The Upper Cretaceous (Turonian) A Jt \ /

Ammonite Family Goilopoceratidae

Hyatt in the Western Interior

of the United States

GEOLOGICAL SURVEY PROFESSIONAL PAPER 1192
The Upper Cretaceous (Turonian) 

Ammonite Family Coilopoceratidae 

Hyatt in the Western Interior 

of the United States

By WILLIAM A. COBBAN and STEPHEN C. HOOK

GEOLOGICAL SURVEY PROFESSIONAL PAPER 1192

Coilopoceras, Hoplitoides, and Herrickiceras, 

chiefly found in New Mexico, provide a 

means for the correlation of Cretaceous 

rocks between the Western Interior, 

South America, Africa, and Europe

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1980
UNITED STATES DEPARTMENT OF THE INTERIOR 

CECIL D. ANDRUS, Secretary

GEOLOGICAL SURVEY 

H. William Menard, Director

Library of Congress Cataloging in Publication Data

Cobban, William Aubrey, 1916-

The Upper Cretaceous (Turonian) ammonite family Coilopoceratidae Hyatt in the Western Interior of

the United States.

(Geological Survey Professional Paper 1192) 

Bibliography: p. 24 

Supt. of Docs, no: I 19.16

1. Coilopoceratidae. 2. Paleontology Cretaceous. 3. Paleontology The West. 

I. Hook, Stephen C., joint author. II. Title. III. Series: United States Geological Survey

Professional Paper 1192. 

QE807.A5C64 564'.53 80-607086

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

Washington, D.C. 20402
CONTENTS

Page

Abstract................................................ 1

Introduction ............................................ 1

Geographic distribution.................................. 1

Family Coilopoceratidae Hyatt........................... 5

Genus Hoplitoides von Koenen, 1898 .................. 5

General statement ............................... 5

Distribution of Hoplitoides ....................... 6

Origin of Hoplitoides ............................. 6

Hoplitoides cf. H. koeneni Solger .................. 6

Hoplitoides cf. H. wohltmanni (von Koenen)........ 7

Hoplitoides sandovalensis Cobban and Hook, n. sp.. 8

Family Coilopoceratidae Hyatt Continued

Genus Coilopoceras Hyatt, 1903 .................

General statement ..........................

Distribution of Coilopoceras .................

Origin of Coilopoceras .......................

Coilopoceras cotteti Hyatt ...................

Coilopoceras springeri Hyatt.................

Coilopoceras inflatum Cobban and Hook, n. sp. 

Genus Herrickiceras Cobban and Hook, n. gen.

Herrickiceras costatum (Herrick and Johnsori). 

Age relationships of Coilopoceratidae ................

References cited....................................

11

11

12

12

13

16

19

22

23

23

24

ILLUSTRATIONS

PLATE 1. Hoplitoides and Coilopoceras.

2. Hoplitoides.

3. Coilopoceras and Hoplitoides.

4. Hoplitoides. 

5-10. Coilopoceras.

11. Hoplitoides and Coilopoceras. 

12-17. Coilopoceras.

18. Coilopoceras and Hoplitoides.

19. Coilopoceras and Herrickiceras. 

20,21. Coilopoceras.

| Plates follow index]

FIGURE 1. Map of New Mexico showing localities of Coilopoceratidae collections

2. Whorl section of Hoplitoides cf. H. koeneni Solger..................

3. Sutures of Hoplitoides cf. H. koeneni Solger .......................

4. Suture of Hoplitoides cf. H. wohltmanni (von Koenen)..............

5. Cross section of Hoplitoides cf. H. wohltmanni (von Koenen)........

6. Cross section of Hoplitoides sandovalensis Cobban and Hook, n. sp..

7. Sutures of Hoplitoides sandovalensis Cobban and Hook, n. sp.......

8. Cross section of Coilopoceras cotteti Hyatt.........................

9. Cross section of Coilopoceras cotteti Hyatt.........................

10. Sutures of Coilopoceras cotteti Hyatt..............................

11. Sutures of Coilopoceras springeri Hyatt...........................

12. Whorl sections of Coilopoceras springeri Hyatt....................

13. Suture of Coilopoceras springeri Hyatt............................

14. Whorl sections of Coilopoceras inflatum Cobban and Hook, n. sp.....

15. Sutures of Coilopoceras inflatum Cobban and Hook, n. sp...........

16. Sutures of Herrickiceras costatum (Herrick and Johnson)...........

9

11

14

15

16

18

19

20

21

22

23

in
IV CONTENTS

TABLES

Page

TABLE 1. Localities at which fossils were collected.......................................................................... 2

2. Dimensions and ratios of Coilopoceras colleti Hyatt, Carthage area ................................................. 14

3. Dimensions and ratios of Coilopoceras springeri Hyatt, Rio Puerco area............................................. 19

4. Dimensions and ratios of Coilopoceras inflatum Cobban and Hook, n. sp............................................. 21
THE UPPER CRETACEOUS (TURONIAN) AMMONITE FAMILY

COILOPOCERATIDAE HYATT IN THE 

WESTERN INTERIOR OF THE UNITED STATES

By WILLIAM A. COBBAN and STEPHEN C. HOOK1

ABSTRACT

The Coilopoceratidae include dominantly compressed involute 

ammonites that are either smooth or broadly ribbed and have a 

characteristic suture in which the bifid lateral lobe has the branch 

nearest the umbilicus in a more lowered position than that of the 

other. The family inhabited the warm waters of the Tethyan realm 

during part of middle Cretaceous time.

Hoplitoides, Coilopoceras, and the new genus Herrickiceras represent the family in the Western Interior. Hoplitoides, the oldest 

member of the family, appeared suddenly in New Mexico in the middle Turonian subzone of Collignoniceras woollgari woollgari 

(Mantell). The few specimens collected have affinities with H. 

koeneni Solger and H. wohltmanni (von Koenen) from the middle 

Turonian of west Africa. A little above the subzone of C. woollgari 

woollgari in New Mexico are rocks containing the new species H. 

sandovalensis associated with Herrickiceras. Coilopoceras was 

derived from Hoplitoides by loss of the truncated venter. The sequence of Coilopoceras in the Western Interior is, from oldest to 

youngest, C. springeri Hyatt, C. colleti Hyatt, and C. inflatum, n. 

sp. These forms are associated with species of Prionocyclus of late 

middle and early late Turonian age. Herrickiceras, which appeared 

suddenly in New Mexico, may have had its origin in Donenriquoceras from the lower Turonian of Spain.

The Coilopoceratidae in the Western Interior are almost confined 

to New Mexico. A few specimens have been found in southern Colorado, and one specimen was collected in central Wyoming. Elsewhere the family is widespread in a belt on both sides of the equator 

in Africa, India, southern Europe, northern South America, and 

Mexico.

INTRODUCTION

Ammonites of the Family Coilopoceratidae preferred 

the warmer waters of the Tethyan region during middle Cretaceous time (Turonian). In the Western Interior region, representatives of this family are almost 

confined to New Mexico, where the family is known 

from only three genera, Coilopoceras, Hoplitoides, and 

the new genus Herrickiceras.

Records of Coilopoceratidae from the Western Interior are few. Hyatt (1903, p. 91-100) originally 

named the family and described three species of

'New Mexico Bureau of Mines and Mineral Resources, Socorro.

Coilopoceras from New Mexico. Aside from his paper, 

the only systematic work that includes a representative of the family is by Herrick and Johnson (1900, 

p. 214), who briefly described an ammonite as a new 

species, Placenticeras costata, which we are assigning 

to Herrickiceras. Coilopoceras has been listed from a 

few stratigraphic sections or localities by Lee (1912, 

p. 599, 622, 624; 1917, p. 195, 197), Dane, Wanek, and 

Reeside (1957, p. 194), Dane, Cobban, and Kauffman 

(1966, p. H7-H9), Dane, Kauffman, and Cobban (1968, 

p. F9, F12, F19), and Lamb (1968, p. 832, 835, 

836, 846).

The specimens described in this report are in the National Museum of Natural History in Washington, 

D.C., and have USNM catalog numbers. Plaster casts 

of some of the specimens are in the U.S. Geological 

Survey's Mesozoic invertebrate fossil collections 

at the Denver Federal Center, Lakewood, Colo., and 

at the New Mexico Bureau of Mines and Mineral 

Resources, Socorro, N. Mex. All photographs were 

made by Robert E. Burkholder of the U.S. Geological 

Survey. The drawings of sutures and whorl sections 

were made by Cobban.

Ranchers who kindly gave us permission to collect 

from the type localities of Coilopoceras inflatum 

(n. sp.), C. springeri Hyatt, and C. colleti Hyatt are B. 

W. Cox, Red Lake ranch near D Cross Mountain northwest of Socorro, Mr. and Mrs. Gene Sauble, Sauble 

Circle Dot Ranch northeast of Springer, and Dean 

Fite, Fite Ranch near the former town of Carthage, 

Socorro County.

GEOGRAPHIC DISTRIBUTION

The ammonites described or recorded in this report 

came from 66 localities in New Mexico; a few ammonites are also recorded from Colorado and Wyoming. 

The localities in New Mexico are shown in figure 1, and 

data concerning the localities, stratigraphic position, 

and collectors are given in table 1.
UPPER CRETACEOUS AMMONITE FAMILY COILOPOCERATIDAE HYATT, WESTERN INTERIOR, U.S.

109° 108° 107° 106° 105°

\ [LOS ALAMOS

x - -'

 T x1/M oSan Ysidro/ SANTA FE 

I 18x?

-_.-i__i

N ^BERNALILLO [

^ n. __^

GUADA\LUPE

x A Cebollita Mesa

D Cross Mountain

_—L', Truth or «jjConsequences o^f56-57

10 20 30 40 50 KILOMETERS

I I I I I

FIGURE 1. Index map of New Mexico showing localities of Coilopoceratidae collections referred to in the text and in table 1.

TABLE 1. Localities at which fossils were collected

Locality 

(fig. D

U.S. Geological

Survey

Mesozoic

locality

Collector, year of collection, description of locality, 

and stratigraphic assignment

D10633 J. D. Powell, 1963. Sec. 10, T. 16 N., 

R. 16 W., McKinley County. Juana 

Lopez Member of Mancos Shale. 

17632 R. P. Bryson, 1937. North of El Vado, 

Rip Arriba County. Mancos Shale.

TABLE I.—Localities at which fossils were collected—Continued

Locality U.S. Geological Collector, year of collection, description of locality, 

(fig. 1) Survey and stratigraphic assignment 

Mesozoic 

locality

D10777 G. R. Scott and Juanita Scott, 1978. 

South of State Highway 95 and 

8.8 km due west of Tierra Amarilla, 

Rio Arriba County. Mancos Shale, 

about base of Juana Lopez Member.
GEOGRAPHIC DISTRIBUTION 3 

TABLE 1. Localities at which fossils were collected—Continued

Locality 

(fig. 1)

U.S. Geological

Survey

Mesozoic

locality

Collector, year of collection, description of locality, 

and stratigraphic assignment

9 ....

10 ...

11 ...

14 ...

16 ...

17 ...

D4395 C. H. Dane, E. R. Landis, and W. A. 

Cobban, 1963, North of Rio Gallina 

in SEV4 sec. 15, T. 25 N., R. 1 E., Rio 

Arriba County. Mancos Shale, base 

of Juana Lopez Member.

D4538 C. H. Dane, 1964. Senorito Canyon in 

SE'^NW^NE1^ sec. 11, T. 20 N., 

R. 1 W., Sandoval County. Semilla 

Sandstone Member of Mancos 

Shale.

D10621 J. D. Powell, 1963. "About 200 yards 

north of State Highway 126 southeast of Cuba" [NW^NE1^ sec. 11, T. 

20 N., R. 1 W., Sandoval County]. 

Mancos Shale.

D3670 R. E. Burkholder and W. A. Cobban, 

1961; S. C. Hook, 1977. NWWSWH 

SEVt sec. 14, T. 19 N., R. 1 W., Sandoval County. Mancos Shale, from 

sectarian limestone concretions in 

silty-shale unit about 10 m (meters) 

below Juana Lopez Member.

D10308 S. C. Hook, 1977. SEWSWW sec. 14, 

T. 19 N., R. 1 W., Sandoval County. 

Mancos Shale, from base of Juana 

Lopez Member.

D3883 C. H. Dane, 1962. Arroyo Lopez, about 

1 km (kilometer) north of Holy 

Ghost Spring, Sandoval County. 

