Early Permian Vertebrates 

from the Cutler Formation 

of the Placerville Area 

Colorado 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 503-C 

Early Permian Vertebrates 

from the Cutler Formation 

of the Placerville Area 

Colorado 

By GEORGE EDWARD LEWIS and PETER PAUL VAUGHN 

With a section on Footprints from the Cutler Formation 

By DONALD BAIRD 

CONTRIBUTIONS TO PALEONTOLOGY 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 503-C 

The typical Cutler Formation of Colorado 

correlates with classic European and with 

other North American Lower Permian 

continental formations 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1965 
UNITED STATES DEPARTMENT OF THE INTERIOR 

STEWART L. UDALL, Secretary 

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director 

For sale by the Superintendent of Documents, U.S. Government Printing Office 

Washington, D.C. 20402 - Price 50 cents (paper cover) 
Abstract __________________________________________ _ 

Introduction ______________________________________ _ 

Early work on the Cutler Formation _____________ _ 

Present study _________________________________ _ 

Acknowledgments ______________________________ _ 

Geography ________________________________________ _ 

Location and extent of area _____________________ _ 

Surface features and areas of outcrop _____________ _ Geology __________________________________________ _ 

Stratigraphy and structure of the Placerville area __ _ 

Cutler Formation of Colorado ___________________ _ 

Cutler Formation of nearby States _______________ _ 

Vertebrate fauna ___________________________________ _ 

Systematic descriptions _________________________ _ 

Eryops cf. E. grand is (Marsh, 1878) __________ _ 

Platyhystrix rugosus (Case, 1910) ____________ _ 

New (but unnamed) genus and species _______ _ 

Diadectes sanmiguelensis Lewis and Vaughn, n. 

SP--------------------------------------

Limnoscelops longijemur Lewis and Vaughn, n. gen., n. sp ______________________________ _ 

CONTENTS 

Page 

C1 

1 

1 

1 

2 

2 

2 

2 

2 

2 

3 

5 

5 

7 

7 

8 

12 

13 

21 

Vertebrate fauna-Continued 

Systematic d escri ptions-Contin ued 

Ophiacodon sp ___________ - ___ - __ - - _ - - - _ - - - --

Cutleria wilmarthi Lewis and Vaughn, n. gen., 

n. SP------------------------------------

Mycterosaurus smithae Lewis and Vaughn, n. sp_ 

Age and correlation of the fauna----------------- 7 ----

Comparison with Early Permian faunas of North 

America ____________________________________ _ 

Comparison with European Early Permian faunas __ 

Paleogeographic considerations ______________________ _ 

Selected references ____ ---- _________ ---_-------------

Footprints from the Cutler Formation, by Donald Baird_ 

Abstract ______________________________________ _ 

Systematic descriptions _______________ -----------

Limnopus cutlerensis Baird, n. sp _____________ _ 

Genus indet., cf. Brachydactylopus Toepelman 

and Rodeck, 1936 ________________________ _ 

Prospectus and problems _________ - __ ------------

References cited _________________ - ___ -_---------

ILLUSTRATIONS 

Page 

C26 

27 

34 

39 

39 

42 

43 

44 

47 

47 

47 

47 

47 

49 

49 

Page 

FIGURE 1. Index map of Colorado __________________________________________________________________________ -_ C3 

2. Diagrammatic section showing geologic formations of the Placerville area ___________________ ------------- 4 

3. Profile and section, Cutler Formation, Placerville area_________________________________________________ 6 

4. Fossil vertebrate locality map, Placerville area________________________________________________________ 9 

5-6. Photographs: 

5. Platyhistrix rugosus, natural mould__________________________________________________________ 10 

6. Platyhistrix rugosus, latex cast______________________________________________________________ 11 

7-13. Drawings: 

7. Diadectes sanmiguelensis, n. sp., type skull____________________________________________________ 15 

8. Diadectes sanmiguelensis, n. sp., type lower jaw and lower left front leg ______________ -_-_--------- 16 

9. Limnoscelopslongifemur, n. gen., n. sp., elements of type and referred specimen____________________ 22 

10. Ophiacodon sp., vertebrae___________________________________________________________________ 27 

11. Cutleria wilmarthi, n. gen., n. sp., type_______________________________________________________ 28 

12. Cutleria wilmarthi, n. gen., n. sp., type skull and referred snout_ ______________________________ --_ 29 

13. Mycterosaurus smithae n. sp., type___________________________________________________________ 35 

14. Sketches of footprints of Limnopus vagus, Limnopus cutlerensis, and korynichniid cf. Brachydactylopus ____ -- _ 48 

TABLE 

TABLE 1. Fossil localities ________________________________________________________ -------------------------------

In 

Page 

C7 

CONTRIBUTIONS TO PALEONTOLOGY 

EARLY PERMIAN VERTEBRATES FROM THE CUTLER FORMATION OF THE 

PLACERVILLE AREA, COLORADO 

By GEORGE EDWARD LEWIS and PETER PAUL VAUGHN 1 

ABSTRACT 

Fossil vertebrates in the Cutler Formation of Colorado were 

first found in the Placerville area in the upper 885 feet of the 

1,100 feet of outcrops. Total thickness of the Cutler in this 

area is estimated at 4,000 feet. Two genera of labyrinthodont 

amphibians, four genera of cotylosaurian reptiles, and three 

genera of pelycosaurian reptiles-in all, nine distinct generawere found. 

In this assemblage only one animal, Platyhystrim rugosus, can 

be confidently assigned to an already known species.· The species 

of Eryops is probably close to, if not identical to, E. grandis. 

The species of Ophiacodon may be either 0. navajovicus or 0. 

mirus. A seymouriid represents an unknown genus and species. 

A captorhinomorph is indeterminate below suborder. Two new 

genera, a limnoscelid and a sphenacodontid, and two new species, 

one of Diadectes and one of Myctf:rrosaurus, are described and 

named. 

The age of this fauna is Early Permian, comparable to that of 

part of the Dunkard- Group and part of the Wichita Group 

(Moran, Putnam, and Admiral Formations) of the United States, 

and to that of the Autunian and lower Rotliegende of Europe. 

These American and European faunas lived in remarkably 

similar environments. Early Permian continental sedimentation in North America and Europe was only rarely and partially 

interrupted by marine transgressions that were of short duration. 

INTRODUCTION 

EARLY WORK ON THE CUTLER FORMATION 

Most of the Permian and Triassic rocks of the Four 

Corners and nearby areas are red sandstone, siltstone, 

and shale that were laid down in continental or shallowmarine environments. These rocks were known generally as the Red Beds for about 60 years after their 

first geologic description. Jules Marcou (1856, p. 140~ 

153, map) worked in the areas of outcrop of the later 

named Abo, Chinle, and Wingat~ Formations in 1853; 

he correlated them with the New Red Sandstone of 

Europe, and included them in his Gypsum Formation of 

Triassic to Jurassic age. W. H. Holmes ( 1877 a, p. 266, 

267; 1877b; 1878, p. 194) was the outstanding pioneer 

explorer who rna pped and studied the areas of outcrop 

of the later named Cutler and Dolores Formations of 

1 University of California, Los Angeles. 

southwestern Colorado; he called them the "JuraTrias * * * Red Beds." This name was in vogue for 

some four more decades: for examples, Scott (1907, p. 

647) wrote of "The Permian and Triassic members of 

the Red Beds", and Tomlinson (1916, p. 245), of "Red 

Beds ti1ne" in his work on "The origin of the 'Red 

Beds'." 

Although correlative rocks in nearby States have 

yielded fossil vertebrates for many years, the Cutler 

Formation of Colorado had been thought to be unfossiliferous before the present study. 

PRESENT STUDY 

V. R. Wilmarth and R. C. Vickers of the U.S. Geological Survey (Wilmarth and Hawley, unpub. data) were 

the first, to our knowledge, to discover fossils in the 

Cutler Formation of Colorado. They collected a few 

weathered-out fragments from two localities. After 

study showed that the fragments had bony structure, G. 

E. Lewis went to the localities with Wilmarth and collected two partial skeletons in 1952. Further search 

at that time yielded more specimens of fossil vertebrates 

and plants. Still more fossil vertebrates were found 

in 1953, when A. S. Romer, S. J. Olsen, and A. D. Lewis 

of the Museum of Compartive Zoology at Harvard College joined G. E. Lewis of the U.S. Geological Survey 

for several weeks of collecting. Preparation of the collections was begun at Harvard, where G. E. Lewis and 

A. S. Romer made preliminary determinations of the 

vertebrate fauna insofar as was possible at that stage of 

preparation. Their preliminary report, cited in Bush 

and others (1959, p. 313), was necessarily inconclusive. 

A. S. Romer turned over his share of this joint study 

to P. P. Vaughn in 1958, when the latter completed 

preparation of the specimens and joined G. E. Lewis in 

the preparation of the present report. Although no 

other work has been done on the paleontology of the 

Cutler Formation of Colorado, Bush and others (1959; 

Cl 
-

C2 CONTRIBUTIONS TO PALEONTOLOGY 

1960) have published the first two of five planned reports on the areal geology of the Placerville and four 

adjoining 71h-minute quadrangles which they have 

mapped geologically; the published scale of these quadrangles is 1 : 24,000. 

ACKNOWLEDGMENTS 

We gratefully acknowledge the kind help of all who 

contributed materially to this study: V. R. Wilmarth 

and R. C. Vickers not only made original discoveries 

and helped in the preliminary fieldwork but also gave 

advice on the geology of the Placerville area. Wilmarth 

and C. C. Hawley helpfully put unpublished information at our disposal; we have drawn on it for our paragraphs on the geology of the area. A. S. Romer, who 

was active in the early stages of this project, graciously 

gave us the results of his study and arranged for much 

of the technical preparation of the fossil vertebrates; 

his preparators, S. J. Olsen and A. D. Lewis, lent their 

considerable talents to both the field and laboratory 

work. The late Mrs. Stockton Smith and Mr. and Mrs. 

F. E. Lambert of Placerville all helped to make our 

stay in the area pleasant and successful. Figures 1 

through 4 were drawn by Mrs. Mary Wagner, and the 

photographs of Platyhystriw rugosus were made by Mr. 

E. P. Krier. All other illustrations of the Cutler fauna 

were drawn by Mrs. H. N. ICavanau of the University 

of California, Los Angeles. 

P. P. Vaughn's participation in this study was supported in part by National Science Foundation grants 

G-12456 and GB-1014. 

GEOGRAPHY 

LOCATION AND EXTENT OF AREA 

This report describes the Placerville area where the 

Cutler Formation crops out in a band from l!J.o to % 

mile wide on both sides of the San Miguel River for 4 

miles upstream and 4 miles downstream from the town 

of Placerville. The town, in San Miguel County, Colo., 

is at the mouth of Leopard Creek, where Colorado State 

Highways 62 and 145 meet 3 miles west-northwest of 

the intersection of 38 ° N. lat and 108 o W. long (fig. 1). 

No common carrier serves the town, formerly a station 

on the abandoned Rio Grande Southern narrowgage 

railroad. 

SURFACE FEATURES AND AREAS OF OUTCROP 

Most of the country around Placerville is a high 

plateau having a rolling surface from 9,000 to 9,500 feet 

in altitude. The sheer and craggy peaks of the San 

Miguel and San Juan Mountains jut high above the 

plateau's surface; streams that have their sources in 

these mountains have cut canyons a thousand or more 

feet deep into the plateau. Less than 20 miles from 

the Placerville area, where the channel of the San 

Miguel River has cut down to about 7,000 feet above 

mean sea level, there are 4 peaks whose altitudes exceed 

14,000 feet, and more than 50 peaks whose altitudes 

exceed 13,000 feet. 

At the upstream and downstream limits of the area 

described in this report, the contact between the base 

of the bright-red Dolores Formation and the top of 

the dark-red Cutler Formation is at river level. Between these limits, the Dolores generally ranges in thickness from 465 to 575 feet; as much as 1,100 feet of the 

upper part of the Cutler is exposed in outcrops as much 

as three-quarters of a mile wide on both sides of the 

river. As much as 1,300 feet of brilliant red cliffs of 

Permian and Triassic rocks makes up the lower slopes 

of the abrupt, almost inaccessible, spectacular canyons 

of the San Miguel and its tributaries; as much as 1,000 

feet of Jurassic and Cretaceous rocks makes up the 

equally steep upper slopes. The difficulty of access no 

doubt explains the many years that passed before the 

discovery of the first fossil vertebrates in the Cutler, and 

the fossil "palmlike" forest of Sannuiguelia lewisi 

(Brown, 1956), the oldest known angiospermous flowering plant, in the Dolores. It is entirely probable that 

further systematic exploration of these cliffs from year 

to year would yield a rich harvest of new faunal and 

floral elements. 

GEOLOGY 

STRATIGRAPHY AND STRUCTURE OF THE PLACERVILLE AREA 

Nearly flat-lying Paleozoic and Mesozoic rocks crop 

out in the canyon walls of the Placerville area. Figure 

2 shows all the formations in stratigraphic order, together with a diagrammatic section made near the old 

Fall Creek Post Office, 21,4 miles upstream from Placerville. V. R. Wilmarth (Wilmarth and Hawley, unpub. data), A. L. Bush (Bush and others, 1959, 1960), 

and their parties found these formations to be complexly 

faulted by three systems of steeply dipping faults that 

trend northwest, north, and northeast. They describe 

Tertiary ( ? ) clastic and basalt porphyry dikes that 

intrude fractures parallel to the northwest-trending 

fault system. The river has recut its present-day 

channel in an old fill of Quaternary sands and gravels, 

remnants of which are plastered against the lower walls 

of the canyon. It is in these remnants that the placers 

that gave the town its name were mined. 
PERMIAN VERTEBRATES, CUTLER FORMATION, PLACERVILLE AREA, COLORADO 03 

108° 106° 104° 

Cache La ...o "~~ OG< ~I 

o;..~ ~rv ~~ f(v 

sou1~ 

Ri~er 

·~<or~ ................ 

~.r/"' J /' "•J- •' 

0 L 0 R A D 0 

0 50 100 150 200 MILES 

FIGURE !.-Locations of Placerville and Ouray. 

CUTLER FORMATION OF COLORADO 

The oldest rocks that crop out in the Placerville area 

are those of the Cutler· Formation into which the San 

Miguel River has cut its canyon. The base of tlie formation is not exposed in this area, where the thickness 

of outcrop ranges from about 250 to 1,100 feet downward from the top of the formation to the lowest exposures. The Upper Triassic Dolores Formation disconforinably overlies the Cutler here, but the disconformity is not apparent at close range. Figure 3 is a 

profile made across the San ~Iiguel Canyon, half a mile 

upstream from Placerville, where the greatest thickness 

of the Cutler For1nation in the report area is exposed. 

Whitman Cross and his associates nam_ed and gave 

us our first specific knowledge of the Cutler Formation. 

Cross (1899, p. 2-3) originally included these rocks as 

part of the Triassic Dolores Formation exposed in the 

Dolores River of the Rico area, hut he suspected tha.t 

the more somber, see1ningly unfossiliferous lower part 

of the formation might be a separate rock unit: 

"Whether or not all the beds now associated with the 

fossiliferous series in the Dolores Formation are really 

of Triassic age remains to be determined by further 

discoveries" (p. 2). "As known between the Animas and 

San Miguel Valleys, the Dolores Formation may be 

roughly divided into a lower, coarser-grained part* * * 

and an upper, finer-grained portion * * * often fossiliferous'' (p. 3). 

Later, Cross and Howe (1905, p. 5) found an angular 

unconformity between these upper and lower parts in 

the valley of Cutler Creek, a tributary of the Uncompahgre River only 20 miles east of Placerville. They 

redefined the Dolores Forma,tion to include only the 

upper part and proposed the name Cutler Formation 
C4 

w _J loz Q w 

::> W> --0 

1- >W 1-::r:-

O_J <I: a_ I1- CD C::<(-

_J <1:<( 1-o::(f) 

<1: w U>(.!)~ (f) 

9400' (f) 

:::> 

0:: 0 

w w 

a.. u a.. ~ 

::J Iw 

9200' 0:: 

u 

9000' 

u 

(f) 8800' (f) 

~ 

0:: 

:::> 

...., 

0:: 

w 

a.. 

a.. 

::J 8600' 

8400' 

8200' 

u 

(f) 

(f) 

<( 

0:: 

8000' I0:: 

lLJ 

a.. 

a.. 

::J 

7800' 

z 

7600' 0::~ 

w-

~~ 

00:: _Jw a.. 

;z 

~ 

1-

<t 

:E 

0:: 

0 

ULLI 

:z 

0 

1-

en 

c 

:z 

<t 

en 

<t 

1-

e 

<t 

c 

z 

~ 

1-

<t 

:::E 

a: 

~ 

:z 

0 

en 

a: 

a: 

0 

::::E 

ENTRADA 

ss. 

:z 

0 

i= 

<t 

:::E 

a: 

0 

LL 

en 

LLI 

a: 

0 

....1 

0 

c 

:z 

~ 

1-

<t 

:::E 

a: 

~ 

a: 

LLI 

....1 

1-

=> 

u 

CONTR<IBUTIONS TO PALEONTOLOGY 

A A' 

San Miguel Canyon 

...... 

Ill 

1:::: 

1:::: 

~ 

-1:::: E 1.,) ::I 

..... ·;;:: Ill ::I ::.,_ Q:o 

. ~ :. . . . . ·. -

2-~·:·_ .. s--~--~<-: 

--- ~ .-:~~---: -.. --~---- ~ ----s .. -~---~ .. _-__ ._. _ _._:_---·:_:_-

From 160 to 200ft thick; light-brown, well-cemented sandstones interbedded with dark shales. 

EROSIONAL 

UNCONFORMITY 

From 675 to 750ft thick; upper 350 to 400ft, Brushy Basin Shale Member, made up chiefly of varicolored shales and siltstones; lower 300 to 

350 ft,Salt Wash Sandstone Member, made up of massive sandstones 

as much as 50 ft thick interbedded with shales and siltstones. 

From 75 to 110ft thick; upper 40 to 65ft, marl member, made up of varicolored limy shales and thin sandstones; overlies Bilk Creek Sandstone 

Member of 15 to 30ft of shaly sandstone. Pony Express Limestone 

Member of 0 to 9 ft of black, thin-bedded limestone at base. 

From 40 to 70ft of massive, crossbedded light-tan, fine- to medium-grained 

sandstone. 

UNCONFORMITY 

From 465 to 575ft thick; upper 15 to 75ft made up of massive, finegrained, bright-red and reddish-tan sandstone that overlies from 400 to 

460ft of interbedded fine-grained, bright-red sandstone, siltstone, shale, 

and limestone conglomerate; from 10 to 40ft of massive white conglomeratic sandstone at base. (Diagrammatic section adjusted to disregard 

minor faults that cut the Dolores here.) 

UNCONFORMITY 

Not more than the uppermost 1,100 ft of formation exposed; made up of 

interbedded clastic sedimentary rock having a textural range from shale 

to coarse conglomerate, chiefly dark red, but contains lesser amounts 

of gray to greenish gray. 

FIGURE 2.-Geologic formations of the Placerville area, and diagrammatic section A-A' near old Fall Creek Post Office. 

See figure 4 for location of section. 
PERMIAN VERTEBRATES, CUTLER FORMATION, PLACERVILLE AREA, COLORADO C5 

for the lmver part of the Dolores as originally defined. 

They provisionally referred the Cutler to the Permian, 

but stated that it might belong, ·wholly or in part, to the 

Pennsylvanian, and added that no fossils had been found 

in the Cutler, which, according to Luedke and Burbank 

( 1962), is about 2,000 feet thiek in the type area. 

The Cutler Formation thiekens northwest and west 

of the type locality, and reaches a thiekness of 4,000 feet 

in the Plaeerville area (Bush, Marsh, and Taylor, 1960, 

p. 431). The thickest seetion we measured here was 

about 1,100 feet thiek in the virtually flat-lying outcrops 

in the Slj2 sec. 2, T. 43 N., R. 11 W., above the contact 

with Quaternary alluvimn at 7,350 feet altitude above 

datum as shown in figure 3. Thus, only about the upper 

fourth of the Cutler Formation crops out in the Placerville area, and all the vertebrate fossils described in this 

report found from 80 to 885 feet below the top of the 

Cutler eome from the upper four-fifths of the outcrops. 

(See table of fossil localities.) 

In the Placerville area, the Cutler Formation is made 

up of interbedded, inter lensing conglomerate, sandstone, 

siltstone, and shale. The coarse components of the conglomerate, as large as small boulders but usually not 

larger than cobbles, consist of well-rounded granite, 

quartz, greenstone, metasedimentary rocks, and a few 

limestone fragments. The matrix is fine- to coarsegrained limy arkosic sandstone. Fine- to coarse-grained 

arkosic sandstone, in beds as much as 30 feet thick, add 

up to a greater aggregate thiekness than do the beds of 

conglomerate, which make up about one-third 9f the 

total thickness of outcrop. There are some beds of 

quartz arenite. The coarse elastic rock outcrops are 

generally a dark red to maroon, but they are gray to 

greenish gray in some places. Bleaching has resulted 

in irregular gray, green, or white blotches. Crossbedding is common. Torrential deposition took place, as 

shown by lateral gradation, interlensing, and interbedding between sandstone and conglomerate. No individual beds of conglomerate can be traced laterally for 

more than a few hundred feet. Finer grained micaceous 

sandstone, siltstone, and shale that weather to hematite 

red commonly contain bleached zones from 1 to 75 mm 

in diameter; these zones seemingly have organic centers. 

These finer elastics yielded almost all the fossil vertebrates; they contain many mud cracks and raindrop and 

other impressions including footprints. (See section by 

Baird, p. C47-C50.) 

CUTLER FORMATION OF NEARBY STATES 

The Cutler Formation, as now defined by the U.S. 

Geological Survey, reaches southward for some 65 miles 

beyond the Colorado-New Mexico boundary to lat 36° 

N., south of which the Abo Formation and the lower 

part of the Yeso Formation replace the Cutler by intertonguing. Lee (1909,p.12) named the Abo and Yeso 

Formations from localities more than 100 miles south 

of the 36th parallel; he believed them to be part of the 

Pennsylvanian Series. 

The Cutler Formation has not been subdivided in 

Colorado and New Mexico, but has been divided in 

nearby southeastern Utah and northeastern Arizona, 

where, from oldest to youngest, five such units are recognized : The Halgaito tongue, the Cedar Mesa Sandstone 

Member, the Organ Rock Tongue (all three, and the 

Hoskinnini Member, of Baker and Reeside, 1929, p. 

1421-1422), the De Chelly Sandstone Member (of 

Gregory, 1917, p. 31), and the Hoskinnini Member. 

VERTEBRATE FAUNA 

The fossil vertebrates from the Cutler Formation of 

the Placerville area inelude several specimens of new, 

interesting, and important forms, but the basic aspect 

of the collection is that of an assemblage from beds of 

Early Permian age in a new geographic area. Figure 4 

is a map that shows 14 numbered localities where vertebrate fossils were found; one of these loeality numbers 

is listed for each specimen described below. Table 1 

gives additional data on fossil localities. The following systematic faunal list ineludes only the animals that 

are determinable at least to suborder, but the collection 

also ineludes indeterminate fragments of which some 

may represent additional genera and species. 

Class Amphibia 

Subclass Apsidospondyli 

Superorder Labyrinthodontia 

Order Temnospondyli 

Suborder Rhachitomi 

Family Eryopsidae 

Eryops cf. E. grandfs 

Family Dissorophidae? 

Platyhystrim rugosus 

Class Reptilia 

Subclass Anapsida 

Order Cotylosauria 

Suborder Seymouriamorpha 

Family Seymouriidae 

New, but unnamed, genus and species 

Suborder Diadectomorpha 

Family Diadectidae 

New species of Diadectes 

Suborder Captorhinomorpha 

Family Limnoscelidae 

New genus and species 

Family Captorhinidae? 

Genus and species indeterminate 
C6 

ALTITUDE 8 

ABOVE 

SEA 

LEVEL 

9200' 

9000' 

8800' 

8600' 

8200' 

SW 

...... 

lb 

c:: 

c:: 

tJ 

~ 

~ E 

::J 

1... 

lb > ::... 2 Q: 0 ...... 

Q) 

::, ~ c tJ\ 

..... E ~ ~ c:: c tJ ::J 

Ct) 0 

10 

::r 

>-

c 

3 

.&:. 

C" 

:c 

0 

'C 

c 

~ 

0 

(.) 

CONTR,IBUTIONS TO PALEONTOLOGY 

0 

0 

1'-

-::J 

0 

.0 

c 

C" 

c 

a. 

a. 

'C 

Bases of Quaternary alluvium and Cutler Formation not exposed 

a' 

NE u 

::r 

a..z 

<to 

o::-

(!)1-

1-f/l 

<tO 

a:: a.. 1-

{/) 

(/) 

=> 

0 o::w 

wu 

0....<( 

0...1---

=>w 0::: 

u 

u 

(/) 

(/) 

<( 

0::: 

=> 

-:> 

0::: 

w 

a_ 

a_ 

=> 

u 

(/) 

(/) 

<( 

0::: 

1--

0::: 

w 

a.. 

a.. 

=> 

2 o::<( 

W:a:; 

3:0::: :3w a.. 

72oo~·r-----------,-----------~-------------------------.--------------------~--,r----_, 0 11;2 MILES 

FIGURE 3.-Pro.file and section B-B' near greatest exposed thickness of Cutler Formation in Placerville area. See .figure 4 

for location of section. 
PERMIAN VERTEBRATES, CUTL.ER FORMATION, PLACERVILLE AREA, COLORADO C7 

Class Reptilia-Continued 

Subclass Synapsida 

Order Pelycosauria 

Suborder Ophiacodontia 

Family Ophiacodontidae 

Ophiacodon sp. 

Suborder Sphenacodontia 

Family Sphenacodontidae 

Subfamily Haptodontinae 

New genus and species 

Suborder Edaphosauria 

Family Nitosauridae 

New species of Mycterosaurus 

SYSTEMATIC DESCRIPTIONS 

The following abbreviations are,used in this section 

of the text to refer to collections of vertebrate fossils: 

AMNH, American Museum of Natural History; 

CNHM, Chicago Natural History Museum; MCZ, 

Museum of Comparative Zoology at Harvard College; 

UMMP, University of Michigan Museum of Paleontology; and USNM, United States National Museum. 

TABLE 1.-Fossil localities 

[All localities are on north wall of San Miguel Canyon. Localities 15 (about ~ mile south by east of Placerville) and 16 (about% milt> south of Placerville) correspond to those of MCZ field Nos. 12 and 11 respectively; both 15 and 16 are imprecisely located and are on the south wall of San Miguel Canyon] 

Locality 

(fig. 4) Permanent 

catalog No. 

!__ ____________ MCZ 2977---------

2-------------- MCZ 2978 ________ _ 3-------------- USNM 22099 _____ _ 

4-------------- MCZ 2979_ -------- 5______________ USNM 22098 _____ _ 6______________ MCZ 2980_ -------- 7 ______________ MCZ 298L _______ _ 

8-------------- MCZ 2982 ________ _ 9-------------- MCZ 2983 ________ _ 10 ______________ MCZ 2984 ________ _ 1L ____________ MCZ 2985 ________ _ 12__ ____________ MCZ 2986 ________ _ 

13______________ MCZ 2987, 

MCZ 2988. 14-------------- MCZ 2989 ________ _ 

Field No. 

