different, for in Anchiceratops the orbit lies under the anterior margin of thehorn. The squamosals, while long, are shorter than in Pentaceratops, and the fenestrae are much
But there is evidence of agreement in the peculiar prominences that characterize thesmaller.
posterior dorsal surface of the Anchiceratops crest, seen also in Pentaceratops No. 1625 A.M.N.H.
The epijugals do show a rather striking similarity but one could hardly call those of Anchiceratops

jugal horns.

Altogether, at least seven specimens of Pentaceratops are known, five of which were collectedby Charles H. Sternberg. Three of them, the type of P. stembergii, No. 6325, and another skull,
No. 1624, with the crest of a third, No. 1625, are in the American Museum, while the others, askeleton without the skull (except the lower jaw), and another skull, are in Upsala, Sweden, andconstitute the types of Pentaceratops fenestratus Wiman. Some material including a fine squamosal isin the National

Museum.

PF.NTACERATOPS FENESTRATUS

1

1

1

Pentaceratops fenestratus Wiman r,nText Fig. 40(A) an almost complete skull, without lower jaw.
Cotype: (B) Skeleton and lower jaw, without skull.
Horizon: Kirtlaiul shales.
Locality: 1 mile south of Kimbetoh Wash, on the south branch of Meyers Creek, San Juan County, New Mexico.
Collector: C. H. Sternberg, 1921.
Cotype:Specimens A and B have no individual bones in common, hence it is only an assumption, buthighly probable, that the specimens are related. The skull of specimen A is the only element thatcan be compared with Osborn's type of Pentaceratops stembergii, with which it agrees in all genericcharacters.
The specific distinctions mentioned by Wiman, on the other hand, are not convincing,although the difference in geologic levels leads one to suppose that the two forms are distinct.
Wiman 's specific characters are: a fenestra present in the squamosal, and shorter and more numerous
The so-called fenestra is demonstrable through the left squamosal only and seems toepoccipitaJs.
be pathologic as it is in so many ceratopsian skulls, more often, as here, on the left side. It may be(See T orosaurus
either a puncture caused by a horn thrust or a bone lesion from the flesh side.
lotus, p. 131, Text Fig. 42.)

The crest in each of the three known skulls of Pentaceratops is defec-

tive posteriorly but the restoration of this region in Osborn's type

No. 1625 A.M.N.H. and is presumably correct.

—

—

is

based upon the separate crest

It does not seem, therefore, as though the number

can be accurately compared. In general proportions,
except along the squamosal
The position of the broad-based horn core, with reference to the orbit infenestratus, differs from that of stembergii; in fact, it does not correspond to Osborn's genericThe only other contrasting detail lies in the epijugal
definition as it is more Triceratops-Wke.
of epoccipitals

the two skulls are alike.

"horns" which are apparently longer in both American Museum specimens and point outward andbackward, while in fenestratus, which is badly crushed and sheared, they project outward and
The nasal horn seems to be longer and more slender in fenestratus. Its posislightly forward.
tion relative to the anterior nares is the same.

Wiman remarks that the orbits are about the same size as the wide lower openings (infraOn the left side of the skull the infratemporal
temporal fossae) and the squamosal fenestrae.
fossa seems abnormally large as compared with thaton the right.

The crushing of the skull may

The fossa was apparently about two-thirds the size of the orbit, which is not excepThe parietal fenestrae are large and subtriangular, with the shorter side directed toward theaccount for this.
tional.

rear; hence, while relatively smaller, they are comparable to those of Chasmosaurus, but are larger

and differ in shape from the elliptical fenestrae of T orosaurus (as restored by Marsh).
The preorbital opening ("lacrymal foramen") seems to be lacking. This is not always demonIt is present, however, in stembergii andstrable in ceratopsian skulls as it is a vestigial structure.
might be seen in fenestratus were the skull in a better state of preservation.
The nasal horn is oval in cross-section; Wiman says this is due to the crushing of the skull and
But I imagine that it would be oval in any
that under ordinary circumstances it would be round.
The tip has disappeared, but the horn must have been moderately high.
case, for that is the rule.
A posteriorly curved nasal horn
It projects upward and forward but curves slightly posteriorly.
and forwardly curved supraorbitals is an anomaly and seems out of reason mechanically. The only
other comparable instance known to me is that of a Triceratops skull, collected by Doctor Loomis in
the Hell Creek beds of Montana, and now in the Amherst College Museum. It is possible that inboth of these skulls the curve of the nasal horn is abnormal, but whether or not it is due to postmortem deformaton I cannot determine.
The horn over the left eye is round in cross-section, while that over the right is laterally comIn either case they are thicker than those of the type of P. stembergii. This, as Wiman
The orbit
says, could be an age differentiation of the individual, or it might be a sexual character.
pressed.

58

Wiman, C, 1930.

THE CERATOPSIA

112

in fenestratus is further forward in relation to the horn base than in st embergii but not as far forward

as in Trkeratops and Torosaurus.

This again may be a mechanical evolutionary trend due in part toa fore and aft thickening of the base of the horn, the Kirtland fenestratus being later in time thanfrom the Fruitland beds. Vascular impressions cover almost the entire cranial roof as
they do the horns, indicative of the advanced age of the individual. It seems evident, therefore, thatthe skull of fenestratus does represent a species distinct from the earlier sternbergti, although thespecific character which gives it its name, fenestratus, may be considered pathologic and therefore notof taxonomic value. However, the general appearance of the skull, the form of the nasal horn, therelative position of the orbit and supraorbital horns, the development and direction of the epijugal
horns, and possibly the apparently greater number of epoccipitals, together with the inclusion in alater formation, are collectively sufficient to confirm the specific distinction which Wiman claims.

sternbergii

Fig. 40.

—Lateral view of skull and skeleton of Pentaceratofs fenestratus, in Upsala,

1/28 natural size,il,ilium;

p, pubis;c, leftr',

coracoid;right ulna;/, lefts,

femur;

left scapula;/',

right femur;//, right scapula;(below)sqj,

left

Sweden (modified from Wiman),fibula;ti', righthumerus;squamosal fenestra (pathologic);i,/,

ischium;

left

tibia;

u , right radius.

Specimen B, the skeleton, has no bones in common with specimen A, the skull, hence the relatwo is assumed, although highly probable. The two animals seem to be of
approximately the same size, the direct point of comparison being the lower jaw and tooth row of
specimen B and the upper jaw of A. Wiman's restoration of the skull in outline as applied to theskeleton gives a most remarkable result, showing the crest extending backward over the entire presacral series of vertebrae, except for the last two or three.
In his drawing, however, the crest is
flattened down so that its long axis is more nearly in line with that of the cranium than in eitherof the American Museum specimens of Pentaceratofs, and, I am sure, in fenestratus itself. In ourown revision of Wiman's reconstruction (Fig. 40), this flattening of the crest is modified and thehead posed somewhat differently, which gives an altered, but not less remarkable, appearance tothe animal.
One doubts whether the crest could be made to lie flat on the back as in Wiman's
figure.
In all of these long-crested and doubtless related forms, Chasmosaurus, Pentaceratofs, andTorosaurus, the crest did extend well over the back; in Chasmosaurus it reached to presacral XIII,
two-thirds of the back; in Pentaceratofs to presacral XVIII. In Torosaurus, the vertebral column
is unknown, but if it was equivalent to that of a Triceratofs of equal body size, such as Triceratofs
brevicornus the crest would reach to beyond the 6th vertebra, more as in Pentaceratofs.
The skeleton lay in a somewhat argillaceous sandstone with numerous carbonaceous planttionship between the1

PENTACERATOPS FENF.STRATUS

113

remains, and was well preserved.
In no place, according to Wiman, did it need any reconstruction.
Wiman's interpretation of the vertebral formula gives 20 presacrals 9 cervicals anddorsals.

—1

1

and 28 caudals, the tail being incomplete. The standard ceratopsian
formula gives 21 presacrals. But the apparent discrepancy here lies in the fact that the 21st presacral
thoroughly coossiticd by its centrum and spine that it appears to be an integral part of thesacrum, and has been so interpreted by Wiman.
He believes that the tail was probably shorter
than in Monoclonius {Centrosaurus), for the last of the preserved vertebrae are so small that only a
few can be lacking. This is another point of agreement with Anchiceratofs in which the number of
caudals is 38 as compared with 46 for Monoclonius (Centrosaurus). The entire skeleton is robust,compared with the Belly River forms, but not more so, relatively, than in Anchiceratofs. The
highest point in the vertebral column lies over presacral XIV, whereas on vertebra X the diapophysis rises higher than in any preceding vertebra, although this is foreshadowed to a much lessextent in IX.
The tenth is the first one on which the capitular rib facet rises from the centrum tothe neural arch and is therefore the first thoracic according to Williston, Brown, and Wiman.
The sacrum, as now constituted in this old animal, contains
vertebrae, as the centrum of thelast presacral is fully fused with that of the succeeding vertebra.
The first parapophysis arises fromthe second and third actual sacrals, but does not sweep aft to the extent seen either in Monoclonius(Centrosaurus) or Triceratops.
Apparently, five parapophyses fuse to form the acetabular bar
which abuts against the ilium, rather than four as in Monoclonius (Centrosaurus) and Triceratops.
Otherwise, the sacrum is not unusual. The ilia are quite similar to those of Monoclonius (Centrosaurus), as seen from below, except that posteriorly they extend further aft. The ilium is quite

There are

also

1

1

sacrals

1

1

Triceratops-Yike except that the pubic peduncle is relatively smaller in Pentaceratops. The pubis iscomparable to that of Monoclonius (Centrosaurus) except for its greater robustness, but the ischium
differs markedly in its degree of curvature, which is greater than that of any other known ceratopsian, even Triceratops.
The shoulder girdle is also very robust but otherwise quite typical. As
posed by Wiman, the distal end of the scapula reaches to within three vertebrae of the anterior endof the pubis (pseudopectineal process), making a very closely coupled animal.
There is nothing distinctive about the fore limbs. The femora, on the other hand, are peculiar.
Wiman says they are somewhat deformed in that they are compressed from anterior to posterior.
This may be so, although a certain fore and aft compression is not unusual with the Ceratopsia.
The remarkable feature, however, is their curvature when viewed from either front or rear. Thisis much more marked than in any ceratopsian I have seen, and must have bowed the thighs outward
in an extraordinary manner.
The distal face of the combined tibia and astragalus is also peculiar inthat it is not perpendicular to the long axis of the bone but looks inward as well as downward,
departing from the horizontal by about 20°. The fourth trochanter of the femur is more prominent
than usual. Whether this bow-legged condition was generic or an individual departure from thenormal cannot be determined from this one specimen. It is certainly unique among all of theceratopsian skeletons which are known to us. The proportionate lengths of the several limb bones
are comparable to those of Chasmosaurus and Monoclonius (Centrosaurus) nasicornus.
Foot bones
are present, but Wiman has not attempted to identify them as they were confused in the quarry.

Dimensions of Skull A(AfterWiman)

Length, from rostrum to highest point of crest
Height of left supraorbital horn
Circumference of same at upper edge of orbit
Height of right supraorbital horn
Circumference of same at upper edge of orbit
Height of nasal horn
Circumference of same at base
Length of epijugal horn core
Circumference of same at base, left
Circumference of same at base, right2160 mm.
600
500
580
520
220
250
100
290
230

THE CERATOPSIA

114

Dimensions of Skeleton B
Length of left dentary
Length of entire vertebral column, as preserved
Total length of the nine cervicals

Length of thoracic region
Length of sacrum
Total length of caudals, as preserved

Length of first three coalesced cervicals
Greatest breadth of sacrum
Length of left half of shoulder girdle, measured over the curve
Length of left coracoid
Length of scapula
Length of right humerus
Greatest proximal breadth of same
Length of radius
Length of ulna
Length of ilium
Length of ischium, measured on curve
Length of left femur
Length of left tibia, inclusive of astragalus
Length of left fibula, inclusive of calcaneum
Breadth of calcaneum

530 mm.
4100
820
880
840
1560
300
610
1000
250
730
646
277

434
577
1120
1000
880
655
600
80

Genus TRICERATOPS Marsh 57

As a result of the labors of Mr. Hatcher and his aides, no fewer than thirty-two ceratopsianskulls, more or less complete, were found in the Lance formation of Niobrara County, Wyoming.
These include the type of nearly every Triceratofs and both of the Torosaurus species. Circumstances were such that the skulls of the upper levels were the best preserved, so that with the exception of Triceratofs horridus and Triceratofs obtusus, which are the lowest in the series, most of thecome from the upper portion and are all quite near one another stratigraphically. Based58
upon all the available data, the skulls have been arranged in their stratigraphic sequence as follows:
types

Level

TRICF.RATOPS
Catalogue

Level

High

MuseumnumberType

19

V.P.M.
T.S.N.M.
U.S.N.M.
U.S.N.M.
U.S.N.M.
U.S.N.M.
U.S.N.M.
U.S.N.M.
U.S.N.M.
U.S.N.M.