Mancos Shale about 6 m above 

Semilla Sandstone Member.

D3884 C. H. Dane and Ed John, 1962. Arroyo 

Lopez about 1 km north of Holy 

Ghost Spring, Sandoval County 

(Holy Ghost Spring 7.5-minute 

quadrangle). Basal part of Semilla 

Sandstone Member of Mancos 

Shale.

D4014 C. H. Dane and E. R. Landis, 1963. 

Arroyo Lopez about 0.6 km north of 

Holy Ghost Spring, Sandoval County. Basal part of Semilla Sandstone 

Member of Mancos Shale.

D4016 C. H. Dane and E. R. Landis, 1963. 

West side of Arroyo Lopez 914 m 

north of Holy Ghost Spring, Sandoval County. Mancos Shale about 

15 m above Semilla Sandstone 

Member.

28873 E. G. Kauffman and G. R. Paulson, 

1964. Arroyo Lopez 0.6-0.9 km 

north of Holy Ghost Spring, Sandoval County. Basal part of Semilla 

Sandstone Member of Mancos 

Shale.

D3702 R. E. Burkholder and W. A. Cobban, 

1961. Ojo del Espiritu Santo Grant 

about 3.8 km N. 60° W. of Ojito 

Spring, Sandoval County. Mancos 

Shale, from base of Juana Lopez 

Member.

D4020 C. H. Dane, 1963. About 1.6 km southwest of Ojito Spring, Ojo del Espiritu Santo Grant, Sandoval County. 

Basal part of Semilla Sandstone 

Member of Mancos Shale.

D4414 C. H. Dane, 1963. NWWSWV4 sec. 17, 

T. 15 N., R. 1 W., Sandoval County. 

Semilla Sandstone Member of Mancos Shale.

D4417 C. H. Dane, 1963; Dane, E. R. Landis, 

and W. A. Cobban, 1963. About 1.8

TABLI

Locality

(fig. 1)

18 ...

19 ...

20 ...

21 ...

22 ...

23 ...

24 ...

25 ...

26 ...

27 ...

28 ...

29 ...

30 ...

31 ...

32 ...

33 ...

: 1. Localities at u

U.S. Geological 

Survey 

Mesozoic 

locality

7992

D6790

D6791

D10575

D10634

16114

7204

15792

15795

D10508

15925

15947

15799

3672

D10469

D10622

hich fossils were collected— Continued

Collector, year of collection, description of locality, 

and stratigraphic assignment

km S. 10 ° W. of Ojito Spring, Ojo del

Espiritu Santo Grant, Sandoval

County. Mancos Shale.

W. T. Lee and T. W. Stanton, 1912.

About 5.6 km south of Casa Salazar

(sec. 11, T. 14 N., R. 3 W.), Sandoval

County. Mancos Shale.

E. R. Landis, 1968. Near center of

sec. 6, T. 14 N., R. 1 E., Sandoval

County. Mancos Shale, 18 m above

top of Semilla Sandstone Member.

E. R. Landis, 1968. NWWNEtt sec. 5,

T. 14 N., R. 1 E., Sandoval County.

Mancos Shale, about 11.5 m below

base of upper ledges of Juana Lopez

Member.

L. F. Gunther and W. A. Cobban,

1965. NL/2 sec. 6, T. 14 N., R. 1 E.,

Sandoval County. Semilla Sandstone Member of Mancos Shale.

L. F. Gunther. Probably in sec. 6, T. 14

N., R. 1 E., Sandoval County. Mancos Shale.

C. B. Hunt and J. W. Wyckoff, 1931.

NWV^NW1/! sec. 5, T. 14 N., R. 1 E.,

Sandoval County. Mancos Shale.

W. T. Lee, 1911. About 4.8 km north

of San Francisco and east of Rio

Puerco, Bernabe M Montano Grant,

Sandoval County. Mancos Shale,

from unit of shale that contains

limestone concretions.

C. B. Hunt, 1931. Northeastern part

of Bernabe M Montano Grant, Sandoval County. Mancos Shale.

C. B. Hunt, 1931. Bernabe M Montano

Grant, 305 m west of east line and

2,743 m south of north line; Sandoval County. Mancos Shale.

Neal La Fon, 1977-78; S. C. Hook and

W. A. Cobban, 1978. NEWNWtt

sec. 7, T. 12 N., R. 2 W.

(unsurveyed), Agua Salada Grant,

Sandoval County. Mancos Shale,

from the cephafopod zone underlying the Semilla Sandstone 

Member.

C. B. Hunt and J. W. Wyckoff, 1931.

Agua Salada Grant, 274 m north of

south line and 914 m west of east

line, Sandoval County. Mancos

Shale.

C. B. Hunt, H. R. Joesting, J. W.

Wyckoff, G. F. Taylor, and R. C.

Becker, 1931; S. C. Hook and S. J.

Frost, 1978. Agua Salada Grant, 305

m north of south line and 1,524 m

west of east line, Sandoval County.

Mancos Shale.

C. B. Hunt, 1931. NEttNEW sec. 15,

T. 12 N., R. 2 W. (unsurveyed), Sandoval County. Mancos Shale.

T. W. Stanton and J. G. Walthers,

1906. "Rio Puerco, 5 miles above

San Ignacio." Mancos Shale.

S. C. Hook, E. A. Merewether, and

W. A. Cobban, 1978. About 1,372 m

west of the southeast corner of Puerco Dam 7 1/2-minute quadrangle, Sandoval County. Mancos Shale.

Neal La Fon, 1978. Bernabe M Montano Grant, 1,524 m west and 305 m

south of northeast corner of Herrera
4 UPPER CRETACEOUS AMMONITE FAMILY COILOPOCERATIDAE HYATT, WESTERN INTERIOR, U.S. 

TABLE I.—Localities at which fossils were collected—Continued

Locality 

(fig. 1)

U.S. Geological 

Survey 

Mesozoic 

locality

Collector, year of collection, description of locality, 

and stratigraphic assignment

35 ...

36...

7 1/2-minute quadrangle, Sandoval 

County. Mancos Shale, about 7.6 m 

below top of Juana Lopez Member. 

15797 C. B. Hunt and others, 1931. Bernabe 

M Montano Grant, 3,962 m west of 

east line and 9,449 m north of south 

line; Sandoval County. Mancos 

Shale.

D10602 E. R. Landis and C. H. Maxwell, 1969; 

S. C. Hook, 1978. Head of arroyo 3.1 

km N. 12° E. of Moquino, Valencia 

County. Mancos Shale, below lowest 

ledge of Juana Lopez Member.

D5340 E. R. Landis and W. A. Cobban, 1966. 

San Jose Canyon in SWViSWV* sec.

4. T. 10 N., R. 7 W., Valencia County. Mancos Shale, 14.6 m above a 

sandy unit. 

D10551 S. C. Hook, 1978. SWV4SEV4SEV4 sec.

5. T. 7 N., R. 9 W., Valencia County. 

D-Cross Tongue of Mancos Shale.

D10321 J. R. Wright, 1977. NW%NWWNEV4 

sec. 22, T. 7 N., R. 8 W., Valencia 

County. About 2 m above base of 

D-Cross Tongue of Mancos Shale.

D7071 C. M. Molenaar, 1969. Southwest 

side of Cebollita Mesa in sec. 17, T. 6 

N., R. 10 W., Valencia County. Base 

of D-Cross Tongue of Mancos Shale.

D2055 C. H. Dane, G. O. Bachman, and 

W. A. Cobban, 1959. South end of 

Cebollita Mesa in sec. 34, T. 6 N., R. 

10 W., Valencia County. Basal 3 m 

of D-Cross Tongue of Mancos Shale.

D10638 S. C. Hook and J. W. Wright, 1979. 

WV4NWV4 sec. 36, T. 3 N., R. 9 W. 

(unsurveyed), Catron County. Basal 

2 m of D-Cross Tongue of Mancos 

Shale.

D7066 C. M. Molenaar, 1969. Southeast of 

D Cross Mountain in NE^NEVi sec. 

30, T. 3 N., R. 8 W., Socorro County. 

Basal 2 m of D-Cross Tongue of 

Mancos Shale.

D10299 G. L. Massingill, 1977. NEV4NEV4 sec. 

30, T. 3 N., R. 8 W., Socorro County. 

Basal 2 m of D-Cross Tongue of 

Mancos Shale.

26203 G. O. Bachman and J. B. Reeside, 

Jr., 1956. SEV4 sec. 25, T. 3 N., R. 9 

W., Socorro County. Basal part of 

D-Cross Tongue of Mancos Shale.

D5773 W. A. Cobban, 1967. NWWNWV4 sec. 

24, T. 3 N., R. 7 W., Socorro County. 

Mancos Shale, from lower part of 

Tres Hermanos Sandstone Member.

D10259 S. C. Hook and W. A. Cobban, 1977. 

SWV4NEV4 sec. 33, T. 3 N., R. 6 W., 

Socorro County. From lower part of 

Tres Hermanos Sandstone Member 

of Mancos Shale.

8336 D. E. Winchester, H. M. Robinson, 

and W. T. Thorn, Jr., 1913. 

SWV4SEV4 sec. 20, T. 2 N., R. 5 W., 

Socorro County. Mancos Shale, from 

"first prominent sandstone above 

Dakota" (Tres Hermanos).

D10260 S. C. Hook, D. E. Tabet, and J. R. 

Wright, 1977. SWWNEV4 sec. 8, T. 3 

S., R. 3 E., Socorro County. Mancos 

Shale, from limestone concretions 

below Tres Hermanos Sandstone 

Member.

40 ...

41 ...

42 ...

TABLE

Locality 

(fig. D

49 ...

50 ...

51 ...

52 ...

53 ...

54 ...

55 ...

56...

57 ...

58...

59 ...

60 ...

61 ...

62...

63 ...

1. Localities at «

U.S. Geological 

Survey 

Mesozoic 

locality

D2042

D7076

D10354

D10356

D10630

D10636

D10644

D7841

D10707

D10811

D10739

D10740

D10785

D10789

D10791

jnicfi fossils were collected— Uontmuea

Collector, year of collection, description of locality, 

and stratigraphic assignment

W. A: Cobban, 1959. SWV4 sec. 9,

T. 5 S., R. 2 E., Socorro County.

Mancos Shale, about 15m below top

of Tres Hermanos Sandstone

Member.

C. M. Molenaar, 1969. Center NViNVi

sec. 15, T. 5 S., R. 2 E., Socorro

County. Mancos Shale, about 15 m

below top of Tres Hermanos Sandstone Member.

Christina Lochman-Balk and students; S. C. Hook and David

Kalvelage, 1976. NWSWV4 sec. 9, T.

5 S., R. 2 E., Carthage area, Socorro

County. Mancos Shale, about 15 m

below top of Tres Hermanso Sandstone Member.

J. R. Wright, 1975, 1976. NWW sec.

16, T. 5 S., R. 2 E., Socorro County.

Mancos Shale, about 15m below top

of Tres Hermanos Sandstone

Member.

S. C. Hook, 1978. NEttNEWSEW

sec. 9, T. 5 S., R. 2 E., Socorro County. Mancos Shale, upper part of Tres 

Hermanos Sandstone Member.

S. C. Hook, J. R. Wright, D. E. Tabet,

and Donald Wolberg, 1979.

NEV4NWH sec. 25, T. 9 S., R. 8 E.,

Lincoln County. Mancos Shale, from

sandstone concretions at top of Tres

Hermanos Sandstone Member.

S. C. Hook, 1979. SWWSEV4 sec. 24,

T. 9 S., R. 8 E., Lincoln County.

Mancos Shale, from sandstone concretions at top of Tres Hermanos

Sandstone Member.

Bruce Black, 1969. Mescal Canyon,

sec. 36, T. 13 S., R. 4 W., Sierra

County. Near base of D-Cross

Tongue of Mancos Shale.

J. R. Wright, 1979. NWV4NWW sec. 1, 

T. 14 S., R. 4 W., (unsurveyed),

Sierra County. Near base of D-Cross

Tongue of Mancos Shale.

S. C. Hook and W. A. Cobban, 1979.

NWV4SEV4 sec. 33, T. 15 N., R. 7 E.,

Santa Fe County. Mancos Shale,

from limestone concretions about

0.6 m above base of Juana Lopez

Member.

S. C. Hook and J. R. Wright, 1979.

Rio del Piano, SEV4NEW sec. 13, T.

26 N., R. 24 E., Colfax County.

Carlile Shale, from concretions

below Juana Lopez Member. 