GELH-53-13 _____ _ GELH-53-14 _____ _ G ELW-52-2 ______ _ G ELH-53-5 ______ _ G ELW-52-L ____ _ G ELW-52~3 ______ _ GELH-53.--17 _____ _ GELH-53-15 _____ _ G ELH -53-16 _____ _ G ELH-53-L ____ _ GELH-53-7 ______ _ G ELH-53-6 ______ _ GELH-53-8 ______ _ 

GELH-53-lQ _____ _ 

Distance True bearing· 

below top distance, in of Cutler miles, from Formation Placerville 

(feet) 

45G-470 

25o-260 

8o-90 

8o-90 

86Q-880 

865-885 

550-570 

600-1}20 

50G-520 

500-520 

1Go-200 

10Q-200 

1Go-200 

55o-575 

290°; 4.13 291°; 3. 63 072°; 0. 45 072°; 0. 48 136°; 0. 88 138°; 0. 90 

125°; 1. 20 127°; 1. 19 

129°; 1. 30 12SI0

; 1. 38 135°; 1. 80 134°; 1. 80 135°; 1. 82 

125°; 2. 68 

These abbreviations are used in figures 7, 8, 12, 

and 13: 

ACET, acetabulum 

ANG, angular 

AR, articular 

C, centrale, coronoid 

D, dentary 

DOl, distal carpal 1 

F, frontal 

FCHT, foramen for 

chorda tympani 

FOBT, obturator foramen 

FSGL, supraglenoid 

foramen 

GLEN, glenoid cavity 

I, intermedium 

IT, intertemporal 

J, jugal 

L, lacrimal 

LLJ, left lower jaw 

MX, maxilla 

N, nasal 

P, parietal, pisiform 

PF, postfrontal 

PM, premaxilla 

PO, postorbital 

PP, postparietal 

PRA, prearticular 

PRF, prefrontal 

QJ, quadratojugal 

R, radius 

RL, radiale 

SANG, surangular 

SM, septomaxilla 

SP, splenial 

SQ, squamosal 

ST, supratemporal 

T, tabular 

TM, tympanic 

"membrane" 

To, unerupted tooth 

U, ulna 

X, indeterminate element 

Class AMPHIBIA 

Subclass APSIDOSPONDYLI 

Superorder LABYRINTHODONTIA 

Order TEMNOSPONDYLI 

Suborder RliACliiTOMI 

Family ERYOPSIDAE 

Eryops cf. E. grandis (Marsh, 1878) 

Specimen MCZ 2980 (from loc. 6), which consists of 

a partial skull and mandible, a series of several vertebrae, and fragments of a pectoral girdle, is tentatively 

referred to Eryops grandis (Marsh, 1878). 

The cranial skeleton is well-enough preserved to 

show, roughly, the proportions characteristic of Eryops. 

Most of the roof and palate are missing, and what is 

left is poorly preserved. It is possible to measure, approximately, the longitudinal distance from the tip of 

the snout to the angle of the lower jaw: about 255 mm. 

This is very close to what the corresponding distance 

must have been in a specimen of E. grandis, from the 

Cutler Formation of northern New Mexico, of which 

Langston (1953, fig. 11) has figured the lower jaw. 

Few details can be made out on the skull, but it is 

interesting that a part of the shagreen of denticles on 

the coronoid bones of the lower jaw can be seen. 

The series of several vertebrae is fairly well preserved; these vertebrae are of the construction characteristic of Eryops. The height of the neural spine 

above the zygapophyses is about 52 mm, perhaps morethe best preserved spine is not complete. Langston 

(1953, fig. 11e) has figured a neural spine having a 

height of 44 mm above the zygapophyses, but this spine 

is from a different specimen than the lower jaw figured 

by him. There are no diagnostic features in the fragments of the pectoral girdle from locality 6. 

There is very little basis for determination of species 

of Eryop8. Eryops specimens from Texas are generally included in the genotypic species E. 111tegacephalU8 Cope, and the New Mexican forms are 

somewhat arbitrarily included in E. grandis. It is possible that several species will eventually be distinguished in both these areas (Langston, 1953, p. 380; 

Romer, 1947, p. 131), but at present no good diagnostic 

character is known to separate the Texan and New 

Mexican forms, and Romer ( 1952, p. 63-64) assigns 

even the forms from the Dunkard of eastern North 

America to E. megacephalus. The New Mexican animals tend to be smaller than the typical Texas specimens of E. megacephalus (Langston, 1953, p. 377-379). 

This difference, of course, may be due to the equivalence 

in age of the New Mexican Cutler to the lower part of 

the Lower Permian Wichita of north-central Texas: 

in Texas, the specimens of E. megacephalus low in the 

Wichita Group are smaller than those higher in the 
C8 CONTRIBUTIONS TO PALEONTOLOGY 

group. (See Romer, 1952, p. 62). For the present, it 

is perhaps best to refer tentatively the specimen from 

Placerville to E. grandis, because of the nearness of its 

geographic occurrence to that of typical E. grandis of 

New Mexico and because of its morphological similarity 

to the specimen figured by Langston (1953). 

Order TEMNOSPONDYLL 

Suborder RHACHITOMI 

Family DISSOROPHIDAE 1 

Platyhystrix rugosus (Case, 1910) 

Figures 5 and 6 

The important specimen MCZ 2982 (from loc. 8) is 

referred to the long-spined rhachitomous amphibian 

Platy hyst-rix rugos,us (Case, 1910), known heretofore 

only from the Cutler ("Abo") Formation of northern 

New Mexico. When better specimens are known, perhaps the Coloradan and New Mexican animals will 

prove to be specifically distinct, but the materials on 

-hand offer no basis for separation. 

The complicated taxonomic history of Platy hystr'ix 

rugosus has been summarized by Langston ( 1953, p. 

403-404) : 

Long flat sculptured neural spines of the Platyhystrim type 

seem to have been recorded first by Cope ( 1881) , who included 

them together with vertebrae of another form in the type of 

Zatrachys apicalis. Case (1910) separated Cope's material, 

designating part as type of A .. spi-dosaurus apicalis (Cope); the 

elongate spines were referred to the pelycosaur Ctenosaurus 

Huene and served as type of Case's C. rugosus. Williston (1911 

a, b) -recognized their generic distinctness from Ctenosaurus 

-and proposed the name Platyhystri-m to receive the long ornamented spines. Like Case he at first regarded them as pelycosaurian in nature, but in 1916 he correctly recognized the 

amphibian affinities of the material. His basis for this conclusion was, however, erroneous, since he mistook a skull of 

Zatrachys found associated with characteristic Platyhystrim 

neural spines in New Mexico for that of the latter. As a result, 

statements that Zatt·achys and Platyhystrim are closely related 

are common in subsequent literature. Several vertebrae associated with Zatmchys skulls in the Welles quarry [in northern New Mexico] are of the usual rather low-spined normal 

rhachitomous construction, and there is no suggestion of scul~ 

ture or ornamented apices. 

Morphologically, the specimen in every way resembles comparable material of Platyhystrix ru-gosus. 

Comparisons have been made with a number of specimens of P. ru-gosus: UMMP 9770, a neural spine; 

UMMP 9771, a proximal part of a rib; and CNHM 

UC 742, parts of neural spines and ribs mixed with 

skull fragments referable to Zatrachys. The figures 

and description published by Langston (1953) have 

been especially useful. 

The new material consists mostly of the impressions, 

and some few bony remnants, of a series of 10 neural 

spines, on slab and counterslab. Most of these spines 

are incomplete proximally, but the seventh and eighth 

have connected to them impressions of the neural 

arches and zygapophyses. When the slab and counterslab were parted, many bony fragments of the spines 

were found, but the bone was badly leached away and 

the tubercular ornamentation had been lost from the 

spines; fairly good pieces of bone are included with the 

impressions of the seventh and eighth spines, but the 

tubercles are not complete even on these. The size and 

pattern of the tubercles can readily be made out in the 

impressions (fig. 5) and on a latex cast (fig. 6) taken 

from them. Also included are an impression of the 

proximal part of a rib and fragments of other bones, 

but these bones too are very poorly preserved. 

The neural spines are undoubtedly from the dorsal 

region. They and the pattern of their tubercles are like 

those described and figured by Langsto'_J. ( 1953) and 

Williston (1911b), and the complete description need 

not be repeated here. The neural arch, as noted by 

Langston ( 1953, p. 402), is of rhachitomous structure. 

There is no sign of transverse barbs of the kind figured 

by Langston ( 1953, fig. 21b, a}, on a presumed middorsal spine, just above the junction between the smooth 

proximal part of the spine and the much longer tubercular part. The only spines in MCZ 2982 that have 

preserved proximal parts seem to be from a region posterior to the middorsal region. A presumed anterior 

dorsal spine figured by Langston (fig. 21a) has no 

transve:r:se barbs. 

The preservation of two attached impressions of 

neural arches allows anteroposterior orientation, and 

we now see, in this first known series of spines of 

P. rugosus, that Langston's hypothetical assignation of 

specific spines to specific vertebral regions is correct. 

T() quote Langston ( 1953, p. 402) : "Presumed anterior 

dorsal spines arched gently forward, expand gradually 

upward toward broad platelike summit, which is 

sharply truncated with upper edge slanting strongly 

downward anteriorly. Presumed middorsal spines 

longer, straighter, more nearly parallel-sided, with 

summits more or less expanded anteroposteriorly and 

rounded above from front to back * * * Presumed 

anterior caudal spines acutely bent backward distally 

* * * very broad and platelike distally, narrower below." We would narrow Langston's diagnosis only to 

this extent: the "presumed anterior caudal spines" seem 

really to be spines from the region immediately anterior 

to the sacrum; Langston himself ( 1953, fig. 21d) labels 

one of his specimens as a "posterior dorsal or anterior 

caudal * * * spine" (italics ours). The first spine of 

the series, as may be seen in the photograph, is displaced from its original position with respect to the 

others. The fourth of the series is the tallest and 

straightest; the tenth spine of the series is a recurved 

spine of the kind thought by Langston to be a possible 

anterior caudal spine. 
~ 

~ 

r 

r 

108°07'30" --~ 

38'02'30" O 'AA ~ 

38'00' 

' \ 

· .. " 

·, 

., 

\ 

"' 'h 

\ 

( 

\ .. -·,. 

s p f: 

(J 

"· 0 

\,. 

'· ' " \ 

A1 f: s 4 

6 "J 

/ .r-0 / ~ I 

37'58'30" L__L_.L.! _____ L_ ______ _, _____ _,_ _______________________ ~<..__l_"------''---__L_'---'--'--.IL----'---L-...L_L_ ________ L__~ Ml 

Base irom U.S. Geological Survey Placerville 

and Little Cone topographic ma ps 

N 1 Y2 0 1 MILE 

1000 0 1000 2000 3000 4000 5000 6000 7000 FEET 

CONTOUR INTERVAL 400 FEET 

DATUM IS MEAN SEA LEVEL 

FIGURE 4.-Fossil vertebrate localities in Placerville area and positions of sections A.-A' and B-B'. 

'"0 

t"l 

::0 

~ 

~ 

< t"l 

::0 

~ 

t"l 

b:j 

::0 

> 

~ 

t"l 

00 

2 

~ 

t" 

t"l 

::0 

"1 

0 

::0 

...... 

~ 0 

~z 

'"0 

t" 

> ('") 

t"l 

::0 

< 

...... 

t" 

t" 

t"l 

> ::0 

t"l 

? 

('") 

0 

t" 

0 

::0 

> 

t:l 

0 

C1 

~ 
ClO CONTRIBUTIONS TO PALEONTOLOGY 

FIGURE 5.-A natural mould of a series of neural spines of the rhachitomous amphibian Phatyhystrix rugosus. The anterior 

end lies to the left. Fragments of bone are visible in l)laces. 

The dimensions of the eighth spine in the series are: 

height of spine from top of prezygapophysis, 222 mm; 

anteroposterior length at summit, about 40 mm ( estimated; the distalmost part is not complete) ; anteroposterior diameter at base, about 12 mm. These dimensions are very close to those of an anterior dorsal spine 

measured by Langston (1953, table 5), for which the 

respective figures are 217 mm, 43 mm, and 11 mm. The 

first spine in the series has an anteroposterior length at 

the summit of about 37.5 mm, the fourth, and largest, 

52.5 mm. These figures may be compared with the 

range of 24 mm to 55 mm for this measurement in the 

specimens studied by Langston (table 5) . Clearly, the 

animal from Placerville is of about the same size as the 

New Mexican animal. 

A latex cast taken from the impression of a proximal 

part of a rib shows that this rib was similar to a tuberculated rib figured by Langston (1953, fig. 22b). The 

fragments of bone other than spines are poorly preserved and, most unfortunately, give no indication of 

the structure of the skull in Platyhystrix rugosus. 

Langston (1953, p. 405) has said that Platyhystrix 

probably represents an unnamed family related to the 

eryopsoids. w· e suggest that either such an unnamed 

family within the Eryopsoidea would be closely related 

to the family Dissorophidae, or that Platyhystrix may 

even be a dissorophid. The earliest dissorophid amphibians are recorded from rocks of late Des Moines 

age ( = htte \Vestphalian) at Mazon Creek, Ill., (Gregory, 1950) in the form of Amphiba,mus (Miobatrachus); 

this early genus was unarmored. In the Early Permian 

there was a variety of armored dissorophids: Alegeinosaurus, Aspidosaurus, Broiliellus, Oacops, Dissorophus, 

and possibly others. 

The evolution of dermal armor in the dissorophids 

seems to have followed at least two diverging paths. 

By using known forms, two morphological, although not 

chronological, series can be constructed using Aspidosaurus as a central genus. Aspidosaurus chiton, from 

the Clear Fork Group of the Lower Permian of Texas, 

bears at the distal ends of its neural spines small roofshaped caps of sculptured bone (Case, 1911b, fig. 13); 
PERMIAN VERTEBRATES, CUTLER FORMATION, PLACERVILLE AREA, COLORADO Cll 

FIGURE 6.- A latex cast taken from MCZ 2982, the specimen of Platyhystrix ntgosus shown on figure 5. The anterior end 

lies to the right. The white areas represent casts of bone impressions in the specimen; the gray areas represent restoration. 

these caps are not separate from the neural spines, but 

the fact that they are separate in other members of the 

family would seem to indicate a dermal origin for the 

armor of 11. chiton. From such a stage may have been 

derived the condition seen in Dissorophus (also from the 

Clear Fork), where the armor plates, free from, but 

resting on, the distally widened neural spines, are 

greatly expanded tmmrd both sides to form, collectively, a broad dorsal cuirass. (See Case, 1911b, 

fig. 45.) 

The morphological series from Aspidosaurus chiton 

to Dissorophus is characterized by transverse expansion 

and freeing of the dermal armor. Cacops, in which the 

armor plates are free but not significantly expanded, 

would serve as a morphologically intermediate form in 

this series; Cacops occurs higher in the Clear Fork 

Group than the preceding genera. (See Olson, 1954.) 

If such a series does represent a truly related group of 

dissorophids, it \vould seem that Alegeinosaurus (Clear 

Fork) and Broiliellus (Wichita) also belong to this 

group, but that other species of Aspidosaurus were on a 

different evolutionary path: A. crucifer, from the "\Vichita Group of the Texas Lower Permian, shows a definite 

tendency toward dorsal ward elongation of the dermal 

armor. 

A neural spine of A. crucifer figured by Case (1911b, 

fig. 15C) is only slightly elongated, but another in the 

collections of the University of Texas (UT 40030-13) 

is so elongated that it resembles one of the shorter spines 

in Platyhystrim rugosus. There is a transverse barb 

just above the junction of the proximal, smooth part of 

the neural spine and the distal, sculptured part of the 
C12 CONTRIBUTIONS TO PALEONTOLOGY 

spine as in one of the spines of P. rugosus figured by 

Langston ( 1953, fig. 21b), and the anterior and posterior edges of the flattened part of the spine bear longitudinal ridges, probably for the insertion of interspinous 

ligament~. 

A difference from P. ruqosus lies in the pattern of 

the sculpture in A. cruoifer, where there are large pits, 

separated by anastomosing ridges, instead of the tubercular ornamentation seen in P. rugosus. However, on 

a part of a spine in the materials (CNHM UC 742) of 

P. rugosus, the sculpture on the proximal part of the 

dermal part of the spine comes as close to pitting as it 

does to tuberculation. Possibly, the greater elongation 

of the spine of A. crucifer in the University of Texas 

collections, as compared with the spine figured by Case, 

is due to a more anterior or posterior position in the vertebral. column. Spines of A. crucifer of this kind are 

probably the basis for Langston's statement ( 1953, p. 

405) that "somewhat differently sculptured spines from 

Texas mentioned by several authors under various 

names probably belong to other species of Platyhystrim." 

Whether or not A. crucifer really belongs in the genus 

Aspidosaurus, its close relationship to the other dissorophids seems fairly clear, and its resemblance to Platyhystrim rugosus would seem to indicate that Platyhystrim 

is at least related to the dissorophids. P. rugosus, then, 

may be an advanced member of a group of dissorophids-or derivatives of the dissorophids- in which 

the evolution of dermal armor proceeded in the direction of dorsalwa.rd elongation rather than lateralward 

expansion. 

It must be emphasized that the grouping of dissorophids used here is based strictly on the patterns of the 

dermal armor and has no demonstrated basis in relative 

ages of the members of the morphological series. In 

fact, there are at the U.S. National Museum fr-agments 

(USNM 21861) of the spines of a large Platyhystrimlike animal from the Pennsylvanian Conemaugh of 

Ohio. These fragments indicate spines much more robust than those in P. rugosus, and the ornamentation is 

more complicated; tubercles are alined in vertical rows 

proximally and anastomose in a vermiculate pattern 

distally. A gross longitudinal fluting is superimposed 

on the tuberculate ornamentation, so that two or more 

bilaterally symmetrical grooves, more obvious distally 

than pwximally, lie along either either side of the spine. 

The edges of the spines bear ridges for the insertion of 

interspinous ligaments. The Platyhystrim-like amphibians may prove to have been a fairly long-lived and 

varied group. 

The importance of the evident connection of Platyhystrim to the dissorophids lies in the evidence thus 

presented for the dermal origin of the ornamented part 

of the neural spine. The superficial resemblance of the 

neural spines of Platyhystrim to those of some of the 

long-spined pelycosaurian reptiles is rema-rkable, especiaJly when one considers such pelycosaurs as Edaphosaurus pogonias and Ctenospondylus casei, in which 

some of the spines are expanded anteroposteriorly and 

are flattened from side to side. To be sure, the transverse bars in Edaphosaurus are more numerous and are 

more extensively distributed along the spine. Convergence in elongation of spines would seem to indicate 

similar adaptations, and this is not unlikely : the dissorophid amphibians were apparently well adapted to 

a terrestrial existence and probably had little to do 

with the water (Romer, 1947, p. 159). Langston (1953, 

p. 405) has pointed out that, whatever the primary 

function of the elongated neural spines may have been, 

quite possibly they could have been turned, through 

preadaptation, to some other use, such as camouflage. 

In the same way, a fin originally developed in response 

to selection for protective function could have become 

preadapted to use in temperature regulation, which 

function Romer ( 1948) has suggest~d for the fin of the 

long-spined pelycosaurs. 

Whatever the function of tne fin, its appearance in 

both rhachitomous amphibians and pelycosaurian reptiles is an extraordinary example of convergence, and 

interesting in that the pelycosaurian spine was purely 

endochondral in origin whereas that of Platyhystrim 

combined endochondral and dermal elements. 

Class REPTILIA 

Subclass ANAPSIDA 

Order COTYLOSAURIA 

Suborder SEYMOURIAMORPHA 

Family SEYMOURIIDAE 

New (but unnamed) genus and species 

A single, fairly well preserved vertebra (MCZ 2983 

from loc. 9) lacking the intercentrum is so similar to 

the vertebrae in Seymouria baylorensis that the animal 

it represents surely belongs to the same family. 

The dimensions of the vertebra are: length of centrum, 8 mm; anterior width of centrum, 11.5 mm; distance between base of neural spine and posterior ventral 

edge of centrum, 24.5 mm; distance between most lateral 

points of postzygapophyses, 30.5 mm. By comparison 

with the vertebrae in Seymour'ia baylorensis figured by 

White ( 1939, figs. 12, 14), this vertebra seems quite definitely to be from the dorsal series. It is about ninetenths as large as those figured by White. 

The following description of MCZ 2983 would, with 

the exceptions noted, fit equally well a vertebra of 

Seymouria baylorensis. The centrum is abruptly constricted along a longitudinal line at the junction of its 

dorsal two-thirds and its ventral third. This constriction is not carried into the anterior and posterior rims, 

so that the ventral third of the centrum, viewed from 

below, has something of an hourglass shape. The ratio 
PERMIAN VERTEBRATES, CUTLER FORMATION, PLACERVILLE AREA, COLORADO C13 

of the distance between the most lateral points of the 

postzygapophyses to the width of the centrum is 2.65 : 1. 

The length of the neural arch measured along the midline is 8 mm, the same as the length of the centrum. 

Even on casual inspection, the neural arches in Seymouria baylorensis seem longer along the midline than 

are their respective centra; from White's illustrations 

( 1939, fig. 12), the ratio is about 1.5: 1 for vertebrae 

selected from several positions along the dorsal series. 

The articular surfaces of the zygapophyses in MCZ 

2983 are tilted at a small angle to the horizontal; although no tilt can be seen in White's illustrat~ons, it 

may occur in some specimens of Seym.ouria bayloren8i8. 

(See Romer, 1956, fig. 129A.) Only the base of the 

diapophysis is preserved, but this is sufficient to show 

that the diapophysis was expanded behind the prezygapophysis, and was connected, via a constricted area, 

with an anteroventral extension that passed to the anterior point of junction of the centrum and neural arch. 

This pattern marks this vertebra as an anterior dorsal. 

In the anterior dorsals of Seymouria b.ayloren8is, too 

(White, 1939, fig. 12), the diapophyses are extended 

anteroventrally, but not so far as in MCZ 2983, and 

there is no marked constriction in the diapophysis. 

On either side of the dorsal surface of the neural arch, 

a raised ridge, gently rounded medially but more prominent laterally, passes from a point above the anterior 

end of the neural arch backward and outward to the 

most lateral point of the postzygapophysis. The articular surfaces of the postzygapophyses are continuous 

medially with the ventrally and somewhat laterally facing surfaces of a broad wedge of the neural arch that 

terminates at the dorsal border of the neural canal; this 

wedge is present also in a vertebra of Seymouria baylorensis at hand but in which the apex of the wedge lies 

nearer to the plane of the articular surfaces of the zygapophyses than it does in MCZ 2983. The neural spine 

of MCZ 2983 is 4 mm wide at its base; it is incomplete 

dorsally but was at least 21h mm high. This spine is 

similar to that of the vertebra of Seymowria baylorensis 

at hand. 

The great similarity to the vertebrae in Seymouria 

baylorensis makes it seem quite certain that we are deali~g with a seymouriid, but there are also differences 

from Seymouria baylorensis, as noted. The differences 

in configuration of the diapophyses and of the wedge on 

the posterior aspect of the neural arch are, perhaps, not 

too important, but the greater ratio of the midline length 

of the neural arch to the length of the centrum in Seymouria baylorensis does seem significant. White (1939, 

p. 388) has suggested that the broad zygapophyses in 

Seymouria are "an adaptive feature rather than a primitive character. The breadth of the zygapophyses 

would permit the vertebral column to undulate laterally 

but would prevent any torsion. The absence of torsion 

in the column would compensate for the weak ilio-femoralis (gluteal) muscles which prevent the body from 

slumping on one side when that foot is lifted off of the 

ground * * * the nature of the vertebrae seems to be 

an adaptation to facilitate terrestrial progression rather 

than a primitive character." Gephyrostegus, a seymouriamorph from the European Upper Pennsylvanian, does not have greatly expanded neural arches 

(Romer, 1956, p. 480-481). 

It would seem that the neural arches became "swollen" 

/within the Seymouriamorpha, probably as a better 

adaptation to land life. Perhaps increase in midline 

length of the neural arch was part of the general phenomenon of "swelling." If so, the lesser length in MCZ 

2983, as compared with Seymouria baylorensis, may be 

a mark of relative primitiveness. This would be consonant with the difference in age that we infer: 

Although Seymouria occurs in the Belle Plains, Admiral, and Putnam Formations of the Wichita Group 

(Romer, 1947, p. 282), Seymouria baylorensis is known 

only from the Arroyo Formation at the base of the Clear 

Fork Group of the Lower Permian of north-central 

Texas. The seymouriid from the Cutler Formation at 

Placerville is associated with other fossils that are probably equivalent in age to the fauna from the lower part 

of the Wichita Group, which underlies the Clear Fork, 

but we have had no opportunity to compare it with the 

inadequately known Seymouria from the formations of 

the Wichita Group. 

It seems unwise to us to establish a new genus or 

species on the basis of this lone vertebra. The interest 

in this specimen lies in its indication of the existence of 

a more primitive seymouriid than Seymouria baylorensi~ in the Early Permian, and in its being the first record 

of any seymouriid from west of the north-central Texas 

area. 

Order COTYLOSAURIA 

Suborder DIADECTOMORPHA 

Family DIADECTIDAE 

Diadectes sanmiguelensis Lewis and Vaughn, n. sp. 

Figures 7 and 8 

We name D iadeetes sanmiguelensis and hereby designate MCZ 2989 from locality 14 as the holotype of a 

new species of Diadeetes Cope, 1878. The dia.gnostic 

characters of this new species are : the shallowness of 

the lower jaw, where the greatest depth, at the region 

of the coronoid elevation, is only one-third as great as 

the length of the jaw; the lowness of the flange of the 

dentary on the labial side of the cheek teeth, all of 

which are exposed to lateral view; and the simple pattern of the cheek teeth, each of which has only one prominent cusp. All these characters are described more 

fully below. The generic determination has been so 
C14 CONTRIBUTIONS TO PALEONTOLOGY 

made for a number of reasons: ( 1) the new species is 

obviously a diadectid ~ ( 2) it resembles the known species of Diadectes more closely than it doe.s any other 

knmvn reptiles; ( 3) the holotype is immature, and it 

would be difficult to say positively that its distinctive 

characters are not due to this im1naturity; and ( 4) the 

nmnenclatorial history of Dia.dectes is already sufficiently complicated. 

Romer ( 1956, p. 486) lists eight synonyms for D iadectes, and Desmatodon may be a ninth. Specimens 

referable "to Diadectes show great variation; as Olson 

(1947, p. 11) has summed it: "Most confusing, especially to one not thoroughly familiar with the genus 

[Diadectes], is the remarkable variation of characters 

that \vould seen1 at first glance to be of specific or even 

generic rank. On examination, however, it becomes 

apparent that there is no clear pattern of variation and 

that the variations at present offer little or no basis for 

taxonomic \vork." Case (1911a, p. 26) set up a new 

genus, Diadectoides, using as genoholotype an immature 

specimen that has since proved to be referable to Diadectes (Olson, 1947, p. 7). Considering the present 

lack of understanding of the variations within the genus 

Diadectes, \Ve believe that it would be ill advised to set 

up a new genus on the basis of an immature specimen when a strong case can be 1nade for referral to 

Diadecte8. 