1822
7239
1208

Holotype

20
21

22
23
24
25

26
27
28
29 \
30 |
31

32

115

Genus and species
frieeratops prorsus
frieeratops sp. indet.

fr'neratops sulcatus

6679

frieeratops sp. indet.

5741
1205

Trneratops elatus
Trneratops prorsus ?

4708
4286
2124
5738

U.S.N.M.

2416

Y.P.M.
U.S.N.M.

4720

1820

Frieeratops elatus

Trneratops sulcata*
1 rieeratops sp. indet.
frieeratops sp. indet.
'frieeratops serratus

Holotypc
Holotype'frieeratops horridus

Triceratops obtusus

Low
Thirteen species of Triceratops have been described, all but four being based upon adequate
material, in every instance a more or less complete skull, together with a varying number of skeletal
The skeletal material does not at present offer any characters, other than that of size (seeparts.
T. ma.xhnus), which may be used for specific determination, and it is to be doubted whether entire
skeletons in each instance would show material variation other than size, with some differences of
proportions, and possibly the relative height of the spinous processes of the dorsal vertebrae, correlated with the development of the crest of the skull and its degree of freedom from the underlying
flesh, as shown by the extent of the vascular impressions on its under side.
We have determined certain common factors in all of the type skulls which are in any degreecomplete, but find difficulty in deciding as to their relative specific value, for a grouping of specimens
according to the character of the nasal horn may give a different idea of relationship from that
Nevertheless, it has been possible toderived from the character of the brow horns, and so on.
recognize certain assemblages of species, but the reduction of the total number has not been satisfactory, even though the practice of giving a distinct specific name to every approximately complete
skull, which was actually done, seems, a priori unreasonable.

Of the new material which has come to light since the Ceratopsia Monograph was published in
1907, all, with the possible exception of the skull of the mounted skeleton in the American Museum,and the huge vertebrae described by Brown/' may be correlated with forms already described.
There are a few skulls of the older Marsh Collection at the Yale Peabody Museum, which, becauseof lack of complete preparation or other inaccessibility, have not been studied in full detail, but theinference is that all would be found referable to already known species.
The species, in order of their publication, but grouped also according to adequacy of the typemateria], are as follows:

Adequate

Inadequate

Triceratops horridus Marsh, 1889

Triceratops alticornis Marsh, 1887

Triceratops flabellatus Marsh, 1889

Triceratops galeus Marsh, 1889

Triceratops prorsus Marsh, 1890

frieeratops sulcatus Marsh, 1890

Triceratops serratus Marsh, 1890

Triceratops maximus Brown, 1933

Triceratops elatus Marsh, 1891
Triceratops calicornis Marsh, 1898
Triceratops obtusus Marsh, 1898
Triceratops brevicornus Hatcher, 1905
Triceratops (Diceratops) hatcheri Lull, 1905

59

T. maximus, Brown, B, 1933, A.

6:

THE CERATOPSIA

1 1

The common factors which may be used are:Size, always considering the indicated individual

age of the specimen. Thus, the Triceratops prorsus type skull is that of an old animal, as the
sutures are almost entirely obliterated, and yet it is the smallest known Triceratops skull, with an
On the other hand, the Triceratops serratus type skull, while
over-all length of but 5 feet 1 inch.
quite young, is 5 feet11

inches,and the Triceratops calicomis, not fully adult, 6 feet 1 0^4 inches.

This closure of the sutures does not necessarily coincide with sexual maturity, but with completionof growth.
Skull proportions is another factor ; thus, the muzzle may be either long or short, and the crest
either broad, in proportion to its length, or relatively narrow.
The form of the rostrum has also been taken into account, as has that of the jugal, and jugal
notch, also the presence or absence of the pseudopineal fontanelle, the form and degree of inclinaBut the most characteristic elements intion of the orbit, and the form of the infratemporal fossa.
all ceratopsians are the horns and the crest; and of these, the nasal horn seems to have the greatest
value as a specific criterion, for its form and size, if present, or even its absence, are all weighed.
The brow horns are perhaps less diagnostic, for a grouping of specimens according to brow-horn
resemblances does not coincide with a grouping based upon the nasal horns, and, moreover, theformer seem to show more individual variation, especially in curvature, than does the nasal; but inno two skulls are either of these elements exactly alike.
The vascular impressions, on the outer surface of the crest and facial bones, are an age criterion
rather than a specific one, for in older animals the horny integument became either heavier or more
The extent of these markings on the inferior aspect of the crest
closely fitting, possibly both.
seems, however, to have been more important, for in some cases they are absent, again they are
limited to a well defined peripheral zone, or they may be more widely diffused.

On the basis of these data, the following conclusions as to specific distinction or synonymy arereached
Triceratops horridus Marsh60
01

greater portion of a skull, with parts of the lower jaws.
No. 1820 Y.P.M.;
Horizon: Lance formation. This specimen is number 31 out of 32, and therefore about the base of the sequence

Holotype:(seep. 115).
Niobrara County, Wyoming.
Collectors: J. B. Hatcher, C. A. Guernsey, and E. B. Wilson, 1889.

Locality:

The main characteristics of this species, which is the genoholotype, are: The skull is that of anaged, and hence full-grown individual, having an estimated over-all length of 6 feet, 8 inches.
This is a large specimen, but not the largest of the species. Of the crest only the proximal partis preserved, and but a small portion of the orbit; otherwise, most of the essential details can bemade out. The muzzle is fairly long, and the rostral very heavy, with deep vascular impressions.
The cutting edge is not so sharp as in some species and is downwardly curved toward the tip.
The nasal horn is broad at the base, short and blunt, with the dorsal contour in line with that of thewhich is a prevailing feature of Triceratops, except in the elatus-calicornis phylum. The
anterior profile of the nasal horn slopes slightly toward the rear. The brow horns are exceedingly
Their base isstout and rugose, were probably fairly long, and slope forward, as in prorsus.
extremely heavy and is elliptical in cross-section. The orbit is not sufficiently outlined for characterization in the type, but it seems to have been elliptical, with the long axis inclined at an angle of
15° or more from the perpendicular. The descending limb of the jugal is robust, with the longitudinal axis nearly vertical, but sloping slightly backward, and with a bluntly rounded median keel
which nearly bisects the bone. There is no trace of the epijugal as a separate element. The jugal
The crest
notch is fairly deep, but the outline of the infratemporal opening is not preserved.
proportions are not obtainable, but the preserved base is heavy, with deep vascular grooves on thenasals,80 Marsh,
61

O.

C, 1889, A, pp. 334-335 (Ceratofs horridus);Hatcher, Marsh, Lull, 1907, PI. XXVI.

1889, B, p. 173 (Trieeratop horridus).

TRICERATOPS PRORSl'S
outer aspect.

117

As preserved, the dorsal outline is an
These may have been present,
setratUS.

Those oil the under side cannot now be seen.

even curve with no prominences on the midline, as
however, farther back, but judging from referred specimens, I imagine not.
To this species, would refer the huge skull No. 1828 Y.P.M., as far as can be ascertained inThis skull carries the manuscript name of "iiigens," in Professor Marsh's
its present condition.
handwriting, but, while that name has been published by Lull, it was without description and was
It is the largest of all Triceratops skulls, measuring over 8 feet in
therefore, disallowed by Hay.
But it is next
length, an aged individual, with deep vascular impressions on the outer surface.
in1

uppermost of the Niobrara County series, showing the conservativeness of this species.
1
would also refer a skull (PL XIII, B) in the South Dakota School of Mines,
No. P271, collected in the Short Pine Hills, Harding County, South Dakota (see map, Fig. 2,This skull, which has an over-all measurement of 5 feet 6]/2 inches, and is that of a not).
No.
fully adult individual, judging from the condition of the sutures, agrees with the type in mostrespects, especially in the character of the horns, but not in the form of the jugal, which however

to theTo twin.! us
1

1

partly restored and may not be of great significance.
Another large skull, No. 12,003 (PI. XIII, A), in the Field Museum of Natural History,
from the Lance formation of Chalk Buttes, Montana (see map, Fig. 2, No. 10), is also probablyisreferable to this species.

It is 6 feet 9 inches in length.

A large skull in the American Museum, No. 5028, was collected by Brown in 1908 from theThis is the skull of an aged animal, and measures
greater than the estimated length of the type,
6 feet 1 0^4 inches in over-all length, hencearematerially larger than in the type. The main
though the actual measurements of the facial region
distinctions of this specimen, as compared with the type, lie in the larger nasal horn, which is more
like that of prorsus in having the tip extend forward to a point nearly over the anterior edge of
The descending limb of the jugal
the rostral, and in the shorter and more erect brow horns.

Hell Creek beds of Dawson County, Montana.

a littlefrom that of the type in its narrower proportions. The skull differs from the type ofprorsus mainly in its much greater size and somewhat shorter horns, and in the apparent lack of
From brevithe defined peripheral zone of vascular impressions on the under side of the crest.
cormts, this skull differs in greater size, longer nasal horn, and also in the lack of vascular zone.
The animal quite evidently belongs to the horridus-prorsus-brevkornus phylum, its closest affinity
being with horridus. It is unique in the disproportionately large facial region, as compared withdiffers also

the relatively abbreviated crest, which simply emphasizes once

more the infinite variation of theceratopsians.

Triceratops horridus, although conservative, seems to have been a widespread species both in
the elatusI would group horridus near prorsus and brevicornus, as opposed tospace and in time.

phylum, although not necessarily in the same ancestral line.

calicornis

Triceratops prorsus Marsh'No. 1S22 Y.P.M.; nearly perfect skull with lower jaw, and six anterior cervicals.
Horizon: Lance formation, No. 19 in the Niobrara County sequence.
Locality: Niobrara County, Wyoming.
Collector: J. B. Hatcher, 1889.
;

Hol<>tvpc:''

The type skull is that of an aged individual, but one of small size; in fact, its over-all length ofbut 5 feet 1 inch, makes it the smallest Triceratops species and specimen known.
The nasal profile is nearly straight to a point about over the middle of the narial opening,
whence it curves gently upward and is continuous with that of the nasal horn. The profile of thewhen viewed laterally.
crest begins at a point below that of the nasals, so that the two are not in line
The orbit is nearly
horn.
nasal
the
tip
of
with
the
level
about
crest rises to a point
Posteriorly, the62

Marsh, O. C, 1890, p. 82.
Marsh, Lull, 1907, Pis. XXXII-XXXVI.

83 Hatcher,THE CERATOPSIA

118

circular, as opposed to the usual elliptical shape, but the slightly

longer axis slopes, as usual, at an

The descending limb of the jugal is narrow andangle of about 45° from the perpendicular.
The jugal notch isaxis
is inclined slightly backward.
the
and
keel,
tapering, without a mediansomewhat
triangular,
averagesize
andopening
beingofinfratemporal
fairly deep and wide, themassivethaninhorridus,
witha sharpalthoughlesslarge,
with curved margins. The rostral ismuzzleisrathershort,
althoughthemargin.
The
cutting edge and downwardly curved inferior
horn,
which
is
long
and
directed
The most distinctive feature of prorsus is the nasal
face is long.
forward so that its tip extends over the forward margin of the rostral, the anterior profile being
inclined forward at an angle of 35° from the perpendicular. This nasal horn is unique, and occurs
in no other skull, although approaching that of brevicornus and the American Museum skull (No.
5028) mentioned above.