S. C. Hook, 1979. West bank of Canadian River 6.4 km east of Springer,

Colfax County. Carlile Shale, from

concretions oelow Juana Lopez

Member.

S. C. Hook, 1979. SWV4NEH sec. 2,

T. 24 N., R. 23 E., Colfax County.

Carlile Shale, from limestone concretions below Juana Lopez

Member.

S. C. Hook and W. A. Cobban, 1979.

Same locality as 60. Carlile Shale,

from limestone concretions 0.3 m

above base of Juana Lopez Member.

S. C. Hook and W. A. Cobban, 1979.

SEV4NEW sec. 11, T. 24 N., R. 23 E.,

Colfax County. Carlile Shale, from
GENUS HOPLITOIDES VON KOENEN, 1898

TABLE I.—Localities at which fossils were collected—Continued

Locality 

(fig. 1)

U.S. Geological

Survey

Mesozoic

locality

Collector, year of collection, description of locality, 

and stratigraphic assignment

limestone concretions 0.3 m above 

base of Juana Lopez Member.

D10772 S. C. Hook and E. H. Baltz, Jr., 1979. 

Inlet canal to Storrie Lake 90 m 

west of State Highway 3, San 

Miguel County. Carlile Shale, from 

2.4 m above base of Juana Lopez 

Member.

D10796 S. C. Hook, 1979. About 0.4 km east 

of State Highway 3 and intersection 

of dirt road just north of BR 6620 in 

Las Vegas NW 7 1/2-minute quadrangle, San Miguel County. Carlile 

Shale, from a limestone concretion 

4.6 m above base of Juana Lopez 

Member.

D10797 W. A. Cobban, 1979. Same locality 

as 65. Carlile Shale, from a limestone 

concretion 6.7 m above base of 

Juana Lopez Member.

66...

Family COILOPOCERATIDAE Hyatt

Hyatt (1903, p. 88) defined this family mainly on the 

nature of the suture. Wright (1957, p. L424) gave a 

much better definition as follows:

"Moderately to very involute, more or less compressed forms, either flat-sided with flat venter that 

becomes narrowly rounded in adult or cordate or 

lanceolate in section with sharp venter; at some stage 

broad, low, rounded ribs spring in pairs from low umbilical tubercles or bulges. Suture characterized by 

very broad, shallow first lateral lobe divided by one or 

more accessory saddles."

Hyatt included only his new genera Coilopoceras and 

Aconeceras in the family. Wright excluded Aconeceras 

and placed Coilopoceras, Hoplitoides von Koenen, and 

Glebosoceras Reyment in the Coilopoceratidae. 

Glebosoceras (Reyment, 1954a, p. 161), originally 

described from the Turonian of Nigeria, resembles 

Coilopoceras except that the ribs bend sharply forward 

on the outer part of the flank. The genus has not been 

found in New Mexico and probably does not occur in 

North America. Young and Powell (1976, p. 25.26) considered Coilopoceras chispaense Adkins (1931, p. 48, 

pi. 4, figs. 5, 7; pi. 5, fig. 2) a Glebosoceras, but C. chispaense lacks the forwardly bent ribs of Glebosoceras, 

and we believe Adkin's species is merely the robust 

and ornamented form of C. springeri Hyatt (1903, 

p. 96).

Genus HOPLITOIDES von Koenen, 1898

GENERAL STATEMENT

Hoplitoides is a slender, involute ammonite that 

has a sulcate to flat venter on the early whorls and a

sharply rounded to narrowly rounded venter on the 

later whorls. Early whorls may have weak to moderately strong, somewhat sigmoidal ribs crossing most 

of the flank with some arising from umbilical bullae. 

Adult whorls are smooth or nearly so. The suture is 

characterized by a broad lateral lobe that tends to be 

deeply bifid and to have one or both of its two branches 

deeply bifid. The rest of the lobes of the external suture 

are much smaller than the lateral one and decrease 

regularly in size away from it.

Hoplitoides is abundant and well preserved in a hard, 

bluish-gray limestone unit along the Mungo River between Mundame and Eliki in Cameroon. Von Koenen 

(1897, p. 11-13) described from there three closely 

related ammonites which he named Neoptychites? 

(Hoplites) lentiformis (1897, p. 11, pi. 2, figs. 1, 4, 7), 

Neoptychites? (Hoplites) wohltmanni (1897, p. 12, pi. 1, 

fig. 2; pi. 2, figs. 3, 9), and Neoptychites? ingens (1897, 

p. 12, pi. 1, fig. 4; pi. 2, figs. 5,8). Shortly thereafter, von 

Koenen (1898, p. 53) named the new genus Hoplitoides, 

assigned his Neoptychites? ingens, N.? (Hoplites) lentiformis, and N. ? (H.) wohltmanni to it, and described the 

new species H. latesellatus (1898, p. 56, pi. 6, figs. 1-3), 

H. wilsingi (1898, p. 59, pi. 5, fig. 2; pi. 6, figs. 6, 7), and 

H. n. sp.? (1898, p. 61, pi. 5, fig. 1; pi. 6, fig. 5). In his 

earlier paper, von Koenen (1897, p. 9, pi. 1, fig. 5a-c) 

described from this locality another ammonite that he 

named Pulchellia gibbosula, but in his 1898 paper, he 

questioned the generic assignment.

Friedrich Solger in 1904 studied the same fauna 

from the Mungo River locality. He (1904) devoted 

many pages and illustrations to Hoplitoides and considered H. latesellatus as the type of the genus. 

Hoplitoides wohltmanni was emended, and von 

Koenen's Neoptychites? (Hoplites) lentiformis was 

assigned to it. Solger also revised H. ingens, named 

three new varieties of it (nodifer, costatus, laevis), and 

assigned to this species von Koenen's H. wilsingi, H. n. 

sp.?, and one of von Koenen's two figured specimens of 

H. latesellatus. Von Koenen's Pulchellia gibbosula was 

assigned to Hoplitoides, and a new subspecies (bipartitus) was described. Solger (1904, p. 151, pi. 4, figs. 8, 9) 

also described the new species H. koeneni.

The Mungo River fauna was studied again in 1932 

by Leonhard Riedel, who figured H. gibbosulus and 

several very good specimens of H. ingens, including 

unusually large individuals. Riedel also described two 

new species, H. autenriethi (1932, p. 126, text fig. 36) 

and H. solgeri (1932, p. 132, pi. 27, figs. 2, 3; text fig. 

37).

Reyment (1955b, p. 77-83) discussed Hoplitoides 

from Nigeria and figured specimens of H. ingens, H. 

gibbosulus, H. koeneni, and a new species H. crassicostatus (Reyment, 1955b, p. 83, pi. 17, figs. 3, 4; text
UPPER CRETACEOUS AMMONITE FAMILY COILOPOCERATIDAE HYATT, WESTERN INTERIOR, U.S.

fig. 41) as well as the new subspecies H. gibbosulus 

makurdiensis. He pointed out that the type of 

Hoplitoides should be Neoptychites? ingens von 

Koenen (1897), inasmuch as H. latesellatus von 

Koenen (1898), designated the type species by von 

Koenen, is a synonym of H. ingens. Other species 

regarded as synonyms of H. ingens by Reyment are H. 

wilsingi and H. solgeri. Hoplitoides autenriethi is 

regarded as a synonym of H. gibbosulus bipartitus 

Solger.

The Hoplitoides beds of Nigeria and Cameroon contain a great variety of forms ranging from slender, 

nearly smooth types (for example, H. wohltmanni and 

H. ingens laevis) to stout, well ornamented ones (H. 

gibbosulus and H. crassicostatus). That these forms 

occur together is shown by Reyment (1955b, p. 98, 99). 

The ammonites from New Mexico that we are assigning to Hoplitoides do not show this range in variation.

DISTRIBUTION OF HOPLITOIDES

Hoplitoides has been recorded from 15 countries in 

the Tethyan Belt. References that mostly include illustrated specimens are as follows: Mexico (Bose, 

1918, p. 225-227), Peru (Briiggen, 1910, p. 735, 736; 

Benavides-Caceres, 1956, p. 475, 476); Columbia 

(Biirgl, 1957, pi. 16; Reyment, 1970, p. 914), Venezuela 

(Renz, 1959, p. 42), Trinidad (Reyment, 1970, p. 914; 

1972, p. 360-364), Brazil (Magalhaes, 1952, p. 15-17; 

Oliveira and Brito, 1969, p. 223-226), Nigeria and 

Cameroon (von Koenen, 1898, p. 56-61; Solger, 1904, 

p. 127-157; Riedel, 1932, p. 125-133; Reyment, 1955b, 

p. 77-83), Tunisia (Pervinquiere, 1907, p. 217-223, 

Algeria (Collignon, 1965b, p. 193, 194), Egypt (Eck, 

1915, p. 193-196; Douville, 1928, p. 28-31), Israel 

(Freund and Raab, 1969, p. 63-66), Lebanon (Basse, 

1937, p. 189-191; 1940, p. 461), Jordan (Gioffredi and 

others, 1976, p. 41), and Spain (Wiedmann, 1959, 

p. 711, 712, 720). Nearly all of these records are from 

Turonian rocks. The genus was also recorded from 

Madagascar (Basse, 1953).

Most records of Hoplitoides are from the lower Turonian. Briiggen (1910, p. 735) recorded the genus from 

the Coniacian of northern Peru, but Benavides-Caceres 

(1956, p. 475, 476) found it only in the lower Turonian of 

that region. Biirgl (1957, pi. 16, fig. 2a, b) gave a Turonian and Coniacian age for specimens from Colombia.

In the Western Interior, Hoplitoides has been found 

only in New Mexico, where it is represented by three 

species of middle Turonian age. The oldest species, H. 

cf. H. wohltmanni (von Koenen) and H. cf. H. koeneni 

Solger, occur sparsely in the lower part of the zone of 

Collignoniceras woollgari (Mantell), and the youngest 

species, H. sandovalensis Cobban and Hook, n. sp., occurs in the next overlying zone of Prionocyclus hyatti 

(Stanton). The ammonite, recorded by Lee (1912, 

p. 624; 1917, p. 197) as Coilopoceras colleti, is H. 

sandovalensis.

ORIGIN OF HOPLITOIDES

Hoplitoides appears suddenly early in the middle 

Turonian in the Western Interior of the United States. 

Its origin has to be elsewhere. The type species, H. ingens (von Koenen), is abundant in the Turonian of 

Nigeria and Cameroon. Reyment (1955b, p. 98, 99) at 

first assigned the species to the lower Turonian, but 

recently he (Reyment, 1976, p. 20.2, 20.12) considered 

a middle Turonian age more acceptable. Specimens 

referred to this species have been recorded from the 

lower Turonian of Tunisia (Pervinquiere, 1907, p. 219), 

Egypt (Eck, 1915, p. 194), Lebanon (Basse, 1940, 

p. 461), Spain (Wiedmann, 1959, p. 712), Trinidad (Reyment, 1970, p. 914), Colombia (Reyment, 1970, p. 914), 

and Brazil (Reyment, 1971, p. 1070), and specimens 

compared to it have been recorded from Peru (Briiggen, 1910, p. 735).

Reyment (1954b, p. 260) would derive the Coilopoceratidae in part from the Pseudotissotiidae and in 

part from the lower Turonian genus Bauchioceras. 

Later, Reyment (1955b, p. 70) was more specific and 

suggested the origin of the Coilopoceratidae from 

Wrightoceras, which, in turn, was derived from 

Bauchioceras. In this scheme, Hoplitoides would be 

derived from Wrightoceras, and Glebosoceras and 

Coilopoceras would be derived from Hoplitoides. 

Barber (1957, p. 62) disagreed with this interpretation, 

and pointed out that Coilopoceras "occurs at a horizon 

several hundred feet below Bauchioceras" at a locality 

in Nigeria.

Perhaps Hoplitoides originated in some other genus, 

such as Choffaticeras, which is widespread in the 

Tethyan region in early Turonian rocks usually a little 

older than those containing Hoplitoides. The suture of 

Choffaticeras recalls that of Hoplitoides in having an 

asymmetrically bifid, broad lateral lobe, of which the 

part nearest the venter is higher than the part away 

from it. For many examples of the suture of Choffaticeras, see Freund and Raab (1969, text figs. 10-13).

Hoplitoides cf. H. koeneni Solger

Plate 1, figures 1, 2; plate 3, figures 4, 5; text figures 2, 3 

Hoplitoides koeneni Solger (1904, p. 151, pi. 4, figs. 