It may be assumed that Diadectes sanm£guelensis is 

closely related to Dia.dectes lentus (Marsh), 1878, the 

only clear-cut species of Diadectes definitely known 

heretofore from the Cutler Formation of northern New 

Mexico--if, as Olson (1947, p. 9) believes, Diasparactus 

zenos Case, 1910, represents a distinct genus. Diadectes [A nim.a,sau'f"US] carinatus (Case and Williston), 

1912, is not clearly different from D. lentus. (See 

Olson, 1947, p. 9.) Olson gave the locality as "Las 

Animas," but Las Animas is in eastern Colorado, and 

it is unlikely that the specimen came from there. There 

are outcrops of upper Paleozoic rocks on both sides of 

the Animas River beginning about 2 miles northeast 

of Animas (Larsen and Cross, 1956, p. 48, pl. 1). 

Diadectes sanmiguelensis, notwithstanding that it is 

based on an immature specimen, is kept separate from 

D. lentus, because ( 1) we believe that, although a mature individual of D. sanmig'uelensis would probably 

have looked more like specimens of known species of 

Di.adectes than MCZ 2989 does, it would still not have 

fitted into the specific pattern of D. lentus and (2) a 

geographic separation in the occurrenees of D. sanmiguelensis and D. lentu.'S exists, at least as known at 

present. 

The type includes a eomplete skull with mandible; 

several cervical vertebrae; a few incomplete ribs; a partial peetoral girdle eonsisting of left and right cla vieles, 

the interclaviele, the left cleithrum, and the left scapulocoracoid; and the left humerus, epipodium, and 

manus. 

The best indication of the im1naturity of the speeimen 

is the nature of the earpus, where ossification is only 

ineipient, and there are rudimentary eenters for only 

the radiale, ?intermedium, ?ulnare, ?pisiform, a centrale, and the first distal carpal. Other indieations are 

the unfinished appearanee of both ends of the humerus 

and the separation of sea pula and eoraeoid. Less dependable eriteria are the smoothness of the bones of the 

skull roof and the faet that many of the sutures in the 

skull are open; in larger individuals referable to Diadectes, the skull is rugose, and the sutures are difficult 

to find. Though the preservation of the proximal part 

of the ulna is not good enough to permit a positive statement, the oleeranon seems not to have been ossified, and 

this lack too would indieate immaturity. The shallowness of the lower jaw, the lowness of the flange of the 

dentary labial to the eheek teeth, and the simple pattern 

of the teeth may also be attributable to immaturity, 

but this deduction is unsure. At first sight, the orbits 

of D. sanmiguelensis seem to be proportionately larger 

than is usual in Dia.dectes, but in faet they are of nearly 

the same size in relation to total skull length as the 

orbits are in a speeimen of D. lentus at hand. 

If the referral to D iadectes is eorrect, the small size 

of the speeimen would, of course, in itself seem to be 

sufficient evidence of immaturity, although early geological age may explain the speeimen's small sizethere seems to have been a fairly steady inerease in size 

of the species of Diadectes during the Early Permian 

(Romer, 1944, p. 142). 

The type skull of D. san1niguelensis is about 85 mn1 

long from the tip of the snout to the posterior edge of 

the ·postparietal bones. It has been distorted in sueh a 

way that the left eheek forms a right angle, and the 

right cheek an obtuse angle, with the table of the skull. 

The bones of the dermal roof are badly fraetured, so 

that it is diffieult in some places to distinguish sutures 

from cracks. The aeeompanying figure has been drawn 

to show not only the sutures but also the conspicuous 

cracks, including those that presented difficulty in 

interpretation. 

The type skull is about one-half as long as the skull 

in the composite restoration given by Olson (1947), 

whieh was based on specin1ens of both Diadectes sideropelicus from the vViehita Group and D. tenuitectus from 

the Clear Fork Group of Texas. It is about three-fifths 

as large as CNHM UC 675, a skull of D.lentttts described 

by Case and Williston (1912) from the Cutler ("Abo") 

Formation of northern New Mexico. The proportions 

of the dern1al roof of D. sanmig·uelensi8 are those figured 

for Diadectes generally. It may be noted that D. sanmdgu,elensis and D. lentttts resemble each other more 

closely than they do the species of Diadectes from Texas 
PERMIAN VERTE.BRATES, CUTLER. FORMATION, PLACERVILLE AREA, COLORADO 

FIGURE 7.-Skull of type specimen of Diadectes sanmiguelensis n. sp., MCZ 2989. A., Lateral view; B, 

dorsolateral view. Parts of several neural spines also are visible. Unshaded areas represent matrix. 

X 1.25. 

C15 
C16 CONTRIBUTIONS TO PALEONTOLOGY 

FIGURE 8.-Diadects sanmiguelensis n. sp. A, Latheral, and B, 

medial views of the right lower jaw of the type specimen, 

MCZ 2989; 0, dorsal view of the left radius, ulna, and manus 

of the type specimen. Unshaded areas represented matrix. 

X 0.88. 

in that both Cutler species have the orbit placed slightly 

farther posteriorly than in the Texan forms; this position may be taxonomically significant. 

Reference may be made here to the recent restorations 

of the skull of Diadectes (Olson, 1947, p. 12, 13; Watson, 1954, p. 382, 383; and Romer, 1956, p. 89) . There 

would be little value in a detailed description of the interorbital region, the region anterior to the orbit, the 

jugal region, or the quadratojugal region of D. sanmiguelensis, for in these regions the patterns of the sutures 

are like those described by Olson, Watson, and Romer, 

but it may be worthwhile to point out that although the 

pattern is not clear above the right orbit it is obvious on 

the left side that the frontal does not enter the orbital 

margin. As in other specimens referable to Diadectes, 

there is a large parietal foramen. 

The cheek and temporal regions deserve special attention because of the conflict of opinion on the presence of 

an intertemporal bone in Diadectes. Olson (1947) has 

drawn in an intertemporal and (1950) has discussed its 

variations in outline and in fusion with neighboring 

elements. Watson (1954) has drawn an extension of 

the parietal, a parietal lappet, in the position of Olson's 

intertemporal. Romer ( 1956, p. 86) has taken a neutral 

position pending further information. The question of 

the presence of an intertemporal in Diadectes is of considerable theoretical importance: Parrington (1958) 

bases his theory of the derivation of all the amniotes 

from a stock other than of the typical labyrinthodont 

amphibians partly on the assumption that the place of 

the intertemporal is taken by a parietal lappet inDiadectes as well as in all other primitive reptiles. We 

hoped that this immature specimen, MCZ 2989, with its 

open sutures, would throw light on this problem. Perhaps it does, but the evidence is inconclusive because of 

the imperfect preservation of the temporal region. The 

left temporal region is too badly cracked to be of use 

here; description will be based on the right side. 

The supratemporal of D. sanmiguelensis is a large 

bone, about 22 mm long, occupying the posterolateral 

corner of the roof of the skull. Its posterior five-sixths 

is raised as a boss above the level of the anterolateral 

one-sixth. The anterolateral part meets the dorsal extension of the squamosal in a short, straight, horizontal 

suture, about 8 mm long, that passes forward to touch 

the postorbital, and thereby barely excludes the parietal 

and the ~intertemporal (or ~parietal lappet) from contact with the squamosal. This short suture between 

supratemporal and squamosal resembles that in Romer's 

reconstruction but is unlike that drawn by either Olson 

or Watson, in which the dorsal extension of the squamosal has a much longer upper edge. The postorbital 

is a large element whose upper edge is longer than that 

of the squamosal-again a feature in agreement with 

Romer's reconstruction; anterior to the postorbital lies 

the postfrontal, which occupies the posterodorsal part 

of the orbital margin. 
PERMIAN VERTEBRATES, CUTLER FORMATION, PLACERVILLE AREA, COLORADO C17 

Between what we may call the undisputed part of the 

postorbital and the undisputed part of the parietal lies 

a bone-or fragment of bone-that meets the postfrontal in front, and that may have met the supratmnporal behind in a restricted contact (the bone 

narrows posteriorly and a small part of it seems to have 

been broken away in this region). The contact of this 

bone with the parietal (or ?main body of the parietal) 

seems to be sutural ; its contact with the ( ?main body 

of the) postorbital seems also to be sutural, but not so 

clearly as its contact with the parietal. Is this bone the 

intertemporal? Its relationships are those of an intertemporal: it meets the parietal above and the postorbital below; it meets the postfrontal in front ~nd may 

have met the supratemporal behind, and it would be 

part of the longitudinal series, postfrontal-intertemporal-supratemporal. Its restricted contact-or the 

bare miss of a contact-with the supratemporal might 

indicate a stage of reduction of the intertemporal. 

'The alternatives to calling this bone the intertemporal 

are to regard it as a part of the parietal or to regard 

it as a part of the postorbital. If it is a part of the 

parietal, it forms the usual parietal lappet, intervening 

between postfrontal and supratemporal. But the contact of this bone with the parietal (or ?main body of 

the parietal) seems clearly to be sutural, and, if the bone 

is not the intertemporal, it would seem more likely, on 

this evidence, that it is a part of the postorbital. This 

latter interpretation would postulate a great reduction 

in the size of the parietal lappet to a small wedge 

between postorbital and supratemporal, and this size 

would be in conflict with the usual pattern of relationships of the lappet. (See discussion of parietal lappet 

in Watson, 1954.) It would seem that the bone in question is the intertemporal. 

Further study, including perhaps the grinding of 

the bones found in this region of MCZ 2989, is indicated, and the present report must be regarded as preliminary. It needs to be stressed that the bones in the 

temporal region are checkered with cracks; it may be, 

for example, that a crack running vertically through a 

constricted part of the ?intertemporal about midway 

in that bone's length is a suture, and that only the anterior pa.rt of the bone is to be regarded as the (even 

more reduced) intertemporal. 

The position of the tabular of D. sanmiguelemis is 

obscure. In lateral view, it is perhaps represented by 

a small fragment of bone ventral to the posterior tip of 

the right supratemporal. In dorsal view, there may be 

seen on the right side a fragmented area of bone immediately posterior to the posterolateral part of the parietal and medial to the supratemporal, from which it is 

demarcated by what seems to be a suture; this fragmented bone is probably part of the tabular. A small 

wedge of the parietal intervenes between the anterior 

parts of the tabular and supratemporal. 

A single postparietal is usually restored for Diadectes (Olson, 1947; Watson, 1954; Romer, 1956), but 

D. sanmiguelensis seems to have a pair of postparietals. 

The paired postparietals may be a sign of primitiveness 

and may be taxonomically significant, but possibly they 

are only another indication of the immaturity of the 

type specimen. 

Within the type skull's right otic notch, external to 

the quadrate, lie several fragments of a thin film of 

bone whose posterior edge extends farther medially 

than. its anterior edge. This film of bone is so similar 

to the remarkable ossified tympanic membrane described in Diadectes by Watson ( 1954, p. 388) that it 

must be the same structure. As Watson (p. 390) points 

out, we cannot at this time say whether this structure 

is the tympanic membrane itself or some extracolumellar part that was inserted into the membrane. The ossified membrane in the type skull of D. sanmiguelensis 

has been displaced somewhat ventrally and slightly 

posteriorly from its attachments as described by Watson. That this film of bone is not part of the quadrate 

has been determined by grinding through the matrix 

surrounding the borders of the membrane until the 

right quadrate, which has apparently been rotated about 

its long axis so that its posterior edge has been moved 

laterally, was reached; anteriorly at least, a layer of 

matrix about 2 mm thick separates the ossified film 

from the quadrate. The presence of an ossified tympanic membrane in D. sanmigueZensis is interesting in 

that it shows, assuming that the specimen is immature, 

that this ossification was not necessarily a feature of 

advanced age in Diadectes. 

The quadrate, whose posterior surface can be seen on 

the left side, looks like that of other specimens referable 

to Diadectes, even to the large facet near its ventromedial corner that Olson (1947, p. 21) feels may have 

served as a place of attachment for a cartilaginous process of the stapes. 

The lower ja.w of D. sanmiguelensis, in its patterns of 

sutures and foramina, fits the general picture of Diadectes, but it is different from this picture in the details 

of its overall proportions and in the degree of development of the dorsal edge of its dentary. The following 

com pari sons are based on the excellent figure of a lower 

jaw of D. lentus published by Welles (1941, p. 426), and 

on a specimen of Diadectes lentus (CNHM UC 675) 

that includes a well-preserved lower jaw, which has 

obscure sutures. 

The immediately obvious difference is the relative 

shallowness of the lower jaw in D. sanmiguelensis, which 
C18 CONTRIBUTIONS TO PALEONTOLOGY 

is 88 mm in its greatest length. This is only about fiveninths as long as the jaw figured by Welles, and only 

about two-thirds as long as that of a particularly small 

specimen of D. lentus ( CNHM UC 675). The ratio of 

the greatest depth of the jaw to the length, measured 

from the highest point of the coronoid elevation, is 

about 1:3 for MCZ 2989 and 1:2 for CNHM UC 675 

and for the reconstruction of the lo,ver jaw figured by 

Romer ( 195·6, fig. 107 0). The measurements were 

taken along the medial surface of the jaw to avoid the 

complication of the flange of the dentary described below. In both MCZ 2989 and CNH~f lTC 675 the center 

of the coronoid elevation lies about three-fifths of the 

way back in the length of the jaw. The difference in 

depth of the jaws is not a matter only of relative elevation of the coronoid process: the ratio of the depth of 

the jaw midway between the anterior end and the coro-· 

noid elevation to the length of the jaw is about 1 : 5 for 

MCZ 2~89 and 1 : 3.5 for CNHM UC 675. These ratios 

show that the jaw of D. lentu.'S is relatively deeper 

throughout its length than that of D. sannviguelensis. 

The other obvious difference between the j a 'vs of these 

two species is the much greater development in D. lenttt8 

of the bony flange that extends upward, labial to the 

cheek teeeth, from the lateral wall of the dentary. This 

flange is highest directly in front of the coronoid elevation and slopes forward and downward to be nonexistent in the region of the "incisors"; there is a trench between the teeth and the flange. The flange completely 

hides the posterior five teeth from lateral view, and 

three teeth anterior to these are partially hidden; in 

the lower jaw figured by Welles, even more teeth are 

hidden. In contrast, in D. sanmiguelensis although 

there is a shallow trench between flange and teeth, the 

flange is very low and aU of the teeth are exposed to 

lateral view. 

The individual bones of the lower jaw in D. sanmiguelensis, as seen in lateral view, are disposed generally 

as in Diadectes (see figures by Romer and Welles, referred to above) , except for differences in proportions 

of the elements associated with the relative shallowness 

of the jaw. Two interesting features may be pointed 

out: ( 1) The suture separating the dentary from the 

surangular and angular in the right lower jaw of 

D. sanmiguelensis seems to have its ventral termination 

at a point much farther forward (about two-ninths of 

the way back in the length of the jaw) than in the left 

lower jaw of D. sanmiguelensis and in Diadectes generally, where it lies about one-third of the way back. The 

lateral surface of the right jaw in MCZ 2989 is checkered with cracks, and it is possible that the suture has 

been incorrectly identified, but if the identification is 

correct, we are provided with a good example of variation in sutural pattern. (2) As in Welles' specimen, 

there is a vertical line of separation running through 

the surangular about one-third of the way forward in 

the length of this bone; this line seems to be present in 

CNHM UC 675 too, and this feature may have more 

significance than has been suspected. 

The type of D. sanmigttelensis has many features in 

common with other species of D iadectes : the depth of 

the surangular is less than that of the angular, and the 

coronoid is exposed laterally above the junction of surangular and dentary. The splenial is imperfectly preserved ventrally and is lacking on the inside of the right 

jaw, but this element is well preserved in the left jaw, 

where it is exposed laterally as a narrow strip lying 

below the dentary and passing posteriorly to a point 

shortly behind the ventral end of the suture between 

dentary and angular. A foramen on the medial surface 

of the articular presumably is for theN. chorda tympani. The junction between articular and prearticular 

cannot be made out. 

Because the prearticular bone has been badly 

crushed and the angular has been split along its ventral 

edge, the relations of the angular with the splenial 

are not certain, but the general features of the medial 

aspect of the lower jaw can be readily made out. There 

are two Meckelian fenestrae (called "anterior fenestra" 

and "medial fenestra" by Welles) as in typical Diadectes. The anterior one is small and bounded by the 

dentary above and the splenial below; the main posterior Meckelian fenestra is large and bounded by the 

splenial anteriorly, by a straplike process of the prearticular above, and by the main body of the prearticular posteriorly. 

Differences fron1 the general pattern in Diadectes 

are: the splenial in D. sanmig'ltelensis forms the 

entire ventral boundary of this fenestra, excluding the 

angular from the fenestral border; this exclusion is 

accomplished by a process of the splenial that passes 

posteriorly along the dorsal edge of the angular to touch 

the prearticular. The anterior border of this main 

Meckelian fenestra lies about one-third of the way back 

and relatively higher in the jaw of D. sanmiguelensis 

than in Diadectes generally, where it is only one-quarter 

of the way back. The collective depth of the dentary 

and prearticular in D. sanmiguelensis is less than onehalf as great as the distance from the lower edge of the 

jaw to the upper fenestral border, but in Welles' specimen of D. lentus and in CNHM UC 675 the collective 

depth of the parts of the dentary and prearticular 

directly above the fenestra is about three-quarters as 

great as the distance from the lower edge of the jaw 

to the upper border of the fenestra. The dentary in 

D. sanmigueleruis bulges medially over the main 
PERMIAN VERTEBRATES, CUTLER FORMATION, PLACERVILLE AREA, COLORADO C19 

~feckelian fenestra .much more than in CNHM UC 675, 

so that the process of the prearticular above the fenestra 

faces ventrally more than it does medially. 

The medial outline of the adductor fossa in D. samtnigt.lelensis, as would be expected from the relative 

shallowness of the jaw, is much longer than it is deep; in 

Dia.dectes generally the length and depth are nearly 

equal. There is a roughly vertical fissure running 

through the coronoid bone, but this is probably only a 

crack. There is no good reason to believe that more 

than one coronoid was present. The articular bulges 

medialward but not so markedly as in Diadectes 

generally. 

It has not been possible to study the marginal dentition in as much detail as would be desirable, because of 

the extreme friability of the teeth and the refractory 

nature of the matrix, but its general features can be 

made out. 

The premaxillary seems to have held three teeth, and 

all of these seem to have been "incisors;" D iadectes (see 

Romer, 1956, fig. 43A) normally has four premaxillary 

teeth, all "incisors." Only the first and third "incisors" 

are preserved on the left side of the type of D. sanmiguelensis; none are preserved on the right side. The 

"incisors" seem to have been procumbent, as in Diadectes 

generally. 

Diadectes sanmiguelensis shows a relatively simple 

pattern of the nine cheek teeth preserved in the 1naxilla, 

which has empty spaces for two more, bringing to fourteen the number of teeth in each upper jaw. Sixteen 

teeth in the upper jaw are shown in one reconstruction 

of Diadectes by Romer (1956, fig. 43A) and 15 

in another (fig. 44A) ; CNHM UC 675 also seems to have 

had 15. The first left maxillary tooth in the type of 

Diadectes sanmiguelensl8 is only about one-half as long 

as the incisor in front of it and is not, or is only slightly, 

procumbent. The right side lacks the fifth and eighth 

maxillary teeth. The seventh right 1naxillary tooth 

seems to be fairly young, but advanced to such a degree 

that the tooth it was replacing had been completely lost. 

Along the lingual sides of the bases of several of the 

maxillary teeth of the type of D. sanm1~guelensits there 

are circularly outlined basal notches of the type found 

in Diadectes generally (vVelles, 1941, p. 427) ; these 

basal notches had to do with resorption of the teeth preliminary to replacement. There is a single row of small 

palatal teeth as in typical Diadectes. 

In the lower jaw, there are two obvious procumbent 

"incisors." The basal part of the second right "incisor" 

shows clearly the longitudinal striae so characteristic of 

the bases of the teeth in Diadectes. The tooth immediately posterior to the second right "incisor" is very short 

and may posE'ibly be in an early stage of replacement of 

a third; there are no others. Posterior to these three 

teeth there are eleven more, the last of which is very 

poorly preserved. There are thus fourteen teeth in the 

lower jaw, and this may be compared with the condition 

in Diadecte8 lentus, where, according to Welles (1941, 

p. 427), the number varies from 14 to 18. Preparation 

in this region of the type lower jaw of D. sanmiguelensis 

is even more difficult than in the upper jaw, but a lingual 

basal notch has been demonstrated alongside at least 

one of the cheek teeth. 

As pointed out earlier, there is a shallow trench between the cheek teeth and the low flange of the dentary 

labial to the teeth. Welles ( 1941, p. 424) has suggested 

that this flange may have supported a horny beak; i£ it 

did, such a beak probably would have been less developed in D. sanm·iguelensis than in other species of Diadectes. The alveolar margin of the dentary in D. santniguelensi.s (MCZ 2989) is appreciably less swollen 

from side to side than is the margin in D. lentus 

( CNHM UC 675) ; this is undoubtedly correlated with 

the lesser development of the cheek teeth in D. 

sanrn~iguelensi.s. 

The general pattern of the teeth midway in the upper 

and lower series can be described even though the cheek 

teeth are not well preserved. In the maxillary series, 

the longer axis of the crown, the transverrse axis, is set 

at an angle o£ about 60° to the lateral surface of the 

maxilla, and the lateral end of the tooth is farther 

forward than the medial end. The largest teeth of the 

maxillary series lie so mew hat posterior to the middle 

of the series; they have a ma.ximum height of about 

7.2 mm (measured from the lingual basal notch), are 

about 5·.2 mm wide along their transverse axes, and are 

about 2.8 mm long along their anteroposterior axes 

(measured near the base) . A typical large maxillary 

cheek tooth has a prominent cusp set off to the lateral 

side of the center of the crown; lateral to the cusp, and 

lower, there is a poorly defined, broadly rounded 

shoulder; medial to the cusp the surface of the crown 

slopes in a gently concave arc to a prominent medial 

shoulder, which is placed lower than the lateral 

shoulder. Posterior to the largest maxillary teeth, the 

teeth are smaller and the shoulders less pronounced. 

The shoulders are gradually lost anterior to the largest 

maxillary teeth and the cusp becomes more prominent 

until, in the anteriormost maxillary teeth, only the cusp 

remains. The state of preservation makes it difficult to 

analyze the pattern of attrition, but wear seems to have 

been most severe in the region between the cusp and the 

medial shoulder. 

The largest cheek teeth in the lower jaw occlude with 

the largest in the maxillary series. As in the maxillary 

teeth, the transverse axis is the longer. A difference 
C20 CONTRIBUTIONS TO PALEONTOLOGY 

from the upper dentition lies in the placement of the 

transverse axis of the lower teeth at nearly a right angle 

to the longitudinal axis of the dentary. The largest 

cheek teeth of the lower jaw have a maximum height of 

about 5.8 mm (measured from the lingual basal notch), 

are about 4.3 mm wide along their transverse axes, and 

are about 2.8 mm long along their anteroposterior axes 

(measured near the base) . The cusp and shoulders of 

the crowns of the lower cheek teeth are oriented contrary to those of the upper teeth : in the lower teeth the 

cusp is set off to the medial side of the center of the 

crown, the higher shoulder is at the medial end of the 

tooth, and the lower shoulder is at the lateral end. Further, in the lower teeth it is the lateral sides that show 

more wear. 

The cusp of the typical large cheek tooth in D. santniguelensis obviously corresponds to the central cusp of 

the typical cheek tooth in Diadectes generally ; Romer 

(1952, p. 86) calls this cusp the primary cusp. The 

shoulders of the cheek teeth in D. sanmiguelensis correspond to the secondary and tertia,ry cusps of Romer's 

terminology. The pattern of wear in D. sanmiguelensis, mostly on the medial side above and on the lateral 

side below, also corresponds generally to the pattern in 

Diadectes, as does the fact that the upper teeth are wider 

than the lower teeth. 

The simple crown of the cheek tooth of Diadectes sanmiguelen8is resembles that figured by Case (1908, figs. 4, 

50) for Desmatodon hollandi, from the Conemaugh 

Group of Pennsylvania, except that in D£adectes sanmiguelensis the slope from cusp to lower shoulder is 

gently concave, whereas in Desmatodon hollandi the 

cusp is sharply demarcated from the shoulder. There 

are more differences : The tooth figured by Case has a 

transverse width of about 10 mm. Romer (1952, p. 86, 

pl. 1, fig. 3) has shown that other cheek teeth in Case's 

specimen of Desmatodon hollandi have a transverse 

width of as much as 11 mm, are closer to the pattern 

normal for Diadectes, and have greater development of 

the secondary and tertiary cusps; he believes that the 

toothed fragment described by Case is part of a dentary. 

The teeth of De8matodon hollandi are about two and 

one-half times as large as the teeth of MCZ 2989, and 

are as large as some in heretofore known specimens referable to Diadectes: the largest tooth in the dentary 

of CNHM UC 675 (D. lentu8) has a transverse width 

of only 11.7 mm. We do not feel that the simple pattern and small size of the teeth of D. 8anmiguelensis 

warrant keeping this species out of the genus Diadecte8. 

For one thing, the type seems to be immature, and it 

is more than likely that the teeth of the mature animal 

would have been larger, and possibly more complicated. 

The cheek teeth in Diadectes sanmiguelensis, even in 

this presumably immature stage, do closely resemble 

at least the anterior cheek teeth of Desmatodon hollandi 

and are not too greatly different from the more posterior 

cheek teeth in that species. Olson (1947, p. 9) feels 

that "The known characters [of Desmatodon hollandi] 

are insufficient to permit a morphological differentiation 

from Diadecte8. The principal interest in the specimen 

is that it indicates the presence of the diadectids in the 

eastern part of North America. Because of the geographic isolation of the type specimen the genus and 

species may be tentatively retained." 

It is of interest here that Romer (1952, p. 87) has 

described a battery of very smail lower cheek teeth of 

a diadectid from the Conemaugh. These teeth, eight 

in a length of 11 mm, have each only a single cusp and 

no shoulders. Romer has suggested that these teeth 

may represent either an otherwise unknown primitive 

diadectid or, not impossibly, a young individual referable to Desmatodon. 

The first five vertebrae are fragmented in the type of 

D. sanmiguelensis. The neural spines are of about the 

proportions figured in the reconstruction by Romer 

( 1944, fig. 1). The spines of the third and fifth vertebrae are clearly quadrangular in cross section, as they 

are in diadectids generally. The spine of the fourth 

vertebra is not complete. That of the axis is not well 

preserved but seems to have been more bladelike than the 

others. Owing to the state of preservation of the materials, it has not been possible to confirm the presumed 

presence of episphenes and hyposphenes. Parts of a 

few ribs are present, but these parts are of no diagnostic 

value. 

The cleithrum, clavicle, and interclavicle are like those 

usually described for Dia,dectes (Case, 1911a, p. 79) except, of course, that they are smaller; the length of the 

interclavicle posterior to the suture between the clavicles is 57 mm. There is nothing unusual about the 

sea pula and coracoid, which resemble those figured by 

Romer (1956, fig. 143B). As is usual for Diadectes, 

there is a good-sized foramen in the supraglenoid buttress. The scapula and coracoid have come apart anterior to the glenoid cavity, and this feature may be 

taken as another indication of the immaturity of the 

speCimen. 