The brow horns are slender, directed upward, outward, and forward for half their length, andthen curved gently inward and upward toward their tip. This reversed curve is characteristic of
calicorms and elatus, although they both differ from -prorsus in the possession of a rugose prominence on the rear of the horn's base. The horns of prorsus are more slender than are those ofeither horridus or brevicornus, and much longer than the latter.
The crest is deeply arched, and helmet-shaped, with an undulating dorsal line which is concave
upward, the rear third being missing. A characteristic feature which links prorsus and brevicornus
is the limitation of the vascular impressions on the inferior surface of the crest to a very clearly
defined marginal zone averaging 15-17 cm. in width. There are deep vascular impressions also on
the dorsal aspect of the crest, the nasals, and horns.
The preorbital fossa lies entirely within the maxillary; the ascending process of the premaxilThe pseudopineal fontanelle is utterly
lary, although long and slender, does not quite reach it.
64
but with nolacking, in possible agreement with the flabellatus type skull as figured by Marsh,

This is, apparently, not a matter of age, for the flabellatus specimen is extremely young,and no matter what the age of other skulls, young or old, it is always present. The mandible israther slender, with a high coronoid process, expanded fore and aft at the summit. The number
other.

of vertical rows of teeth is, in the maxillary, about 30, in the mandible, about 33.
Triceratops prorsus is nearest to Triceratops brevicornus in relationship, agreeing in general

proportions, in the presence of the vascular zone around the periphery of the inferior aspect of thecrest, and in the rather large nasal horn and its general slope which, however, is greater in prorsus.

They disagree in the shorter and stouter brow horns of brevicornus, but their assignment to thesame phylum can hardly be questioned.
65

andSeveral skulls have been identified as pertaining to this species, notably No. 2100
warrant
for
such
seems
to
be
littlethere
butMuseum;National
StatesNo. 1205 of the United
assignment if the highly diagnostic nasal horn is taken into account, for that of the skull No. 2100
very different in character and is of the elatus type, while No. 1205, a fragmentary skull, possesses
none at all in its present mutilated state.
No. 2100 is the skull now borne on the mounted skeleton, but it is not the one figured in the66
paper restoration of the animal, published by Marsh, for which he used the type skull of prorsus,
now at Yale. The skeleton is a composite one and includes at least ten catalogue numbers andMany of the separate bones were figured bytherefore as many, if not more, individual animals.
Marsh or Hatcher in discussing the morphology of the Triceratops skeleton, but always called
Triceratops prorsus. I have yet to find specific characters in the skeletal elements other than theisskull, and see

no possible assurance of the correctness of these specific identifications of the separatebones for, aside from skull and jaws, the type of prorsus includes only the six anterior cervicalvertebrae and some of their ribs, and it is only by actual association of a specifically identifiable
skull and a more or less complete skeleton in two or more instances, that skeletal contrasts of a
specific nature can be determined.
64

Hatcher, Marsh, Lull, 1907, PL XLV.
Marsh, Lull, 1907, Pis. XXX-XXXI.

65 Hatcher,

69 Loc. cit.,p.

190, Fig. 125.

TRICERATOPS HRKVICORNUS

119

There is a -ingle brow horn, No. 4842 U.S.N.M., which pertains to one of the individuals
making up the greater part of the mounted skeleton. It was figured in the Ceratopsia Monograph," and was referred by Marsh to prorsus but, as Hatcher says, resembles more nearly the same7

element inl'ri< era tops

elatus.

Tr'n cramps prorsus

isavery popular name, and is used repeatedly in identifying material, buton the other hand, the species seems to have been rare, for but one skull, and that the type,isreferable to it without question.

Triceratops brevicornus Hatcher 08
9Holotype: " No. 1834 Y.P.M.; skull and partial skeleton.
Horizon: Lance formation, No. 9 in the sequence.

Wyoming.

Locality:

Niobrara County,

Collector:

Hatcher, Utterback, Sullins, Bostwick, 1891.

The skull, which is that of an old individual, is 5 feet 8 inches long, and hence larger thanprorsus but smaller than the average of 6 feet 4 inches. The skull proportions resemble those of
The dorsal profile
prorsus, except that the muzzle is relatively longer in proportion to the face.
of the entire skull forms a more or less continuous line, the crest rising in a gentle curve toward the
The rostral is proportionately very heavy, with a deeply excavated inferior surface; therear.

rather sharp, but comparatively straight, although pointing downward toward thetip.
The descending limb of the jugal is narrow and parallel-sided, while the rather blunt mediankeel divides the jugal into equal halves. The jugal slopes gently backward. The jugal notch is deep

cutting edge

isand wide, and the infratemporal opening is large and triangular, with the rounded apex behind. The
15° with the perpenorbit is an elongated ellipse, with the long axis forming an angle of about
than in prorsus,
smallerbut
prominent,
ratherstout,
very
short
and
horn
is
dicular.
The nasal
diameteris muchThe
longlatterspecies.
asintherostrum
and it does not extend forward over the
nasal
of
the
with
that
continuous
horn
core
is
the
profileofgreater than the transverse. The dorsal
somewhatismarginanterior
The
horn.
that
of
the
bones and sweeps upward in a gentle curve into
convex, and is inclined slightly forward toward the tip of the horn.
The brow horns are short, stout, and abruptly tapering, more nearly circular at the base thanContrasted with the longer
in any other species, except the specimen of elatus, No. 2100 U.S.N. M.

horns of prorsus and horrtdus, they curve gently forward and outward.
The crest of brevicornus is not very long, being proportionately shorter than in prorsus, and notin havingso sharply curved transversely as in the latter species. The two crests resemble each otherzone oflimitedthethe dorsal profile undulating and slightly concave, and in the possession ofvascular impressions on the under side; the latter is also true of No. 2100 U.S.N. M., mentioned
The number of epoccipitals is 19 for prorsus, and apparently 17 for brevicornus. The
above.
number of maxillary teeth also corresponds at 30. The mandible is of medium proportions, thecoronoid process is rather low and not much expanded at the summit, in contrast to that of prorsus
which is high with a marked expansion. The predentary is heavy to match the jaw, and rather

sharply pointed.

The preorbital fossa seems to lie entirely within the maxillary, although the ill-defined sutures
make this difficult to determine with certainty.
But one other skull known to me seems referable to this species and that was collected by
Mr. W. H. Utterback in the Hell Creek region of Montana, in 1904, and is now preserved in theThis skull conforms with the type except for certain minor variainches for the type,tions as follows: Length over-all is 6 feet 3 inches as compared with 5 feet 8
which brings theheavier,andlargersomewhatthough both are aged animals. The nasal horn isratio
of muzzle tothealthoughshorter,
appearcenter of mass further forward and makes the muzzle
Carnegie Museum in Pittsburgh.

67

Loc. cit., p. 128, Fig. 108.

88 Hatcher,

1.

B..

1905, p. 413.

"Hatcher, Marsh, Lull, 1907, Pis. XL1-XL1I.

THE CERATOPSIA

220

A

similar cause may have given rise to a difference in inclination
over-all length is about the same.
which is more erect in the type. The brow horns are
septum,nasalof the hinder margin of thecompared with the over-all length of the skull,
specimen,Museumrelatively shorter in the Carnegie
truncated appearance of the type. Theirsomewhatabrupt,theand taper more uniformly, without
but not in the anterior margin.
concerned,
is
horn
the
of
so far as the masscurvature corresponds

smaller.

The orbits are similar in shape and inclination, but those of the larger skull are relatively
and aft
The jugals are alike, except that in the Carnegie skull they have a somewhat greater foreof theend
anterior
at
the
curve
marginal
gentlerdiameter. The jugal notch is wider, owing to a
crest
is
The
type.
in
the
than
ovoid
squamosal. The infratemporal fossa is smaller and moreundulatory, and the curve rather more
The mandible, rostral, and predentaries agree. This skull is without doubt

similar in general proportions but the dorsal profile

is

less

abrupt at mid-length.
included under individual and possiblyreferable to brevkornus, the differences being such as aresexual, but not age variation.

Triceratops serratus Marsh70

No. 1823 Y.P.M.; nearly perfect skull with lower jaw.
Horizon: Lance formation, No. 18 in the sequence.
Locality: Niobrara County, Wyoming.

Holotype:

71

Collector:

C. E. Beecher, 1889.

and hyoid, but no other skeletal
The skull is fairly large— 5 feet 1 1 inches—although below the average; but as thematerial.
had it lived. The muzzle andanimal was immature, it might have attained average proportions
The facial profileline with each other.
face are long, and the profile of the face and crest are infrom the simple
concave, then convex, forming a reversed curve, differing thereinThis type consists of a magnificently preservedskull, jaws,

first slightly
The orbit is a broad ellipse, withcurve, concave upward, found in every other species but obtusus.
descending limb of the jugal
The
45°
perpendicular.
thefrom
the long axis inclined as usual somedilatation, narrows to aslight
after
a
then,
length,half its
is narrow, parallel-sided for about
jugal of flabellatus moretheresembles
thus
It
keel.
rounded point. There is no trace of a medianwidth in the latter.
greatersomewhat
thebeing
than that of any other species, the main distinction
notch is deep,
jugal
The
backward.
slightly
The axis of the jugal is nearly vertical, but inclines
triangularnearly
more
being
of
insteadand the infratemporal fossa large and almost quadrangular,anteroinferior
theof
exceptionthe
The angles of the fossa are rounded, withas in most species.
with the jugal
fossa lies between the nasal and maxillary, having a slight contact
preorbital
The
one.
form in which
other
in
any
than
rugosetoward the rear. The rostral is rather small, lighter and lesspoint
does notthehorizontal,asmore nearly
this element is preserved, and the inferior border isirregular
but
sharp
fairlyIt is deeply excavated beneath, with aproject downward, as is usual.
perfectly formed as in prorsus, however; this may be an age
nor
so
sharp
so
not
cutting edge,
The nasal horn was a separate ossification, andvariation, the serratus skull being the younger.
transversely comwas lost in maceration, but it could have been neither robust nor long. It wasthat of the nasals as in thepressed at the base, and the dorsal outline was probably continuous withprorsus-brevicomus-horridus group, in contrast to that of elatus and calicorms.

isThe brow horns were slender and much more erect than in any species other than -flabellatus.
As less than one-half their length is preserved in each instance, one cannot be sureof the reversal

been restored as though it wereof the curve either in serratus or flabellatus, although both haveof
the horn, in the rear. It is one
base
the
at
prominenceboss-like
present. There is, however, athird of the squamosal.
proximal
to
the
down
line
obliqueof a series of three which extend in an
obtusus, although inandcalicomis,
elatus,ofhornsThis prominence is characteristic of the brow
The base of thelacking.
issquamosalontothethese species the continuation of the prominences
70 Marsh,
71

O. C, 1890, pp. 81-82.
Hatcher, Marsh, Lull, 1907, Pis. XXVI1-XXIX.

TRICERATOPS FLABELLATUS
horn

is

somewhat

proportions are,inatbecomes more nearly circular, distally. The crest
seems much wider in proportion to its length, thanThis is due, however, to the transverse curvature of the crest, which

elliptical,
firstprorsus for instance.

121

but

the section

sight, unusual, for

it

As a
is highly convex.
matter of fact, the relative measurements, taken oxer the curve of the bone, are much the same.
This is true also of the undulations of the midline, although the name serratus was based upon the"series of bony projections on the median line of the parietal crest." The name could, with equal
propriety, be applied to prorsus and brevicortHts, on this detail alone. The very slight elevation of
To whatthe midline of the crest toward the rear agrees with fabellatus and no other species.
extent this may be due, in each specimen, to immaturity is not clear. The number of vertical rowsof maxillary and mandibular teeth is about 28 in each instance, which is the average number fordiffers in each case, that of serratus being flattened, while the prorsus crest

The number of epoccipitals is 7.
The mandible, which is somewhat pathologic in the right ramus, is long and slender, in
harmony with the facial portion of the skull. The predentary bears the same proportions, while theTriceratops species.

1

coronoid process is only moderately expanded fore and aft at the summit.

Triceratops flabellatus Marsh 72
No. 1821 Y.P.M.; nearly complete skull associated with several vertebrae, a few limb bones, etc.
Horizon: Lance formation, No. 10 in the sequence.
Locality: Niobrara Countv, Wyoming.
Collector: J. B. Hatcher, 1889.
Holotvpe:"'1

The type is a very young, partly disarticulated skull, of which the length is 6 feet 2 inches.
The depth and relative shortness, which seem to be juvenile proportions, indicate that had theanimal lived, it would have attained a fairly large size, probably above the average. These general
proportions would presumably have changed with age, and hence are not considered specificcharacters.