8, 9; test figs. 42, 43) has moderately slender whorls, of 

which the early ones are ribbed. The venter is broadly 

truncated out to a rather large diameter. Solger 

described the ribs as broad and wavelike and attaining 

their greatest height on the outer part of the flank. He 

gave a count of 10 for one-half whorl. Two specimens
GENUS HOPLITOIDES VON KOENEN, 1898

were illustrated, a small one that shows the flank ribbing in a lateral view and a larger one that shows an 

end view. The end view reveals a conspicuous truncation of the venter to a diameter of at least 37 mm 

(millimeters) and a narrowly rounded venter at a 

diameter of 57 mm. Several external sutures were illustrated by Solger, but none is from a whorl exceeding 

23 mm in "Windungsradius" (a little more than the 

whorl height). These sutures are rather simple for the 

genus.

A partly crushed specimen (pi. 2, figs. 1, 2), 76 mm in 

diameter, from a limestone concretion in the upper 

part of the Mancos Shale underlying the Tres Hermanos Sandstone Member, shows considerable resemblance to H. koeneni. This specimen, from USGS 

Mesozoic locality D10260 (fig. 1, loc. 48), has a little 

more than one-half whorl of the body chamber preserved. The last whorl of the phragmocone has a narrow sulcate venter 2 mm wide at a diameter of about 

33 mm (fig. 2). The venter is poorly preserved on the 

body chamber, but it appears to be narrowly truncated. Ten low, broad, straight ribs per one-half whorl 

are present on the phragmocone (pi. 3, fig. 5). These 

ribs are strongest on the outer part of the flank, and 

every second or third extends to the umbilical 

shoulder. The ribs weaken on the body chamber and almost disappear. The suture is difficult to see, and only 

part of it could be drawn (fig. 3A). A simple pattern is 

revealed, and in this manner it resembles the suture of 

H. koeneni at comparable diameters (Solger, 1904, text 

figs. 42b, 43b; Reyment, 1955b, text fig. 37a). The 

specimen seems to differ from H. koeneni only in its 

narrower venter. No other ammonites were found with 

this specimen, but Mammites depressus Powell was 

collected from about the same stratigraphic position at 

a nearby locality (USGS Mesozoic loc. D10377 in 

SEttNW1/* sec. 5, T. 3 S., R. 3 E.).

Another specimen of Hoplitoides, which has a simple 

suture comparable to that of H. koeneni and the 

specimen from locality D10260, is represented by a 

moderately slender phragmocone 98 mm in diameter 

from USGS Mesozoic locality 8336 (fig. 1, loc. 47). This 

phragmocone has a narrow, truncated venter to a diameter of at least 64 mm. The venter is not preserved on 

the next one-fourth whorl, but it is narrowly rounded at 

a diameter of 78 mm. About eight broad, very weak ribs 

are present per one-half whorl. Most of the external 

suture is shown in figure 3B. This suture also resembles 

some of the simpler sutures of H. ingens (von Koenen) 

figured by Solger (1904, text figs. 29b, c, 39b, 41b). 

The New Mexico specimen was associated with Collignoniceras woollgari woollgari (Mantell).

Types. Figured specimens USNM 252968, 275876.

5 mm

FIGURE 2. Whorl section (restored) of Hoplitoides cf. H. koeneni 

Solger at a diameter of 55 mm. From USGS Mesozoic locality 

D10260 (fig. 1, loc. 48). Figured specimen USNM 252968 (pi. 1, 

figs. 1, 2).

Hoplitoides cf. H. wohltmanni (von Koenen)

Plate 1, figures, 3, 4; text figures 4, 5

Three specimens from the basal part of the Tres Hermanos Sandstone Member of the Mancos Shale, (fig. 1, 

loc. 45) resemble Hoplitoides wohltmanni (von Koenen, 

1897, p. 12, pi. 1, fig. 2; pi. 2, figs. 3, 9) in the whorl section and suture. One of the specimens, a phragmocone 

95 mm in diameter (pi. 1, figs. 3, 4), is almost smooth 

and has a moderately digitate suture (fig. 4) much like 

those illustrated by von Koenen (1897, pi. 2, fig. 9) and 

Solger (1904, text figs. 25-27) for H. wohltmanni as 

well as some sutures of H. ingens (von Koenen) figured 

by Solger (1904, text figs. 34c, d). The specimen differs 

from von Koenen's species in having a truncated 

venter out to a much greater diameter. The venter of 

the New Mexico specimen is truncated out to a diameter of at least 65 mm, beyond which the venter is not 

preserved until near the end of the specimen, where the 

venter is narrowly rounded at a diameter of 91 mm. A 

larger specimen, from the same locality, is part of a 

smooth phragmocone whose cross section (fig. 5) is like
UPPER CRETACEOUS AMMONITE FAMILY COILOPOCERATIDAE HYATT, WESTERN INTERIOR, U.S.

5 mm

5 mm

FIGURE 3. Part of the external sutures of Hoplitoides cf. 

H. koeneni Solger. A, figured specimen USNM 252968 (pi. 1, figs. 

1, 2) at a diameter of 37.5 mm, from USGS Mesozoic locality 

D10260 (fig. 1, loc. 48). B, figured specimen USNM 275876 at a 

diameter of about 64 mm, from USGS Mesozoic locality 8336 (fig. 

1, loc. 47). Heavy line marks middle of venter.

that of H. wohltmanni (von Koenen, 1897, pi. 2, fig. 3). 

The third specimen, from USGS Mesozoic locality 

D10259 (fig. 1, loc. 46), is a small phragmocone that 

has a narrowly truncated venter out to a diameter of 

35 mm; the venter is not preserved beyond that size. 

Types. Figured specimens USNM 252969, 255609.

Hoplitoides sandovalensis Cobban and Hook, n. sp.

Plate 2; plate 3, figures 6-8, 12-16; plate 4; plate 11, figure 1; 

plate 18, figures 4-6; text figures 6, 7

This species is characterized by its slender section, 

early disappearance of the truncated venter, and 

complex suture. The species has been found only in 

Sandoval County, N. Mex., where it is represented by 

22 specimens from six localities. Umbilical ratios 

range from 0.04 to 0.09 and thickness ratios range 

from 0.24 to 0.30.

A septate fragment 122 mm in diameter was selected 

as the holotype because it reveals an inner whorl that 

has a sulcate venter and several later whorls that have 

sharp venters (pi. 2, figs. 6, 7). All visible whorls have 

their maximum thickness near the umbilicus. Whorl 

sections of a small paratype are shown in figure 6. The

10 mm

FIGURE 4. External suture of Hoplitoides cf. H. wohltmanni (von 

Koenen) at a diameter of 91.5 mm, from USGS Mesozoic locality 

D5773 (fig. 1, loc. 45). Figured specimen USNM 252969 (pi. 1, figs. 

3, 4). Heavy line marks middle of venter. Dashed line marks umbilical seam. From Cobban and Hook (1979, text fig. 11).

FIGURE 5. Cross section through the older part of a body chamber 

of Hoplitoides cf. H. wohltmanni (von Koenen) from USGS 

Mesozoic locality D5773 (fig. 1, loc. 45). Figured specimen USNM 

255609. From Cobban and Hook (1979, text fig. 10).

innermost whorls of the holotype are not exposed, but 

at a diameter of about 11 mm, the venter is very narrow and sulcate. The venter becomes sharp at some 

diameter between 11 and 20 mm. On two paratypes, 

from the same locality as the holotype, the sulcate 

venter flattens and then sharply rounds at diameters 

of 29 and 35 mm (pi. 2, figs. 1-3; pi. 3, figs. 6-8).

The whorls of the holotype are almost smooth, but 

under oblique lighting, faint, broad, slightly flexuous 

ribs are discernible even on the smallest visible whorl 

at a diameter of about 11 mm. The ribs are highest 

near the venter on the innermost visible whorl. The in-
GENUS HOPLITOIDES VON KOENEN, 1898

ner one-third to one-half of the flank is devoid of ribs. 

Ribbing is so faint on this species that counts are difficult and uncertain even under oblique lighting. The 

few counts that could be made with any certainty were 

seven or eight per one-half whorl.

Hoplitoides sandovalensis is large. One specimen 

in the collections is septate at 198 mm, but larger 

specimens were seen in the field. The paratype figured 

on plate 4 has a diameter of 207 mm at the base of the 

body chamber.

The suture is more deeply digitate than that of most 

figured sutures of Hoplitoides (fig. 7). The first lateral 

lobe is very broad and divided by three or four long 

branches. The first lateral saddle is high and narrow 

and much divided by long branches.

Hoplitoides sandovalensis has a very large 

CeH/opoceras-like siphuncle that is separated by a 

small, hollow area from the shell forming the venter. 

The ventral shell material is thin and easily removed 

on weathering, which exposes the siphuncle. Where the 

siphuncle is eroded, the hollow venter typical of 

weathered Coilopoceras is formed (pi. 3, figs. 12, 13).

Hoplitoides sandovalensis resembles the African 

species described by von Koenen (1898, p. 58, pi. 5, 

fig. 3; pi. 7, figs. 4, 5) as H. ingens in having an early 

loss of the sulcate venter. The whorl sections of large 

specimens of H. ingens are more inflated than those of 

H. sandovalensis, and studies by Solger (1904, p. 

137-151), Riedel (1932, p. 128-132), and Reyment 

(1955b, p. 79-81) revealed that H. ingens is a variable 

species ranging from nearly smooth to costate with 

some individuals having umbilical bullae.

The African species described by von Koenen (1897, 

p. 12, pi. 1, fig. 2; pi. 2, figs. 3, 9) as Neoptychites? 

(Hoplites) wohltmanni and later assigned to Hoplitoides by Solger (1904, p. 133) resembles H. sandovalensis in its slender section and nearly smooth shell 

but differs in retaining the truncated venter to a larger 

size as well as in having a bifid first lateral lobe.

The species of Hoplitoides from Brazil, described by 

Magalhaes (1952, p. 15, text fig. 2; 1953, p. 49, text 

figs. 1, 2) and Oliveira and Brito (1969, p. 223-225, pi. 

3; text figs. 5, 6), resemble H. sandovalensis in having 

smooth or nearly smooth shells, but differ in having 

simple sutures. The inner whorls of the Brazilian 

species have not been described or illustrated.

FIGURE 6. Cross section through the inner whorls of Hoplitoides sandovalensis Cobban and Hook, n. sp. Paratype 

USNM 275885 (pi. 18, figs. 4-6) from USGS Mesozoic 

locality D10508 (fig. 1, loc. 27).
10 UPPER CRETACEOUS AMMONITE FAMILY COILOPOCERATIDAE HYATT, WESTERN INTERIOR, U.S.

10 mm
GENUS COILOPOCERAS HY ATT, 1903 11

Hoplitoides hourcqui Collignon (1965b, p. 193, pi. F, 

figs. 3a, b), from the lower Turonian of Algeria, 

resembles H. sandovalensis in its nearly smooth shell 

and slender section, but the African species has a wider 

umbilicus (ratios 0.12-0.15) and a simpler suture 

characterized by a broad first lateral saddle and bifid 

first lateral lobe.

Other species of Hoplitoides differ from H. sandovalensis in having broader whorls, stronger ornamentation, truncated venter at larger diameters, or important differences in the suture.

Hoplitoides sandovalensis has been found only in the 

Rio Puerco valley in southwestern Sandoval County 

(fig. 1, Iocs. 24-32, 34). Specimens occur in limestone 

concretions in the Mancos Shale. Other ammonites in 

the collections with H. sandovalensis are Spathites 

puercoensis (Herrick and Johnson), Prionocyclus hyatti (Stanton), Proplacenticeras pseudoplacenta (Hyatt), 

and Shuparoceras.

Types. -Holotype USNM 275877, paratypes USNM 

275878-275885.

Genus COILOPOCERAS Hyatt, 19O3

GENERAL STATEMENT

Coilopoceras is a slender to robust, involute ammonite that has a narrow, sharp venter on early whorls 

and a narrowly rounded to well-rounded venter on later 

whorls. Species in the Western Interior are dimorphic; 

one form is more compressed than the other and tends 

to be smooth or nearly so. The stouter form has broad, 

foldlike primary ribs, narrower secondary ribs, and, on 

some specimens, low, rounded ventrolateral tubercles.