The,humerus is about 56.5 mm in its greatest length; 

this is about one-half the size of a humerus of Diadectes 

sp. figured by Case (1911a, fig. 28} and about one-fourth 

the size of a h¥merus of D. tenuitectus described by 

Romer (1944, p: 142}. The ends of the humerus, as 

would be expected in an immature specimen, are unfinished: the ectepicondyle and capitellum were not ossified. As is usual in Diadectes, the humerus has the 

tetrahedral shape characteristic of primitive tetra pods ; 
PERMIAN VERTEBRATES, CUTLER FORMATION, PLACERVILLE AREA, COLORADO C21 

the proximal half is twisted at a right angle to the distal 

half. Th.e entepicondylar foramen has the same shape 

and relatiOns as generally in D iadeotes. The humerus 

can be used to distinguish D. sanmiguelensis and all 

other species of Diadeotes, from D iasparaot~s z,enos 

Case, 1910. 

Dimsparaotus zenos is an incompletely known diadectid from the Cutler Formation of northern New 

Mexico. Nothing is known of the top of its skull, and 

the palate and lower jaw are imperfectly known. Case 

and Wil~iston (1913) have presented a fairly complete 

postcran1al osteology, but it is still not clear whether or 

not episphenes and hyposphenes were present in the 

vertebral column. Olson (1947, p. 9) regards Diasparaotus as a distinct genus. Case and Williston (1913 

p. 21) have pointed out the remarkable fact that th~ humerus in Diasparaotus zenos lacks a supinator process, or, at best, has only a poorly developed one. In 

their words, "there is no such process; the shaft of the 

left humerus is perfectly smooth at the position of the 

process, but on the right humerus there is a slightly 

elevated rugosity." The figure of their specimen of 

Diasparaotus zenos (fig. 10) shows a humerus about 124 

mm in length from the proximal articular surface to the 

distal end of the capitellum and there seems to be no . ' supinator process. 

In Diadeotes the supinator process generally arises 

from the preaxial side of the humerus about midway 

between the proximal articular surface and the distal 

end ?f the ectepicondy le. In the type of D. sanmiguelensu;: the supinator process is definitely present and 

pr?minent a~though not perfectly preserved, and it 

arises, preaxmlly, about midway in the length of the 

humerus. Since the ectepicondy le was not ossified it 

may be see~ that the supinator process lay somewl1at 

father p~oximal!y th~n. it ~id in Diadeotes generally. 

There Is notlung distinctive about the radius. The 

~tate of preservation of the proximal end of the ulna 

IS not good enough to permit a positive statement, but 

the fact that the olecranon seems not to have been ossified is .additional evidence of immaturity. In DLadeotes 

there IS generally a prominent olecranon. (See Case 

~911a, fig. 27.) Ossification of the carpus is only incip~ Ient and there are rudimentary centers for the radiale 

~he first ~istal carpal, a centrale, and what may be th~ Interme~Ium, ulnare, and pisiform; the carpus is far 

less ossified than the carpus figured for D iasparaotus 

zenos by Case and Williston ( 1913, fig. 12). Romer 

(1956, p. 381) points out that the diadectid carpus is 

generally poorly ossified. There is nothing unusual 

about the metacarpus, and the phalangeal formula is 

the usual 2-3-4-5-3. The digits are 1nuch like those 

figured for Diasparaotus zenos (Romer, 1956, p. 381). 

'7"61-349 0-65---8 

Order COTYLOSA URIA 

Suborder CAPTORHINOl't'IORPHA 

Family Lll't'INOSCELIDAE, 

Limnoscelops longifemur Lewis and Vaughn, n. gen. and n. sp. 

Figure 9 A-G 

The type of Lhnrnosoelops longifemur (MCZ 2984 

from loc. 10) consists of a small jaw fragment, the tips 

o:f two teeth, seven incomplete vertebrae, a partial pelvic 

girdle, proximal and distal parts of a femur, the proximal part of an ulna, and other fragments. These parts 

were found as associated loose scrap. The similarity of 

the vertebrae to one another, the fitness in size of these 

vertebrae to the rest of the elements, and the size of the 

head of the femur relative to the dimensions of the 

acetabulum all indicate that these bones are the remains 

of one animal. This specimen clearly represents a new 

species of a new genus of cotylosaurian reptile. 

'The combined generic and specific diagnosis is : V erte,-

brae similar to those of Limnosoelis and Limnosoeloides. 

Posterior part of pubic symphysis thick. Large, circular depression in anterior face of conjoined internal 

ridges of pubes. Femur similar to femora of Oaptorhinus and Labidosaurus. The outstanding demonstrable feature of Limnosoelops longifemur is the combination of limnoscelidlik;e vertebrae with a captorhinidlike 

femur. 

The fragment of the lower jaw is so small-about 

1 em X 2 em-and so poorly preserved that it is uninformative. The distal tips of two teeth about 11f2 mm 

long, and impressions of two more tips, occur in the 

matrix adhering to this fragment. The better preserved 

of the two tips is round in cross section; its diameter at 

its proximal end is 3 mm, and it tapers to a blunt point. 

A ground section shows no sign of labyrinthodonty. 

Of the parts of vertebrae present, only a single dorsal 

vertebra approaches completeness, and even in this the 

zygapophyses, the neural spine, and the ventral half of 

the centrum are missing. The centrum is notochordal, 

has a canal of the typical hour-glass shape, and must 

have been roughly circular in anterior or posterior aspect. The greatest width of the centrum, measured 

at the anterior end, is 25 mm. The centrum is about 16.5 

mm long, measured along the lateral side on the level 

of the notochordal canal. This centrum is similar in 

both proportions and absolute size to a dorsal centrum 

of Limnosoeloides dunka,rdensis measured by Romer 

( 1952, p. 89), in which the corresponding dimensions are 

26 mm and 16 mm. The dimensions of a dorsal centrum 

in a specimen of Limnosoelis paludis figured by Williston (1912, p. 462) are about 25 mm by 18 mm (calculated from Williston's figure). The ratio of the width 

of the centrum to the distance between the centrum and 
C22 CONTRIBUTIONS TO PALEONTOLOGY 

F 

FSGL 

G 

FIGURE 9.-Limnoscelops longifemur, n. gen., n. sp., elements of the type specimen, MCZ 2984. 

A, B, 0, Lateral, ventral, and anterior views of the preserved part of the innominate bone; 

D, E, ventral views of the proximal and distal parts of the left femur; F, G, anterior and 

posterior views of a dorsal vertebra; H, MCZ 2979, a series of articulated vertebrae referred 

to Limnoscelops longifemur; I, MCZ 2981, a part of the left scapulocoracoid of an undetermined captorhinomorph. Unshaded areas represent matrix. All X 0.67. 
PERMIAN VERTEBRATES, CUTLER FORMATION, PLACERVILLE AREA, COLORADO C23 

the base of the neural spine, measured along the posterior surface, is about 1.1: 1 in both MCZ 2984 and the 

specimen of Llmnosoelis paludis figured by Williston. 

The vertebrae of Limmosoelops longifemur are typical of limnoscelids in general; they resemble most 

closely those of Limmosoeloides dunkardensis. The 

neurocentra! sutures in the vertebrae are not visible, 

in contrast to the lumbar vertebrae of Limnosoeloides 

dwnkardensis figured by Romer (1952, fig. 10). The 

neural arch in L~"mnosoelops longifernur has the "swollen" appearance of such typical cotylosaurs as Limnoscelis and Limnosoeloides. A broad, wedge-shaped 

process projects downward to end at the dorsal border 

of the neural canal on the posterior surface of the neural 

arch. The ventral end of this process, whose two ventrolaterally facing surfaces are continuous with the articular surfaces of the postzygapophyses, is notched in 

the midline. Such a process is found also in Limnosoelis 

paludis (Williston, 1912, fig. 15), and we have found it 

on vertebrae of the only known specimen of Lhnnosoeloides dunkardensis (USNM 12166). The hyposphenes 

are connected to a similar process in Diadeotes, but Limnosoelops, Lhnnoscelis, and Limnosoeloides lack hyposphenes. Oaptorhinus, Oaptorhinikos, and Labidosauruslack such a process, and it probably did not occur in 

any of the Captorhinidae. 

Because the lateral parts of the zygapophyseal processes and their articular surfaces are missing, it is not 

possible to measure the greatest width of the neural 

arch on this specimen, but a referred specimen (see 

below) shows that the zygapophyses were widely separated and the articular surfaces were in a nearly horizontal plane as in L,imnmsoelis and Limnosoeloides. The 

costal articular surface is not well preserved, but there 

seems to have been a ridge passing from about midway 

on the anterior edge of the centrum upward to the 

dia pophyseal area behind the prezygapophysis as in 

Limnosoelis. A small notch occurs between the areas 

for the capitular and tubercular parts of the rib. There 

is a din1ple about 4-5 mm in diameter behind the costal 

ridge and immediately dorsal to the probable line of 

the neurocentra! suture. This depression is not as deep 

on the best preserved vertebra as it is on a fragment of 

another vertebra. Such dimples occur also in a series 

of four articulated vertebrae of Limnosoeloides dunka,rdensis (see Romer, 1952, fig. 10) where the dimples 

are deeper in the posterior than in the anterior vertebrae 

(personal examination). 

Probably the best preserved vertebra is a more anterior one than the more deeply dimpled fragment that 

articulates with a partial vertebra that includes part of 

the centrum. The ventral surface of this centrum is 

flattened in a longitudinal strip about 5 mm wide. Willist on ( 1911a, p. 387) has described such a flattened surface on the centrum in Limnosoelis paludis, in which it 

apparently is not a constant feature (Williston, 1912, p. 

458) . There are several partial caudal vertebrae similar 

to those figured for Lin1nosoeloides dunkardensis by 

Romer ( 1952, fig. 10). 

The preserved part of the left innominate bone consists of the acetabular parts of the pubis and ischium 

and a bit of the posterior acetabular part of the ilium, 

and of the thickened, symphyseal parts of the pubis 

and ischium below the acetabulum on both sides. The 

blade of the ilium, which in Diadeotes and Limnosceli8 

contains the external shelf apparently characteristic of 

the most primitive cotylosaurs, is totally lacking as it is 

in the specimen of Limnosoeloides dunkardensis. Maturity is indicated by the lack of visible sutures between 

the pelvic elements. The length of the acetabulum is 

43 mm, measured from the anteroventral corner to a 

point midway on the rim of the aeetabular part of the 

ischium, about equal to the corresponding distance in 

the specimen of Lirnnosoeloides dunkardensis ( calculated from Romer, 1952, fig. 11) and about two-thirds 

as great as in the specimen of Limnosoelis paludis figured by Williston ( 1911a, fig. 6). 

Limnosoelops longifemur, L,imnosoelis paludis, Limnosoeloides dunkarden8is, and the captorhinid cotylosaurs (see Romer, 1956, fig. 150-I for Labidosaurus) 

all have a thickened ridge passing from the internal 

surface of the acetabular part of the pubis to end at the 

thickest part of the pubic symphysis, which is greatly 

thinned anterior to this ridge. In Limnoscelis paludis 

and Llmnosoeloides dunkardensis, the pubic symphysis 

is considerably thinned posterior to this ridge also. 

(See Romer, 1956, fig. 150-H; 1952, fig. 11.) In Limnosoelopslongifemur there is some thinning posterior to 

the ridge, but it is much less pronounced than in the 

other two animals. The thickest part of the pubic symphysis is about 29 mm; this is about twice the thickness of Limrnoscelo·ides dunkarde1USis and slightly less 

than that of the specimen of LimnosoeliJs palrudis figured 

by Williston (1911a, fig. 6). Two em posterior to this 

thickest part the depth of the symphysis has decreased 

only to 22 1nm; and 3 em poste,rior to the thickest part 

the depth of the (probably ischiadic) symphysis has decreased only to about 17 mm. The acetabular length 

is about two-thirds that of the same specimen of LirnLnosoelis paludis. 

Lirlnnosoelops longije1nur has a conspicuous circular 

depression, about 18 mm in diameter and about 4 mm 

deep at the center, on the anterior face of the thickest 

part of the pubic symphysis, the anterior surface of 

the conjoined internal ridges of the pubes. This feature is unmatched in any other known cotylosaur. The 
C24 CONTRIBUTIONS TO PALEONTOLOGY 

depression on the anterior face of the conjoin.ed internal 

ridges of the pubes in Limnoscelops longifernur makes 

this face more nearly vertical than it is in Li1nnoscelis 

or Lim;nosceloides. In this, Lhnnoscelops is more like 

the captorhinids than are the other two genera. 

The external opening of the obturator foramen is 

similarly placed in Li1nnoscelops, Limnoscelis, and Limnosceloides. In Limnoscelis, as in Labidosaurus, the 

internal opening of the foramen lies anterior to the 

internal ridge of the pubis, but in Lirn/Jwrweloides, the 

opening lies at the upper end of the ridge (Romer, 1952, 

p. 90). Limnoscelopslongifemu,r shows a somewhat intermediate condition in that the opening lies immediately anterior to a crest above the greatest depth of 

the ridge, but the position of the opening is more like 

that in Lim;nosceloides than it is like that in Limnosceiis. 

The proximal fragment of an ulna is about fivesevenths the size of the corresponding part of Limnoscelis paludis figured by Williston (1912, fig. 27), but 

the two are morphologically indistinguishable. 

The hind led of Limnoscelops longifemur is represented in the type by only the proximal and distal ends 

of the left femur; they are very similar to those of 

Labidosaurus, but what is left of its stumps seems to 

indicate that the shaft was more slender and more like 

that of Oaptorhinus. The relative slenderness in Limnoscelops is a significant difference from Labidosaurus, 

a much smaller reptile by comparison of the proximal 

and distal ends. (See Case, 1911a, fig. 48.) 

The complete femur may have been at least 130 mm 

long from the most proximal point on the head to the 

end of the posterior condyle, and at least 122 mm long 

from the most proximal point on the head to the center 

of the intercondylar notch. This calculated distance 

from head to intercondylar notch is about one and onefourth times the comparable length in Li'lnnosceloides 

dunkardensis (USNM 12166). The pelves are about 

the same size in these two; therefore, Limnoscelops 

longifemur had proportionally much longer femora, 

and probably also had proportionally longer hind legs 

and slenderer shaft than Limtnosceloides dunkardensis: 

The stump of the shaft on the proximal fragment of 

Limnoscelops longifernrur is about 17 mm thick ( measured in the plane of the head of the femur) as compared to about 25 mm in Limnosceloides dunkardensis 

(calculated from Romer, 1952, fig. 12). The proximal 

and distal ends of the femur in Limnosceloides are not 

so wide in comparison with the shaft as in Limnoscelis 

whose femur is short, stoutly built, and in general comparable to the femur in Seymouria. (See Romer, 1952, 

fig.12; 1956, figs.171A., B, 0, F.) 

The trochanteric crest is set off from the head by a 

distinct notch as in Labidosaurus (Romer, 1956, fig. 

171G), but in contrast to Lhnnoscelis, makes almost 

a right angle with the head, and does not flare widely 

at the front. The trochanteric crest in Labidosaurus 

and L,imnoscelis is directed anteriorly as well as ventrally, so that it makes an obtuse ventral angle with the 

head; only the base of the crest is preserved in Limnosceloides dunkardensis (USNM 12166). There is a 

prominent excavation on the posterior side of the posterior condyle as in Labidosaurus and Lim;noscelis, but 

in contrast to Limnosceloides. 

To sum up the significant morphologic features of 

Limnoscelops longifemur: The vertebrae are typically 

limnoscelid, the preserved parts of the pelvis are much 

like those in Lirrunosceloides except for the thicker symphysis, and for the almost vertical, captorhinomorphlike face of the conjoined internal ridges of the pubes. 

Romer (1956) recognizes three families of captorhinmnorph cotylosaurs: the Limnoscelidae, the Romeriidae, and the Captorhinidae. The consensus seems to be 

that vertebral structure is more conservative than the 

structure of the appendages, as illustrated by the currently accepted classification of labyrinthodont amphibians; thus, the classification of Limnoscelops must depend more on its vertebrae than on the other materials 

available to us. We therefore tentatively assign Limnoscelops to the family Limnoscelidae. Romer's assignment of Limnosceloides to this same family was also 

only tentative. Limnoscelis, known only from the Cutler (El Cobre Canyon) of New Mexico, has heretofore 

been the only unquestioned representative of this family. Limnoscelops, for the time being, is best thought 

of as a limnoscelid advanced in the direction of the 

captorhinids. 

The romeriids and captorhinids are closely related, 

the captorhinids having apparently been derived from 

the romeriids. The postcranial skeleton of the romeriids is, unfortunately, still unknown. Protorothyris and 

Romeria of the romeriids are known from the lower 

part of the Wichita Group in Texas, M elanothyris is 

known from the lower part of the Dunkard Group in 

the eastern United States, and Oephalerpeton may be 

a romeriid from the Allegheny Formation of Illinois. 

The Wichita Group has yielded only a few primitive 

captorhinids, but the advanced Oaptorhinus and Labidosaurus are common in the over-lying Clear Fork 

Group. 

The known limnoscelids could not have been the actual ancestors of the romeriids or captorhinids if we 

consider their respective ages. The phylogenetic divergence must therefore have occurred no later than 

Middle Pennsylvanian time. 
PERMIAN VERTEBRATES, CUTLER FORMATION, PLACERVILLE AREA, COLORADO C25 

Limnoscelops longifemur Lewis and Vaughn, referred specimen 

Figure 9H 

We refer an articulated series of four vertebrae (MCZ 

2979 from loc. 4) to the new coty losurian species Lin-~;­

noscelops longifernur Lewis and Vaughn. It has not 

been possible to prepare fully these vertebrae owing to 

an extremely difficult matrix, but diagnostic characters 

are clearly evident. 

The second vertebra in the series has a centrum 12.5 

mm in length. This is considerably less than the length, 

16.5 mm, of the centrum of the best preserved, apparently dorsal, vertebra of the holotype. In the speci1nen 

of Limnosceloides dunkardensis, the centra increase in 

length passing posteriorly, from 16 mm in a dorsal vertebra. to about 19 1nm in the five vertebrae immediately 

anterwr to the sacrum. There is a similar increase in 

the holotype of Limnoscelops longifemur: In one of the 

vertebrae determined as posterior to the best preserved 

vertebra (on the basis of a more pronunced dimple 

above the junction of centrum and neural arch), the 

centrum is about 18 mm long. The dimples on the 

referred vert.ebrae are deeper than any in the holotype and are very much like those in the specimen of 

Lirnnosceloides dunkardensis; if the correlation, derived 

from the materials of the latter animal, of farther posterior position with deeper dimples is correct, the referred vertebrae are from a posterior position. The 

small size of the centra may be due to immaturity: 

traces of a persistent neurocentra! suture can be seen 

immediately below the dimple on several of the 

vertebrae. 

'The centrum of the second vertebra in the series has 

a transverse width of approximately 15 mm at the anterior end. The ratio of width to length for this centrum, 1.2: 1, is not greatly different from the same ratio 

for the posterior vertebra of the holotype whose length 

was measured as 18 mm and whose width is about 20 mm 

1.1 : 1. It will be noted that this posterior centrum of 

the holotype is narrower than the holotype's dorsal 

centrum. In the specimen of Lirnnosceloides dunkardensis too, the centra not only become longer posteriorly, 

but they also decrease somewhat in width, although not 

as markedly as in the materials of Lhnnoscelops longife:nwr. The decrease observable in the holotype of 

L~rnnoscelops longifernur is 5 mm (frmn 25 mm to 20 

mm); Romer (1952, p. 89) records a maximun1 decrease 

?f 3 .mm (fro~ 26 mm to 23 mm) passing posteriorly 

Ill Lzrn,noscelm'des dunkardensis. 

In the first vertebra of the referred series, the distance bet':een the most lateral points of the postzygapophyses IS about 33 mm. The ratio of this distance to 

the width of the centrum is about 2.2: 1, assuming that 

the first and second centra have the same width· this 

' 

ratio is greater than the ratio 2: 1 calculated for Lirlnnoscelis paludis from Williston's illustration ( 1912, fig. 

15) . The transverse distance across the waist of the 

neural arch of the referred first vertebra is 25 mn'l. 

This distance is 28 mn1 in the best preserved vertebra 

of the holotype. The zygapophyses lie in a nearly horizontal plane. The costal facets of the vertebrae are too 

poorly preserved to add to the description of the holotype. 

This referred specimen might have been made the 

type of a new species assigned to Limnosceloides if the 

holotype of Lirnnmscelops longifem.ur were not known, 

but the geographic proximity of this specimen to the 

latter makes it highly probable that the referral to Limnoscelops longi fem.rur is correct. 

Order COTYLOSAURIA 

Suborder CAPTORHINOM:ORPHA 

Family CAPTORHINIDAE ~ 

Genus and species indeterminate 

Figure 91 

Almost an entire scapulocoracoid (MCZ 2981 from 

loc. 7) is questionably referred to the Ca ptorhinidae. 

It qonsists of the parts in the vicinity of the glenoid 

cavity, including the scapular blade up to a short distance ·above the supraglenoid buttress, and a large part 

of the coracoid plate. This specimen probably came 

from a mature animal, as indicated by the lack of 

visible sutures. 

The glenoid cavity has the screw-shaped articular 

surface common in cotylosaurs. The supraglenoid buttress has the outline of an isosceles triangle; the sides 

are slightly shorter than the base along the dorsal border 

of the glenoid cavity. The buttress faces more posteriorly than it does laterally. The supraglenoid foramen 

pierces the buttress immediately below the apex of the 

triangle, nearer the blade of the scapula than the posterior border of the buttress. There is a large supracoracoid foramen. The coracoid plate is incomplete 

posterior to the glenoid cavity; hence, it is not possible 

to say whether there was a process for the coracoid head 

of the triceps muscle as in pelycosaurs. 

The scapulocoracoid is very close in size to that of a 

specimen of Oaptorhinikos chozaensis (USNM 21275) 

which it closely resembles, especially in details of the 

supraglenoid area. In both, the supraglenoid buttress 

has the isosceles outline described, and the supraglenoid 

foramen lies near the scapular blade. Both specimens 

resemble Labidosa·u/f"1J,S in this characteristic (Romer, 

1956, fig. 143-C); in Oaptorhinus, the foramen lies even 

farther forward, almost on the blade. The resemblance 

to the scapulocoracoid in Oaptorhinikos is so close that 

this bone from the Cutler (MCZ 2981) probably repre-
C26 CONTRIBUTIONS TO PALEONTOLOGY 

sents a captorhinomorph cotylosaur, if not actually a 

ca ptorhinid. 

If we may attempt a comparison with other known 

cotylosaurian components of the fauna described in this 

paper, we see at once that MCZ 2981 could not have 

belonged to the seymouriid (MCZ 2983) assumed to 

have had a pectoral girdle like that in Seymouria baylorensis (White, 1939, fig. 17) :the glenoid cavity in Seymouria is too narrow from top to bottom and is not 

well developed as a screw-shaped socket. The scapulocoracoid of the holotype of Diadeotes sanmiguelensis is 

of roughly the same size but has the supraglenoid foramen nearer the glenoid cavity, and a supraglenoid buttress that passes smoothly into the posterior edge of the 

scapular blade without an abrupt decrease in thickness. 

It is doubtful that MCZ 2981 could ha.ve belonged to 

the limnoscelid Limnosoelops longifenvur, represented 

by MCZ 2984 and MCZ 2979, assuming that Limnosoelopslortgifemur had a pectoral girdle whose size relative 

to its pelvic girdle was roughly similar to the ratio of 

the pectoral to pelvic girdle in Limnosoelis paludis. 

The individual of Limnosoelopslongifemur represented 

by MCZ 2984 is estimated to have had a glenoid cavity 

in which the straight-line distance between the most 

anterior and most posterior points on the rim was about 

33 mm based on the ratio of the length of the acetabulum 

to the length of the glenoid cavity in Limnosoelis paludis, as calculated from Williston ( 1911a, figs. 4, 6), and 

on the acetabular length of 43 mm in MCZ 2984. This 

is considerably larger than the distance of 20 mm seen 

in MCZ 2981. 

We conclude that this scapulocoracoid represents a 

captorhinomorph cotylosaur, possibly a captorhinid. 

SUBCLASS SYNAPSIDA 

Order PELYCOSAURIA 

Suborder OPHIACODONTIA 

Family OPHIACODONTIDAE 

Ophiacodon sp. 

Figure 10 

An articulated string of three whole and two half vertebrae and intercentra (MCZ 2977 from loc. 1) represents a species of Opkiaoodon Marsh, 1878. None of the 

neural spines are completely preserved. These vertebrae are from the posterior dorsal region as shown by 

the narrow separation of parapophysis and diapophysis 

and by the presence on the ventral side of the centrum 

of a flattened area bounded by a pair of longitudinal 

ridges. The vertebrae fit Ophiaooden in that: (1) The 

neural arches are not excavated on the lateral sides of 

their laminae ; ( 2) the centra lack a sharp ventral keel 

in these posterior dorsal vertebrae; ( 3) the neural canal 

sends a narrowed extension far ventrally, almost to the 

notochordal canal, as seen in a cross section of the centrum ground to approximately the plane of minimal 

area of the notochordal canal-such an extension is 

fmmd in ophiacodonts and edaphosaurs, but not in sphenacodonts (Romer and Price, 1940, fig. 17); and (4) 

the sides of the centrum converge ventrally toward the 

ridges bounding the narrow, ventral flattened area, with 

only the slightest suggestion of concavity. 

The only genus of ophiacodontids that fits the above 

description is Ophiaoodon. The margins of the ventral 

surface of the centrum are rounded in Olepsydrops and 

Varanosaurus (Romer and Price, 1940, p. 214). 

The nomenclatorial history of the genus Vphiaoodon 

is complicated, having seven synonyms; Romer and 

Price (1940, p. 225) have reviewed this history. The 

two species of Ophiaoodon known from the Cutler Formation of northern New Mexico are 0. navajovious 

(Case, 1907) and 0. mirus Marsh, 1878. Ophlaoodon 

mirus is very similar to 0. uniform·is from Texas, and it 

is difficult to distinguish the postcranial skeleton of 0. 

mirus from that of 0. navajovious except that 0. navajovious is a somewhat smaller animal (Romer and Price, 

1940, p. 233, 237). 

The greatest length of each of the complete centra is 

16.5 mm. This may be compared with the known 

lengths of posterior dorsal vertebrae in Ophiaoodon 

navajovious, 12-18 mm; 0. mirus, 18-22 mm; and 0. 

uniforrmis, 15-19 mm. (See Romer and Price, 1940, table 3; these authors also list a questionable specimen of 

0. uniformis, which has a "lumbar" vertebra 13 mm 

long.) The ratio of the length of the centrum to the 

width of the posterior end of the centru1n is 1.1 :1; in 

both 0. navajovious and 0. mirus this ratio va.ries from 

0.9 :1 to 1.2 :1 for posterior dorsal vertebrae. The height 

from the bottom edge of the centrum to the top of the 

posterior zygapophysis is 25.5 mm; this height would 

fit 0. navajovious, in which the range, for mid-dorsals 

through "lumbars," is about 22-26 mm; 0. mirus, in 

which the same range is about 26-31 mm; or 0. uniformis, in which the range is about 26-31 mm, according to Romer and Price ( 1940) The least height recorded for 0. retroversus, from Texas, is 36 mm, and 

0. major, also from Texas, is an even larger animal. 