The dorsal profile is much straighter than usual, that of the face and crest being nearly in
The nasal profile is a gentle curve, the degree of which remains the same throughout,
The nasal horn is missing, as in the serratus type. Marsh's restorainstead of varying as is usual.
line.

horn with an anterior margin which slopes somewhat backward.
might, however, have been restored with equal propriety, to resemble that of brevicoruus. In
other words, this essential specific feature is lacking. The brow horns rise more erectly than in any
other species, except Triceratops (Dkeratops) hatcheri, but their forward curvature above the base
The horns are laterally compressed near their base; distally,
is somewhat greater than in the latter.
they are more nearly circular. The orbit is an elongated ellipse of slightly irregular outline, withthe long axis inclined at 45° from the perpendicular, the maximum inclination for Triceratops. The
descending limb of the jugal is quite broad, and lacks a median ridge or keel. It resembles that ofserratus more nearly than that of any other.
The jugal notch is not deep, but the infratemporal
fossa is a broad oval with but one angle, the antero-inferior one. The face is deep, but of moderate
length, while the muzzle is very short. The rostral and predentary are both missing. The crest,
while wide for its length as measured over the curve, appears narrower, due to its curvature, than ineither serratus or calicornis, wherein the crest is comparatively flat, when viewed from above.
It issmooth both above and below, with no trace of vascular impressions, except immediately in thewake of the supratemporal fossa. The epoccipitals are 19 in number, which is near the average,
while the number of maxillary teeth, apparently about 35, seems excessively great, especially as thenumber of mandibular teeth, apparently 30, is near the average and one assumes that they would
approximately correspond.

tion shows, in outline, a truncatedIt"Marsh, O. C, 1889, B, p. 174.
73

Hatcher, Marsh, Lull, 1907,

Pis.

XLIV-XLV.

THE CERATOPSIA

122

The
The mandible seems rather slender for so deep a facial region of the skull.
coronoid process is moderately expanded at the summit, and is not hook-like, as in Monoclonius{Centrosaurus).
The preorbital fossa was apparently entirely within the maxillary, although the depression wasbounded also by the lacrymal and jugal on the rear side and below, respectively.
T. flabellatus is an isolated species, the affinities of which lie perhaps as near serratus as any
In these two, the jugals are the most similar, and while the nasal horn has been lost inother.
each instance, they may also have been alike. Proportions differ, for serratus is long and slender,
viewed laterally, while flabellatus is deep. This, as well as the bosses on the horn base andsquamosal of serratus, may be an age distinction. The dorsal profiles are, in general, alike, except
The flabellatus skull is smoothfor the prominences along the midline of the crest in serratus.
throughout, lacking the vascular impressions so well marked in serratus, but this is a matter of age.
T. serratus also stands alone except for this suggested affinity. Finally, they were found very neareach other, although the flabellatus comes from a slightly higher level.

Triceratops elatus Marsh 74
Holotype: 75 No. 1201 U.S.N.M.; skull.
Horizon: Lance formation, No. 12 in the sequence.
Locality:

Niobrara County, Wyoming.

Collector: J. B. Hatcher, 1890.

This specimen represents
6 feet 2^4 inches in length.

asomewhat immature animal of average size, the skull measuring

The dorsal profile of the skull is distinctive, the facial portion having

a decided hollow curve straightening out toward the cranium proper, whichisthe highest point,

except for the extreme rear of the crest ; in this it resembles Triceratops calicornis, its nearest relative.
The muzzle is rather slender and of moderate length, although the rostral is fairly large.

The latter has deep vascular grooves and a comparatively straight inferior margin which points
decidedly downward toward the tip. The narial opening is very large. The nasal horn is peculiar,
although resembling that of calicornis more than any other species in having the dorsal margin
The horn core, while bearing vascularslightly below and not continuous with that of the nasals.
impressions, is truncated, the anterior and superior margins being at right angles with each other,
the former overhanging the base of the muzzle and inclining slightly backward.
The brow horns are long and massive, extremely heavy at the base where they are strongly
compressed laterally, becoming more circular in section toward the tip. The rear of the base bears
The horn curves strongly forward,
a marked prominence, as in calicornis, obtusus, and serratus.
reversing slightly toward the extreme tip.
The orbit is a broad oval of regular outline, with the broader end uppermost, and inclines at
an angle of about 15° out of the perpendicular. The jugal is unique in that it is ""[-shaped, having
no posterior limb, as in every other ceratopsian skull, the posterior margin being continuous with asomewhat irregular suture which extends directly upward and forward to the orbit. Skull No. 2 1 00, 76
on the mounted skeleton in Washington, is suggestive of elatus in this, as in certain other features,
but the jugal is broader. The descending limb is long and rather narrow, with curved, nearlyparallel front and rear margins.
The longitudinal ridge, which is but slightly developed, lies near
the rear instead of being in the center of the bone.
The jugal notch is deep and wide, and theinfratemporal fossa unusually large and triangular, with the apex pointing toward the orbit.
Unfortunately, the jugal complex is visible only on the left, and, as the bone seems abnormal, one
would like to compare it with that of the other side were it possible.
74

Marsh, O. C, 1891, p. 265.
Hatcher, Marsh, Lull, 1907, PI. XLIII.
76
Hatcher, Marsh, Lull, 1907, PI. XXX.

75

TRICERATOPS CALICORNIS

123

The crest is of average size and curves strongly upward toward the rear, the dorsal profile
being only slightly undulating. The epoccipitals and epijugals are lacking. They were originally
The squamosal is very wide, especially at its
present, however, the former numbering about 21.
in
form
as
calicomis. The area of the crest lying aboutsame
generalthemid length, but has muchthe supratemporal fossa, especially toward its rear, is deeply excavated and evidently pathologic.
Otherwise, the sculpturing, especially of the vascular grooves, is not so very marked on either surfaceof the crest, above or below.

To the species elatus may also be referred the skull No. 21 00 U.S.N. M., at present associatedwith the mounted skeleton at Washington. This fine skull is complete, except for the muzzle,
which has been restored. Its dimensions are about those of the elatus type, the over-all length being
6 feet 3 1 j inches for No. 2100 U.S.N.M., and 6 feet 2->4 inches for elatus. The small nasal horn
The browis like that of elatus with its dorsal surface depressed below the level of the nasal bones.
horns, on the other hand, differ in their angulation, being strongly anteroverted, with a reversed

curve toward the tip, and in the form of the basal section which is nearly circular. The orbit is alsonearly circular, in contrast to its elliptical form in elatus. The epijugal has a high ridge, and thejugal itself is broad, with a limited posterior limb, resembling somewhat the peculiar jugal of elatus.
One marked peculiarity which resembles prorsus and brevicornus, rather than elatus and calicomis,
which, inis the limited peripheral zone of vascular impressions on the under side of the crest
The maxillary
this instance, seems correlated with an outward and upward flare of its margin.

The affinities of this skull lie clearly with Triceratofs elatus Marsh,featurebeing
the peripheral zone of vascular impressions on the under side of
discordant
the only
teeth number 28 vertical rows.

the crest.

Yet another skull of somewhat doubtful affinity, but nearer elatus perhaps than any other, is
77
of Triceratofs in the American Museum of Natural History. Thisthat on the mounted skeleton
mount (PI. XIV, A) is composite, the skull, No. 5116, having been collected by C. H. Sternberg
in Weston County, Wyoming, while the skeleton, No. 5033, No. 5039, No. 5045, was collected byBrown and Kaisen in 1909 in the Hell Creek region in Montana. This is a large skull, 6 feetiy2 inches, of an adult but not an aged individual, as the sutures are still very clearly defined. In
general proportions, it differs from elatus in being relatively shallow for its length, especially in the
cranial region, and in the enormous crest which is smooth above and below and has an even margin,
without epoccipitals in its present condition, although doubtless the usual number was originally

The muzzle has the proportions of elatus rather than of calicomis, with a large narial
The nasal horn is rather larger than usual, but shows the depression of the dorsal contour
The brow horns are enormous, strongly anteroverted, as inslightly below that of the nasals.
No. 2100 U.S.N. M., but almost straight beyond the base, which is circular in cross section. The

present.

opening.

almost to the anterior limit of the premaxillaries. All of the horns have deep vascular
The orbit is nearly circular, as in No. 2100 U.S.N.M., while the jugal is rather
narrow, tapering and raking backward rather more than usual. The jugal notch is very shallow,
but the infratemporal fossa is relatively larger than in the elatus type, almost semi-circular in form,tips extend

impressions.

with the upper margin nearly straight. This skull evidently belongs to the elatus-calicomis phylum,
There is infinite variation in all
but of its strict specific identity with elatus one cannot be sure.
Triceratofs skulls.
Triceratops calicomis Marsh
Holotype:78

No. 4928 U.S.N.M.;

skull

and portion of skeleton.

Horizon: Lance formation, No. 17 in the sequence.
Locality: Niobrara County, Wyoming.
Collector: J. B. Hatcher, 1889.
77 Osborn,

H. F., 193 3.
Marsh, O. C, 1898, p. 92.
"Hatcher, Marsh, Lull, 1907, Pis. XXXV1II-XXXIX.

78

7 *

THE CERATOPSIA

124

This is one of the largest Triceratops skulls on record, having an over-all length of 6feet

10^4 inches, in spite of its being not fully adult. The disproportionately long muzzle increases
The dorsal profile isthe length over that of elatus which, otherwise, it resembles most closely.
very comparable to that of elatus, as superimposed outlines would show. The imperfection of themedian portion of the crest in the present specimen makes the comparison of this region of lessvalue, however.

The orbit is an elongated ellipse, slightly broader above and, as in elatus, inclined at an angle
The jugal is of medium width, and tapers to a point in theof about 15° from the perpendicular.

from that of elatus in having the usual rear branch above, and is, therefore,
But that of elatus may be abnormal, and were
might
found
preserved,itbeto resemble that of calicornis.
There is aside
that of the opposite
two-thirds
ofthetoward
rear
jugal
about
way
the
of
the bone.
slight longitudinal ridge on the
wide,
with
curvedoutline.
The jugal notch is of moderate depth, but is
The infratemporal fossa is rather small for the size of the skull and differs, not only in this,but also in shape, from that of elatus, being oval in form, with a rather long apex pointing downward
and forward. The muzzle is very long, more like that of Chasmosaurus than Triceratops. The
face is also long.
In this respect, calicornis differs from Chasmosaurus in which, despite the fact
The narial opening in calicornis is very large, inthat the muzzle is long, the face is very short.
distal half.

It differs

T-shaped rather than in the form of an inverted L.

correspondence with the large muzzle. The rostral is also large, with a very convex profile. The
downwardly curving inferior margin is rather sharp-edged.
The nasal horn is very peculiar, and here, as in prorsus, it was the most distinctive feature in
the eyes of Professor Marsh, who gave the name calicornis to the species because the rear of thissmall nasal horn resembled a horse's hoof as seen from below. As in elatus, the dorsal margin of
the horn core is not continuous with, but below that of the nasal bones, the horn being thus sharply
marked off from the nasals. The horn is convex in front and concave behind, hence the hoof-like
form. There are vascular impressions on the rounded anterior surface. Viewed laterally, the horn
has a pointed apex. The horn of both the elatus type and of the skull No. 2100 U.S.N. M., on themounted skeleton at Washington, are of the same general character, although the hollowed rearsurface is peculiar to the present specimen.
The brow horns are large, agreeing with those of elatus in size, massiveness, and general curvaThey have a very
ture, and in the possession of a boss-like prominence on the rear of the base.
heavy base from which they taper rapidly, curving sharply forward but without the reversed curve

toward their tip.