Coilopoceras has a very diagnostic and unusual 

suture. The lateral lobe is very broad and deeply bifid, 

and the two branches (accessory lobes) also tend to be 

deeply bifid. On most specimens the branch farthest 

from the venter is in a more lowered or adapical position, and its bifurcating saddle is not as deep as that of 

the other branch. The rest of the lobes of the external 

suture are much smaller than the lateral one and 

decrease regularly in size toward the umbilicus. These 

smaller lobes are bifid or trifid and number five or six.

Douville (1911, p. 308, 309) studied the external 

sutures of a few species of Coilopoceras and concluded 

that the older species had more symmetrically bifid 

lateral lobes than those of younger forms. In his study

FIGURE 7. External sutures of Hoplitoides sandovalensis Cobban 

and Hook, n. sp. A, Paratype USNM 257881 (pi. 3, figs. 15, 16) 

from USGS Mesozoic locality 15797 (fig. 1, loc. 34). B, Paratype 

USNM 275883 (pi. 3, figs. 12-14) from USGS Mesozoic locality 

3672 (fig. 1, loc. 31). C, Paratype USNM 257884 (pi. 4) from 

USGS Mesozoic locality D10508 (fig. 1, loc. 27). D, Paratype 

USNM 275880 (pi. 2, figs. 8-10) from USGS Mesozoic locality 

15799 (fig. 1, loc. 30).

Douville (1911, text fig. 37) designated by numbers 

and letters the major divisions of the lateral lobe.

Hyatt (1903, p. 91) was impressed by the hollow keel 

of Coilopoceras and, hence, the source of the generic 

name. The siphuncle is very large, and where exposed 

on weathering, it has the appearance of a tube that has 

periodic constrictions at the intersections with the septae (pi. 1, fig. 9; pi. 10, figs. 1, 3, 5, 6; Hyatt, 1903, 

pi. 10, fig. 2; Barber, 1957, pi. 3, figs, la, 2b). This condition is well shown on weathered specimens of other 

ammonites similar to Coilopoceras, such as 

Hoplitoides hourcqui Collignon (1965b, pi. F, fig. 3b), 

H. ingens (von Koenen) (Riedel, 1932, pi. 24), 

Glebosoceras glebosum Reyment (Collignon, 1965a, 

pi. 402, fig. 1686), the ammonites figured by Eck (1915, 

pi. 16, fig. 3; pi. 19, fig. 2) as Pseudotissotia segnis 

Solger and Tissotia schweinfurthi Eck, and those 

figured by Douville (1928, pi. 3, fig. 7b; pi. 4, fig. Ib; pi. 

5, fig. Ib) as Leoniceras quassi Peron and L. segne 

Solger, the latter two probably being species of Choffaticeras according to Freund and Raab (1969, p. 56, 

60). A very conspicuous concave venter was formed on 

specimens that had the siphuncle removed by weathering (pi. 3, figs. 7, 8) (Hyatt, 1903, pi. 10, fig. 2; Parnes, 

1964, pi. 1, fig. 8).

Coilopoceras was very large. The holotype of C. 

springeri Hyatt is 400 mm in diameter. The types of C 

eaglefordense Adkins and C. chispaense Adkins have 

diameters of 525 mm and 361 mm. Parnes (1964, p. 10) 

observed in the field specimens of his C. zihoricum that 

had diameters of 700-800 mm. A large phragmocone of 

C. inflatum Cobban and Hook, n. sp., is 393 mm in 

diameter (pi. 14). Lamb (1968, p. 835) recorded 

specimens of Coilopoceras 455 mm in diameter from 

New Mexico.

Hyatt (1903) illustrated only the holotypes of his C. 

colleti and C. novimexicanum and just the suture of his 

C. springeri. Mention was neither made of variation 

within each species nor how the species related to one 

another in time. The lack of other illustrations of these 

species has led to confusion in the identifications and 

ages of these species. As an example, Lee (1912, p. 599) 

recorded C. colleti from both the lower and upper parts 

of the Mancos Shale, whereas the species is really very 

restricted stratigraphically. At least one of the forms 

recorded as C. colleti by Lee (1912, p. 624) is a new 

species of Hoplitoides, which we are naming H. sandovalensis. The present work is an attempt to more 

precisely define each species, to show something of the 

intraspecific variation, and to relate the species in 

time.

At least 27 species of Coilopoceras have been 

described from various parts of the world. Many of 

these names are probably synonyms, especially where
12 UPPER CRETACEOUS AMMONITE FAMILY COILOPOCERATIDAE HYATT, WESTERN INTERIOR, U.S.

several names have been proposed for specimens from 

the same locality and stratigraphic position. Many 

species have been defined largely on small details of 

the lateral lobe of the suture. Some species have been 

based on weathered specimens that have poorly 

preserved sutures. Most species have been illustrated 

by only one or two specimens, and little or nothing has 

been noted as to changes with growth as well as variation within the species.

In the present work we have observed considerable 

variation within the specimens from each locality in 

New Mexico. In each collection consisting of several 

specimens or many, some individuals are slender and 

nearly smooth, whereas others are stouter and more 

strongly ornamented. Most specimens are within one 

or the other end of this variation. For example, collections of C. colleti Hyatt consist of dominantly stout, 

well-ribbed specimens with a few slender, nearly 

smooth individuals, whereas the proportions are 

reversed in collections of C springeri Hyatt. We are 

treating these as variable populations of each species, 

although some authors would probably give separate 

specific names to the stout form and the slender form.

DISTRIBUTION OF COILOPOCERAS

Coilopoceras has been recorded from many parts of 

the world, all in or close to the Tethyan belt. The best 

references are as follows: California (Anderson, 1958, 

p. 249), New Mexico (Hyatt, 1903, p. 91-99), Texas, 

Adkins, 1931, p. 37, 46-51; Powell, 1965, p. 514-517), 

Mexico (Jones, 1938, p. 125, 126; Powell, 1965, 

p. 518-522; Gonzalez-Arreola, 1977, p. 169-171), Trinidad (Reyment, 1972, p. 364), Venezuela (Hedberg and 

Sass, 1938, p. 80; Renz, 1959, p. 19, 22, 42), Colombia 

(Biirgl and Dumit-Tobon, 1954, p. 31, 32; Biirgl, 1957, 

p. 128, 138), Peru (Briiggen, 1910, p. 733-735; Benavides-Caceres, 1956, p. 472-475), Ecuador (J. B. Reeside, Jr., in Wasson and Sinclair, 1927, p. 1270, 1271), 

Brazil (Magalhaes, 1952, p. 12-15; de Oliveira and 

Brito, 1969, p. 227-231), France (Roman and Mazeran, 

1920, p. 28-30), Lebanon (Basse, 1937, p. 188, 189), 

Israel (Parnes, 1964, p. 5-13; Freund and Raab, 1969, 

p. 66; Lewy, 1975, p. 36, 38, 42); Algeria (Pervinquiere, 

1910, p. 72-76), Nigeria (Schneegans, 1943, p. 137; 

Reyment, 1955b, p. 77; Barber, 1957, p. 55), Angola 

(Hoppenar, 1958, p. 80), Madagascar (Boule and 

others, 1907, p. 49, 50; Collignon, 1965a, p. 24, 62-66), 

India (Dassarma and Sinha, 1975, p. 69-72).

The genus has been recorded from rocks of Cenomanian, Turonian, and Coniacian age, but mostly from 

the Turonian. The Cenomanian record was based on 

two Algerian species described by Pervinquiere (1910, 

p. 72-76, pi. 3, figs. 11-23; text figs. 35-38) as C.

africanum and C. haugi. Reyment (1955a, p. 575-579; 

1955b, p. 75) questioned the generic assignment and 

suggested that the species were schloenbachiids. The 

suture of the Algerian species resembles that of true 

Coilopoceras in the general appearance of the first 

lateral lobe, but the rest of the external suture has only 

two or three other lateral lobes in contrast to five or six 

for C. colleti, the type of the genus.

The Conician records are from Peru, Venezuela, 

Israel, and New Mexico. The northern Peruvian record 

by Briiggen (1910, p. 733-735) was not well documented stratigraphically, and later work by Benavides-Caceres (1956, p. 391, 472-475) in northern Peru 

revealed Coilopoceras only in the Turonian. In 

Venezuela Renz (1959, p. 42) recorded Coilopoceras sp. 

with Paralenticeras leonhardianum (Karsten) in the 

basal part of the Luna Formation, which he assigned to 

the Coniacian. The Israel record of Coilopoceras in the 

Coniacian is questionable. Parnes (1964, p. 5, pi. 1, figs. 

8-11; text figs. 2, 3) described the new species C. 

zihoricum from strata that he believed were of early 

Coniacian age. Later work by Lewy (1975, p. 25, 30) 

cast doubt on this assignment. The records of Coilopoceras in the Coniacian of New Mexico (Reyment, 

1956, p. 38; Dassarma and Sinha, 1975, p. 72, 123) are 

unfounded.

In the United States Coilopoceras is almost confined 

to New Mexico and western Texas. An occasional 

specimen has been found in southwestern Colorado 

(Lamb, 1968, p. 832), and a single specimen has been 

found in central Wyoming. All occurrences are in the 

middle and upper Turonian. The genus is best documented in New Mexico, where the oldest species, C. 

springeri Hyatt, occurs in the late middle Turonian 

ammonite zone of Prionocyclus hyatti, and the 

youngest species, C inflatum Cobban and Hook, n. sp., 

occurs in the ammonite zones of Prionocyclus macombi 

and Scaphites warreni of early late Turonian age.

ORIGIN OF COILOPOCERAS

Ammonites from three stratigraphic horizons in 

New Mexico reveal the origin of Coilopoceras from 

Hoplitoides. The oldest of these ammonites is 

Hoplitoides cf. H. wohltmanni (von Koenen) and H. cf. 

H. koeneni Solger, which are represented by a very few 

specimens from Socorro County. These species occur in 

the lower part of the Tres Hermanos Sandstone 

Member of the Mancos Shale as well as in the uppermost part of the underlying Mancos Shale. The specimens have truncated venters (fig. 2) at diameters of as 

much as 70 mm. These Hoplitoides are from beds that 

contain Tragodesmoceras socorroense Cobban and 

Hook, Proplacenticeras pseudoplacenta (Hyatt),
GENUS COILOPOCERASHYATT, 1903 13

Spathites rioensis Powell, Watinoceras cobbani Collignon, Mammites depressus Powell, and Collignoniceras woollgari woollgari (Mantell).

The next younger horizon is represented by the new 

species H. sandovalensis, which occurs in limestone 

concretions in the Mancos Shale in the Rio Puerco 

valley of southern Sandoval County. This species has 

an inconspicuous truncated venter that is confined to 

one or two of the early whorls (fig. 6). The venter of the 

later whorls is sharp. Hoplitoides sandovalensis is 

present in 10 collections from six localities. Eight of 

the collections were made many years ago by T. W. 

Stanton, W. T. Lee, C. B. Hunt, and others. Some of 

their collections include Spathites puercoensis (Herrick and Johnson), Prionocyclus hyatti (Stanton), and 

Shuparoceras sp. One of the two collections made by us 

has only H. sandovalensis, and the other has, in addition, a specimen of Shuparoceras. The presence of 

Spathites puercoensis and Prionocyclus hyatti in the 

other collections may be a result of collecting from a 

thicker sequence of rocks.

The youngest horizon is represented by Coilopoceras 

springeri Hyatt in the Semilla Sandstone Member of 

the Mancos Shale and equivalent rocks in northern 

Sandoval County. This species closely resembles 

Hoplitoides in its general appearance and suture, but it 

differs in lacking a truncated venter in the early 

whorls. Ammonites associated with C springeri include Spathites puercoensis (Herrick and Johnson) and 

Prionocyclus hyatti (Stanton).

Coilopoceras was thus derived from Hoplitoides by a 

progressive reduction in the extent of venter truncation and finally by its disappearance. There are no 

differences between the suture and the general appearance of the adult whorls of the youngest species of 

Hoplitoides and those of the oldest species of 

Coilopoceras.

Coilopoceras colleti Hyatt

Plate 1, figures 7, 8; plate 3, figures 1-3; plate 5; plate 6, figures 1-8; 

plates 7-9; text figures 8-10

1903. Coilopoceras colleti Hyatt, U.S. Geological Survey Monograph 44, p. 91, pi. 10, figs. 5-21; pi. 11, fig. 1.

1903. Coilopoceras novimexicanum Hyatt, U.S. Geological Survey 

Monograph 44, p. 94, pi. 10, figs. 1-4.