The facts of similarity in size, similarity in geographic location, and presence in the same geological 

formation would seem to indicate that the species represented may be either 0. navajovious or 0. mirus. The 

size actually fits into the size range of 0. navajovious, 

but we feel that it misses fitting into the range of 0. 

m,irus by too narrow a margin to allow a choice between 

the species on the basis of these vertebrae alone. 
PERMIAN VERTEBRATES, CUTLER FORMATION, PLACERVILLE AREA, COLORADO C27 

A B 

FIGURE 10.-0phiacodon sp., MCZ 2977. A, Ground transverse section through 

the first vertebra in the string; B, the"stririg of vertebrae in lateral view. Un· 

shaded areas represent matrix. X 1. 

Order PELYCOSAURIA 

Suborder OPHIACODONTIA ~ 

Genus and species undetermined 

A left tibia and an articulated fragment of a femur 

(MCZ 2991 from loc. 16) are thought to be those of an 

ophiacodont. The dimensions of the tibia are: length, 

90 mm; estimated proximal width, 36 mm (the posterior 

condyle is incomplete) ; distal width, 22 mm; diameter 

of narrowest part of shaft, about 11.5 mm. The tibia 

is obviously pelycosaurian. Because it does not have 

the stocky shape of the edaphosaurian tibia, comparisons may be restricted to specimens of ophiacodonts 

and sphenacodonts having tibiae of roughly comparable 

length. 

The ratio of the length of the tibia to the narrowest 

part of the shaft is 7.8: 1, greater than in some species 

of ophiacodonts. For example, in V aranosaurus aeut-irostris it is 6: 1; in Ophiacodon navajovicus, 6: 1; in 

0. un·iformis, 7.7: 1. The ratio may be the same as in 

0. mirus, or it may be greater as in Olepsydrops collettii 

where it is 8.8: 1. This ratio is greater in sphenacodonts: TT aranops brevirostris, 9.5: 1; Dimetrodon natalis, 9.4: 1; D. milleri, 11.5: 1 (approximate figures based 

on Romer and Price, 1940, fig. 38) . The figures for the 

ratio of the length to the proximal width overlap when 

ophiacodonts are compared with sphenacodonts, and in 

both these groups are found tibiae from 61 to 114 mm in 

length where the ratio (based on Romer and Price, 1940, 

table 4) is very close to that for MCZ 2991. 

These pelycosaurian limb bones may be part of an 

ophiacodont, considering the ratio of the tibial length 

to the narrowest part of the shaft. The ratio of the 

length of the tibia to the length of posterior dorsal 

vertebrae has a considerable range in the two known 

ophiacodonts from the Cutler Formation of northern 

New Mexico: for Ophiacodon navajovicus, 4.9: 1 to 7: 1, 

for 0. mirus, 4.5: 1 to 5.6: 1 (based on Romer and Price, 

1940, tables 3 and 4). The length of the tibia of MCZ 

2991 is 5.5 times as great as the length of each of the 

posterior dorsal vertebrae in MCZ 2977, described on 

page C26 as belonging to Ophiacodon sp.; this ratio fits 

easily into the range of the ratio of the length of the 

tibia to the length of posterior dorsal vertebrae for the 

New Mexican ophiacodonts. Possibly, MCZ 2991 belongs to the species of Ophiacodon represented by MCZ 

2977. 

Order PEL Y·COSA URIA 

Suborder SPHENACODONTIA 

Family SPHE·N ACODONTIDAE 

Subfamily HAPTODONTINAE· 

Cutleria wilmarthi Lewis and Vaughn, n. gen. and n. sp. 

Figures 11, 12A 

We here name Outleria wilmarthi, a new species of a 

new genus of haptodontine pelycosaurs, and designate 

as the type USNM 22099 from locality 3 : a fractured 

skull that is fairly complete except for parts of the 

bones of the snout, the mandible, the first 12 vertebrae, 

several additional presacral and caudal vertebrae, parts 

of the rib cage, the pectoral girdle, the incomplete left 

humerus, the right epipodials, and the right carpus. 

The specific name is given in honor of V. R. Wilmarth, 

who found the holotype and who was the first, to our 

knowledge, to discover fossils in the Cutler Formation 

of Colorado. 

Because Outleri,a wilmarthi is the only known species 

of the new genus, the following diagnosis does not differentiate between generic and specific characters : Skull 

has the diagnostic characters of the Sphenacodontidae 

(Romer and Price, 1940, p. 283-284), including a flange 

on the angular bone, and having the proportions of the 

nonsecondontosaurine sphenacodontids. Temporal fe-
FIGURE 11.-0utleria wilmarthi n. gen., n. sp. View of the left side of the type specimen, USNM 22099. Unshaded areas represent matrix. X 0.56. 

0 

~ 

c 

~ ~ 

t:l:1 

~ ~ 

0 

z 

UJ. 

1-3 

0 

~ t:z::1 

0 

~ t"' 

0 

~ 
PERMIAN VERTEBRATES, CUTLER FORMATION, PLACERVILLE AREA, COLORADO C29 

FIGURE 12.-0utleria wilmarthi n. gen., n. sp. A, tight lateral view of the skull of the type specimen, USNM 22099 ; B, 

MCZ 2987, a snout fragment referred to Outleria wilmarthi. Unshaded areas represent matrix. Both X 1.125. 

nestra is narrow from front to back, elongated vertically, narrower ventrally than dorsally, and has its long 

axis steeply inclined to the horizontal axis of the skull. 

The largest maxillary teeth lie about one-third of the 

way back in the length of the maxilla and are not 

1narkedly developed as canines. No "step" in the anterior part of the alveolar border of the maxilla. 

Known postcranial skeleton of same general proportions 

as that of the varanopsid Varanops bre11irostris, except 

that the limbs of 0. w{lmarthi are proportionately somewhat longer and the postcranial skeleton of 0. wilmarthi 

is closer in some respects to the sphenacodontid pattern 

than it is to the varanopsid pattern, as in the more posterior position of the supraglenoid foramen and the 
C30 CONTRIBUTIONS TO PALEONTOLOGY 

absence of an incisure in the anterior border of the 

coracoid plate. 

The sphenacodontid characters of the skull will distinguish 0. wi11marthi from all nonsphenacodontid pelycosaurs in this diagnosis. The "normal" proportions of 

the skull will distinguish 0. wibnarthi from the species 

of Secodontosaurus within the Sphenacodontidae. The 

lack of pronounced canines, the lack of a "step" in the 

maxilla, and the varanopsidlike proportions of the postcranial skeleton will distinguish it from the men1bers of 

the Sphenacodontinae; and the shape of the temporal 

fenestra will distinguish it from other known members 

of the Haptodontinae. 

Romer and Price (1940, p. 260) listed the following 

characteristic sphenacodontian features: ( 1) The posterior region of the skull is broad. ( 2) The dorsal and 

lateral surfaces of the skull are sharply demarcated in 

the preorbital and temporal regions; the temporal opening is barely visible in dorsal view. (3) The posterodorsal corner of the orbit, where the. postfrontal and 

postorbital bones meet, projects lateral~ard as a boss 

that distinctly sets off this region of the lateral margin 

of the dorsal surface of the skull from the more posterior part of the margin. ( 4) The articular surface 

of the quadrate is well posterior to the occipital condyle 

as shown by the position of the first vertebra; the occiput is concave in dorsal view. ( 5) The cervical and 

anterior dorsal vertebrae have sharp ventral edges, and 

a cross section of a dorsal vertebra shows no extension 

of the neural canal reaching toward the notochordal 

canal. (Such an extension does exist in ophiacodonts 

and edaphosaurs; see Romer and Price, 1940, fig. 17.) 

( 6) The lateral surfaces of the neural arches are excavated between the transverse processes and the base of 

the neural spine. (7) The clavieles are expanded ventrally. (8) The scapula is tall and narrow. (9) The 

supraglenoid foramen lies anterior to the supraglenoid 

buttress of the scapula. (10) The supraglenoid buttress 

faces as much sideward as it does rearward. (11) There 

is an open suture between the posterior coraeoid and 

the anterior elements of the primary shoulder girdle; 

it is characteristic of the sphenacodonts that the coracoid ossified slowly. 

Outleri,a wiltlnarthi clearly belongs to the suborder 

Sphenacodontia because this new genus and species 

shows all eleven of the preceding easily observable 

characters; within the suborder, it is a spl1enacodontid 

easily distinguished from the more primitive varanopsid Sphenaeodontia. We place it in the family Sphenacodontidae on the basis of the presence of a well-developed, posteroventrally directed flange that forms the 

ventral and posterior edges of the angular bone and 

has a posterior notch somewhat like that of therapsid 

reptiles. The Sphenacodontidae, alone among pelycosaurs, have such a flange (Romer and Price, 1940, p. 

284). Outler2:a is a primitive haptodontine sphenacodontid. It lacks the secodontosaurine elongation of 

the snout, the sphenaeodontine enlargement of the canine teeth, and the fonnation of a "step" in the anterior 

part of the alveolar border of the maxilla. The lacrimal 

bone probably reached the narial border in primitive 

style as suggested by the arrangement of the fragments 

of bone in the anterior region of the snout; this arrangement would distinguish 0. wihnarthi frmn both the 

secodontosaurine and the sphenacodontine pelycosaurs. 

The lack of lacrimal entry into the narial border in 

Secodontosawrus may be related to the extreme length 

of the snout. The shortness of the lacrimal in the sphenacodontines may be related to great dorsal ward enlargement of the maxillary bone associated with the development of large "canine" teeth. 

Outleria differs from the advaneed sphenacodontids 

in these eranial features as well as in the rest of its osteology, particularly the lack of elongation of the neural 

spines, but resembles H aptodus, the only known genus 

of the primitive subfamily Haptodontinae. Outleria 

is therefore assigned to this subfamily that eontains its 

nearest relatives, the species of Haptod,us from the European Autunian and Rotliegende. 

The following deseription of 0. wilmarthi will notrepeat many of the eharacters already described except for 

elaboration on some points. The eomparisons of Outleria with H aptodus are based on the revised deseription 

of this latter genus by Romer and Price ( 1940, p. 297-

309) who consider the five Autunian-Rotliegende forms, 

H aptodus, "Palaeohatteria," "Pantelosaurus," "Oallibrachion," and "Datheosau.rus" as congeneric. 

The skull was erushed in such a way that the posterior half of the right side has been foreed upward 

and somewhat forward, and the posterior half of the 

left side has been forced downward and somewhat baekward. In this way, the left maxilla has been torn away 

from the more dorsal part of the snout, and the right 

orbit has been narrowed dorsoventrally. The snout was 

erushed in such a way that a line drawn along the dorsal 

surface of the anterior part of the nasal bones may be 

projected into the eenter of the orbit, while the posterior 

parts of the nasal bones remain in their original position 

anterodorsal to the orbits. 

The parts of the premaxillae anterior to the nares 

are lacking. The length of the skull, as preserved, 

measured along the left side from the most anterior 

point of the speeimen to the posterior end of the quadrate, is 137.5 mm. The right quadrate is not present, 

but if the right and left quadrates were similarly located, the same measurement on the right side would 
PERMIAN VERTEBRATES, CUTLER FORMATION, PLACERVILLE AREA, COLORADO C31 

give a length of about 125 mm. If we take the average 

of these measurements and add 5 mm for the approximate length of the missing part of the premaxilla (and 

the preserved cross sections of the anterior1nost premaxillary teeth indicate that this is a safe approximation), 

we arrive at a skull length of about 136 mm. This 

skull length is very close to that of a specimen of D,inwtrodon natal is ( 138 mm) figured by Romer and Price 

(1940, fig. 5B). This comparison accentuates the nonsphenacodontine appearance of the dentition of 0. rtoilmarthi/ D. natalis has a relatively enormous "canine" 

tooth. 

The left orbit of USNM 22099 seems to have preserved its original, nearly circular outline. It is 42.5 

mm in greatest length and 38.4 mm in greatest height. 

Crushing has reduced the height of the right orbit 

to about 30 mm. The orbits, whose centers lie about 

seventh-tenths of the way back in the length of the skull, 

bulge above the general plane of the interorbital region. The temporal fenestra, which has a narrow, 

rounded triangular shape and its anteroventral a.pex 

lying anterior to its anterodorsal angle, is about 11 mm 

long along its dorsal base and about 21 mm long along 

its slanted long axis. 

The ventral edge of the lateral surface of the skull 

is concave in the region below the orbit and temporal 

fenestra as in all sphenacodontids. As in H aptodus, 

the alveolar border of the maxilla is gently convex, but 

not so convex as in Dimetrodon andSphenacodon, where 

the convexity is accentuated by a "step" into which the 

large anterior teeth of the dentary fit in the anterior 

part of the maxilla. 

The pattern of sutures in the skull in 0. 1oilmarthi 

is mostly like that of the sphenacodontids generally and 

deserves little attention here. Figure 12.A. shows our 

identifications of the bones and fragments. The nature 

of the specimen will not permit a statement as to 

whether or not the frontal bone enters the orbital margin. The preserved part of the jugal ends anteriorly 

somewhat behind the anterior edge of the orbit, but 

this is probably due to postmortem loss of the anterior 

part; the jugal seems to have overlapped the lacrimal 

and probably terminated in an anterior angle wedged 

between lacrimal and maxilla, as in other sphenacodontids. 

Bones of the lateral surface of the snout are present 

only on the right side, except for the maxilla. The area 

of the lacrimal bone is worthy of special attention. We 

have identified a large, somewhat cresc,ent-shaped fragment of bone at the anterior edge of the orbit as the 

posterior part of the lacrimal. Anterior and dorsal to 

this lies another fragment that we have identified as the 

major part of the prefrontal. The prefrontal has a 

longitudinal fissure running through it in the specimen, 

but the bone can be traced around the junction of the 

lateral and dorsal surfaces of the skull onto the dorsal 

surface, where it meets the nasal and frontal. The 

prefrontal hides the junction of nasal and frontal fron1 

lateral view, as it does also in at least Sphenacodon 

feroJJ and Di1netrodon 1nilleri among other sphenacodontids. (See Romer and Price, 1940, figs. 4E, 5.A..) 

The rather limited entry of the prefrontal into the 

orbital margin in the specimen, as compared to the 

much more extensive entry of the lacrimal, is probably 

due to the same crushing that decreased the height of 

the right orbit; the prefrontal probably formed a larger 

part of the orbital n1argin in life than it does in the 

fossil. The distortion that displaced the prefrontal was 

probably also the cause of the longitudinal fissure in 

this bone. 

Directly anterior to the described fragments of lacrimal and prefrontal lie several s1naller fragments. The 

n1ore ventral of these, and probably a fragment anteroventral to the body of the prefrontal, are probably parts 

of the lacrin1al; the pelycosaurian lacrimal characteristically expands a short distance anterior to the orbit. 

A larger fragment anterior to these, above and immediately behind the part of the maxilla that bears the 

largest teeth, is probably part of the maxilla, although 

it is broken away from the rest of this bone; this is 

shown by the presence behind this fragment of a part 

of an unerupted replacement tooth. The 1naxilla a pparently was shallow below the orbit, expanded to a 

deptl1 of about 18-19 mm in the region of the largest 

teeth, and became shallow again as it approached the 

naris. Immediately behind the naris, entering the 

narial margin and bordered by maxilla below and nasal 

above, lies an incompletely broken fragment of bone 

that we l1ave identified as the anteriormost part of the 

lacri1nal. Crushing destroyed the connecting piece between this anteriorn1ost part and the huge orbital part 

of the lacrimal, caused the proximity of the nasal to 

the deepest part of the maxilla, and greatly altered the 

proportions of the snout in the specimen. 

Well-preserved teeth are visible only on the right side. 

The premaxillary bone is not preserved ex~,ept for very 

small fragments, but its teeth are present, although the 

anteriormost are not complete. There are two recurved 

teeth in the premaxilla, each about 6 mm long from 

alveolar border to tip. Behind these, there is a cross 

section of a mueh smaller tooth that probably also belonged to the premaxillary series. The first maxillary 

tooth lies posterior to a diastema of about 3.5 mm; this 

tooth is 4 mm long. The teeth graduaily increase in 

size for about one-third of the way back in the maxilla; 

the two largest teeth are here, as in H aptodus. (See 
C32 CONTRIBUTIONS TO PALEONTOLOGY 

Romer and Price, 1940, figs. 40, 4D.) The posterior 

one, fairly well preserved, has a length of about 9.5 mm 

and an anteropOsterior diameter, measured at the alveolar border, of 4 mm. The anterior one, whose tip 

has been broken away, may have been slightly longer. 

These two largest teeth, like all the maxillary teeth, are 

gently recurved and somewhat flattened from side to 

side; posterior to them the maxillary teeth gradually 

decrease to a least diameter of only about 1.5 mm near 

their bases. 

Crushing, with the loss of parts of the maxilla, makes 

it impossible to state accurately the number of maxillary teeth, but a rough estimate would be 20-22 ; a space 

immediately anterior to the largest teeth may represent 

a missing tooth, so that the largest teeth are either the 

fourth and fifth or the fifth and sixth in this series. 

This estimate may be compared with estimates of 22 

maxillary teeth (including empty sockets) for Haptodus longicaudatus, skull length 70 mm; and 18 for 

H aptodus saxonicus, skull length 180 mm. The two 

largest teeth are the sixth and seventh in the maxillary 

series in both H. longioaudatu-s and H. saxonicu-s. H. 

long·ioaudatu:s is pictured having three premaxillary 

teeth, the third about half the length of the anterior 

two, and H. saxonicus is pictured having five premaxillary teeth, the last so mew hat shorter than the others 

(Romer and Price, 1940, fig. 40, D). 

The depth of the mandible is greatest below the orbit 

in the region of the coronoid elevation, just behind the 

posterior termination of the dentary bone. Anterior 

to this, it becomes slimmer. Posteriorly, owing to the 

presence of the angular flange, the depth remains about 

the same as in the coronoid region until the articular 

area is reached. The flange on the angular bone and 

the posterior notch generally look like these structures 

in sphenacodontids; excavation of the matrix medial 

to the flange has demonstrated the platelike structure 

of the angular in this region. The surangular seems 

to play a somewhat more direct role in the dorsal border 

of the notch than it does in the sphenacodontines; in 

this, 0. wilmarthi resembles the condition figured for 

H aptodus saxo""icus by Romer and Price ( 1940, fig. 

4D) . The articular bone has been displaced posteriorward. Poor preservation of the bone makes analysis 

of the articular area difficult, but the articular seems to 

have carried a way with it a lateral dermal cover probably consisting of the inturned part of the angular and 

the turned-out part of the prearticular. A large opening in the right mandible, bounded by surangular, dentary and angular, is probably not a true fenestra but 

is more likely a postmortem effect of crushing. Of the 

mandibular dentition, only a few small posterior teeth 

are visible. 

The first 12 vertebrae, a few additional presacral 

vertebrae, and a few caudal vertebrae are preserved. 

Diagnostic sphenacodontid characters-a sharp ventral 

edge on the centrum, lack of extension of the neural 

canal towards the notochordal canal, and excavation of 

the lateral surfaces of the neural arches-have already 

been noted. 

The fourth vertebra has a length, measured along the 

ventral edge in a straight line, of about 12 mm. The 

transverse diameter of the posterior end of the centrum 

is 11.9 mm. The height of the neural spine, measured 

from the zygapophyses, is about 23.5 mm. By Romer's 

system of linear units, where the unit, based on the 

radius of the centrum, is equal to r 213 (Romer and 

Price, 1940, p. 8), the spine has a length of about 7.2 

units. The posterior diameter of the centrum of the 

ninth vertebra is about 12 mm, and the height of the 

neural spine of this vertebra is about 26 mm; in linear 

units, the height of this neural spine is 7.9. The spines 

of vertebrae 10, 11, and 12 are of about the same height 

as that of vertebra 9; rearward, there seems to be no 

trend to increase in elongation. The 12th vertebra, as 

shown by its position relative to the pectoral girdle and 

by the attachment to it of a long rib, is part of the dorsal 

series and well posterior to the cervical region, as is 

the 12th vertebra in all pelycosaurs. We may, therefore, take the length of 7.9 units as approximately that 

of the tallest spines, and this measurement may be compared with lengths in other pelycosaurs. 

According to Romer and Price (1940, p. 104), "Leaving aside * * * genera in which these structures are 

unusually elongated, the spine in many ophiacodonts 

and sphenacodonts tends to have a length (measured 

from the zygapophyses) of 8 to 10 units. In some 

edaphosaurs, the spines appear to have been but half 

this height." The neural spine length is about 8 units 

in the primitive sphenacodont V aranops. (Romer and 

Price, 1940, p. 274). Exact data on the sizes of adult 

vertebrae in Haptodus are not available, but a comparison of reconstructions of V aranops brevirostris and 

Haptodus saxonicus (Romer and Price, 1940, figs. 55, 

58) shows that the proportionate lengths of the spines in 

these animals must have been much the same. Immature specimens referable to H aptodus have shorter 

spines (Romer and Price, 1940, p. 306). Among the 

sphenacodontines, the length of the spines in Sphenacodon ranges from 14 to ·20 units and in D·imetrodon 

from 91 to 157 units (Romer and Price, 1940, p. 325, 

333) . The l~ngth is not known with certainty for S ecodontosaurus, but Rmner and Price (p. 313) think it 

probable that this genus paralleled Dimetrodon in the 

development of its spines. 

Outleria wil!marthi has thus retained, in the length of 
PERMIAN VERTEBRATES, CUTLER FORMATION, PLACERVILLE AREA, COLORADO C33 

its neural spines, a primitive feature i~ which it resembles the varanopsids; this feature is consonant with 

the other haptodotine fea;tures of this species. The 

neural spines in 0. wilmarthi are longer from front to 

back at the top than they are at the base. They resemble 

the spines of V aranops brevirostT'is in lateral outline and 

length but are thicker from side to side (about 5 mm) 

than those of V. brevirostris ( CNHM UR 348, about 

2mm). 

The atlanta! centrum is similar to that in Dimetrodon 

limbatus. (See Romer and Price, 1940, pl. 23E.) There 

is no line of junction with any underlying element on 

the anterior face, and the depth is about equal to that of 

the axial centrum; therefore, the atlantal centrum seems 

to have reached the ventral line of the vertebral column 

as in other sphenacodonts, but is unlike the condition 

in ophiacodontids where the axial intercentrum underlies the atlanta! centrum. The neural spine of the axis 

is longer from front to back than in the more posterior 

vertebrae. The anterior edge of the forward-projecting 

part of the axial neural spine is vertical as in V aranops 

brevirostris (Williston, 1911b, pl. I -2) and Dimetrodon 

limbatus (Romer and Price, 1940, pl. 23B). The spine 

is not continued dorsally above this forward projection 

in Outleria or in V aranops, but is in Dimetrodon. In 

Ophiacodon (Romer and Price, 1940, fig. 44A), the anterior and dorsal edges of the axial neural spine meet 

at an acute angle. In the rest of its structure, including 

the zygapophyses and diapophyses, the axis of 0. wilmarthi is much like that of D. litmbatus. 

Few proximal ends of ribs are preserved. Well-developed capitular and tubercular processes are both 

present; however, the separation of these processes is 

imperfect, and the condition is therefore intermediate 

between holocephaly and dichocephaly. The capitular 

and tubercular processes are thickened; the bone between them is thin and has a broadly concave notch at 

its proximal edge. The ribs, in their general configuration as well as in their proximal ends, resemble those 

of V aranops brevirostris figured by Williston ( 1911b, 

pl. I-1). The proximal ends of the ribs are not well 

known in H aptodus. The stage of development of the 

ribs in 0. wilmarthi is that which would be expected in 

a primitive sphenacodontid. 

There is nothing distinctive about the cleithrum. The 

ventral part of the clavicle is broadly expanded as in all 

sphenacodonts. The general character of the scapulocoracoid has already been described. The supraglenoid 

foramen is small and on the blade of the scapula, but 

very near the supraglenoid buttress, as in other sphenacodontids such as Sphenacodon ferow and Dimetrodon 

limbatus. This position contrasts with V aranops brevirostm, in which the foramen is far forward on the 

blade (Williston, 1911b, pl. V-1. Note: Williston has 

labeled all his figures of V aranops bremrostris as "V aranosmurus brevirostris," because of mistaken referral of 

the species) . The foramen also lies far forward in 

Aer·osaurus greenleorum (Romer and Price, 1940, fig. 

22) ; this position is a useful distinction, because A. 

greenleorum, a probable varanopsid, occurs in the Cutler Formation of northern New Mexico, and, being of 

about the same size as 0. wilmarthi, might be confused in 

isolated postcranial elements with this species. We have 

examined a cast of a skull of Aerosaurus sp., taken from 

a specimen at the University of California at Berkeley, 

and it is obvious that this animal is, in its cranial structure, quite different from 0. wilmarthi. V. brevirostris 

has a large incisure in the anterior border of its coracoid 

plate; no such incisure is present in 0. wilmarthi or in 

other sphenacodontids for which this part of the girdle 

is known (Romer and Price, 1940, fig. 23). 

The left humerus is present, but its ends are poorly 

preserved. It is about 82 mm long. The right radius 

and ulna are each about 67 mm long. The fact that 

the olecranon is missing probably indicates immaturity; 

it is interesting here that the only known specimens of 

V aranops brevirostris are also immature (Romer and 

Price, 1940, p. 270) and that they show little development of the olecranon. 

Outleria wilmarthi was of about the same size as 

V aranops brevirostris: the skull length is about 136 

mm as compared to 140 mm in a specimen of V. brevirostris listed by Romer and Price ( 1940, table 1) . The 

average lengths of the humerus, radius, and ulna in V. 

brevirostris are, respectively, 73 mm, 62 mm, and 57 mm 

(Romer and Price, 1940, table 5). The limbs of Outleria wilmarthi are thus proportionately longer than 

those of V. brevirostris. In this respect Outleria fits 

a sphenacodontid rather than a varanopsid pattern. 

(See Romer and Price, 1940, p. 268, 284.) 

The incompletely preserved right carpus consists of 

a fragment of the pisiform, the ulnare, a part of the 

intermedium, both centralia, and traces of the third 

and fourth distal carpalia. Both centralia are in contact with the third distal carpal, and the preaxial centrale overlaps the third distal carpal as in Dimetrodon 

but in contradistinction to the condition in Ophiacodon 

(Romer and Price, 1940, fig. 40) ; this overlap may be 

associated with the narrowing of the carpus characteristic of sphenacodontids. (See Romer and Price, 1940, 

p. 284.) The ulnare is about 21 mm long, somewhat 

more than 1.5 times as long as that of a specimen of 

V. brevirostris figured by Williston (1911b, pl. VIII); 

this measurement is in keeping with the sphenacodontid 

elongation of the limb. 
C34 CONTRIBUTIONS TO PALEONTOLOGY 

Cutleria wilmarthi Lewis and Vaughn, referred specimen 

FIGURE 12B 

We also refer a skull fragment (MCZ 2987 from loc. 

13) to the new species Outleria wilmarthi Lewis and 

Vaughn. The specimen includes right and left premaxillae, the anteriormost parts of the left nasal and 

lacrimal bones, the anterior part of the left maxilla, the 

left septomaxilla, the anterior part of the left mandible, 

the left premaxillary dentition, and the anterior parts 

of the left maxillary and mandibular dentitions. 