The crest is only partially preserved, the entire left squamosal and about a third of the medianelement only being present. The left squamosal is about twice as long as broad, with a uniformly
curved, rather than undulating, margin. Otherwise, the margin is smooth and rather thin. There
were probably the usual number of epoccipitals, perhaps 19 in all, although but two are preserved.
A few shallow vascular impressions are present on the upper surface of the crest. Below, they are
deeper, especially in the posterior part of the squamosal, and extend further in from the margin,
there being no limited zone of vascular grooves such as that of prorsus, brevicornus, and the skull
No. 2100 U.S.N. M. The crest is unusually wide when viewed from above, being over twice aswide as long, according to Hatcher's figure. 80 The pseudopineal fontanelle is present, and large,
but the radiating canals, if they formerly existed, are not preserved.
The preorbital fossa lies
between the nasal and maxillary, and is reduced to a rather wide, elongated slit.
The dentaries are of great size; otherwise, according to Gilmore, 81 they show no distinctive
characters. There are 38 rows of teeth in the left dentary, opposed to 28-32 in the maxillary, theexact number being difficult to determine.
If this is the lower jaw actually belonging to the skull,
it is difficult to account for this discrepancy, for no fore and aft or orthal movement of the mandible
was possible. Microscopic striae of wear on the worn surface of the teeth prove vertical movement
only.
80 Hatcher,81

Marsh, Lull, 1907, PL XXXIX.
Gilmore, C. W., 1919, B, p. 101.

TRICERATOPS OBTUSUS

125

Undoubtedly, the relationship between elatus and calicorms is very close; the elongated muzzleo£ cslicomis, the detailed form of the nasal horn, and the peculiar jugal of elatus seem to be aboutIndeed, Hatcher
the only distinguishing features, all of which may be due to individual variation.
expresses the opinion that the two species may prove to be synonymous. They certainly represent agroup quite apart from the frorsus-brewcornus-horridus phylum. If they prove to be of the same
species, the name elatus takes precedence.

Triceratops obtusus Marsh 82

Text Fig. 41
83

No. 4720 U.S.N.M.; a nearly complete skull and jaws, except for the parietal portion of the crest.
Horizon: Lance formation; No. 32, and therefore, the lowermost in the sequence.
Locality: Niobrara County, Wyoming.

Holotype:Collector:

J. B.

Hatcher, 1890.

Hatcher could locate but little of this skull in the National Museum collections, either to figure
84
Monograph. Later, Gilmore found the remaining portions, andrestored the skull, the unique yellow color of which made error of association virtually impossible.
The type is an old individual with an estimated length of at least 7 feet, hence one of thelargest on record. The muzzle anterior to the nasal horn, however, is missing, and the length ofor describe in the Ceratopsia

region is subject to considerable specific variation. The nasal profile is unique among Triceratops specimens in being convex instead of concave, although this may be due in part to crushing,
The dorsal contour of the crest is conjectural, but as restored by
especially toward the rear.
thisGilmore begins considerably below the level of the nasals, though rising above that level toward
the rear. The orbit is large, a rather elongated ellipse, the axis of which is inclined at an angle ofabout 30° from the perpendicular.
The descending limb of the jugal is very broad for its length, and has a marked median ridge.
The jugal notch is rather shallow and wide, and the infratemporal fossa very small for the size ofthe skull, triangular in shape, with the apex toward the rear. The nasals are very broad, especiallyover the posterior limit of the nares, and the two sides converge rapidly toward the anterior end.
The nasal horn is reduced to a rather broad, rounded, rugose prominence, with deep vascular
Laterally, the nasal profile reminds one of that of Arrhinoceratops of the Edmonton
grooves.
formation.
In the latter, however, the profile is sharp-edged, while in obtusus it is broad.
The brow horns are very massive at their base, and have a protuberance at the rear as in elatus
and calicornis. But they are relatively shorter, and lack the great forward curvature of the horns ofthese species. The horns of obtusus also resemble somewhat those of brevicomus, but they are relatively less stocky and taper to a longer point without showing a reversed curve.
The crest is only partly preserved, the right squamosal being entire, the left somewhat less so,
There are deep vascular grooves on the dorsal
but nothing is present of the parietal element.
They are not limited beneath tosurface of the crest and on the under surface of the squamosal.
a peripheral zone. Epoccipitals must have been present although now the margin of the squamosals
The mandible is very robust, with a low, broad coronoid, the form
is smooth, without undulations.
of which has apparently been altered by crushing, as shown in the figure. The number of mandibular
tooth rows is 28, that of the maxillary series, which is partly broken away, cannot be determined.

The individual teeth are very large.
The nearest ally of Triceratops obtusus seems to be horridus, the main distinction between themlying in the nasal horn, which varies considerably among the several skulls attributed to the latter
species, although never to the point of obsolescence.
is

specialized; otherwise,

82

it

is

a generalized type.

Marsh, O. C, 1898, p. 92.
Gilmore, C. W., 1919, B, PI. 4.
84
Op. cit., pp. 98-101, PI. 4.

88

In its loss of nasal horn and great size, obtusus
It isinteresting to see the reduction of the nasal

THE CERATOPSIA

126

from the ancestral line of any other species
horn so low in the Lance series, as this debars obtusus
occurs two-thirds of the way up from the bottom of
except perhaps T. (Dkeratofs) hatcheri, whichis shown by a detached nasal horn of quite similar
speciesvalidaconstitutes
the sequence. That it
1825. This horn is straighter on top and with aNo.
collection,
Museumcharacter in the Peabodycannotbe attributed to any other species than this.
Itlaterally.
less rounded apex when viewed

"\

\

,.-

Fig. 41.

Left lateral view of skull of Triceratop obtusus, holotype, 1/12 natural size.

there
That Triceratop obtusus came from the same general ancestry as Trkeratofs horridus
times. Arrhinoceratofs
can be little doubt, although it may represent a distinct line since Edmonton
inthe long squamosal.
notablydifficulties,
presents
itis a structural ancestral possibility, although
to a discussion of
once
at
I
pass
"inadequate,"
being
species of Trkeratofs

The remaining
apparent relationship
Dkeratofs, of which the type is ample for description, and also because of its
with Trkeratofs obtusus.
85
Triceratops (Diceratops) hatcheri Lull

Holotype:80

No. 2412 U.S.N.M.;

skull

without the lower jaw.

Horizon: Lance formation, No. 11 in the sequence.
Locality: Niobrara County, Wyoming.
Collector: J. B. Hatcher, 1891.

This genus and species was described by Hatcher in his incomplete manuscript but left, unfortunately, without a name, which had to be supplied by the present author, who edited and completed
the first Ceratopsia Monograph.
85

Lull, R. S., editorial note in Hatcher, J. B., 1905, p. 413.
86 Hatcher, Marsh, Lull, 1907, Pis. XLVII-XLVI1I.

TRICERATOPS (DICERATOPS) HATCHERI127

The generic characters, as given by Hatcher, are: "Nasal horn core absent. Squamosal bones
pierced by large fenestrae, while smaller ones penetrate the parietals.
The inferior border of thesquamosal lacks a quadrate notch." Of these characters, 1 would dismiss the second as pathologic;
for historically, the squamosal is never fenestrated as a normal character, although repeated instancesof perforations through this bone occur, due either to disease or injury.
p.

131, Text Fig. 42;

Arrhmoceratofs brachyops, p. 107, PI. XII;

(See Torosaurus latus,

Chasmosaurus brevirostris,

A; and Pentaceratops fenestratus, p. Ill, Fig. 40.) The entire region of the left squamosal, where the largest of these "fenestrae" occurs, is badly diseased on the under side; moreover, the perforation practically obliterates the area of insertion of one of the most important neck
PI. VII,muscles which served to wield the head, so that the animal must have been partly incapacitated as aresult.

The first and third characters are largely differences of degree, rather than of kind. This is
Of specific validity

especially evident if one compares Diceratops hatcheri and 'Triceratops obtusus.

I have no doubt, but real generic distinction from Triceratops is highly questionable.
There isnothing like the contrast in crests, for instance, shown in Triceratops and Torosaurus. (See beyond,

p.

130.)

The skull, that of an aged individual, is about 6 feetslightly below the average for Triceratops skulls.

1inch in over-all length, and therefore

It is unique, for no other specimens

known to me

can be referred to this species.

The muzzle is long with a comparatively small rostral, although the sutural limits of the
The inferior border of the rostral is curved downward toward the tip.

latter are not discernible.

The dorsal profile of the nasals and of the crest is almost in line, the former being concave, as usual,convex profile of obtusus. The orbit is an elongated ellipse, with the axis

as contrasted with theinclined at an angle of about 20°

from the perpendicular.

The descending limb of the jugal is of medium width, with a low ridge posterior to the midline.
It is approximately vertical.
The jugal notch is very shallow, as the outer anterior marginof the squamosal is very little below the summit of the notch.
generic character, i.e., absence of quadrate notch.

This is evidently Hatcher's third

The infratemporal fossa is of medium size, oval, with the apex pointing downward and forward.
The nasal horn core is lacking entirely, the nasals rounding into the curve of the muzzle without abreak in the even contour. The nasals terminate in a broad, rounded, rugose area more suggestiveof Triceratops obtusus than of any other form, and, as in the latter, they are twice as broad at therear as at the forward end.

The brow horns are comparatively short and robust, erect when viewed laterally, although
There is but a slight forward curve. The horns seemflaring apart somewhat as seen from in front.

to arise further back than usual with reference to the orbits, but this is more apparent than real, forthe erect character of the horns heightens the illusion. The base of the horn is nearly circular incross-section, instead of being laterally compressed as in most other species.

The crest is broad, at least twice that of its length, when viewed from above, and its dorsal
is nearly straight, without undulations but with a slight upward turn toward the rear.
Although a portion of this as well as the distal ends of the horns are artificial, the indicated curves
are well carried out and are probably correct. The number of epoccipitals is 19, 5 on each squamosal,
withover the end of either squamoso-parietal suture, exactly as in Triceratops. The crest ishighly vascular above and below with no limited zone on the inferior face.
The perforations
through the crest number four, and are asymmetrical, the left squamosal containing a large subtriangular one at about its mid-length, and a lesser, irregular one in front, near the infratemporal
fossa.
The right squamosal has another irregular aperture in nearly the same place as the larger one
on the left, but having less than one-fifth the area of the latter.
There is yet another smaller
perforation through the right side of the parietal, halfway between the squamosal and the rear
margin. Below, the area in front of the largest aperture is tumid, thickened, and irregular, whichheightens the impression that all of these perforations are pathologic and may be cystic openings
comparable to those through the squamosal of the Torosaurus latus type mentioned above, andprofile1

THE CERATOPSIA

12 8

Surely they can have no taxonomic significance.
such the result of disease, or injury, or both.
skull, except perhaps the absence of the nasal
this
One wonders how many of the peculiarities ofinaffectingthe behavior of the animal including
horn, may be due to this diseased condition which,the carriage of the head, reacted upon the entire organism.
The number of maxillary teeth is 24, less than the usual number.
Diceratops may be of sub-generic, but hardly of generic rank, for it is clearly a modified
asTriceratops, possibly the culmination of the evolutionary trend seen in Tricerato-ps obtusus and out
The species hatcheri I would consider valid.

of its lineage.

"INADEQUATE" SPECIES OF TRICERATOPS
The three or four remaining species of Triceratops, I have called "inadequate" because of
insufficiency of the type in each case, for while each form may be absolutely valid, it is impossible
They will have to remain ill
to define it in terms of the common factors we have been using.
defined until more perfect material is found in each instance.
Of these, Triceratops galeus, consisting of a single nasal horn core, No. 2410 U.S.N. M.,
Hatcher has already discarded as based upon insufficient evidence. He says, however, that it
resembles the nasal horn of Torosaurus gladius more than any known species of Triceratops, andmay have pertained to that genus and species.

It alsoresembles fairly closely that of the skull,

No. 5 1 1 6, on the mounted skeleton of Triceratops in the American Museum, which Hatcher neversaw, and which has been referred tentatively to elatus. The evidence is too slender for determination of the species under discussion, and galeus, which is from the Denver beds of Colorado, mustremain a nomen nudem pending further discovery.
Triceratops alticornis Marsh 87
88

No. 4739 U.S.N. M.; pair of brow horns with the communicating cranial bones.
Holotype:
Horizon: Denver beds.
Locality: On the banks of Green Mountain Creek, near Denver, Colorado (Fig. 2, loc. 17).
Collector: G. L. Cannon, Jr., 1887.

Here, the brow horns alone must determine the specific characters, which makes a clear definiThe main distinction of these horns lies in their curvature, for while anterovertedtion impossible.
at an average slope for Triceratops, they are otherwise straight in lateral aspect, but slope outward
and then upward in a single curve, when viewed from the front. Aside from this, there is nothing
Here, again, the validity of thisto distinguish these horns from those of several other species.
species must await further discovery.

Triceratops sulcatus Marsh™
Holotype: 90

No. 4276 U.S.N.M.; fragmentary skull, vertebrae, etc.