1938. Coilopoceras colleti Hyatt. Roman, Les ammonites jurassiques et cretacees, p. 498, pi. 51, figs. 476, 476a.

1942. Coilopoceras colleti Hyatt. Moreman, Journal of Paleontology, v. 16, no. 2, p. 218.

1953. Coilopoceras colleti Hyatt. Magalhaes, Revista Cientifica, 

v. 4, nos. 1-2, pi. 1, fig. 3.

1955. Coilopoceras colleti Hyatt. Reyment, Geologiska Foreningens i Stockholm Forhandlingar, v. 77, pt. 4, p. 579, text 

fig. la.

1957. Coilopoceras colleti Hyatt. Wright in R. C. Moore, ed., Treatise on invertebrate paleontology, Part L, Mollusca 4, 

p. L427, fig. 546 (la-c).

1958. Coilopoceras colleti Hyatt. Luppov and Drushchitz, Principles of paleontology-handbook for paleontologists and 

geologists of USSR, v. 6, pi. 64, figs. 5a, b.

1975. Coilopoceras colleti Hyatt. Dassarma and Sinha, Paleontologia Indica, n. ser., v. 42, pi. 12, fig. 6.

Hyatt (1903, p. 91) characterized this species as 

having foldlike costae that are highest on the middle of 

the flank and widest on the outer part of the flank 

where they weaken and disappear. Hyatt observed 

that on most of the outer whorl of the holotype, every 

other rib began at the umbilicus. Most of Hyatt's 

description concerns the very early growth stages and 

the details of the suture. Dimensions of the holotype 

were given by Hyatt as follows:, diameter, 67 mm; umbilicus (of internal mold), 7 mm on one side and 8 mm 

on other; thickness (between costae), 18 mm. The holotype is entirely septate. A rib count was not given by 

Hyatt, but about 10 ribs are visible on one-half whorl 

at a diameter of 57 mm (Hyatt, 1903, pi. 10, fig. 5).

Hyatt described only the types of C colleti and C 

novimexicanum from Carthage. We have at hand more 

than 30 specimens of C colleti from this locality, which 

give a better scope of the species. The specimens consist mostly of internal molds of very fine grained sandstone and only small patches of shell material. Most 

are undistorted, and broken specimens reveal wellpreserved inner whorls (pi. 5, figs. 1-6, 11, 12). The 

specimens came from a sandstone unit about 18-24 m 

below the top of the Tres Hermanos Sandstone 

Member of the Mancos Shale.

Hyatt (1903, pi. 11, fig. 1) presented a very good 

cross-sectional drawing of the holotype of C. colleti, 

which shows a progressive change in whorl section 

from broader than high at first to higher than wide 

later, and changes in the venter from broadly rounded 

to well rounded to ogival and finally to sharp. In the 

collections at hand from Carthage, the smallest whorl 

observed is 7 mm in diameter. The venter is sharp at 

this diameter and the lateral ribs are clearly discernible. The innermost visible whorl of another specimen 

(pi. 5, fig. 13) has a sharp venter at a diameter of 14 mm 

and clearly discernible ribs.

The specimens from Carthage grade from slender, 

weakly ribbed forms to moderately stout, strongly ribbed forms. The whorl section and ornamentation of the 

holotype of C. colleti is representative of the stout 

form. The slender forms are a little more involute (umbilical ration average of 0.07) than the stouter forms 

(average 0.08). Inasmuch as C. colleti from Carthage is 

the type for the genus, we are presenting in table 2 the 

dimensions and ratios to the diameter of most measur-
14 UPPER CRETACEOUS AMMONITE FAMILY COILOPOCERATIDAE HYATT, WESTERN INTERIOR, U.S.

able specimens of Coilopoceras at hand from the 

Carthage area (fig. 1, Iocs. 49-53).

Five adults from the Carthage area have diameters 

from 279 to 328 mm. Each has part or most of the body 

chamber. The species, however, attained still larger 

sizes. A septate specimen consisting of a fourth of a 

whorl (unfigured hypotype USNM 275895) has a whorl 

height of 180 mm.

Ribs on juveniles are rectiradiate, straight to slightly 

sinuous, and divisible into primaries and secondaries. 

Primaries begin at or near the umbilical shoulder, and 

secondaries arise about midflank. One or two secondaries separate the primaries. On small specimens less 

than 40 mm in diameter, primary ribs arise from low 

umbilical bullae. As the whorls enlarge, the bullae 

move progressively outward on the flank, which 

results in the primaries becoming bullate on the inner 

one third of the flank on juveniles of about 50 mm 

diameter. On the smaller juveniles, all ribs become accentuated a little at the ventrolateral shoulder (pi. 5, 

figs. 2, 3, 5, 6), which gives rise to an ogival whorl section (pi. 6, figs. 1, 3, text fig. 8). The primary and 

secondary ribs of juveniles typically weaken and flatten on the outer part of the flank before rising into the 

low ventrolateral swellings. As the whorls enlarge, the 

primary ribs become higher and broader and form 

foldlike swellings at midflank, and the ventrolateral 

swellings may rise into circular, rounded tubercles (fig. 

9). Secondary ribs disappear on the last adult septate 

whorl, where their position is indicated by low ventrolateral tubercles. The ventrolateral tubercles continue 

onto the adult body chamber and finally weaken and 

merge into a well-defined, rounded ventrolateral 

shoulder. The elongate lateral swellings also persist 

onto the adult body chamber, where they usually 

number four per one-half whorl. These swellings are as 

broad as the interspaces.

Primary ribs do not vary much in number on the 

specimens from the Carthage area. Rib counts on onehalf whorl for 20 specimens average 5.1 and range from 

3 to 7, of which the lower numbers tend to be for the 

larger specimens. Ventrolateral swellings or tubercles 

average 11 per one-half whorl and range from 9 to 15.

Hyatt (1903, pi. 10, figs. 7, 8) illustrated the complete suture of the holotype of C. colleti. The external 

sutures of a stout form and a slender form from the 

Carthage area are presented herein (fig. 10). These 

closely resemble each other and differ from that of the 

holotype only in being a little more dissected. The 

lateral lobe is almost symmetrically bifid, and its two 

branches tend to be bifid. The suture of the holotype of 

C. novimexicanum Hyatt is most unusual and cannot

TABLE 2.— Dimensions and ratios of Coilopoceras colleti Hyatt, 

Carthage area

[Leaders (...), no measurement]

USNM No.

275888 .......

278083 .......

275889 .......

275896 .......

278084 .......

278085 .......

278086 .......

278087 .......

278088 .......

278089 .......

9780QO

278091 .......

275897 .......

275894 .......

278092 .......

275899 .......

278093 .......

278094 .......

278095 .......

278096 .......

275904 .......

Diameter 

(mm)

....... 30.3

....... 46.0

....... 46.4

....... 49.8

....... 63.8

....... 64.7

....... 65.9

....... 84.6

....... 89.2

....... 91.4

....... 96.5

....... 104.0

....... 104.3

....... 117.8

....... 120.8

....... 123.5

....... 128.5

....... 191.5

....... 255.5

....... 284.5

....... 322.0

Umbilical width 

(mm) and ratio

2.2 (0.07) 

5.9 (0.13) 

4.1 (0.09) 

4.9 (0.10) 

3.4 (0.05)

8.0 (0.12) 

6.0 (0.09) 

5.5 (0.07) 

5.6 (0.07) 

4.6 (0.05)

7.8 (0.08) 

7.1 (0.07) 

11.5 (0.11) 

10.4 (0.09) 

6.6 (0.05)

10.1 (0.08) 

6.7 (0.05) 

16.8 (0.09) 

16.0 (0.06) 

24.0 (0.08) 

34.4 (0.11)

Thickness (mm) 

and ratio

7.9 (0.26) 

13.7 (0.30) 

12.2 (0.26) 

14.5 (0.29) 

17.2 (0.27)

19.7 (0.30) 

18.7 (0.28) 

22.2 (0.26) 

22.4 (0.27) 

25.3 (0.28)

24.0 (0.25) 

28.5 (0.27) 

34.8 (0.33) 

35.8 (0.30) 

34.5 (0.29)

33.0 (0.27) 

32.0 (0.25) 

56.0 (0.29)

111.0 (0.34)

FIGURE 8. Cross section of the holotype of Coilopoceras colleti 

Hyatt from Carthage, N. Mex. (from Hyatt, 1903, pi. 11, fig. 1).
GENUS COILOPOCERAS HYATT, 1903 15

be matched by our material from the Carthage area. 

Hyatt's drawing of the external suture shows very

20mm

FIGURE 9. Cross section through the outer whorl of a large adult 

Coilopoceras colleti Hyatt at a diameter of 292 mm. Hypo type 

USNM 275904 (pis. 8, 9) from USGS Mesozoic locality D10354 

(fig. 1, loc. 51). Dashed lines are intercostal section.

long lobes having numerous branches. The ventrad 

branch of the first lateral lobe is deeply bifid and its 

ventrad branch is greatly elongated and digitated so 

much so that it resembles an independent lobe. 

Possibly the holotype of C. novimexicanum represents 

the slender form of C. colleti that has an aberrant 

suture.

Aside from the Carthage collections, the only 

sizeable collection of C colleti at hand consists of 21 

specimens from a limestone concretion found northeast of Llaves at USGS Mesozoic locality D4395 (fig. 

1, loc. 4). None of the specimens is an adult, and most 

are phragmocones. The largest diameter that could be 

measured is 119 mm. These specimens, like those from 

the Carthage area, range from slender and nearly 

smooth (pi. 7, figs. 3-6) to moderately robust and well 

ribbed (pi. 7, figs. 7-9). Umbilical ratios are from 0.06 

to 0.13, averaging 0.09, and thickness ratios are from 

0.25 to 0.35, averaging 0.28. Rib counts for one-half 

whorl are 4 to 7 primaries, averaging 5.4, and 9 to 16 

secondaries, averaging 11.

Coilopoceras novimexicanum was described by 

Hyatt (1903, p. 94, pi. 10, figs. 1-4) from the same 

locality as C. colleti. A rib count was not given, but the 

number visible in the lateral view (Hyatt, 1903, pi. 10, 

fig. 1) appears comparable to that of the holotype of C. 

colleti. Most of Hyatt's description concerns the 

details of the suture which contrast greatly to that of 

the holotype of C. colleti in having longer and narrower 

lobes with more numerous and longer branches.

Outside the Carthage and Llaves areas, Coilopoceras 

colleti is represented by very few specimens. A single 

specimen each from USGS Mesozoic localities D4016 

and D10622 (fig. 1, Iocs. 12, 33) seem well assigned to 

C. colleti. A few other specimens from USGS Mesozoic 

localities D3702 and D3883 (fig. 1, Iocs. 14, 9) may 

represent this species.

The only ammonite associated with C. colleti in the 

Carthage area is Prionocyclus, which is represented 

chiefly by large specimens or by fragments of large 

adults. This Prionocyclus possibly represents large 

adults of P. macombi Meek. The concretion that contained C. colleti in the Llaves area also yielded many 

specimens of P. macombi.

Outside the Western Interior region, C colleti has 

been recorded from Mexico (Gonzalez-Arreola, 1977, 

p. 170, fig. 2b, c). The figured Mexican specimen is a 

large septate fragment of a robust individual that has 

strong, broad, foldlike ribs and a C. colleti-\ike suture. 

The specimen seems too inflated for C. colleti and may 

represent the new species C. inflatum Cobban and 

Hook. Specimens identified as Coilopoceras aff. colleti
16 UPPER CRETACEOUS^MMONITE FAMILY COILOPOCERATIDAE HYATT, WESTERN INTERIOR, U.S.

FIGURE 10. Sutures of Coilopoceras colleti Hyatt from the Carthage area. A, Hypotype USNM 257894 (pi. 5, figs. 14, 15). B, Hypotype

USNM 275899.

have been recorded from Colombia (Biirgl, 1957, p. 

138) and Nigeria (Reyment, 1955b, p. 77, fig. 37b).

Types.-Hypotypes USNM 275886-275904, 

278083-278096.

Coilopoceras springer! Hyatt

Plate 1, figures 5, 6; pkte 3, figures 9-11; pkte 6, figures 9,10; plate 

10; plate 18, figures 7-10; plate 19, figures 1-9; text figures 11-13 

1903. Coilopoceras springeri Hyatt, U.S. Geological Survey Monograph 44, p. 96, pi. 12, figs. 1-3. 

1931. Coilopoceras eaglefordense Adkins, University of Texas

Bulletin 3101, p. 46, pi. 4, figs. 4, 8; pi. 5, fig. 1. 