The premaxillae of the two sides are in contact 

throughout their entire height.. The dorsal process of 

the premaxilla fits into a rectangular indentation in the 

anterior and medial part of the nasal; it ends posteriorly at a point above the middle of the naris. The 

premaxilla is overlapped by the maxilla below the naris. 

The nasal occupies almost the entire dorsal border of 

the. naris. The ante,rior part of the lacrimal lies posterior to the fragment of the nasal bone. The suture 

between lacrimal and nasal is easily seen in the ventral 

?art of the junction of the two fragments; altho11gh it 

Is not so clearly evident dorsally, a ground section of 

the dorsal part of the junction proves that the two 

fragments are from distinct elements. The lacrimal 

overlaps the nasal in this ground section; this relationship is also seen ventrally, where the thin lacrimal occupies a plane a fraction of a millimeter lateral to the 

planes of the nasal and maxilla. 

The lacrimal probably reached the naris in life but 

now misses the narial border by about 5 mm; considerable breakage in this area also affects the maxilla. If 

the referral to 0. wilmarthi is correct, and it seems to 

us to be clearly justified, this specimen offers additional 

evidence for the entry of the lacrimal into the narial 

bor~er in this species of pelycosaur. The overlap of the 

lacrimal on the maxilla is obvious. The maxilla forms 

the posterior half of the ventral border of the naris and 

the poster?ventral corner externally, and apparently 

took part In most of the posterior border of the naris 

tmderlapping the lacrimal. 

The septomaxilla is well preserved and divides the 

na~is into an an~srior main opening and a smaller posterior septomaxillary foramen as in Dimetrodon limbatus (Romer and Price, 1940, pl. 16A-D). The foot 

of the septomaxilla rests on the premaxilla and maxilla 

where these two elements meet; its posterior arm reaches 

the nasal and maxilla and probably underlaps the 

laerimal. 

There are four premaxillary teeth. The first is small, 

abo~t 4 mm long and 1.5 mm thick at the base, but it is 

set In a large socket, almost 3 mm wide, and probably 

represents the tip of a partially erupted replacen1ent 

tooth. The second is about 9 mm long and 4.5 mm thick 

at the base. The third and fourth lie posterior to a 

disastema of 4.5 mm, and each is about 4.5 mm long. 

These two teeth, set in a posterior prolongation of the 

premaxilla under the maxilla and pressed closely together, must have functioned as a single tooth. 

The first maxillary tooth, posterior to a diastema of 

4.5 mm, is about 5 mm long and 2.7 mm thick at its base· 

behind it the teeth gradually increase in size to th~ fifth maxillary tooth (the most posterior tooth preserved) . This tooth, whose tip has been lost, was at 

least 10.5 mm long and is 5.1 mm thick at its base. The 

tooth immediately anterior to it is 6.1 mm long (from 

projected alveolar border to tip; part of the root is exposed in the specimen) . The first of the largest teeth 

in the type is either the fourth or the fifth maxillary 

to~th. ~ine teeth of the mandibular dentition, fairly 

uniform In appearance, are visible. 

The last two premaxillary and the first four maxillary teeth are reeurved, as are these teeth in the type. 

Reeurvature is not evident in the anterior premaxillary 

teeth or in the fifth maxillary tooth. The reeurvature 

of the premaxillary teeth in the type may have been accentuated by the crushing of the anterior part of the 

snout. Further, the recurvature of the first of the largest maxillary teeth in the type is less than that of the 

other. teeth; the tooth has been broken in such a way 

that It seems more recurved than it probably actually 

was. Thus, the apparent small differences in dentition 

between the type and the referred specimen may not be 

real; they are very much alike. The larger size of the 

dentition of MCZ 2987 indicates an individual of more 

advanced age than the type. 

Order PELYCOSAURIA 

Suborder EDAPHOSAURIA 

Family NITOSA URIDAE 

Mycterosaurus smithae Lewis and Vaughn, n. sp. 

Figure 13 

We name a new species of M ycterosaurus Williston, 

1915, Mycterosatl-rus Mnithae, and designate MCZ 2985 

from locality 11 as the type. The type consists of the 

most of a skull, laeking the snout; a string of five poorly 

preserved vertebrae and their ribs; the proximal half 

of a femur; the proximal half of a tibia; and other, 

poorly preserved fragments. 

This new species is best diagnosed by eomparison 

with the genotype, M ycterosaurus longiceps Williston, 

1915, as follows: Skull and postcranial skeleton of 

same size as those in M. longiceps; temporal fenestra 

of only three-tenths as much area as that in M. longiceps; zygomatic arch more than twice as deep, and distance from posterior border of temporal fenestra to 
PERMIAN VERTEBRATES, CUTLER FORMATION, PLACERVILLE AREA, COLORADO C35 

. h . I R1g t s1de 

FIGURE 13.-Skull of type specimen of Mycterosauru8 smithae n. sp., MCZ 2985. A, 

Right lateral; B, left lateral; 0, dorsal views. Fragments of a limb bone and of 

ribs are visible behind the skull. Unshaded areas represent matrix. X 1. 

posterior border of squamosal about one and one-half 

times as long as in M. longiceps; largest maxillary teeth 

about two-thirds as thick at base as in M. longiceps. 

This new species is named in honor of the late Mrs. 

Stockton Smith, of Placerville, Colo., from whose property and with whose generous cooperation many of the 

fossils described here were collected. 

Mycterosaurus longiceps Williston, 1915, is known 

only from the Mitchell Creek nodular deposit of the 

Clyde Formation of north-central Texas (the synonym 

Ettrnatthe,v·i.a bolli Broom, 1930, is based on a specimen, 

AMNH 7002, that probably came frmn the same locality). (See discussion in Romer and Price, 1940, p. 

409.) Romer and Price (1940, p. 408-412) give a full 

description of the osteology of M. longiceps. Their 

description is based not only on Williston's type 

(CNHM UC 692) but also on Broom's materials and 

on additional specimens ( CNHM UR 90 and CNHM 

UC 169). The holotype of M. longiceps consists of a 

skull and a few postcranial fragments. The greater part 

of the description of the postcranial skeleton is based 

on CNHM UR 90 and UC 169, which include no cranial 

materials. There is some reason to suspect that CNHM 

UR 90 and UC 169 might really belong to Glaucosaurus 

megalops Williston, 1915, a species based on a skull 

found in the same Mitchell Creek nodular deposit: 

Glattco8aUl"lt8 Tnegalops seems to have affinities with the 

caseid pelycosaurs; Romer and Price ( 1940, p. 421) 

consider G. megalops as "probably representing an early 

stage in the evolution of the caseids." 

One of us, in discussing the origin of the family 

Caseidae, commented on the possible caseid connections 

of G. megalops but noted that, unlike the caseids, the 

dermal roof of the skull in G. rnegalops was not pitted 

(Vauglm, 1958b, p. 988) ; this statement was based on 

published descriptions of G. rrnegalops (for example, 

Romer and Price, 1940, p. 422) . Since that time, an 

examination of the type of G. megalops (CNHM UC 

691) has demonstrated that this small pelycosaur does 

have a markedly pitted skull roof that heightens its 
C36 CONTRIBUTIONS TO PALEONTOLOGY 

resemblance to the caseids. The postcranial materials 

assigned to M ycterosaurus longiceps have a definitely 

caseidlike appearance, as noted by Romer and Price 

(1940, p. 412). The pelvis, with its remarkably long 

anterior extension of the iliac blade, is particularly 

caseidlike. The skull in G. megalops is only about threefifths as long as the skull in M. longiceps. The ratio 

of the· size of the skull to the size of the postcranial 

skeleton in the reconstruction of M. longlceps by Romer 

and Price would seem to be a ratio proper for the "normally" proportioned pelycosaurs. To put the skull of 

G. megalops onto this postcranial skeleton would seem 

to produce a pelycosaur having a disproportionately 

small head; but exactly this deviation from the "normal" pelycosaurian proportions is characteristic of the 

caseids-and we are left with our problem. 

Unfortunately, the holotype of M. smithae does not 

include really helpful evidence. The vertebrae and ribs 

are too poorly preserved to be useful here. The preserved parts of femur and tibia are near in size and 

proportions to those assigned toM. long-iceps, but it is 

not possible to say whether or not the femur in J/. 

smithae had the unusually prominent adductor crest 

seen in the femur assigned toM. longiceps. (See Romer 

and Price, 1940, p. 412.) The most that can be said of 

the type of M. smithae is that there is no evidence to 

dispute the reconstruction given by Romer and Price. 

Probably the best evidence for the correctness of their 

reconstruction is the similarity between the scapulocoracoid included in CNHM UC 169 and the scapulocoracoid 

associated with Broom's skull of M. longiceps ("Eumatthevia bolli"). We note that there is no trace of a supraglenoid foramen in either of these scapulocoracoids. 

The caseids also lack the supraglenoid foramen; this 

may further confuse or may indicate, as Romer and 

Price believe, that both M ycterosaurus and Glaucosaurus are related to the caseids. 

This problem may be resolved in the future, because 

it is now possible to compare the skulls of M. smithae 

and M. longiceps and so contribute to our knowledge of 

the skull of Mycterosaurus. 

The similarity of M. smithae to M. longicep8 convinces us that MCZ 2985 represents a species of 11/ ycterosaurus. All the snout anterior to the orbit is lacking, 

but measurements taken posterior to the anterior border 

of the orbit, including distance from anterior border 

of orbit to posteroventral corner of cheek, dimensions 

of orbit, height of temporal region, interorbital width, 

and width of parietal region, are so much like the corresponding measurements taken on the type of M. longiceps that the small discrepancies cannot be distinguished 

from possible slight changes due to distortion, and the 

estimated total length of the skull for M. longiceps 

(about 89 mm, Romer and Price, 1940, p. 433) corresponds to the estimate for the total length of the skull 

in M. smithae, assuming that the snout in M. smithae 

was as long as that in M. longweps. 

There is little possibility that M. smithae may belong 

to any other known genus of pelycosaurs. Bayloria 

more·i Olson, 1941, Tetraceratops insignis Matthew, 

1908, Elliotsmithw longiceps Broom, 1937, Anningia 

megalop8 Broom, 1927, Haptodwslongicauda&us (Credner, 1888), Oasea broilii Williston, 1910, Eothyr-Us park:eyi Romer, 1937, Oolobomycter pholeter Vaughn, 1958, 

Glaucosaurus megalops Williston, 1915, B asicranodon 

fortsillen8is Vaughn, 1958, and Nitosaurus jacksonorum 

Romer, 1937, are other small pelycosaurs with which 

M. smithae has been compared by examination of specimens or published descriptions. All these are significantly different from M. smithae in known features of 

the skull except for Basicranodon fortsillensis and Nitosaurus jacksonorum. 

Basicranodon fortsillensis is known only from a 

fragment of the brain case and may prove to belong to 

M ycterosaurus when better known. The parts that are 

known of the skull of NUosaurus jacksonorum (Romer 

and Price, 1940, p. 406), the premaxilla, maxilla, and 

dentary, with a dentition, are about the size and character of that in lJ!. smithae; therefore, we could expect 

the skulls of both to be about equal in size. The postcranial elements found in the same nodule with the skull 

of MCZ 2985 are, however, of about the sa.me size as 

the corresponding postcranial elements assigned toM. 

longiceps-the femur and tibia seem to be of the same 

dimensions, and the central lengths of the vertebrae are 

about the same-whereas both the central lengths of the 

vertebrae and the length of the tibia inN. jacksonorlun 

are about one and one-half times those in M. longicep8 

(Romer and Price, 1940, table 5). The skull in N. 

jacksonorum therefore seems to have been much smaller 

in proportion to total body size than was the skull in 

M. smithae. 

Postmortem crushing has somewhat distorted the 

skull, especially in the region of the left cheek where 

forward displacement of the squamosal has shortened 

the anteroposterior length of the temporal fenestra; the 

fenestra of the right side seems to have been preserved 

unaltered. The large orbits bulged above the general 

level of the roof of the skull, as in M ycterosauru8 longiceps. The interorbital region is narrow as in M. longicep8, and the roof widens gradually as it passes into the 

parietal region, without the abrupt postorbital widening seen in V arano8auru8 and more markedly in V aranop8. It is not possible to say whether or not the 

frontal entered the orbital margin. There is a large 

parietal foramen as in M.longiceps. 
PERMIAN VERTE.BRATES, CUTLER FORMATION, PLACERVILLE AREA, COLORADO C37 

The supratemporal is remarkably large, about 4.4 mm 

wide and a little more than twice the width of that 

restored forM. longiceps, and has an extensive contact 

with the postorbital; nothing has been known of the 

supratemporal in M ycterosaurus until now; Romer and 

Price ( 1940, p. 21) restored it in dotted outline. This 

wide supratemporal seems to corroborate the opinion of 

Romer and Price that M ycterosaurus is related to the 

caseids: the supratemporal is wide in Oasea and Ootylorhynchus, and in Oolobomycter pholeter, an eothyridid relative of the caseids (Vaughn, 1958b, p. 982). 

The posteroventral corner of th~ cheek cannot be completely determined, but the rough outline preserved on 

the right side suggests that the posterior border of the 

cheek sloped downward and backward, that the articular end of the quadrate was nearly in line with the 

maxillary tooth row, and that there was no pronounced 

concavity of the border of the cheek between the marginal dentition and the quadrate; all these features are 

in M. longiceps. The presumably long snout has not 

been preserved; therefore, the inclusion or exclusion of 

the lacrimal from the narial border cannot be determined: in M. longiceps, Oolobomycter pholeter, and in 

advanced sphenacodontids it is excluded, probably as a 

result of the enlargement of maxillary "canine" teeth. 

The maxilla in M. smithae enters the orbital margin as 

in M.longiceps and prevents a contact between lacrimal 

and jugal. This lack of contact is a rare condition in 

pelycosaurs but is found also in Oasea, Ootylorhyn.chus 

(Romer and Price, 1940, figs. 3-7, pl. 20), and therelated Eothyris (Vaughn, 1958b): this common condition is further evidence of affinity between M ycterosaurus and the caseids. 

The temporal fenestra is much smaller in M. smithae 

( 8 mm deep by 5 mm long) than in M. longiceps ( 14 mm 

deep by 10 mm long), but the shape of the fenestra, 

a vertical ellipse, is the same in the two species. The 

postorbital bar is about 3 mm thick in both species, the 

smaller size of the fenestra in M. smithae being associated with a thicker zygomatic arch and a greater postfenestral width of the squamosal. The smaller fenestra 

probably is a more primitive character than is the larger 

fenestra; it is likely that fenestral expansion in M ycterosaurus took place by thinning of the zygomatic arch 

and reduction of the postfenestral area of the 

squamosal. 

There is no appreciable difference in the structure of 

the lower jaw as compared with that of M. longiceps. 

The lower jaw is rather shallow anteriorly, is deep in 

the region of the coronoid elevation, and tapers rapidly 

to be shallow again in the articular region in both 

species. The figures in this report would give the impression of a lower jaw more shallow in the coronoid 

region than that of M. longiceps, but this appearance 

results from the separation of a fragment from the jaw. 

This fragmentary film of bone with a backing of matrix 

fits perfectly into place over the rest of the jaw and 

shows that the depth of the lower jaw near the coronoid 

elevation is about 12 mm in both species. The lower 

jaw is not well enough preserved to permit discussion 

of its individual elements. 

Only a small part of the dentition is preserved; most 

of this can be seen in the figure. A longitudinal section 

through a tooth in the right maxilla about a quarter 

of the way back in the length of the orbit shows that 

this tooth projected 4 mm beyond its socket. This projection is almost twice as long as the tooth figured in 

the same region of M. longiceps as reconstructed by 

Romer and Price ( 1940, pl. 21), but the teeth in this 

region of the type of M. longiceps are not completely 

preserved; from an inspection of their thickness at the 

lines of breakage, they seem to have been 4 mm long-or 

longer. A right maxillary tooth 15.7 mm in front of the 

anterior border of the orbit in MCZ 2985 projected at 

least 3.5 mm beyond its socket; the tip of this tooth was 

broken away, and the tooth may have been as much as 5 

mm long. This is the region of greatest elongation of 

the teeth in JJf. longiceps (in which the longest tooth has 

an estimated length of 6.5 mm, according to Romer and 

Price, 1940, pl. 21; the tips of the teeth are lacking in 

this region in the holotype) . The bases of the maxillary teeth of M. smithae (about 2 mm) are thinner than 

those of M. longiceps (about 3 mm) some 15.7 mm in 

front of the orbit. 

The considerable battery of palatal teeth is shown in 

the figure. Palatal teeth are not exposed on the holotype of M. longiceps, but Broom (1930, p. 3) noted that 

"the pterygoids show a considerable number of small 

pointed teeth in both the anterior and middle parts" of 

the type of Eumatthevia bolli ( AMNH 7002). We conelude that the upper dentitions in M. srnithae and 1.V. 

longioeps are similar but thicker and probably longer 

in ltf. longiceps. 

Several lower teeth are preserved on the left side near 

the anterior border of the orbit, and on the right side 

a short distance in front of the orbit; the longest on 

the better preserved left side are 4 mm in length and 

about 1.2 mm thick at their bases. They taper toward 

their bluntly pointed tips and are gently recurved. Two 

associated small fragments of bone having teeth of similar shape are included in the type, but these fragments 

cannot be fitted onto the rest of the skull. The dentition of the lower jaw is not known in M. longiceps. 

The remains of the postcranial skeleton are so poorly 

preserved that nothing significant can be added to the 

comments already given. There is no evidence in these 
C38 CONTRIBUTIONS TO PALEONTOLOGY 

materials to indicate that Romer and Price have not 

correctly assigned the postcranial elements in their reconstruction of AlycterosaW!"lts longiceps. It must be 

noted that although the skull of MCZ 2985 was not 

found in actual articulation with the postcranial remains, all the parts were found in the same nodule, with 

the skull lying at a right angle to the vertebral column 

and about a centimeter a way from it. 

:Mycterosaurus smithae Lewis and Vaughn, referred specimen 

The first vertebrate fossil found in the Cutler Formation at Placerville (USNM 22098 from loc. 5), a string 

of seven or more poorly preserved posterior dorsal vertebrae, a partial left femur, and fragments of other 

bones, is referred to the new pelycosaurian species A/ ycterosaurus smithae Lewis and Vaughn because of the 

similar size of the vertebrae, shape and dimensions of 

the femur, and the occurrence in the same formation 

and area as the type. The length of one vertebral centrum is about 8.5 mm compared to central lengths of 

about 6 .. 8 mm in an ?anterior dorsal vertebra of the type 

of M. 811tithae, about 6.0 nun in an anterior dorsal vertebra of the type of j;J. longiceps (CNHM UC 692), and 

about 8.5 mm in posterior dorsal vertebrae of another 

specimen referred to A!. longiceps (CNHM UC 169). 

The preservation of the vertebrae is not good enough 

to permit further comparisons. 

The femur is fairly well preserved in its proximal 

part, and is of exactly the same dimensions and proportions as in the type of AI. longiceps. Part of the 

shaft of the femur is preserved; it has the same dimensions and shape as the corresponding parts of the femora 

of M. longiceps (CNHM UC 169). The length of the 

femur probably was about equal to that of one femur 

of M. longiceps ( 49 mm) measured by Romer and Price 

(1940, table 4); they record a length of 55 mm for another such femur. No further comparisons can be made. 

Order PELYCOSAURIA 

Incertae sedis 

Several additional specimens from the Cutler Formation of the Placerville area probably represent pelycosaurs, but it has not been possible to assign these materials to definite suborders. 

Two recognizable fragments and several poor sera ps 

(MCZ 2978 from loc. 2) include a fair impression of 

what seems to be the posterior part of a pterygoid and 

three of the teeth of the transverse row and a large part 

of the quadrate process. Another fragment may be part 

of the shaft of an epipodial of a pelycosaur of the same 

size. These fragments seem to represent a pelycosaur 

about the size of Dilnetrodon limbatus. 

Two fragments of an interclavicle (MCZ 2988 from 

loc. 13) consist of the anterior part (the bowl and part 

of the shaft) and the posterior part (of the shaft) . The 

medial part is missing so that the total length is not 

known, but it was at least 77 mm long from the center 

of the bowl to the distal end of the shaft. The bowl 

is about 18 mm long and about 47 mm wide. The shaft 

is 8 mm wide, is elliptical in cross section, and has a 

thickness of about 3 mm. The distal end of the shaft 

is tapered and forked, having two prongs. The proportions of the bow I suggest that this interclavicle may have 

belonged to an ophiacodont. 

A left tibia of pelycosaurian aspect (MCZ 2986 from 

loc. 12) is about 63 mm long, 18 mm wide at its proximal 

end, 12.5 mm wide at its distal end, and 5 mm wide at the 

narrowest part of the shaft. The proximal end is not 

well preserved. This tibia resembles the tibiae of several kinds of pelycosaurs (Romer and Price, 1940, fig. 

38) in its proportions, but we are unable to suggest a 

more definite identification. 

The incomplete distal end of a femur (MCZ-no number) found 50 feet below the seymouriid vertebra (MCZ 

2983 from loc. 9) must have been at least 35 min wide, 

and seems referable to a small pelycosaur. 

Indeterminate remains 

A small, poorly preserved lower jaw having both 

rami was found at the same locality as the vertebrae 

(MCZ 2977 from loc. 1) identified as Ophlacodon sp. 

These vertebrae suggest a pelycosaur about equal in 

size to a mature specjmen of Ophiacodon navajoviCUB; 

this jaw is much too small to have belonged to the same 

skeleton as the vertebrae. The jaw bears many small, 

conical teeth and tapers towards the symphysis; it may 

not be complete posteriorly, but is about 41 mm long 

as preserved. The depth 5 mm behind the anterior end 

of the jaw is about 4 mm, but in the coronoid region 

is about 7 mm. The best preserved tooth, some 8.5 mm 

posterior to the anterior end of the jaw, is about 1 mm 

long from alveolar border to tip. A section through one 

of these teeth shows no sign of labyrinthodonty. This 

jaw is too small to warrant even tentative assignment 

to M ycterosaWf"U.8 smithae, but is probably reptilian, 

possibly pelycosaurian, and must remain indeterminate 

until better specimens of the same animal are known. 

One poor, unidentifiable fragment of bone (MCZ 2990 

from loc. 15) probably is part of a dermal skull roo£. 

Several other scraps of bone were found with the distal part of the probably pelycosaurian femur described 

in the last section. One sera p is probably part of a 

dermal skull roof. Two others are fragments of either 

one or two vertebrae that indicate a centrum about 15 

mm wide and a neural arch in which the lateralmost 
PERMIAN VERTE.BRATES, CUTLER FORMATION, PLACERVILLE AREA, COLORADO C39 

points on the postzygapophyses are about 23 mm apart. 

This vertebra may be that of a captorinomorph 

cotylosaur. 

AGE AND CORRELATION OF THE FAUNA 

COMPARISON WITH EARLY PERMIAN FAUNAS OF 

NORTH AMERICA 

Analysis of the significance of the several faunal elements frmn the Cutler Formation of the Placerville 

area and consideration of the fauna as a whole make 

possible the correlation of the upper part of the Cutler 

of Colorado with other stratigraphic units in the United 

States beyond much reasonable doubt. 

The presence of Eryops cf. E. grandis in the fauna of 

the Cutler at Placerville is of no great help in precise 

correlation: although the specimen corresponds 1nost 

closely to E. gra.ndis of the Cutler of New Mexico, the 

genus is known to have existed frmn early Conemaugh 

time to late Arroyo time (Vaughn, 1958a). The most 

that can be said is that specific differences in this genus 

are based largely on size differences, and the specimens 

from the Cutler, both of Colorado and New Mexico, 

tend to be sn1aller than those from the Wichita and 

Clear Fork 'Groups of Texas. 

The n1onotypic genus Platyhystriw has been unknown until this time frmn anywhere except the Cutler 

Formation outcrops near Arroyo de Agua, Rio Arriba 

County, N.Mex., and from the Halgaito Tongue in San 

Juan County, Utah (Platyhystriw cf. P. mgosus, 

V a uglm, 1962, p. 534-535). Langston ( 1953, p. 409-

411) concluded that the vertebrate fauna from the Cutler near Arroyo de Agua is equivalent in age to the 

faunas from the Moran and Admiral Formations of the 

Wichita Group of north-central Texas, which are the 

continental equivalents of the uper part of the marine 

Wolfcamp to the west and southwest. Vaughn (1962, 

p. 538) believes that the Halgaito Tongue also is of 

Wolfcamp age. The presence of P. rugosus in the Cutler at Placerville is excellent evidence of a late Wolfcamp age. 

We believe that the new but unnamed sey1nouriid 

from the Cutler of the Placerville area represents a morphologically more primitive genus than Sey1nouria,, 

probably of about the same age as that of the faunas of 

the lower to middle part of the Wiehita Group of Texas. 

This unna1ned ·sey1nouriid has been eompa.red to the 

somewhat younger 8eymmtria. baylorensis of the Clear 

Fork Group of Texas, but not to the inadequately known 

Seyrnouri..a of the Moran, Putnam, and Admiral Formations in the Wichita Group. 

Diadectes sanrr!Jiguelensi.s is not the first diadectid to 

be reported from Colorado: one was found in the Sangre de Cristo Formation in Fremont County (Brill, 

1952, p. 834) . The known diadectids frmn the Cutler 

(formerly designated "Abo") Formation of northern 

New Mexico are Diadectes lent'tts and Dia.sparactus 

zenos. The immaturity of the type makes Diadectes 

sanrrdg'ttelen.<si.s of little value in stratigraphic correlation because of the uncertainty of its taxonomic affinities; its resemblance in some respects to Desmatodon 

might suggest the possibility of an age near the Pennsylvanian-Pennian boundary. But Diadectes sensu 

stricto is restricted to Early Permian time, and there is 

no cogent reason to sugge.-;t that D. san1nig·uelensi.s is 

pre-Pennian in age, older than the C1.1tler of New 

Mexico. 

We have named and described Li1nnoscelops longijemJUr as a 1nember of the Limnoscelidae, a family otherwise known only fron1 the Cutler of northern New 

Mexico, the Halgaito Tongue of southeasten1 Utah, and 

from the Dunkard Group of the Ohio-PennsylvaniaWest Virginia area of the Eastern United States. L. 

longije'lTvur semns to indicate an Early Per1nian age and 

a stratigraphic position that corresponds to that of the 

Cutler Formation of New Mexico, whence comes Li1nnoscel·is, and the Dunkard Group of West Virginia 

where the new limnoscelid's nearest known relative, 

Li1nnoscelo·ides dttnkardensis, was fmmd (Romer, 1952, 

p. 88-92, 99-100). Both the Cutler of New Mexico 

and the Dunkard correlated with the lower to middle 

parts of the Wichita Group of Texas. 

The captorhinomorph cotylosaur of undetermined 

genus and specie.s belongs to a suborder that ranges from 

Upper Pennsylvanian to middle Permian rocks in 

North America. If it is a member of the ca ptorhinid 

family, as we believe, then it belongs to a fa1nily that 

ranges from Lower to middle Permian in North America; it most closely resembles Oaptorh/nikos chozaens-i.s, 

a species from the upper part of the Clear Fork Group 

of Texas. Therefore its age probably is Early Permian. 