Horizon: Lance formation, No. 16 in the sequence.
Locality: Niobrara County, Wyoming.
Collector: J. B. Hatcher, 1890.

There is, in addition, the plesiotype, No. 4286 U.S.N. M.,

91

consisting of a pair of brow horns

with the connecting cranium, which has been sectioned for the brain. This is number 26 from the
top in the stratigraphic series and therefore considerably lower than the holotype.
87

Marsh, O. C, 1887, pp. 323-324 (Bison alticornis).
Marsh, O. C, 1889, B, pp. 174-175 (Ceratofs alticornis).
88
Hatcher, Marsh, Lull, 1907, Fig. 106, p. 115.
89
Marsh, O. C, 1890, B, p. 422.
90 Hatcher, Marsh,
Lull, 1907, p. 133-134, Figs. 112-113.
111

tbid., Fig.

113.

TRICF.RATOPS MAXIMUS

129

Yet a third specimen in the National Museum, No. 1208, has been referred to this species.
This consists of a nasal horn and a pair of brow horns, only one of which shows the sulcations
which give the name to the species. Marsh's description states that "the most distinctive characterOnof the skull is seen in the horn cores of the frontal region, which are very large and elongate.
which
has
suggestedgroove,
there
is
a
deep
core,
horn
the posterior surface of the upper half of eachthe specific name."
The holotype, unfortunately, includes at present only a portion of one brow horn, which is
obliquely truncated distally as though broken during the lifetime of its owner, and this does notshow the distinctive sulcation on the rear, of which Marsh spoke. Possibly, as Hatcher suggests,

the mate to this horn, which cannot

now be located, was the one which showed the distinctive

character.

The plesiotype, No. 4286, shows the sulcations on both horns very well, but they are on theantero-internal and not the posterior face of the horn.
92
the left horn has a rather shallow sulcation on
In the third specimen, No. 1208 U.S.N. M.,

the anterior side and a much deeper one on the antero-internal face, extending throughout the
The sulcations on the other horn are so slight that they might bedistal two-thirds of the horn.
attention not called to them.
wereimpressions
vascularfor
taken
than those we have mentioned, the only additional recorded
other
and,
rare
are
horns
Sulcatedbrachyops from the Edmonton (see PI. XII), and a
Arrhinoceratops
typeof
instances are in theone on the antero-internal face of the left horn of Torosaurus latus type,and of the right horn of Triceratops brevicornus type. I doubt, however, the specific value of thisBothfeature alone, especially as there are no other diagnostic characters with which to correlate it.
pointed,
and
being
small
of
No.
4286
horns,
thatnasal
No. 4286 and No. 1208 possess associatedarising as a separate ossification which is now coossified with the underlying nasals. This horn doesIn
not rise above the level of the nasal profile and the anterior face slants slightly forward.
distinct
low
but
being
a
there
undulating,No. 1208, the dorsal outline of the nasals is slightly
hump over the nares, then a depression, in front of which is a very small, rounded nasal horn withThus, the two nasal horns agree in being small;a nearly vertical anterior face, as preserved.

slight indication ofotherwise, they are quite unlike.
The lower jaw, associated with the holotype, is not specifically distinctive.
At present, therefore, the species Triceratops sulcatus cannot be defined. Although it may ulti-

mately prove to be a distinct form, one cannot even determine its relationship with other Triceratops
phyla except by elimination. If either of the nasal horns is distinctive, sulcatus cannot belong to
the prorsus-brevicomus-horridus group; but whether its relationship lies with the obtusus or theelatus phylum, the evidence does not show.

Triceratops maximus Brown 93
Holotype: No. 5040 A.M.N.H., a series of eight free vertebrae and two cervical ribs.
Horizon: Lance formation, Hell Creek beds.
Locality: Rock Creek, 20 miles south of Lismas, Garfield County, Montana.
Collector: P. C. Kaisen, 1909.
Specific characters, as given by Brown, are as follows: "Axis rib reduced in size. Third cervicalCentra of free cervical vertebrae short, vertical and transverse diameters of articularrib massive.
faces nearly equal; sides deeply constricted; ventral surface flat.

Anterior dorsal centra higher thanbroad."

Brown stresses further the deeply excavated sides and the flat, very rugose, ventral surfaces of
the cervicals, the extremely large neural canal, a vertical series of three large foramina on each sideof the cervical centra, spaced approximately one inch apart, and the extraordinary size of all thevertebrae.
92
93

Hatcher, Marsh, Lull, 1907, PI. XXXVII.
Brown, B., 1933, A.

THE CERATOPSIA

130

This species cannot now be denned in terms of the criteria we have been using, for the skull
A careful comparison of the description and dimensions given by Brown fails to distinguish the vertebrae from those of Triceratops "ingens" (No. 1828 Y.P.M.) in so far as equivalentbones are present in the two specimens, except that in certain dimensions cervical IV of maximus is atrifle larger, and the three equally spaced foramina on the side of the centrum are represented by one
isabsent.

large one and others less clearly defined and not so regularly spaced. The other specific characters
mentioned are common to both. In the dorsal vertebrae of T. "ingens" the centra have either been

destroyed or are as yet hidden in the huge mass of matrix which envelops the specimen.
T. "ingens" is a gigantic representative of the horridus species, but features other than size whichmight distinguish them are not now evident.
The
Triceratops maximus may prove to be but another huge specimen of the same species.
diagnostic
characters,
andassociatedwithsimilarcompletetoshow
sufficiently
discovery of a skull
vertebrae, is necessary for final proof either of uniqueness or synonymy with previously described
forms.

Genus TOROSAURUS Marsh 94

The known characters of Torosaurus lie in certain regions of the skull, for the skeleton, except
While material pertaining to the genus may
for a few limb bone fragments, is totally unknown.
The skull characters have to do first with proporexist in our collections, it cannot be recognized.
the portion anterior to the orbits is abbreviated, and the crest extended in width andAs a consequence, the distinctive squamosal bone is extremely long and narrow,recalling that of Chasmosaurus of the Belly River, and Pentaceratops of the Fruitland, both of whichtions, forespecially in length.

may be in the line of its ancestry.

Yet another generic characteristhe persistence of parietal

fenestrae, which are characteristic of all ceratopsians below the Lance, but absent in all known Lance
genera other than Torosaurus. In neither skull is the muzzle preserved, so that one cannot deter-mine whether it was elongated, as in most long-crested forms, such as Chasmosaurus and Pentaceratops, or short, as in the average Triceratops.

In the restoration of the Torosaurus gladius skull(PI. XVI), the cranium and muzzle of which were modeled by the author a number of years ago,
Torosaurus certainly could not have had a deep, abbreviatedTriceratops was used as a guide.

muzzle such as characterizes the short squamosal forms, Monoclonius and Centrosaurus.
But two specimens of Torosaurus are known, both of which come from the very summit of theLance series of Niobrara County, Wyoming.
Torosaurus latus Marsh95
PI.
Holotype:

96

No. 1830 Y.P.M.

;

skull without

XV

lower jaw.

Horizon: Lance formation, No. 1 in the sequence.
Locality: Niobrara County, Wyoming, near the summit of the bluff on the north side of Lightning Creek, about
2 miles above its confluence with Lance Creek.
Collector: J. B. Hatcher, 1891.

author.

brow horns,parietals.

/ inches overall, as now restored by the2
The tntire cranium, including the left maxillary, the nasal horn, and the bases of theThis skull is that of an old individual, about 7 feet 1islpreserved, together with both squamosals, and the anterior third of the fused

On the left side, a portion of the antero-external outline of the fenestra seems to be

The dorsal
present, but the form and extent of these distinctive features are highly conjectural.
profile of the nasals is in line with that of the preserved part of the parietals. There is reason tobelieve that beyond this the crest curved upward, balancing the upward curve of the nasals forward
into the nasal horn.
94

Marsh, O. C, 1891, p. 266.
Marsh, O. C, 1891, p. 266.
90 Hatcher, Marsh, Lull, 1907, Fig. 118.
95

TOROSAIRUS LATUS

131

The orbit is somewhat oval, with the broadened apex to the rear, and the long axis nearly horiThe descending limb of the jugal isil, in contrast to the more nearly circular orbit of gloditlS.
not entire, but is fairly broad with apparently a low median keel. The infratemporal fossa is small,
The anterior free margins of the squamosals are not pretriangular, with rather straight margins.
•served, so that the form and depth of the jugal notch are conjectural.
The nasal horn is small, but equal to that of the average Triceratops, acutely pointed, with
Its position relative to thethe anterior face inclined backward, except toward the extreme summit.

The brow horns are large, and hollow for at least half their
They rise over theoval in cross-section, with the apex pointing forward.
They arise
posterior half of the orbit which, in turn, underlies the anterior third of the horn.
nares is similar to that in Triceratops.
the base

length;is

EfOC

openings

1/ascu.ia:r/ianie Is

cPhotograph of the visceral surface of the squamosa] of Torosaurus latus, No. 1830, Yale Peabody Museum,Fig. 42.
showing distribution and relationship between cystic openings, erosion, and vascular channels. The similarity between thepathological conditions in the dinosaur and prehistoric man is of great importance, leading toward the same diagnosis.

rather close together, and are inclined outward and forward.

There is no axial curvature in the pre-served portions, for only about one-third of the left is present, and very little above the base of theright.

The crest proportions seem slightly broader for their length than in gladius, but this is not
The mid-dorsal region is broadly rounded transversely and with extremely low undulaThe crest is smooth, both above and below, and with small marginal undulations. The
tions.
reliable.

pseudopineal fontanelle is unique, differing from that of gladius, as well as all Triceratops species,
The two apertures are separated by over 3 cm. of bone. Fromin being paired rather than single.
runs backward and outward to terminate in a larger, elongatedgrooveeach of these, a wide, shallow
aperture which penetrates the crest.

The preorbital fossa lies between the maxillary and nasal, and is similar in form and size tothat of the average Triceratops.

Examination of the squamosal bone (Text Fig. 42) of Torosaurus latus type, No. 1830
We submitted a photograph of the area
Y.P.M., reveals unquestioned evidences of disease.
involved, and a plaster cast of the openings, to Dr. Roy L. Moodie, who writes as follows:"The photograph shows lesions which are identical with lesions found on the skull and skeletal elements offrom the Channel Islands. There have been four cases of this disease studied from the Indian
mounds. In one case there were evidences of seventy-five tumors on the skull alone. Comparisons with recent
cases of the dread disease have led me to regard the condition as Multiplr Myeloma, although there are someprehistoric Indians

discrepancies in such a diagnosis.

"The association of open lesions, depressed areas, called 'erosions,' which are due to pressure atrophy fromsmall tumors of subperiosteal origin and elongated channels, are so strikingly similar in the dinosaur bone (Fig.
42) that there would seem to be no doubt of the close relation between the condition in the dinosaur and prehistoricman.

"The etiology of the disease is uncertain, but recent work in medical laboratories would lend favor to thesuggestion that such cystic tumors have to do with a disturbance in the parathyroid.

j

THE CERATOPSIA

32"The openings may be due to tumors arising in the medullary portion of the bone. Such pathological condiand among Tertiary and Pleistocene mammals."
tions appear first in the Triassic and are found in later reptiles
Torosaurus gladius Marsh97
PI. XVIan
No. 1831 Y.P.M.; nearly complete parietal, right squamosal, nasal horn and both brow horns,
theskull.
fragments
of
other
and
condyle,occipital
epijugal,Horizon: Lance formation, No. 3 from the summit of the Niobrara County sequence.
betweenNiobrara County, Wyoming, very near that of Torosaurus lotus, on the divide midway

Holotype:

98

Locality:

Lightning and Cow creeks and about a mile from their confluence.
Collector: J. B. Hatcher, 1891.