1931. Coilopoceras chispaense Adkins, University of Texas Bulletin 3101, p. 48, pi. 4, figs. 5, 7; pi. 5, fig. 2.

1976 [1978]. Glebsoceras (sic) chispaense (Adkins). Young and 

Powell, Annales du Museum d'Histoire Naturelle de 

Nice, v. 4, pi. 4, fig. 2; pi. 5, fig. 6.

1976 [1978]. Coilopoceras eaglefordense Adkins. Young and Powell, 

Annales du Museum d'Histoire Naturelle de Nice, 

v. 4, pi. 5, figs. 4, 5.

Only the suture of the holotype was illustrated. 

Hyatt described the type as a smooth shell 400 mm in 

diameter that consists largely of a phragmocone and a 

small part of the body chamber. Most of Hyatt's 

description concerns the details of the suture. The 

suture differs from that of C. colleti in having the first 

saddle in the lateral lobe of Douville's scheme 

(Douville, 1911, fig. 37) as high as the middle 

(Douville's 2) saddle, the third saddle relatively high, 

and by the addition of an adventive lobe. The overall 

appearance of the lateral lobe is one having five fairly 

long branches (fig. 11C). This type of lateral lobe is 

present in a few other species, such as C. indiduraense 

Jones (1938, pi. 11, fig. 11), C. duartei Oliveira and 

Brito (1969, text fig. 11), and C. n. sp. B. (J. B. Reeside, 

Jr., in Wasson and Sinclair, 1927, pi. 9, fig. 3).

The holotype was said to have come from Rit du
GENUS COILOPOCERASiTfATT, 1903 17

Plain, Coif ax County, (fig. 1), which is Rio del Piano on 

present topographic maps, such as the Abbott NW and 

Sauble Circle Dot Ranch 7 1/2-minute quadrangles. The 

Carlile Shale of Turonian age, which forms the bedrock 

along much of this drainage (Dane and Bachman, 

1965), is the logical source of the specimen. Recently, 

Hook examined the outcrops along Rio del Piano (fig. 

1, loc. 59) and found three specimens of C. springeri in 

very large, septarian, silty limestone concretions in the 

upper part of a shale unit equivalent to the Blue Hill 

Member of the Carlile Shale of areas farther north and 

northeast. A second collection of C. springeri (five 

specimens) was made from the same unit of concretions along the banks of the Canadian River 23 km farther southwest (fig. 1, loc. 60).

The eight specimens of C. springeri from the Rio del 

Piano and Canadian River localities are moderate to 

large size. Six of the eight specimens are slender and 

smooth, whereas the others are a little stouter and 

have low, foldlike, straight, rectiradiate, primary ribs 

that are strongest on the lower one-half of the flank 

(pi. 6, figs. 9, 10). Ribs per one-half whorl number four 

and six for the two ornamented specimens. None of the 

specimens has a suture comparable to that of the 

holotype in having an adventive lobule on the lateral 

lobe; instead the lateral lobe is like those shown in 

figure 11 (A, B).

Very few other fossils were associated with C. 

springeri in the concretions along the Rio del Piano 

and Canadian River. These fossils include two specimens of Prionocyclus hyatti (Stanton), two specimens 

of Proplacenticeras pseudoplacenta (Hyatt), and three 

fragments of large Shuparoceras.

Specimens that we believe are C. springeri occur in 

the Mancos Shale at several localities along the 

southeastern margin of the San Juan Basin (fig. 1, Iocs. 

4-7, 10-13, 15-17, 21, 23). One of the largest and best 

preserved collections, from USGS Mesozoic locality 

D3670 (fig. 1, loc. 7), consists of fragments of 28 

phragmocones 70 to 190 mm in diameter. These 

specimens, which retain some of their nacreous shell 

material, came from septarian limestone concretions in 

a dark-gray shale unit in the Mancos Shale. Preservation of the sutures is excellent (fig. 115, Q. Most of the 

specimens have slender whorl sections and smooth or 

nearly smooth shells (pi. 3, figs. 9-11). Under oblique 

lighting, faint ribs are discernible on the outer one-half 

of the flank of most specimens. These ribs are slightly 

flexuous and attain their greatest height about twothirds of the distance from the umbilicus to the venter. 

Although most of the specimens are slender, a few 

fragments of inflated individuals are present. Several 

broken specimens reveal the whorl sections. The venter

changes from well rounded on the very early whorls to 

lanceolate (fig. 12). These specimens were associated 

with Prionocyclus hyatti (Stanton).

Specimens that seem assignable to Coihpoceras 

springeri occur in moderate abundance in the basal 

part of the Semilla Sandstone Member of the Mancos 

Shale at its type section in the southwestern part of 

the San Juan Basin (Dane and others, 1968, p. F19). 

Twenty-six specimens from three collections (fig. 1, 

Iocs. 10, 11, 13) at this locality are suitable for 

measurements of dimensions (table 3). Inasmuch as 

these specimens are chiefly internal molds, all dimensions are of internal molds only. These specimens differ 

a little from those of locality D3670 in having more 

pronounced ribbing. An occasional well-ribbed individual may have umbilical bullae (pi. 18, figs. 7, 8) 

and in this respect are closely similar to C. colleti. 

Perhaps the Semilla specimens occupy an intermediate 

position in age between that of locality D3670 and that 

of typical C. colleti.

The specimens from the Semilla Sandstone Member 

were associated with Prionocyclus hyatti (Stanton) 

and Inoceramus howelli White as well as many other 

bivalves and a few gastropods (Dane and others, 1968, 

p. F17-F19). In addition, a few collections from the 

Mancos Shale include Spathites puercoensis (Herrick 

and Johnson) (fig. 1, Iocs. 15, 21, 23), Proplacenticeras 

pseudoplacenta (Hyatt) (fig. 1, loc. 21), and Shuparoceras (fig. 1, loc. 7).

The specimens from Chispa Summit, Jeff Davis 

County, Texas, described by Adkins (1931, p. 46-49, 

pi. 4, figs. 4, 5, 7, 8; pi. 5, figs. 1, 2) as the new species C. 

eaglefordense and C. chispaense, represent the smooth 

and ribbed forms of C. springeri. The sutures illustrated by Adkins are comparable to those of the 

topotypes of C. springeri collected by Hook on the Rio 

del Piano. We visited the type locality of Adkin's 

species and collected 10 specimens, of which 7 are 

smooth and 3 have broad, foldlike primary ribs. Most 

have sutures like those on specimens from the Rio del 

Piano-Canadian River area as well as those from the 

Rio Puerco area, but two have five branches of the 

lateral lobe as in the suture of the holotype of C. springeri. One of these sutures is shown in figure 13.

The specimens at the type locality of Adkins' species 

were associated with Prionocyclus hyatti (Stanton) 

as indicated by Powell (1965, p. 516, 517). In a later 

paper, however, Young and Powell (1976, p. 

25.15-25.23) show P. hyatti as a zone above a zone of 

Coilopoceras eaglefordense [C. springeri]. We found P. 

hyatti associated with the smooth and ornamented
18 UPPER CRETACEOUS AMMONITE FAMILY COILOPOCERATIDAE HYATT, WESTERN INTERIOR, U.S.

10 mm

10 mm
GENUS COILOPOCERAS HYATT, 1903 19

5 mm

FIGURE 12. Whorl sections of a septate fragment of Coilopoceras 

springeri Hyatt from USGS Mesozoic locality D3670 (fig. 1, loc. 

7). Hypotype USNM 275919.

forms of C. springeri at Adkins' locality. Shuparoceras 

was also found with these.

Types.-Hypotypes USNM 275906-275919, 

278101-278123.

Coilopoceras inflatum Cobban and Hook, n. sp.

Plate 1, figures 9-11; plate 11, figure 2; plates 12-17; plate 18, 

figures 1-3, 11-13; plates 20, 21; text figures 14, 15

We interpret this species as consisting of a dimorphic pair. Most specimens are inflated and conspicuously ribbed. The others are almost smooth and 

have slender whorl sections. The species was derived 

from C. colleti through changes in the stout form. The 

stout form of C. inflatum tends to be more inflated, the 

venter is sharper, and the ventrolateral tubercles are 

lost at a smaller diameter.

The holotype (pi. 11, fig. 2) is part of a large

FIGURE 11. External sutures of Coilopoceras springeri Hyatt. A, 

Hypotype USNM 275916 at a whorl height of 75 mm, from 

USGS Mesozoic locality D3670 (fig. 1, loc. 7). B, Hypotype 

USNM 275907 (pi. 3, figs. 9-11) at a whorl height of 36 mm, 

from USGS Mesozoic locality D3670 (fig. 1, loc. 7). C, Hypotype 

USNM 275917 at a whorl height of 50 mm, from the same locality as A and B. D, Hypotype USNM 275918 at a whorl height of 

92 mm, from USGS Mesozoic locality 28873 (fig. 1, loc. 13).

TABLE 3 Dimensions and ratios of Coilopoceras springeri Hyatt,

Rio Puerico area

[Leaders (...), no measurement]

USNM No.

278101 .

275913 .

278102 .

278103 .

278104 .

275911 .

278105 .

278106 .

278107 .

275909 .

275908 .

275906 .

275912 .

278108 .

278109 .

278110 .

278111 .

278112 .

275915 .

278113

278114 .

278115 .

278116 .

278117 .

278118 .

275910 .

278119 .

278120 .

278121

Diameter

(mm)

............. 35.0

............. 37.8

............. 39.8

............. 44.5

............. 44.7

............. 49.7

............. 50.3

............. 54.2

............. 61.3

............. 63.6

............. 64.8

............. 66.0

............. 72.3

............. 73.3

............. 73.4

............. 76.3

............. 80.6

............. 87.0

............. 87.7

............. 92.1

............. 94.6

............. 100.0

............. 112.0

............. 117.0

............. 122.0

............. 133.0

............. 241.0

............. 248.5

............. 260.3

Umbilical width

(mm) and ratio

2.9 (0.08)

2.4 (0.06)

2.2 (0.06)

2.8 (0.06)

2.8 (0.06)

4.5 (0.09)

2.3 (0.05)

3.5 (0.06)

2.7 (0.04)

4.0 (0.06)

3.0 (0.03)

3.5 (0.05)

4.8 (0.07)

3.7 (0.05)

3.5 (0.05)

3.8 (0.05)

4.4 (0.05)

4.5 (0.05)

4.3 (0.05)

6.4 (0.07)

3.9 (0.04)

5.0 (0.05)

6.0 (0.05)

8.0 (0.07)

7.3 (0.06)

12.2 (0.09)

15.0 (0.06)

20.7 (0.08)

20.3 (0.08)

Thickness (mm)

and ratio

9.2 (0.26)

9.4 (0.25)

10.7 (0.27)

10.7 (0.24)

11.0 (0.25)

13.0 (0.26)

12.2 (0.24)

16.0 (0.30)

16.8 (0.27)

15.6 (0.25)

16.0 (0.25)

16.5 (0.25)

21.0 (0.29)

17.5 (0.24)

22.3 (0.30)

20.8 (0.27)

19.3 (0.24)

20.2 (0.23)

21.7 (0.25)

....

24.5 (0.26)

24.0 (0.24)

25.8 (0.23)

26.4 (0.23)

....

37.2 (0.28)

61.0 (0.25

75.0 (0.30)

86.0 (0.33)

phragmocone of the stout form that exposes two of the 

inner whorls. A little less than one-half of the outer 

whorl is preserved; its umbilical width is 24 mm and its 

diameter (restored) is estimated at about 258 mm, 

which would give an umbilical ratio of about 0.09. The 

maximum costal whorl thickness is 101 mm (ratio 

0.39). About one-fourth of the innermost whorl is visible, and its diameter is estimated at about 60 mm. The 

early part of this whorl closely resembles similar-size 

whorls of the stout form of C. colleti in having an 

ogival section, prominant rectiradiate primary ribs 

arising from umbilical bullae, primary ribs separated 

by a secondary one, and all ribs terminating in nodelike 

ventrolateral swellings. The main difference is in the 

more robust whorl section of C. inflatum. The next 

whorl has a diameter of about 130 mm and a costal 

whorl thickness of 51.3 mm. Ventrolateral swellings 

are present on the older part of this whorl, where they 

number about 10 per one-half whorl. These swellings 

weaken and disappear on the younger part. The outer 

whorl has only broad, radial swellings crossing much 

of the flank.

Whorl sections of three stout paratypes are shown in 

figure 14. Differences between these sections and those
20 UPPER CRETACEOUS AMMONITE FAMILY COILOPOCERATIDAE HYATT, WESTERN INTERIOR, U.S.