Ophiacodont.ids, in the form of Olepsydrops, first 

appeared in Late Pennsylvanian time (Romer, 1961, p. 

1, 4; Romer and Price, 1940, p. 212; Peabody, 1957, p. 

947), but Ophiacodon apparently was restricted to the 

time of deposition of the Cutler Fonnation in Colorado 

and New Mexico, and of the Wichita Group of Texas. 

The vertebrae of Ophiacodon from the Cutler at Plaeerville, insofar as their size and morphology are coneerned, 

agree with those of 0. navaj<JtJicus and are very similar 

to those of 0. 1nir'tt.s, both from the Cutler of New Mexico. Ophia.eodon nniformis, the Texas species most 

c.losely related to 0. na·z,ajovic'lt8 and 0. 1niru.s, ranges 

from the Putnam Formation to the Clyde Formation 

of the Wichita Group (Romer and Price, 1940, p. 242). 

Accordingly, the Ophiacodon in the Cutler Formation 

at Placerville is still another item of evidence for cor-
C40 CONTRIBUTIONS TO PALEONTOLOGY 

relating the upper part of the Cutler of Colorado with 

the Cutler of New Mexico and the middle part of the 

Wichita Group of Texas. 

The nearest relatives of Outleria wilirrlarthi are the 

species of H aptod?M from the European Autunian and 

Rotliegende. Because the new genus and species from 

the Cutler of the Placerville area of Colorado represent 

the first-recorded non-European ha ptodontine, this specimen offers no chance for direct comparisons with other 

North American faunal elements. Sphenacodon, known 

only from the Cutler of New Mexico, is very similar 

to the short-bodied species of Dimetrodon from the 

lower to middle part of the Wichita Group of Texas 

(to which they are restricted; the more advanced species 

of this genus are known only from younger formations 

of Texas) except for the much less elongate neural spines 

and the slightly less specialized dentition of Sphenaaodon. The morphological evolutionary sequence leading to the more advanced species of Dimetrodon probably paralleled the stages shown by the series of contemporaries Outleria of the Cutler of Colorado to 

Sphenacodon of the Cutler of New Mexico to Dimetrodon of the Wichita of Texas. 

M ycterosaurus smithae, the new species from the Cutler at Placerville, seems to be more primitive than its 

nearest relative M. longicep8 from the Clyde Formation of Texas, whose thicker teeth and larger temporal 

fenestra may reasonably be considered as more advanced. This evidence, although inconclusive, does 

suggest a somewhat older age than that of the Clyde, 

and, once more, possible equivalence with the Moran 

and Admiral Formations of Texas. 

Brill ( 1952, p. 834, 870) reported the discovery of 

Diadecte8 sp. and pelycosaurs in the Sangre de Cristo 

Formation in westernmost Fremont County, Colo., 

about 120 miles eastward from the Placerville area 

across the old Uncompahgre highland area of Early 

Permian time. It is entirely probable that the two 

faunas and those parts of the Cutler and Sangre de 

Cristo Formations in which they occur are virtually 

contemporaneous. 

'The area of outcrop of the vertebrate-bearing Permian formations of Texas has been the classic collecting ground for what are perhaps the best known Permian vertebrate faunas in the United States. Just as 

Marsh is remembered for having pioneered in research 

on the Baldwin collection from the New Mexican Permian red beds, Cope is remembered for having pioneered 

in research on the Boll collection from the Texas red 

beds, and both continued their researches for some two 

decades. We have known of these faunas for some 85 

years because of these rival pioneers, each having first 

published reports on the Permian age and the paleontology of these respective areas of interest in the same year 

(1878). Case (1908, 1911a, 1911b) and Williston 

(1911a, 1911b, 1912) both collected and studied Permian 

vertebrates after the deaths of Marsh and Cope. Williston's successor at the University of Chicago, Romer, 

and the latter's students both at Chicago and Harvard, 

have devoted many years to extremely informative and 

useful work on the American Permian vertebrate faunas and related subjects. 

We have made frequent reference to faunal elements 

of the Texas Permian red beds. The general information on the geology (Moore, 1949) and paleontology 

(Romer, 1958) of these rocks has been so well summarized by others that only an outline, and some of the 

more pertinent details, need be repeated here. 

Moore ( 1949) considered that the Pueblo, Moran, 

Putnam, Admiral (these four of W olfcam p age), Belle 

Plains, Clyde, and Lueders (these three of Leonard~ 

age) make up the Wichita Group, and that the Arroyo 

Formation is at the base of the Clear Fork Group; this 

is the nsage now accepted and used by us in this report. 

So recently as 1935, Romer (19'35, fig. 2, p. 1604, and 

fig. 5, p. 1654) considered that the Wichita Group 

(including the Moran, Putnam, Admiral, and Belle 

Plains Formations) marked the top of the Pennsylvanian, and the Clear Fork Group (including the Clyde, 

Lueders, Arroyo, Vale, and Choza Formations) the base 

of the Permian. Romer and Price (1940, p. 23) showed 

the definitely "Pennsylvanian" Cisco Group as including the Pueblo Formation, overlain by the "Permian or 

Pennsylvanian" Moran, Putnam, Admiral, and Belle 

Plains Formations to make up the Wichita Group, overlain by the definitely "Permian" Clear Fork Group including the Clyde and Arroyo Formations in northcentral Texas. 

Olson ( 1955, p. 226) believed the Permian sequence 

involved to be, in ascending order, as follows: the 

Moran, Putnam, Admiral, Belle Plains, and Clyde Formations making up the Wichita Group; the Lueders, 

Arroyo, Vale, and Choza Formations, the Clear Fork 

Group. Seltin's interpretation (1959, p. 498) of these 

Permian stratigraphic divisions is, in ascending order, 

as follows: the Early Permian Admiral, Belle Plains, 

and Clyde Formations comprising the Wichita Group; 

the Leuders [sic], Arroyo, Vale, and Choza Formations, 

the Clear Fork Group. 

Omitting those genera which offer no basis for correlation, what fatmal elements of the upper Paleozoic red 

beds of Texas are pertinent for comparison with the 

fauna of the Cutler Formation in the Placerville area 

of Colorado~ Of a score of amphibians, only Eryops is 

common to the Cutler of Placerville and the Wichita 

and Clear Fork of Texas; we have already pointed out 
PERMIAN VERTE.BRATES, CUTLER FORMATION, PLACE-RVILLE AREA, COLORADO C41 

that this genus ranges throughout the Wichita and Clear 

Fork, and that the smaller individuals that tend to occur 

in the lower parts of the Wichita are -closer to the Cutler 

specimen than are those from the upper part of the 

Wichita and from the Clear Fork. The Cutler seymouriid seems more primitive than Seym,.otUrria baylorensi8 of the Clear Fork; we have not had the 

opportunity to compare it with the inadequately known 

Seymmtria from the Wichita. The immature D·iadectes 

sanmiguelensis, though smaller, more closely resembles 

D. lentU8 from the Cutler of New Mexico than it does 

any of the even larger adults of the two Texan species, 

D. sideropelicus and D. tenuitectus, with which meaningful comparisons of stratigraphic implication cannot 

be made bceause of the immaturity of the specimen. 

Limnoscelops longifemur is nearer to the limnoscelids-especially to Lim;noscelo·ides-than any other captorhinomorphs; Limnosceloides of the Dunkard and 

Lirwnoscelis of the New Mexican Cutler· are of Wolfcamp age. The femur of Lim;noscelops does, however, 

show a morphological approach to that of OaptorhinU8, 

a genus that appears in the middle part of the Wichita. 

The captorhinomorph of undetermined genus and species from the Cutler at Placerville most closely resembles 0 aptorhinikos of the Vale and Choza Formations 

of the Clear Fork Group, but we are not certain that 

it belongs to the same family. 

The Opkiacodon is closest to 0. uniformis if compared to the Texan species of this typically Wichita 

genus (Romer and Price, 1940, p. 230); 0. uniformis 

first appears in the Putnam Formation. 

M ycterosaurus smithae from the Cutler at Placerville 

seems to be more primitive than its nearest relative, M. 

longiceps of the Clyde Formation; this feature suggests 

an age for M. smithae equivalent to that of the Moran 

or Admiral Formations. 

After weighing all this evidence, we conclude that 

the upper part of the Cutler Formation, exposed in the 

Placerville area of Colorado, probably is equivalent in 

age and stratigraphic position to the Moran, Putnam, 

and Admiral Formations of Texas. 

The fauna of the Cutler at Placerville is not comparable to that of the Hennesey and other formations of 

Oklahoma which seem without exception to be of Clear 

Fork age (Romer and Price, 1940, p. 28). 

Marsh (1878, p. 409) was the pioneer who placed 

the Cutler of New Mexico in the Permian, but opinion 

has varied. Williston and Case (1912, p. 4, 12) believed 

it to be "in part at least of upper Pennsylvanian age." 

Darton ( 1928, p. 158, pl. 37) stated that the age is 

Permian and published a reconnaissance geologic map 

that shows the chief areas of outcrop of the vertebrate·· 

bearing Cutler of New Mexico. Not many years ago, 

Romer (1935, p. 1629, 1633-1635, 1650-1653) believed 

the Cutler of New Mexico to be Pennsylvanian, even 

lower than the Wichita Group of Texas, which hereferred to the top of the Pennsylvanian. Romer and 

Price (1940, p. 23-24, 28-30, 33-34) placed the Pennsylvanian-Permian boundary "between lower and upper 

Wichita" and correlated all the Cutler of New Mexico 

with the Wichita except for the Cutler at El Cobre 

Canyon which they considered provisionally to be Upper Pennsylvanian. Romer (1946, p. 186) continued to 

believe that the El Cobre Canyon fauna "may well be 

of uppermost Pennsylvanian rather than lower Permian." Later he (Romer, 1958, p. 164) stated: "It has 

been frequently assumed that the base of the Permian 

in Texas was the base of the Wichita Group, although 

some workers, as the writer on occasion (1935), have advocated a higher position * * * the whole question of 

the boundary is as yet unsettled." 

A different opinion was held by Langston ( 1953, p. 

409-410, 412), who considered that the evidence from 

most of the fish, amphibian, and reptilian faunas of 

the New Mexican Cutler indicated an age about the 

same -as the comparable faunas "from the lower and 

middle Wichita (Moran-Admiral) beds of Texas," and 

that there was little value in assigning the El Cobre 

Canyon fauna of the Cutler to the Pennsylvanian on 

morphological grounds alone, the conservative course 

being to consider it also as Permian. But the senior 

writer joined Romer only a few years ago (in Bush and 

others, 1959, p. 313) when the fossils had "not been 

completely removed from the rock matrix and fully 

prepared," to make a tentative correlation of the Cutler 

at Placerville with that ("Abo") at El Cobre Canyon. 

They pointed out the moot question of the position of 

the Wiqhita Group, and reached the tentative conclusion that the Cutler at Placerville might be either very 

low Permian or uppermost Pennsylvanian. But the 

present, more detailed study after the fossils have all 

been fully prepared has necessitated considerable revision of the 1959 faunal list, and has convinced us that 

the age is Early Permian beyond all reasonable doubt, 

equivalent to that of the Moran, Putnam, and Admiral 

Formations of Texas. 

We reached the same conclusion with regard to the 

Cutler of El Cobre Canyon, N. Mex. One of us 

(Vaughn, 1963, p. 286) has now made further collections there and, after studying all the old and new 

evidence, concluded once more that it "would seem to 

demonstrate equivalence in age of the El Cobre and the 

Arroyo de Agua beds * * * to the lower and middle 

parts of the Wichita Group* * * (Wolfcampian) * * * 

Early Permian." 
C42 CONTRIBUTIONS TO PALEONTOLOGY 

The basic similarity of the Cutler faunal assemblages 

from Placerville and New Mexico is to be expected when 

we consider their apparent equivalence in age, their 

proximity, and their similar paleogeographic situations: both assemblages lived during about the same 

time near the southwestern edge of the ancient Uncompahgre highland (Baker, Dane, and Reeside, 1933, p. 

975). Erosion of this highland yielded the clastic sediments of the continental area where these land-dwelling 

vertebrates lived in Early Permian time. 

To a somewhat lesser degree, a similar situation obtains in the more distant Monument Valley area of 

northeasten1 Arizona and southeastern Utah, where 

Baker ( 1936, p. 29, 30, 35) reported the discovery of 

fragmentary remains of fossil vertebrates in the Cutler 

Formation, where it is divided into subordinate units 

named (in ascending order) the Halgaito Tongue, 

the Cedar Mesa Sandstone Member, the Organ Rock 

Tongue, the De Chelly Sandstone Member, and 

the Hoskinnini Tongue. The Halgaito and Organ 

Rock Tongues yielded Baker's very fragmentary fossil 

vertebrates, determined by Case to be of Permian age ; 

they were Ophiacodmd ["Ephiaoodon" (sic) ]'or Sphenacodon? of the Halgaito, Diadectes? ["N otodon" 

(sic)] and Sphenacodon? of the Organ Rock. Fossil 

plants from the Organ Rock Tongue were also determined to be of Permian age by White. No vertebrate 

fossils were reported from the typical sandstone 

members. 

Recently, Vaughn ( 1962, p. 532-538) reported the 

discovery of much better material from the Halgaito 

Tongue, including Eryops sp., Platyhystrix cf. P. 

rugosus, Diadectes sp., a limnoscelid that may be specifically identical to Lirrvnoscelops longifemrur, Ophiacodon cf. 0. navajovicus, and a sphenacodontid pelycosaur close to if not generically identical to Sphenaeodon. On the basis of this faunal evidence, he believes 

"the Halgaito Tongue * * * in the vicinity of Mexican 

Hat, Utah is Wolfcampian in age* * * dearly * * * 

of Early Permian age, but greater in age than the Clear 

Fork Group of northcentral Texas." This is the same 

conclusion that we have reached about the upper part 

of the Cutler Formation where it crops out in the Placerville area of Colorado. Moreover, our faunal list from 

the latter, when cmnpared to Vaughn's faunal list from 

the Halgaito Tongue of the Cutler, and with the probable Diadectes ["Notodon" (sic)] and "Sphenacodon?" 

reported by Baker (1936, p. 35) from the Organ Rock 

Tongue, an association cha:~acteristic of the Cutler of 

New Mexico, clearly indicates virtual contemporaneity. 

It has been shown that Diadectes sanmiguelensis, 

although having some points in common with Desmatodon hollandi of the Conemaugh, is nevertheless probably referable to D iadectes and closest to the Early 

Permian species D. lentus of the Cutler of New Mexico. 

Linvnoscelops long,ifemur, however, has as its nearest 

demonstrable relative Lhnnosceloides drztnkardensis 

from the Dm1kard of West Virginia, a group of rocks 

; that has also yielded an Ophiacodon-like animal 

(Romer, 1952, p. 88, 96). Ophiacodon is a genus typical 

of the Wichita Group of Texas and of the Cutler Formation of New Mexico. Romer (1952, p. 100) concluded that "the Dtmkard, as a whole, is essentially comparable to the Wichita Group of Texas" in spite of the 

difference in faunal facies. We agree with Romer, and 

believe that the ages of the faunas from the Cutler of 

Placerville, Colo., the New Mexican Cutler, the lower 

and middle parts of the Wichita of Texas, and the 

Dunkard of the Ohio River valley are virtually the 

same. 

The most recent report on the fauna of the red beds 

of Prince Edward Island, Canada, is by Langston 

(1963), who lists: two genera of fish; Eryops Jnegacephalus; a brachyopid; a small Seymouria sp.; a very 

small diadectid; a Diadectes sp. similar to the diadectid 

of the species of the Admiral Formation; an ophiacodont; the sphenacodontid B athygnathus borealis; a 

nitosaurid close to M ycterosaurus; and the caseid Trichasaurus sp. The fauna shows relationship to the Cutler, Wichita, and early Clear Fork faunas and to the 

Autunian-Rotliegende faunas, which is not surprising 

when we consider that Prince Edward Island is about 

midway between these other occurrences. These Early 

Permian faunal assemblages probably had a fairly continuous holarctic distribution. 

COMPARISON WITH EUROPEAN EARLY PERMIAN 

FAUNAS 

Outleria wibnarthi is the first haptodontine pelycosaur to be described from North America. H aptodus, 

of the Autunian of France and the lower Roliegende of 

Germany, is closely comparable to the new genus from 

the Cutler except for the shape of the temporal fenestra. 

Outleria, like H aptodus, is a morphologically primitive 

sphenacodontid that differs from the more advanced 

but contemporary sphenacodontines in the lack of a 

"step" in the upper jaw, in the lack of development of 

"canines," and in the short neural spines of the 

vertebrae. 

Orzdl eria, very close in morphology and stage of evolution-and therefore also very close in age-to H a,ptodu,s 

of the Lower Permian Autunian and Rotliegende of 

western Europe, is the newest link in the chain of eviclence that shows the virtual contemporaneity of these 

two European stratigraphic units to the Cutler, Moran, 

Putnam, and Admiral Formations. As they are becoming better known, it becomes increasingly clear that 
PERMIAN VERTE.BRATE,S, CUTLER FORMATION, PLACERVILLE AREA, COLORADO C43 

the Early Permian European and North American vertebrate faunas were much alike. Among the reptiles, 

we may cite the similarity of the following North American and European genera respectively: the captorhinids 

Oa.ptorhin-ikos and Gecatogornphi~ts, the areaeoscelids 

A ra.emwelis and K a.daliosa.urus, the diade.ctids Diadectes 

and Pha.nerosa.urus, the pelycosaurs Ootylorhynchus 

and Enna.tosa.urus, Edaphosa.ur1.ts nOL'Omewicanus and 

E. credneri, Outleria and H a.ptodus. The plants, fish 

and amphibians show comparable resemblances. 

The Autunian and lower part of the Rotlieg~nde o:f 

Europe ( Gignoux, 1960, p. 17 4-176, 244-252), the Dunkard of Ohio and "\Vest Virginia, the Cutler and Sangre 

de Cristo of Colorado and New Mexico, the Pueblo, 

Moran, Putnam, and Admiral of Texas, and their correlatives in nearby States are continental facies and 

age equivalents of the marine W olfcamp of Texas and 

the Sakmarian Stage of Russia. 

PALEOGEOGRAPHIC CONSIDERATIONS 

The geologic and paleogeographic environments o:E 

the western and central European areas where Lower 

Permian continental vertebrate-bearing rocks crop out 

are so similar to those of comparable North American 

rocks that they lead to an inescapable conclusion: the 

Early Permian fish, amphibians, and reptiles lived in 

remarkably similar environments in these two parts o:E 

the world. 

The Early Permian animals and plants of what is 

now the Placerville area of Colorado lived in a-for 

those times-fairly typical continental environment, 

just south of the ancient Uncompahgre highlands o:E 

Precambrian crystalline rocks. The erosion of thes«~ 

rocks, under climatic conditions of at least seasonal 

aridity, produced highly arkosic sediments. The Cutler Formation increases in thickness from the type locality on Cutler Creek (about 2,000 ft) to the Placerville area (about 4,000 ft) 20 1niles to the west. Some 

60 miles farther west-north west, in the Paradox Basin, 

the Cutler Formation ranges from 0 to 8,000 feet in 

thickness near the Uncompahgre front. "In late Paleozoic time the Uncompahgre uplift * * * was bordered 

on the southwest by the deep Paradox Basin * * * 

About 16,000 feet of Pennsylvania, Permian, and Lower 

to Middle ( ? ) Triassic strata fill the trough and pinch 

out abruptly against the Uncompahgre front" (Elston, 

Shoemaker, and Landis, 1962, p. 1858, 1861). 

The Early Permian uplands and highlands of Colorado (Uncompahgre and Front Range), New Mexico 

(Bravo, Defiance, Pedernal, Sierra Grande, and Zuni), 

Arizona (Defiance) , and Texas (Amarillo, Cimarron, 

Matador, and Wichita) are all ancient positive areas 

of Precambrian crystalline rocks, across some of which 

Pennsylvanian or older Paleozoic rocks overlap. Early 

Permian detritus from these high areas flooded into the 

basins and troughs that flank them to become the Lower 

Permian fanglmnerates, arkosic and other continental 

clastic rocks that reflect increasing semiaridity and aridity. The occasional transgressions of shallow arms of 

the seas that lay to the south and west were of limited 

extent and duration before regression; they probably 

took place first in one area, then in another, and so on, 

never flooding more than a part of some of the basins 

or troughs at any one ti1ne. But the paleogeographic 

and paleotectonic situation was probably such that many 

land-dwelling vertebrate genera and species were able 

to migrate from one region to another. The supposed 

Early Permian sea often postulated (for example, Hills, 

1942, fig. 3) as a continuous barrier between the "fourcorners" area and the north -central Texas area probably never existed. 

Gilluly (1963, p. 143-144, fig. 7) recently outlined 

the Pennsylvanian and Permian structural evolution 

that produeed this paleogeographic environment in the 

Roeky Mountain area.: 

The best known of the * * * orogenies took place in Colorado and Wyoming, where the former shelf area was broken by 

huge normal faults and block uplifts to form the Ancestral 

Rockies * * * Most of these tilted horsts and trap-door uplifts 

exposed Pre-Cambrian plutonic bodies from the beginning, and 

some of those that originally had thin cara{Jaces of Paleozoic 

sedimentary rocks were soon denuded. From the uplifts huge 

volumes of coarse arkose spilled into the bordering lowlands, 

to form deposits, partly continental, partly marine * * * In 

some of the deeper basins the total thickness, which includes 

an unknown thickness of Permian beds, is as much as 13,000 

ft * * * The uplifts began in Early Pennsylvanian times and 

continued through Early Permian times, at different rates in 

different places. 

In western and central Europe, there were severa] 

large dry-land areas of older rocks formed by Variscan 

and Sudetian folding during Carboniferous time. They 

were flanked by basins and troughs into which poured 

the detritus eroded from the uplands and highlands of 

ancient rocks. These areas of dry land, having Precambrian rocks at their cores, existed in France (Massif 

Central and Vosges), Germany (Black Forest, Rhenish 

Massif, Fichtelgebirge, Erzgebirge, and Schiefergebirge), and Czechoslovakia (Sudeten Mountains and 

Bohemian Massif) . The flanking troughs were continental geosynclinal areas formed by the coalescence of 

Stephanian basins. Brinkmann ( 1954, p. 125) has 

pointed out that the noteworthy Autun and Creusot 

troughs of the Massif Central area can be traced to the 

upper Rhine, along both sides of the Black Forest and 

Vosges Massifs, and onward into central Bohemia. 

The Autunian (Franee) and lower Rotliegende (Germany) sediments flooded into the troughs as piedmont, 

flood-plain, and littoral deposits; the isostatic response 
C44 CONTRIBUTIONS TO PALEONTOLOGY 

to the weight of these deposits permitted their accumulation to thicknesses as much as 2,000 m during Early 

Permian time, when the sea transgressed southward 

during only a short interval and never extended farther 

than the North German Basin. 

Increasing aridity, indicated by the record in the 

rocks, progressed from Stephanian (Late Carboniferous) time through Autunian (Early Permian) and 

became intense in Saxonian (middle Permian) time 

when the upper part of the Rotliegende accumulated 

to thicknesses of as much as 800 m. Early in the Permian, deposition of some carbonaceous clastic sediment 

and a few thin coal seams, as well as brown and red 

arkosic sediments, shows that there was some alternation between times of humid, semiarid, and arid cli1nate. 

The Indo-Gangetic alluvial area of India today ma.y 

show us analogous environmental situations where previously existing seaways have been silted up in the not 

very remote past. Near the coast, the Lower Permian 

probably was deposited in an environment most closely 

paralleled today in the Kathiawar-Cutch area with its 

monsoon climate: 

Some 46,000 sq mls between the Rann of Cutch and the Gulf 

of Cambay is a world apart * * * The Rann is a vast expanse 

of naked tidal mudflats * * * here and there the banks of dead 

creeks are picked out in a white skeletal outline of salt or scum. 

To the N the desert of mud and the desert of sand in the Thar 

merge almost imperceptibly. The normal dendritic pattern of 

the creeks has been interrupted by earthquakes * * * prolonged 

silting by the mainland rivers 1and tectonic uplift have attached 

it to the mainland * * * The old channel (doubtless tidal or 

seasonal) joining the Little Rann * * * and the Gulf of Cambay is marked by the lakes and marshes of the Nal depression * * * Physically it is an alternation of little * * * plateaus * * * and tiny alluvial basins * * ·* The environment is 

generally arid enough, but * * * there is some climate variation. Cutch averages 12-15 ins., and as little as 1.4 have been 

recorded; from the.air, the arid aspect of its erosional features 

is striking. The Kathiawar coastlands, except in the SE, re.-

ceive 15-20 ins., but the highland centre and the Cambay coast 

have over 25 and Junagadh * * * about 40 * * * The natural 

cover of most of the region is * * * very open and l;tunted * * • 

almost desert in places (Spate, 1954, p. 595-598) . 

The more inland areas could have resembled more 

inland parts of the Indus or Ganges-Brahmaputra 

Valleys: 

The western valley section * * * orf Sind * * * is probably 

an old Indus course; it expands in the S into the marshy Lake 

Manchar, which when full covers some 200 sq mls and is then 

the largest fresh-water lake in India. It is alternately fed and 

drained by the Aral, a stream reversible as the Indus is high 

or low. At low water Manchar covers only 14 s.q mls * * * 

The Assam or Brahmaputra Valley is an extension of the 

Indo-Gangetic trough * * * extends for over 400 mls * * * 

most of this great area is formed of the detrital terraces of the 

Brahmaputra and its numerous tributaries * * * The channel 

is of course braided and shifting * * *The climate shows some 

slight modification of the standard monsoonal type * * * Large 

areas are covered with sal forest and with tall reed-jungle 

in the swamps and jhils of the immense floodplain (Spate, 1954, 

p. 551-553) . 

Similar conditions are found today in the Orinoco 

and Amazon Basins. 

Given these paleogeographic similarities, it is no accident that there are striking stratigraphic, paleontologic, and paleobotanic resemblances between not only 

the American and European continental Permian, but 

also Lower and Upper Triassic, the time of deposition of 

which saw a continuation of similar environments on 

both continents. 

SELECTED REFERENCES 

Baker, A. A., 1936, Geology of the Monument Valley-Navajo 

Mountain region, San Juan County, Utah: U.S. Geol. Survey 

Bull. 865, 106 p. 

Baker, A. A., and Reeside, J. B., Jr., 1929, Correlation of the 

Permian of southern Utah, northern Arizona, northwestern 

New Mexico, and southwestern Colorado: Am. Assoc. Petroleum Geologists Bull., v.13, p. 1413-1448. 

Baker, A. A., Dane, C. H., and Reeside, J. B., Jr., 1933, Paradox 

formation of eastern Utah and western Colorado: Am. Assoc. 

Petroleum Geologists Bull., v.17, p. 963-980. 

Brill, K. G., Jr., 1952, Stratigraphy in the Permo-Pennsylvanian 

zeugogeosyncline of Colorado and northern New Mexico: Geol. 

Soc. America Bull., v. 63, no. 8, p. 809--880. 

Brinkmann, Roland, 1954, Abriss der Geologie: 7th ed., Stuttgart, F. Enke, v. 2, 359 p. 