This is a huge skull, measuring, as restored, about 8 feet 5 inches over all, and hence thegreater of thelargest known skull of a land animal, actually exceeded in size by only a few of theyounger indiIt
wasa
extremelyold.
notmodern whales. The animal was apparently adult, butvidual than the latus type.
The dorsal profile of the skull, as restored, is flatter than that of latus, the line of face andmargin. The orbit iscrest being continuous, although the latter rises slightly toward the posterior
preserved innearly circular, in contrast to the oval one of latus. The descending limb of the jugal is
There is a fairly large,
part on the left side, is of medium width, and flat on the outer aspect.
except on its anterior
unknownarefossa
infratemporal
theoflimitsThe
epijugal.
rounded, rugose
Its actual form
latus.
thanthatof
proportion
inlargersomewhat
beenside, but it seems to have
and with
section,rugose,elliptical
basal
with
an
conical,
horn
is
nasal
cannot be determined. The
the anterior face nearly vertical.
The brow horns are slender for the size of the skull, and arise behind the orbits, the forward
margin of the horn being immediately over the posterior limit of the orbit. This position of thehorns is unique. The horns are flattened transversely at their base, and are elliptical in cross-section
The right one curves toward the median line when viewed from in front, the left
throughout.
&in the lessbeing straight. Laterally, the posterior margin curves more than the forward one, andmuchof this isperfect left there is some indication of a reversal of the curve toward the tip.
postmortem cannot be determined.
The median bar of the parietal, convex above, concave below, is very
crest is immense.

How

The

thin and bears four low undulations.

Marsh states that in this species the parietals entirely enclose

the fenestrae, while in latus the sauamosalforms a portion of the outer limit of the aperture.

But

the distal part of the inner border
I find the evidence in the two skulls is about the same; in Radius,
long, and in latus 270 mm., in
mm.
about
300
surface,suturalof the squamosal shows a distinct
distance when indications oflesserforaroundedsmoothlyfront of which the border in each is
Chasmosaurus there
ancestral
presumablyIntheagain.
sutural connection with the parietal begin
fenestra andgenerally an overlapping suture in that portion of the parietal which lies between thethe contact
the squamosal (see p. 68), except in the Yale specimen No. 2016 Y.P.M. in whichthat ofresembles
squamosal
the
that
so
between the two portions of the parietal is incomplete
parietal.
theforcontinuity
suturalthe
Torosaurus in having a smoothly rounded portion interrupting
The rear margin of the parietals is thin and undulatory, but there is no sure indication that Torosaurus ever possessed epoccipitals. The squamosal is extremely long, reaching the maximum length
ever attained by this bone. At the forward end there are three slight undulations, but the remainder
entireof the outer margin is smooth and rounded. There is no trace of vascular impressions on theiscrest.

.

The pseudopineal fontanelle is single, as in Trkeratops, in contrast to its paired condition inlatus, with97

two radiating grooves terminating in large foramina, only one of which is preserved.

Marsh, O. C, 1891, pp. 266-267.

98 Hatcher, Marsh, Lull, 1907, Fig. 119.

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PLATESPLATE II
MONOCLONIUS (CENTROSAURUS) FLEXUS
No. 2015 Yale Peabody Museum.
A. Left lateral view showing entire skeleton.
Right side (photograph reversed), showing
B.

N. E. Wright.
1/26 natural size.

140

restoration

by R.

S.

Lull

and

PLAT]

141

PLATE III
A.

Anterior view of

MONOCLONIUS (CENTROSAURUS) FLEXUS, show-

ing restoration and skeleton of Yale Peabody Museum specimen, No. 2015.
B.

Skin impression of

MONOCLONIUS (CENTROSAURUS) CUTLERI,

from the flank region.

American Museum specimen, No. 5427, about 1/2

natural size.

Courtesy of the American

Museum of Natural History.

142

PLATE III

143

PLATE IV
PROTOCERATOPS ANDREWSI
A.

Ventral view of skeletal mount in original supine position, No. 6416

B.

Lateral view of No.

6467 A.M.N.H.

Courtesy of the American

Museum of Natural History.

144

A.M.N.H.

PLATEi

145

PLATE V
A.

Skull of

CHASMOSAURUS KAISENI, type, No. 5401 A.M.N.H., 1/8

natural size.
B.

Skull of

PENTACERATOPS STERNBERGII type, No. 6325 A.M.N.H.,

1/14 natural size.
Courtesy of the American

Museum of Natural History.

146

PLAT1. V

PLATE VI
CHASMOSAURUS BELLI
No. 5402 A.M.N.H.
A.

Lateral view of skull.

B.

Dorsal view of skull.

1/10 natural size.
Courtesy of the American Museum of Natural History.

148

l'l.A

I

1

\
.

I

PLATE VII
Skull of

CHASMOSAURUS BREVIROSTRIS, type, No. 5436 Ct. Royal

Ontario

Museum of Palaeontology, about 1/12 natural size.

Courtesy of the Royal Ontario Museum of Palaeontology.
Skull of

CHASMOSAURUS cf. KAISENI, No. 40 University of Alberta,

about 1/8 natural size.

Courtesy of the University of Alberta.

150

PLAIT. VII

PLATE VIIISTYRACOSAURUS ALBERTENSIS
Type, No. 344 G.S.C.
A.

Lateral view of skull.

B.

Dorsal view of skull.

1/12 natural size.
Courtesy of the Geological Survey of Canada.

152

PLAT]VII

PLATE IX
A.

Skeletonof

MONOCLONIUS (CENTROSAURUS) NASICORNUS,

type, No.

5351 A.M.N.H., 1/30 natural size.

Courtesy of the American Museum of Natural History.
B.

Skeleton of

BRACHYCERATOPS MONTANENSIS, type, No. 7951, alsoparatypes Nos.

7952-7957 U.S.N.M., 1/10 natural size.

Courtesy of the United States National Museum.

154

PLATE IX^^iffiPH

155

PLATE X
ANCHICERATOPS LONGIROSTRISA.

Lateral view of skull, No. 8535 G.S.C., 1/10 natural size.

B.

Dorsal view of skull, No. 8535 G.S.C., 1/10 natural size.

C.

Skull and skeleton as mounted in the National

No. 8538 G.S.C., 1/25 natural size.
Courtesy of the Geological Survey of Canada.

156

Museum of Canada, at Ottawa,

PLAT]

157\

PLATE XIANCHICERATOPS ORNATUS
Endocranial cast of paratype, No. 525^ A.M.N.H., 3/4 natural size.
A. Dorsal view; B. Right lateral view; C. Ventral view. After Brown.
Abbreviations:a.s.c.

ascending semicircular canal.

cbl.

cerebellum.

cbl.p.

process of cerebellum.

cer.

cerebrum.

cer.p.

process of cerebrum.

h.s.c.

horizontal semicircular canal.

med.
op.a.

medulla oblongata.
ophthalmic branch of internal carotid artery.

pit.

pituitary body.

p.s.c.

posterior semicircular canal.

Cranial nerves
I

II

Olfactory.

VII

Optic.

III

Oculomotor.

IV

Trochlear.

V

Trigeminus.

VI

Abducens.

Courtesy of the American Museum of Natural History.

PLATE XI

159

PLATE XIIARRHINOCERATOPS BRACHYOPS
Type, No. 5135 Ct. Royal Ontario Museum of Palaeontology.
A.

Oblique anterior view of skull.

B.

Lateral view of skull.

1/10 natural size.
Courtesy of the Royal Ontario Museum of Palaeontology.

160

PLATE XII

161

PLATE XIII
A.

Skull

of

TRICERATOPS HORRIDUS,

No.

12,003

Field

Museumof

Natural History, 1/12 natural size.
Courtesy of the Field Museum of Natural History.
B.

Skull of

TRICERATOPS HORRIDUS, No. P271 South Dakota State Schoolof Mines,

1/12 natural size.

Courtesy of the South Dakota State School of Mines.

162

PLATE Mil

PLATE XIVA.

Mounted skeleton of TRICERATOPS cf. ELATUS, at American Museum of
Natural History, 1/38 natural size.

Courtesy of the American Museum of Natural History.
B.

Mounted skeletons of CHASMOSAURUS BELLI, at the National Museum of
Canada;left, plesiotype,

No. 2245;

right,

Courtesy of the Geological Survey of Canada.

164

No. 2280.

PLATE XIV

165

PLATE XVTOROSAURUS LATUS
Type, No. 1830 Y.P.M., restored by R. S. Lull.
A.

Lateral view of skull.

B.

Anterior view of skull.

About 1/16 natural size.
Yale Peabody Museum.

166

PLATE XV

167

PLATE XVITOROSAURUS GLADIUS
Type, No. 1831 Y.P.M., restored by Hugh Gibb and R. S. Lull.
A.

Lateral view of skull.

B.

Oblique anterior view of skull.

About 1/16 natural size.
Yale Peabody Museum.

168

PLATE XVI169

PLATE XVIIFLESH RESTORATION OF CHASMOSAURUS BELLI
A.

Left lateral view.

B.

Anterior view.

C.

Right lateral view.
Restored by Mr. L. S. Russell of the Geological Survey of Canada.

Publishedwith the permission of the Director, Geological Survey of Canada, Dept. of

Mines, Ottawa, Canada.

170

PLATE Mil

171

.

INDEX
Synonyms are

species or genera arc discussed are in bold-face type.

Pages on whichinitalics,

Asteriskssignify illustrations.

96.

Agath.ium.is sylvestris, 2.

Ceratops alticornis,

Ceratopsian species from, 9, 78, 83, 86, 87, 91,
92, 94, 95, 103, 104, 106.
albertensis (Styracosaurus), 28,* 87, 88, VIII.

Ceratofs horriilus, 96, 116.

Ceratops beds, 6.

Alphabetical List of Genera and Species, 19.

Ceratopsian localities,

Albert.).

128.

alticornis (Triceratops),

Anchiceratops, 33, 19, 51, 56, 57, 65, 71, 72, 73, 74, 76,
81, 98, 100, 102, 103, 108, 110, 113.

28,* 103, 104, 105, 106, 108, X.

ornatus, 71, 103, 107, 110, XI.

andrewsi (Protoceratops), 74, 75,* 76, 77,* 78, 80,* IV.
Angular, 37.
apertus (Centrosaurus), 84.
Arrhinoceratops, 74, 81, 98, 103, 106, 107, 108, 125, 126.
brachyops, 27, 28,* 29, 106, 110, 127, 129, XII.
Articular,
Atlas,

map of,

11.

Ceratopsoidea, 6, 81.
coalesced, 39,* 40.

Chalk Butte region, Montana, 14.
Chameleon, 25.
Chasmosaurus, 24-28,* 39, 51, 54, 57, 58, 66, 68, 70,
74, 77, 85, 88, 89, 91, 92, 93, 98, 99, 102, 104, 106,
107, 113, 124, 130, 132.
belli, 1, 27, 28,* 62, 66, 67,* 92, 93, VI, XIV.
brevirostris, 94,

127, VII.

kaiseni, 26, 27,

28,* 68, 85, 94, 95,* 96, 97, 110,

V, VII.

37.

restoration of,39.

Bearpaw formation, 6.
belli

Ceratops paucidens, 93.

Cervical vertebrae, 39, 40, 41,* 42.*

Alveolar grooves, 33.

longirostris,

3,

XVII.

Chclonia, 25.

(Chasmosaurus), 28,* 67,* 92, 93, VI, XIV.

Classification, 74.

86, 87, 91, 92, 94, 95, 109, 110.
Big Horn Basin, Wyoming, 15.

Climate of Dinosaur Environment, 20.
Colorado, Ceratopsian species in, 16, 128.
Combat, methods of, 22-23.
Converse County, see Niobrara Co., Wyo.,

Bison alticornis,

Cope, E. D., 81.

Belly River formation,

1,

6.

Ceratopsian species in, 8, 10, 26, 27, 29, 81, 83, 84,

1.

Black Buttes, Wyoming,

3.

Brachyceratops, 5, 39, 74, 78, 79, 84, 97, 98, 99, 100,

102, 110.

montanensis, 32, 97, 98, 99, IX.
brachyops (Arrhinoceratops), 28,* 106, XII.
Brain, 71, 72,* 73.

Coracoid, 50,*

5 1.

Coronoid, 37.
crassus (Monoclonius), 82.
Crest, 24, 34.

Crocodilia, 65.
cutleri (Centrosaurus), 87, III.

brevicornus (Triceratops), 28,* 119, 120.

dawsoni (Monoclonius), 83, 84.

(Chasmosaurus), 94, VII.
British Columbia, 18, 64.

Dendy, A, 7

Brontosaurus, 20, 52.

Denver formation, 3, 128.
Denver and Arapahoe formations, 6.

brevirostris

Brown, B., 1, 52, 72, 73, 86, 102, 103, 129.
calicornis(Triceratops), 123, 124, 125.

Camptosaurus, 38, 81.

1

Dentary, 37.

Diceratops, 3, 6, 107, 108, 126, 127.

Diplodocus, 52.

canadensis (Eoceratops), 91.

Discovery, history of,

Caudal vertebrae, 49-50.

Distribution, geographic, 9, map, 11.

Centrosaurus,

1,

24, 26, 29, 30, 33, 34, 39, 40, 51, 56,

3.

geologic, 6.

65, 66, 68, 69, 74, 77, 78, 81, 83, 84, 85, 88, 89, 92,

Ditmars, R. L., 93.

100, 101, 102, 104, 106, 113, 122, 130.

Dja-doch-ta formation, 8, 74.
Ceratopsian species in, 8, 74.
Dorsal vertebrae, 42,* 43,* 44,* 46.*

apertus, 3 5, 38, 40, 82, 84, 85, 86.
cutleri, 47,

87,

48, 53, 58, 60, 61, 63, 64, 66, 69, 85,

Edmonton formation, 1, 6.

III.

nexus, 28,* 30, 31,* 32-36,* 37, 41,* 43,* 44,* 46,*

49,* 50,* 52, 53,* 54,* 55,* 57, 58,* 59,* 60,
61,* 62,* 63, 64, 66, 69, 81, 82, 85, 86, 87, 98,
II, III.

nasicornus, 30, 32, 42, 43,* 45,* 47, 48, 51-57, 60,

61, 63, 64, 85, 86, 87, 90, 91, 113, IX.
Ceratopsidae, 24, 75, 78, 81.
Ceratops,

1,

5,

3.

74, 81, 94, 96.

montanus, 26, 96, 97.

Ceratopsian species

in,

8,

9,

26, 27, 78, 103,

106, 109, 110.

XIV.
Environment of Ceratopsia, 20-21.

elatus (Triceratops), 122, 123,

Eoceratops, 74, 91, 96, 108, 110.
canadensis, 84, 91, 94, 95, 97, 98, 102.
cpoccipitals, 34.

Evolutionary Changes, Progressive, 24.
Feeding habits, 21-22.

104,

.

INDEX

174

Manus, 56,* 57.
Marsh, O. C, 1, 114, 116, 117, 120, 121, 122, 123, 128,

Femur, 59,* 60.
Fenestra, parietal, 24, 34.

130, 132.

fenestratus (Pentaceratops), 111, 112.*

Matthew, W. D., 20.

Fibula, 61.*
flabellatus (Triceratops),

Maxillary, 33.

121, 122.

41,* 43,* 44,* 46,*
49,* 50,* 53,* 54,* 55,* 58,* 59,* 61,* 62,* 86, II,flexus (Centrosaurus), 28,* 31,* 36,*

III.

Flora of dinosaur environment, 20.
Footprints, 64.
Fossa, preorbital, 32.
Fossa, supratemporal, 34.

Fox Hills formation, 6.

maximus (Triceratops), 129, 130.
Mexico, 18.
Mivart, St. George, 65.
Mongolia, 5, 18, 74.
Monoclonius, 1, 5, 26, 29, 74, 81, 85, 86, 88, 89, 91, 92,
96-101, 103, 108, 130.
crassus, 3, 30, 40-45, 47, 48, 49, 51, 54, 58, 59, 60,
61, 81,82, 83, 96, 102.

Frill, see crest.

dawsoni, 30, 83, 84, 91, 102.

Fruitland formation, 6.

fissus,

Ceratopsian species in, 8, 26, 27, 108.
Genera and species, Alphabetical List of, 1 9.

recurvicornis, 3, 81, 83, 97.

Geological sequence of Ceratopsia,

Gilmore, C. W.,

1,gladius (Torosaurus)

3, 8 1.

sphenocerus,

3,30, 37, 81, 82, 83, 90, 91.

Monoclonius belli, 92.
Montana, ceratopsian species

8.

72, 90, 95, 97, 99.
28,* 132, XVI.

in,

13, 78, 82, 90, 96, 97,

117, 119, 123, 129.

,montanensis (Brachyceratops), 97, 98, 99, IX.

Gorgosaurus, 23.

80,* 81.

gracilis (Leptoceratops), 78, 79,

Granger, W., 1, 74, 76.
Gregory, W. K., 74.
Gregory, W. K. and Mook, C. C, 75, 76, 77.
Hatcher, J. B., 1, 62, 73, 82, 119, 126, 127.

montanus (Ceratops), 96.
Moodie, R. L., 2, 131.
Morosaurus, 52.

Morphology, general, 30-73.

Mounted specimens, 64, 65, 66.

hatcheri (Diceratops), 28,* 126.

Nasal, 32.

Hay, O. P., 25.
Hayden, F. V., 3.

Nasal septum, 32.

Hell Creek beds,

nasicornus (Centrosaurus), 43,* 45,* 86, IX.

New Mexico, 4.

3, 6.

Ceratopsian species

14, 29,in,

111, 117, 119, 123,

129.

Ceratopsian species in, 16, 108, 111.
Niobrara County, Wyo., 3, 6.

Horn, nasal, 30.
Horn, supraorbital, 30.

Ceratopsian species in, 15, 29, 116.
Nopcsa, F., 58, 60.

horridus (Triceratops), 28,* 116, XIII.

North Dakota, ceratopsian species in,

Huene, F. v., 18, 32, 99.
Humerus, 53,* 54.
Hyoid, 37, 38.*

obtusus (Triceratops), 28,* 125, 126.*

Ilium, 47,* 49,* 5 7.

ornatus (Anchiceratops), 103.

Integument, 66, 69, 70.
Ischium, 58.*

ovatus (Styracosaurus), 90.

Jaw, lower, 37.
Judith River formation,
Ceratopsian species

O'Harra, C. C,

14.

1.

Ojo Alamo formation, 6.
Osborn, H. F., 1,71, 108, 109,

1

10.

Palatal aspect of skull, 35, 36,* 67.*
3,

Parasaurolophus, 82.

5.

in, 8,

26, 29, 82, 83, 96, 109.

Parietal, 34.

W. A., 1, 38, 106, 107, 108.

Jugal, 33.

Parks,

kaiseni (Chasmosaurus), 28,* 94, 95,* V, VII.

Pathologic bone, 107, 111, 121, 127, 131,* VII.

Kindle, E. M.,

Pelvis, 48.

1.

Kirtland formation, 6.
Ceratopsian species

Pentaceratops, 4,
in, 8,

Lacrymal, 33.
Lacrymal foramen, see preorbital

fenestratus,

28,* 130, 131,* 132,

XV.

78, 79, 80,* 81.

longirostris (Anchiceratops),

126.

Postfrontal fontanelle, 25-26,

Premaxillary, 32.
prorsus (Triceratops), 28,* 117, 118, 119.

Protoceratopsidae, 24, 74, 75.

28,* 104, 105, 106, X.

Lower Ravenscrag formation,
Lull, R. S.,

Phrynosoma, 3 1
Phylogeny, 24, 28.*
Polyonax mortuarius, 3.
Predentary, 37.

1.

Leptoceratops, 24, 26, 76, 78, 98.
gracilis,

110, 111, 112,* 127.

Pes, 62,* 63.

Ceratopsian species in, 8, 26, 27, 28, 109, 110, 116,
117, 119, 120, 121, 122, 123, 125, 126, 128,
130, 132.
latus (Torosaurus),

6, 39, 66, 74, 77, 94, 95, 98,

sternbergii, 27, 28,* 108, 109,* 110, V.

fossa.

Lambe, L. M., 83, 84, 87, 91, 92.
Lance formation, 6.

Lane, H. H.,

5,103, 108, 130.

111.

13.

Protoceratops, 2, 5, 24, 26, 39, 74, 79, 100, 110.

andrewsi, 74, 75,* 76, 77,* 78, 80,* 81, IV.
restoration of, frontispiece.

101,

INDEX

175

ToroMurus,

Protorosaurus, 92.

ins,

Pubis, 57, 5S.*3,

6,26, 27, 29, 66, 68, 73, 74, 92, 107,

no,

iii9,

1

14,

127, 130.

Radius. 55,* 56.

gladius, 28,* 88, 107, 114, 128, 130, 131, 132, XVI.

Rattlesnake beds, 17.

l..tus,Triceratops,

6, 26, 29, 30, 31, 32, 33, 34, 35, 36, 37,

64, 71, 72,* 73, 74, 77, 82, 89, 91, 96, 98, 99, 100,
101, 103, 106, 114, 127, 128, 131, 132.
alticornis, 3, 27, 115, 128.

1.

Sacrum, 46, +7,* 4S, 49.*St.

1,

38, 39, 40, 47, 48, 49, 51, 52, 53, 54, 55, 57, 58, 62,35.

Russell, L. S..

Mary formation, 78.

San Juan County, New Mexico, 6.
Ceratopsian species in, 16-17.
Saskatchewan, localities, 13.

brevicornus, 27, 28,* 35, 102, 108, 109,

elatus,107, 114, 115, 118, 119, 120, 122, 123, 124,

125, 128, 129, XIV.

Sense organs, 73.

72, 98, 114, 115, 118, 120, 121, 122.

serratus (Triceratops), 38,* 120, 121.

flabellatus, 71,

Skeleton, appendicular, 50-63.

galeus, 115, 128.

(Diceratops) hatchcri, 28,* 114, 115, 121, 126.

Skeleton, axial, 30-50.

Monoclonius (Centrosaurus)

flexus,30, 31,* 32-

35, 36,* 37-38.

Chasmosaurus, 66, 67,* 68, 95,* V, VI, VII.

South America, 1 8.
South Dakota, ceratopsian species in, 14, 117.
sphenocerus (Monoclonius), 83.
Sphenodon, 71.

horridus, 3, 28,* 71, 114, 115, 116, 117, 118, 119,

125, 126, 130, XIII.
"ingens," 29, 117, 130.
maximus, 115, 129, 130.
obtusus, 28,*

107, 115, 120, 122, 125, 126,* 127,

128, 129.
prorsus, 25, 28,* 37, 40, 60, 71, 76, 107, 109, 110,

115, 116, 117, 118, 119, 120, 121, 123, 124.
35, 38,* 71, 78, 98, 109, 114, 115, 116,

37.

Squamosal, 33, 34.
Stanton, T. W., 2.

serratus,

Stegosauria, 24.

sulcatus, 71,

Sternberg, C. M.,

117, 120, 121, 122.

64, 104.
sternbergii (Pentaceratops), 28,* 108, 109,* 110, V.
1,114, 115, 128, 129.

Two Medicine formation, 5, 6.

Sternum, 51, 52,* 5 3.

Ceratopsian species
Tyrannosaurus, 23, 71.

Stratigraphic sequence, table of, 7.

Ulna, 54,* 55.

Stvracosaurus, 4, 25-27, 33, 68, 74, 82, 87, 89, 91.
albertensis,

ovatus, 5,122,123, 124, 125.

Schuchert, C, 20.

Splenial,

114, 115,

117, 118, 119, 120, 121, 123-125, 129.
calicornis, 29, 114, 115, 116, 118, 120, 121,

Scapula, 50,* 51.

Skull, of114, 127, 129, 130, 131,*

XV.

Trachodon, 5 8, 72.

Red Deer River, Alberta, 4.
Romer, A. S., 65.
Rostral. 31,

22, 25, 28,* 111,

132,

recurvicomis (Monoclonius), 83.

28,* 83, 87, 88, 90, 91, 104, VIII.
90, 104.

sulcatus (Triceratops), 128, 129.

Surangular, 37.

in,

8,

84, 90, 97, 109, 110.

Vertebrae, cervicals, 39,* 40, 41,* 42.*

Vertebrae, dorsals, 42,* 43,* 44,* 45,* 46.*
Vertebral column, of Monoclonius(Centrosaurus)

flexus,39-50.
of Chasmosaurus, 68, 69.

Sweetwater County, Wyoming, 16.
Tait, J. and Brown, B., 73.

Vertebral formula, 39.

Tapirus, 79.

Williston, S. W., 74, 113.

Teeth, 35.
Tetrapodosaurus borealis, 64.
Texas, 1 7.
Tibia, 60, 61.*

Wiman, C, 111, 112, 113.
Wyoming, ceratopsian species in,

Vomer,

3 5.

15, 117, 119,122, 123, 125, 126, 128, 130, 132.

120, 121,