Broom, Robert, 1930, On a new primitive theromorph ( Eumatthe'IJia bolli) : Am. Mus. Novitates, no. 446, p. 1-4. 

Brown, R. W., 1956, Palmlike plants from the Dolores formation (Triassic), southwestern Colorado: U.S. Geol. Survey 

Prof. Paper 274-H, p. 205-209. 

Burbank, W. A., 1930, Revision of geologic structure and stratigraphy in the Ouray district of COlorado, and its bearing on 

ore deposition: Colorado Sci. Soc. Proc., v. 12, p. 151-232. 

Bush, A. L., Bromfield, 0. S., and Pierson, C. T., 1959, Areal 

geology of the Placerville quadrangle, Colorado: U.S. Geol. 

Survey Bull. 1072-E, p. 299-384, pls. 4-8, figs. 1~ 16. 

Bush, A. L., Marsh, 0. 'T., and Taylor, R. B., 1960, Areal geology 

of the Little Cone quadrangle, Colorado: U.S. Geol. Survey 

Bull.1082-G, p. 423-492, pls.18-19, figs. 42-46. 

Case, E. C., 1907, Revision of the Pelycosauria of North America: 

Carnegie Inst. Washington Pub. 55, 176 p. 

---1908, Description of vertebrate fossils from the vicinity 

of Pittsburgh, Pennsylvania: Carnegie Mus. Annals, v. 4, p. 

234-241. 

---1910, New or little known reptiles and amphibians from 

the Permian(?) of Texas: Am. Mus. Nat. Hist. Bull., v. 28, p. 

163-181. 

---1911a, A revision of the Cotylosauria of North America: 

Carnegie Inst. Washington Pub. 145, p. 1-122. 

---1911b, Revision of the Amphibia and Pisces of the Permian 

of North Ameriea: Carnegie Inst. Washington Pub. 146, p. 

1-179. 

Case, E. C., and Williston, S. W., 1912, A description of the skulls 

of Diadectes lentus and Animasa1u·us carinatus: Am. Jour. Sci. 

v. 33, p. 339-348. 

---1913, Description of a nearly complete skeleton of Diasparactus zenos Case, in Case, E. C., and others, Permo-Carbon-
PERMIAN VERTE.BRATE.S, CUTLER FOJRMATION, PLACERVILLE AREA, COLORADO C45 

iferous vertebrates from New Mexico: Carnegie Inst. Wash· 

ington Pub. 181, p. 17-35. 

Cope, E. D., 1878, Descriptions of extinct Batrachia and Reptiles 

from the Permian formation of Texas: Am. Philos. Soc. Proc., 

v. 17, p. 505-530. 

---1881, The Permian formations of New Mexico: Am. Naturalist, v. 15, p. 1020-1021. 

Cross, Whitman, 1899, Description of the Telluride quadrangle 

[Colo.]: U.S. Geol. Survey Geol. Atlas, folio 57, p. 1-15. 

Cross, Whitman, and Howe, Ernest, 1005, Geography and general 

geology of the [Silverton] quadrangle: U.S. Geol. Survey Geol. 

Atlas, folio 120, p. 1-25. 

Cross, Whitman, and Larsen, E. S., Jr., 1935, A brief review oj: 

the geology of the San Juan region of southwestern Colorado: 

U.S. Geol. Survey Bull. 843, p. 1-138. 

Darton, N. H., 1928, "Red Beds" and associated formations in 

New Mexico, with an outline of the geology of the State: U.S .. 

Geol. Survey Bull. 794, 356 p. 

Elston, D.P., Shoemaker, E. M., and Landis, E. R., 1962, Uncom .. 

pahgre Front and salt anticline region of Paradox Basin, Colo·· 

rado and Utah: Am. Assoc. Petroleum Geologists Bull., v. 46,, 

p. 1857-1878. 

Gignoux, Maurice, 1960, Geologie Stratigraphique: 5th ed., Paris, 

Masson, 759 p. 

Gilluly, James, 1963, The tectonic evolution of the western 

United States: Geol. Soc. London Quart. Jour. v. 119, p. 133--

174. 

Gregory, H. E., 1917, Geology of the Navajo country; a recon-· 

naissance of parts of Arizona, New Mexico, and Utah: U.S .. 

Geol. Survey Prof. Paper 93,161 p. 

Gregory, J. T., 1950, Tetrapods of the Pennsylvanian nodules 

from Mazon Creek, Illinois: Am. Jour. Sci., v. 248, No. 12, p .. 

833-873. 

Hills, J. M., 1942, Rhythm of Permian seas-a paleogeographie 

study: Am. Assoc. Petroleum Geologists Bull., v. 26, No. 2, p .. 

217-255. 

Holmes, W. H., 1877a, Report of William H. Holmes, geologist of' 

the San Juan Division: U.S. Geol. and Geog. Survey Terr. 

(Hayden) 9th Ann. Rept., p. 237-276. 

Holmes, W. H., 1877b. In Hayden, F. V. (in charge), Geological 

and geographical atlas of Colorado and portions of adjacent 

territory: U.S. Geol. and Geog. Survey Terr. (Hayden), sheets 

14, 15. 

Holmes, W. H., 1878, Report on the geology of the Sierra Abajo 

and west San Miguel Mountains: U.S. Geol. and Geog. Survey 

Terr. (Hayden) lOth Ann. Rept., p. 187-195. 

Langston, 'Vann Jr., 1953, Permian amphibians from New Mexi·· 

co: California Univ. Pubs. in Geol. Sci., v. 29, p. 349-416. 

---1963, Fossil vertebrates and the late Palaeozoic red beds 

of Prince Edward Island: Natl. Mus. Canada Bull. 187, Geol.. 

Ser. 56, p. 1-36. 

Larsen, E. S., Jr., and Cross, Whitman, 1956, Geology and petrology of the San Juan region, southwestern Colorado: U.S. Geol. 

Survey Prof. Paper 2.58, p. 1-303. 

Lee, ,V, T., 1909, Stratigraphy of the Manzano group of the Rio 

Grande Valley, New Mexico: U.S. Geol. Survey Bull. 389, 141 

p. 

Luedke, R. G., and Burbank, W. S., 1962, Geology of the Ouray 

Quadrangle Colorado: U.S. Geol. Survey Geol. Quad. Map GQ-· 

152. 

Man:ou, Jules, 1856, Resume and field notes, with a translation 

by W. P. Blake [Whipple's rec-onnaissance near the thirty-fifth 

parellel], in U.S. War Dept., Reports of explorations and sur--

veys to ascertain the most practicable and economical route! 

for a railroad from the Mississippi River to the Pacific Ocean: 

v. 3, pt. 4, p.121-164. 

Marsh, 0. C., 1878, Notice of new fossil reptiles: Am. Jour. Sci., 

ser. 3, v.l5, p. 409-411. 

Moore, R. C., 1949, Rocks of Permian(?) age in the Colorado 

River Valley, north-central Texas: U.S. Geol. Survey Oil and 

Gas Inv. Prelim. Map 80, (2 sheets), scale 1 inch to 1 mile. 

Olson, E. C., 1947, The family Diadectidae and Its bearing on the 

classification of reptiles: Fieldiana, Geology, v. 11, p. 1-53. 

---1950, The temporal region of the Permian reptile Diadectes: Fieldiana, Geol'Ogy, v.lO, p. 63-77. 

---1954, Fauna of the Vale and Choza: 7, Pelycosauria: 

Family Caseidae: Fieldiana, Geology, v. 10, p. 193-204. 

---1955, Fauna of the Vale and Choza: 10, Trirnerorhachisincluding a revision of the pre-Vale species: Fieldiana, Geology,v.lO,p.225-274. 

Parrington, F. R., 1958, The problem of the classification of reptiles: Jour. Linnaean Soc. London, Zoology, v. 44, and Botany, 

v. 56, p. 99--115. 

Peabody, F. E., 1957, Pennsylvanian reptiles of Garnett, Kansas: 

edaphosaurs: Jour. Paleontology, v. 31, p. 947-949. 

Romer, A. S., 1935·, Early history of Texas red-beds vertebrates: 

Geol. Soc. America Bull., v. 46, p.1597-1658. 

---1944, The Permian cotylosaur Diadectes tenuitectus: A.m. 

Jour. Sci., v. 242, p.139--144. 

---1946, The primitive reptile Lirnnoscelis restudied : Am. 

Jour. Sci., v. 244, p.149-188. 

---1947, Review of the Labyrinthodontia: Mus. Comp. Zool. 

Bull., v. 99, p. l-368. 

---1948, Relative growth in pelycosaurian reptiles~: Roy. Sci. 

South Africa Spec. Pub., Robert Broom Comm. Vol., p. 45-55. 

---1952, Late Pennsylvanian and Early Permian vertebrates 

of the Pittsburgh-West Virginia region: Carnegie Mus. Annals 

v. 33, p. 47-113. 

---1956, Osteology of the Reptiles: Chicago Univ. Press, 772 

p. 

---1958, The Texas Permian red beds and their vertebrate 

fauna, in Weston, T. S., ed., Studies on fossil vertebrates. 

Essays presented to D. M.S. Watson: London, Athlone, p. 157-

179. 

---1961, A large ophiacodont pelycosaur from the Pennsylvanian of the Pittsburgh region: Mus. Comp. Zool. Brev., no. 

144, 7 p. 

Romer, A. S., and Price, L. I., 1940, Review of the Pelycosauria : 

Geol. Soc. America Spec. Paper 28, 538 p. 

Scott, W. B., 1907, An introduction to geology: 2d ed., New York, 

MacMillan, 816 p. 

Seltin, R. J., 1959, A review of the Family Captorhinidae: Fieldiana, Geology, v. 10, p. 461-509. 

Spate, 0. K. H., 1954, India and Pakistan: New York, Dutton, 

827p. 

Stevenson, J. J., 1906, Carboniferous of the Appalachian basin: 

Geol. Soc. America Bull., v. 17, p. 65-228. 

Tomlinson, C. W., 1916, The origin of the red beds; a study of 

the conditions of origin of the Permo-Carboniferous and Triassic red beds of the western United States: Jour. Geology, v. 

-24, p. 153-179,238-253. 

Vaughn, P. P., 1958a, On the geologic range of the labyrinthodont 

amphibian Eryops: Jour. Paleontology, v. 32, p. 918-922. 

---1958b, On a new pelycosaur from the Lower Permian of 

Oklahoma, and on the origin of the family Caseidae: Jour. 

Paleontology, v. 32, p. 981-991. 
C46 CONTRIBUTIONS TO PALEONTOLOGY 

Vaughn, P. P., 1962, Vertebrates from the Halgaito tongue of the 

Outler formation, Permian of San Juan County, Utah: Jour. 

Paleontology, v. 36, p. 529-539. 

---1963, The age and locality of the late Paleozoic vertebrates 

from El Cobre Canyon, Rio Arriba County, New Mexico: Jour. 

Paleontology, v. 37, p. 283-286. 

W.atson, D. M. S., 1954, On Bolosau1·u.s and the origin and classification of reptiles: Mus. Comp. Zoology Bull., v. 111, p. 297-

449. 

Welles, S. P., 1941, The mandible of a diadectid cotylosaur: California Univ. Pub., Geol. Sci. Bull., v. 25, p. 423-432. 

White, T. E., 1939, Osteology of Seymouria baylorensis Broili: 

Bull. Mus. Comp. Zoology, v. 85, p. 325-409. 

Williston, S. W., 191la, A new family of reptiles from the Permian of New Mexico: Am. Jour. Sci., v. 31, p. 378-398. 

---191lb, American Permian Vertebrates: Chicago Univ. 

Press, 145 p. 

---1912, Restoration of Limnoscelis, a cotylosaur reptile from 

New Mexico: Am. Jour. Sci., v. 34, p. 457-468. 

---1915, A new genus and species of American Theromorpha, 

Jfycterosaurus lon.uiceps: Jour. Geology, v. 23, p. 554-559. 

Williston, S. W., and Case, E. C., 1912, the Permo-Carboniferous 

of northern New Mexico: Jour. Geology, v. 20, p. 1-12. 
FOOTPRINTS FROM THE CUTLER FORMATION 

By DONALD BAIRD 2 

ABSTRACT 

Footprints occur in the Lower Permian Cutler Formation near 

Placerville, Colo. Limnopus cutlerensis n. sp., a small species 

similar to the Late Pennsylvanian L. 1'agus of Kansas, is ascribed 

to an eryopoid labyrinthodont. A korynichniid pes imprint similar to that of B-rachydactylopus represents a small diadectid 

cotylosaur. Early Permian red beds ichnofaunas are quite different from contemporaneous dune-sand ichnofaunas; the latter 

represent tetrapod faunas ot which skeletal records are lacking. 

Three specimens of fossil footprints in the Museum of Comparative Zoology provide supplementary information on the 

tetrapod fauna of the Cutler Formation. I am indebted to 

George Edward Lewis, Peter Paul Vaughn, and Alfred S. Romer 

for the opportunity to study these specimens, and to Albert E. 

Wood and Joseph T. Gregory for access to comparative material 

at Amherst and Yale. 

SYSTEMATIC DESCRIPTIONS 

Genus LDINOPUS Marsh, 1894 

Limnopus cutlerensis Baird, n. sp. 

Figure 14 B, 0 

Type.-A trackway of five manus-pes sets on a channeled surface of reddish-brown micaceous siltstone· 

trackway preserved as a natural mold; MCZ 233. ' 

Source.-Cutler Formation, Lower Permian. Locality 20, 80 feet above road level, north of mouth of Fall 

Creek, Mrs. Stockton Smith property, San Miguel 

County, Colo. Collected by S. J. Olsen, 1953. 

. The form-genus Llmnopus as redefined (Baird, 1952) 

diffe~ from Oursipes in having shorter digits and a 

prominent rounded pad at the base of digit I in manus 

and pes. In pes structure Limnopus resembles Sa'ltrichnites s~lamandroide8 Geinitz from the Rotliegende of 

Bohemia, but the manus of Savlrichn?:tes is pentadactyl 

rather than tetradactyl ( cf. a topotypic specimen at 

Y ~le, YPM 3764) . As text figure 14 demonstrates, 

Llm/'!_,opus cutlerensis shows close affinities with the type 

spe?Ie~, L. v.ag'lts Marsh, frmn the ·upper Pennsylvanian 

(VIrgil Senes) of Kansas. Although the differencessmaller size, disproportionately smaller manus, more 

turne~ -.out ~anus and pes, more posterior position of 

pes digit V m L. c·utlerensis-are not great, they justify 

2 Princeton University, Princeton, New Jersey. 

a specific distinction. Measurements of the type trackway are as follows : 

Stride: 55-75 mm; n1ean of six, 62 mm. 

Pace of manus: 38-44 mm; mean of four, 41 mm. 

Pace of pes: 41-54 mm; mean of four, 49 mm. 

Trackway width: 55-57 mm. 

Pace angulation between pedes: 75°-91°; mean of 

three, 79° 

The trackmaker had a gleno-acetabular length (or 

"wheelbase") of about 48 mm-slightly more than half 

tha.t of the type individual of Limnopus vag'lts-and a 

total length estimated at 140 mm. By its morphology 

and proportions the trackm~ker seems to have been a 

small temnospondy Ions amphibian, probably an eryopoid rhachitome. 

The known distribution of Limnopttts footprints, last 

summarized in 1952, is enlarged by this and other additional records. A slab at Amherst (Hitchcock colln. 

26/14) demonstrates that Thenaropus heterodactylus 

King (1845) from the Conemaugh Group (early 

Virgil?) near Greensburg, Pa., is a valid species of 

Limnop'lts and closest in form to L. littoralis (Marsh) 

from the Virgil of Kansas. The earliest known occurrence of the genus is in an equivalent of the Cow Run 

Sandstone of Stevenson (1906) (Conemaugh Group, 

Missouri) in Jefferson County, Ohio, where my field 

party found trackways of Dimnop'lt8 heterodactylus 

(MCZ 253) in 1955 . 

Of course, we cannot determine how many amphibian 

genera are represented by the various Limnopus trackways, or whether these genera fanned a natural taxonomic group. The ichnological record tells us only that 

trackmakers of varied size but of similar foot structure 

and body proportions ranged from Colorado east to 

Pennsylvania and persisted from Late Pennsylvanian 

into Early Permian time, that is, from the Missoud 

into theW olfcamp. 

Genus indet., cf. BRACHYDACTYLOPUS Toepelman and Rodeck, 

1936 

Figure 14D 

llf aterial.-Isolated imprint of right pes, preserved 

as a natural mold; MCZ 231. 

C47 
C4S CONTRIBUTIONS TO PALEONTOLOGY 

B c 

0 1 CM 

0 1 2 3 4 5 6 7 8 9 10 CM 0 10 CM 

FIGURE 14.-A, Limnopus vagus Marsh, trackway with hypothetical reconstruction of trackmaker in walking pose (from Baird, 

1952). B, Limnopus cutlerensis n. sp. (type trackway, MCZ 233); footprint outlines restored. 0. L. cutlerensis, composite restoration of right manus-pes set, enlarged. D ,· korynichniid right pes imprint, cf. Brachydactylopus ( MCZ 231). 

Source.-Micaceous reddish-brown siltstone near top 

of Cutler Formation. Locality 21, west side of the 

second side-canyon east of Placerville, a quarter of a 

mile south of San Miguel River, San Miguel County, 

Colo. Collected by A. D. Lewis, 1953. 

This footprint, although too indistinct for generic 

identification, is evidently referable to the form-family 

Korynichniidae, a widely distributed group of Permi~n 

and Carboniferous footprint genera. The pes is pentadactyl with digits I to IV forming a sequence of increasing length; digit V is small and set well back on the 

lateral 1nargin of the foot. The digit tips made deep 

oval impressions and there is no evidence of cia ws. The 

tarsal area is marked by the deep impression of an 

ovoid plantar pad, the long axis of which is somewhat 

obliquely inclined toward the direction of motion and 

forms a right angle with the axis of digit IV. Such a 

pad is characteristic of korynichniid footprints. 

The small size and posterior, offset position of digit V 

distinguish this footprint from I chniotherhtm and 

[{ orynichntum of the German Rotliegende and the English Lower Permian. (See Korn, 1933, and works cited 

in Korn.) "Jfegaba.roJYU-S frmn the Upper Pennsylvanian (Benwood Limestone Member, Monongahela Formation, Virgil) of Ohio (Baird, 1952, p. 839) has a 

similar fifth digit but differs from the Cutler footprint 

in its heavy, splayed digits and reniform tarsal pad. 

Closer comparisons can be made with Brachydactylopus 
PERMIAN VERTEBRATES, CUTLER FORMATION, PLACE-RVILLE AREA, COLORADO C49 

fontis Toepelman and Rodeck ( 1936) from the Permian 

and Pennsylvanian Fountain Formation of the Colorado Front Range. Another similar form is Tridentichnu.s supaiensis (Gilmore (1927) (with which I synonymize Ammobatraahu.s turbatans Gilmore, 1928), 

from the Supai Formation of the Grand Canyon, Ariz. 

Another species of korynichniid footprints, left undescribed at the untimely death of Frank E. Peabody, 

occurs in the Upper Pennsylvanian (Rock Lake Shale 

Member, Stanton Limestone, Virgil) of Garnett, Kans. 

All the American forms just listed are here referred for 

the first time to the form-family Korynichniidae. Until 

they can be comprehensively restudied, and until better 

mruterial of the Cutler species is available, further comparisons are unprofitable. 

Korynichniid footprints have been correlated with 

diadectid cotylosaurs by Nopcsa (1923) and Lotze 

(1928), although Korn (1933) believed the affinities of 

K orynichnium to lie with the procolophonids rather 

than the diadectids. (See, however, the recent summary 

by Schmidt, 1959, p. 116.) In my opinion the direct · 

correspondence of korynichniid manus imprints to the 

articulated manus of Diadectes described in the preceding section, and the long-known similarity of the pes 

imprints to the pes of Diadectes as described by Romer 

and Byrne ( 1931), leave little doubt that the korynichniid footprints are of diadectid origin. The conspicuous imprint of a tarsal pad in all korynichniid pes 

tracks correlates well with the massive diadectid astragalus ( cf. Schaeffer, 1941, p. 431). The isochronous 

distribution of korynichniid footprints and diadectid 

skeletons is supporting evidence. 

A third footprint specimen from the Cutler (MCZ 

232), found near locality 6 by G. E. Lewis in 1953, consists of an ar:c of four round digit-tip impressions which 

measures 75 mm in span. This footprint may be that 

of a korynichniid but it might equally well have been 

made by an amphibian such as Eryops. 

Some hundreds of footprints from the Cutler 

("Abo") Formation of New Mexico were collected for 

the University of Missouri in 1946 by Carl C. Branson 

(Branson and Branson, 1946). I ha.ve not, unfortunately, had the opportunity to accept Dr. Branson's 

generous invitation to examine this noteworthy collection and to make comparisons with the Cutler specimens described above. 

PROSPECTUS AND PROBLEMS 

Except for a few piecemeal descriptions of species, 

footprints from red beds facies of the Lower Permian 

have been little studied in recent years. The classic 

ichnofaunas from North American red beds-those of 

the Supai and Hermit Formations in the Grand Canyon 

of Arizona (Gilmore, 1926-1928) and the Clear Fork 

Group at Castle Peak, Tex. (Moodie, 1929, 1930)-were 

gravely misunderstood by their describers and need extensive redescription and taxonomic revision before they 

can be compared fruitfully with contemporary footprints and skeletal material. (I have assembled, in the 

form of latex molds, the 1naterial for such a study.) 

In Europe the situation is somewhat better. The 

Rotliegende ichnofauna of Central Europe has been exhaustively studied by Pabst (1908 and earlier) and reinterpreted by subsequent authors, although its nomenclature is still confused through Pabst's arbitrary use 

of a pseudo-Linnaean system of names. This Rotliegende fa una also occurs near Birmingham, England 

(Hardaker, 1912). There is thus a useful European 

standard of comparison for further work on the ichnology of Permian red beds in this country. Another 

major task is the tracing of Permian footprint genera 

back into the Pennsylvanian; much undescribed Pennsylvanian material awaits study and nearly all the described forms need restudy. 

Quite a different set of problems are presented by the 

trackways recorded in Permian beach and dune sands. 

Footprints made in this environment-for example, 

tr~ose from the Coconino Sandstone, the De Chelly Sandstone Member of the Cutler Formation of Arizona, and 

the Lyons Sandstone of Colorado--are quite unlike 

those from Cutler and other contemporary red beds; 

their affinities lie rather with Permian dune-sand footprints from Great Britain (reviewed by Hickling, 1909) 

and the Corn berger Sandstein of Germany (Schmidt, 

1959) . Footprints made in sloping sand are much more 

difficult to interpret than those made on mudflats, but 

so far as I can see the ichnofaunas of red beds and dune 

sands ha.ve nothing in common. To add to our difficulties, the dune-sand environment rarely preserved 

skeletal remains. Thus one contribution of ichnology to 

Permian faunistics is to remind the student-of-bones 

that an evolving facies-fauna quite different from his 

familiar red beds fauna was lurking offstage, so to 

speak, ready to supply taxonomic novelties whenever 

changing conditions in the red beds area favored their 

introduction. 

REFERENCES CITED 

Baird, Donald, 1952, Revision of the Pennsylvanian and Permian footprints Limnopus, Allopus and Baropus: Jour. Paleontology, v. 26, no. 5, p. 832-840, pls.122-124, 4 text figs. 

Branson, E. B., and Branson, C. C., 1946, Footprints from the 

Abo formation of New Mexico [abs.]: Geol. Soc. America 

Bull., v. 57, p. 1181. 
C50 CONTRIBUTIONS TO PALEONTOLOGY 

Gilmore, C. W., 1926, Fossil footprints from the Grand Canyon: 

Smithsonian Misc. CoHn., v. 77, no. 9, 41 p., 12 pls., 23 text figs. 

---1927, Fossil footprints from the Grand Canyon: second 

contribution : Smithsonian Misc. CoHn., v. 80, no. 3, 78 p., 21 

pls., 37 text figs. 

---1928, Fossil footprints from the Grand Canyon : third 

contribution: Smithsonian Misc. Colin., v. 80, no. 8, 16 p., 5 

pls., 7 text figs. 

Hardaker, W. H., 1912, On the discovery of a fossil-bearing 

horizon in the 'Permian' rocks of Hamstead Quarries, near 

Birmingham: Geol. Soc. London Quart. Jour., v. 68, pt. 4, 

p. 639-681, 30 text figs. 

Hickling, George, 1909, British Permian footprints: Manchester 

Lit. Philos. Mem., v. 53, pt. 3, no. 22, 31 p., 4 pls. 

King, A. T., 1845, Description of fossil footmarks, found in the 

Carboniferous series in Westmoreland County, Pennsylvania: 

Am. Jour. Sci., v. 48, no. 2, p. 343-352, 9 text figs. 

Korn, Hermann, 1933, Eine flir die Kenntnis der Cotylosaurier 

des deutschen Perms bedeutsame Schwimmfahrte von Tambach [A significant trackway from Tambach for knowledge 

of the Cotylosauria of the German Permian] : Palaeobiologica, v. 5, no. 2, p. 169-200, pl. 15, 4 text figs. 

Lotze, F., 1928, Die Tambacher Sphaerodactylu,m-Fiihrten [The 

Sphaerodactylum tracks from Tambach] : PaUiont. Zeitschr., 

v. 9, p. 170-175. 

Marsh, 0. C., 1894, Footprints of vertebrates in the Coal Measures of Kansas: Am. Jour. Sci., ser. 3, v. 48, p. 81-84, pls. 2-3. 

Moodie, R. L., 1929, Vertebrate footprints from the Red Beds 

of Texas: Am. Jour. Sci., ser. 5, v. 17, p. 352-368, 9 text figs. 

---1930, Vertebrate footprints from the Red Beds of Texas, 

II: Jour. Geology, v. 38, p. 548--565, 16 text figs. 

Nopcsa, Franz, 1923, Die Familien der Reptilien [The families 

of the Reptilia] : Geologie u. PaUiontologie Fortschr., no. 2, 

210 p., 6 pls. 

Pabst, Wilheim, 1908, Die Tierfahrten in dem Rotliegenden 

"Deutschlands" : A cad. Leop.-Carol. Nova Acta, v. 89, no. 2, 

p. 313-481, 35 pls., 36 text figs. 

Romer, A. S., and Byrne, Frank, 1931, The pes of Diadectes: 

Notes on the primitive tetrapod limb: Palaeobiologica, v. 4, 

p. 25-48, 9 text figs. 

Schaeffer, Bobb, 1941, The morphological and functional evolution of the tarsus in amphibians and reptiles: Am. Mus. Nat. 

History Bull., v. 78, art. 6, p. 395-472,21 text figs. 

Schmidt, Hermann, 1959, Die Cornberger Fahrten im Rahmen 

der Vierflissler-Entwicklung [The trackways from Cornberg 

in the frame of the evolution of the tetrapods] : Iiessisches 

Landesamt fiir Bodenforschung Abh., no. 28, 137 p., 9 pls., 

57 text figs. 

Toepelman, W. C., and Rodeck, H. G., 1936, Footprints in Late 

Paleozoic red beds near Boulder, Colorado: Jour. Paleontology, v.10, no. 7, p. 660-662,2 text figs. 

U.S. GOVERNMENT PRINTING OFFICE: 1965 o-761-349