20 mm

FIGURE 13. Most of the external suture of a hypotype (USNM 278123) of Coilopoceras springeri Hyatt at a whorl height of 203 mm. From 

the Chispa Summit Formation at the type locality of C eaglefordense Adkins and C. chispaense Adkins (Adkins, 1931, fig. 7, loc. 2627) 

(USGS Mesozoic loc. D10753).

of C. colleti (Hyatt, 1903, pi. 10, fig. 6) (text fig. 9) are 

readily apparent. Whorl sections of C. inflatum reveal 

changes from a well-rounded venter to one that is 

fastigate, then sharply lanceolate, and finally broadly 

lanceolate.

The holotype is one of six specimens of Coilopoceras 

from the basal 3 m of the D-Cross Tongue of the Mancos Shale at USGS Mesozoic locality D2055 at 

Cebollita Mesa in southern Valencia County, N. Mex. 

(fig. 1, loc. 40). Four of the specimens collected with the 

holotype are inflated and have 4 to 7 primary ribs per 

one-half whorl and 13 to 15 secondary ones. The dimensions of these inflated specimens and the holotype are 

given in table 4. The sixth specimen (unfigured 

paratype USNM 278099), less than one-half whorl of a 

phragmocone, differs from the others in having a 

slender whorl section and an almost smooth shell, this 

individual is interpreted as the compressed, nearly 

smooth member of the dimorphic species pair.

In the D Cross Mountain area, about 30 km southeast of Cebollita Mesa, C. inflatum also occurs in the 

basal part of the D-Cross Tongue of the Mancos Shale. 

A collection, from USGS Mesozoic locality D7066 (fig. 

1, loc. 42), consists of five specimens of Coilopoceras 98 

to 197 mm in diameter that have umbilical ratios of 

0.08 and 0.09 and thickness ratios of 0.29 to 0.40. Four 

of the specimens are readily referable to the inflated 

form of C. inflatum in their robust form and disappearance of ventrolateral swellings on the larger 

whorls. The fifth specimen (pi. 16, fig. 3), however, is

slender and very weakly ribbed, and has the smallest 

umbilicus (ratio 0.29); it is assigned to the slender, 

rather smooth member of the dimorphic species pair. 

One of the other specimens (pi. 17) is unusual in having 

as many as five secondary ribs separating the 

primaries on the younger part of the phragmocone. An 

occasional specimen from other localities has as many 

as three secondaries between primaries (pi. 15). These 

more densely ribbed individuals recall C. multicostatum Lewy (1975, p. 42, pi. 1, figs. 1, 2, text figs. 

15A-D, H) from Sinai and Egypt, which differs in its 

narrower whorls and simpler suture.

The rarity of the slender, rather smooth form is further emphasized by the presence of a single individual 

among 11 specimens of C. inflatum from another locality in the D Cross Mountain area (D 10638, fig. 1, loc. 

41). This specimen (unfigured paratype USNM 

278100), a phragmocone 280 mm in diameter, has an 

umbilical ratio of 0.06 and a whorl-thickness ratio of 

0.31.

Collections of C. inflatum from the Oscura area in 

Lincoln County (fig. 1, Iocs. 54, 55) have entirely different ratios of the slender, fairly smooth form to the

FIGURE 14. Whorl sections of the stout form of Coilopoceras inflatum Cobban and Hook, n. sp. A, Paratype USNM 275922 (pi. 

12; pi. 13, fig. 2) at a diameter of 258 mm, from USGS Mesozoic 

locality D10321 (fig. 1, loc. 38). B, Paratype USNM 275938 at a 

diameter of 102 mm, from USGS Mesozoic locality D2055 (fig. 1, 

loc. 40). C, Paratype USNM 275923 (pi. 14) at a whorl height of 

202 mm, from USGS Mesozoic locality D10634 (fig. 1, loc. 22). 

Dashed lines are intercostal sections.
GENUS COILOPOCERAS HYATT, 1903 21

20mm

TABLE 4. Dimensions and ratios of Coilopoceras inflatum Cobban 

and Hook, n. sp.

USNM No.

Diameter

(mm)

Umbilical width 

(mm) and ratio

Thickness (mm) 

and ratio

275938.............. 104.0 10.2(0.10) 36.5(0.35)

278097 .............. 106.5 11.0(0.10) 37.3(0.35)

275921 .............. 124.5 10.7(0.09) 44.0(0.35)

278098 .............. 201.5 17.6 (0.09) 76.0 (0.38)

275920 .............. 251.0 24.0 (0.10) 97.5 (0.39)

inflated ornamented form. Two nearby collections 

(USGS Mesozoic Iocs. D10636 and D10644) from the 

same stratigraphic position consist of 17 slender individuals and 26 robust ones. Examples from these 

localities are shown in plates 20 and 21.

The largest specimens of C. inflatum are extremely 

robust (pis. 12-14). One huge individual, septate at a 

diameter of 393 mm, has an extraordinary thickness 

ratio of 0.54 (pi. 14; text fig. 14Q.

The suture of C. inflatum is similar to that of C. colleti in having the lateral lobe distinctly bifid (fig. 15). 

An important difference, however, is in the deep bifurcation of the ventral branch of this lobe of C. inflatum.

Coilopoceras inflatum closely resembles the very 

stout fragment from Mexico referred to C. colleti by 

Gonzalez-Arreola (1977, p. 170, fig. 2b, c). The suture 

of the Mexican specimen seems to be simpler, and the 

ventral branch of the first lateral lobe is not as deeply 

bifid. The only other well-inflated form of Coilopoceras 

is the Nigerian species C. discoideum Barber (1957, p. 

55, pi. 2, fig. 1; pi. 3, figs. 1, 2a, b; pi. 25, figs. 1-4). A 

lateral view of a paratype (Barber, 1957, pi. 3, fig. 2a) 

suggests that the inner whorls have ventrolateral 

swellings much like those of similar-size specimens of 

C. inflatum. Coilopoceras discoideum differs, however, 

in its lanceolate inner whorls, instead of fastigate ones 

and in its smooth adult whorls. Coilopoceras chispaense Adkins (1931, p. 48, pi. 4, figs. 5, 7; pi. 5, fig. 2) 

is also an inflated form that seems to lack the noded 

growth stage of C. inflatum.

The deep bifurcation of the ventral branch of the 

lateral lobe is matched by many species of Coilopoceras such as C. requienianum (d'Orbigny, 1840, pi. 

93, fig. 4), C. haugi Pervinquiere (1910, fig. 37), C. 

grossouvrei Hyatt (1903, pi. 12, fig. 7), C. sinaiense 

Lewy (1975, fig. 15 I-K), C. scindiae (Vredenburg, 

1907, pi. 16, fig. 2), C. jenksi and C. newelli (BenavidesCaceres, 1956, figs. 52, 53), and the Brazilian species C. 

lucianoi (Oliveira, 1969, fig. 1) as well as those described by Oliveira and Brito (1969, figs. 9,10,12) as C. 

sergipensis, C. brasiliensis, and C. mauryae.
22 UPPER CRETACEOUS AMMONITE FAMILY COILOPOCERATIDAE HYATT, WESTERN INTERIOR, U.S.

10 mm

10 mm

FIGURE 15. External sutures of Coilopoceras inflation Cobban and 

Hook, n. sp. A, Holotype USNM 275920 (pi. 11, fig. 2) at a whorl 

height of 73 mm, from USGS Mesozoic locality D2055 (fig. 1, loc. 

40). B, Paratype USNM 275939 at a whorl height of 65 mm, from 

USGS Mesozoic locality D10602 (fig. 1, loc. 35). Heavy lines mark 

middle of venter.

The holotype of C. inflatum was associated at USGS 

Mesozoic locality D2055 (fig. 1, loc. 40) with a few 

fragments of large Prionocyclus that may be P. wyomingensis Meek. A collection (US1GS Mesozoic loc. 

D2056) 5 m above D2055 contains P. wyomingensis 

Meek, Scaphites warreni Meek and Hayden, and Inoceramus dimidius White.

Types.—Holotype USNM 275920, paratypes, 

USNM 275921-275939, 278097-278100.

Genus HERRICKICERAS Cobban and Hook, n. gen.

Type species.—Placenticeras costatum Herrick and 

Johnson, 1900.

This genus is proposed for involute, compressed ammonites that have on the inner whorls a sulcate venter 

bounded on each side by a sharp keel bearing clavate 

tubercles. The external suture has a very broad, deeply 

bifid first-lateral saddle and a smaller bifid lateral lobe 

that has the branch nearest the umbilicus in a more 

lowered position.

The genus is known only from H. costatum (Herrick 

and Johnson) of middle Turonian age. Herrickiceras 

appeared suddenly in New Mexico in rocks that contain Hoplitoides sandovalensis. Herrickiceras may 

have had its origin in either Donenriquoceras Wiedmann (1959, p. 758, pi. 7, figs. 1-4; text figs. 13, 14) or 

Imlayites (Leanza, 1967, p. 196, pi. 4, figs. 1-4; pi. 6, 

figs. 1, 4-6), both of early Turonian age. Donenriquoceras, from Spain, resembles Herrickiceras in its

compressed form, very small umbilicus, venter bounded by tubercles in the inner whorls, and in the bifid 

lateral lobe having the branch nearest the umbilicus in 

a more lowered position; it differs in lacking a sulcate 

venter bordered by sharp keels and in having a narrower first-lateral saddle. Imlayites, from Colombia, 

resembles Herrickiceras in its compressed form, very 

small umbilicus, and sulcate venter; it differs in lacking ventrolateral tubercles, and its suture is simpler 

and arranged differently.

Herrickiceras is named in honor of Clarence L. Herrick for his pioneer studies of the geology of central 

New Mexico, including the Rio Puerco valley, the 

source of most of our Coilopoceratidae. For an excellent biography of Herrick, the reader is referred to 

Herrick (1955).

Herrickiceras costatum (Herrick and Johnson)

Plate 19, figures 10-18; text figure 16

1900. Placenticeras costata Herrick and Johnson, Bulletin of the

Scientific Laboratories of Denison University, v. 11, art. 9,

p. 214, pi. 28, figs. 2, 3. 

1900. Placenticeras costata Herrick and Johnson, Bulletin of the

University o.f New Mexico, v. 2, p. 40, pi. 2, figs. 2, 3. 

1954. "Hoplitoides" cf. "H. " munieri Pervinquiere. Kummel and

Decker, Journal of Paleontology, v. 28, no. 3, p. 317, pi. 33,

figs. 1, 2; text figs. 7A, 10.

The holotype, and only specimen described, was 

destroyed when the Hadley Laboratory at the University of New Mexico in Albuquerque burned May 23, 

1910. According to Herrick and Johnson (1900), the 

type was 95 mm in diameter and 21 mm in thickness. 

Their description of the form and ornamentation is as 

follows:

Shell lenticular, compressed, of moderate size; umbilicus very 

small; volutions deeply embracing, widest a little distance from the 

umbilicus; dorsum flat or slightly channeled, crossed by a continuation of the nodes; surface marked by numerous irregular, subtriangular and curved ribs, the larger ones extending from the dorsum to the umbilicus and separated by one or more short, oblique 

ribs originating on the dorsum where they give rise to small 

elongate nodes; aperture apparently narrowly cordate, flaring on 

either side of the volution embraced by it.

Herrick and Johnson described the outer part of the 

external saddle and noted that the first-lateral saddle 

was wider than the lateral lobe. The suture is shown in 

the lateral view of their drawing of the type (Herrick 

and Johnson, 1900, pi. 28, fig. 3). The lateral lobe is 

bifid, and the part nearest the umbilicus is in a more 

lowered position than the other part. In addition, the 

umbilical one-half of the lateral lobe is trifid, whereas 

the ventral one-half is deeply divided into two long, 

narrow lobules. The first lateral saddle of the external 

suture is symmetrically divided by a long, narrow lobe.

Herrick and Johnson's drawings show about 16 flexuous ribs per one-half whorl and show that each rib
AGE RELATIONSHIPS OF COILOPOCERATIDAE 23

crosses the sulcate venter. The ribs are broadest on the 

outer part of the flank.

An excellent specimen collected by Neal La Fon, of 

Albuquerque, is selected as a neotype (USNM 275940) 

to replace the destroyed type. La Fon's specimen, an 

adult 118 mm in diameter, has nearly one-half whorl of 

the body chamber preserved. The phragmocone is uncrushed but is a little distorted. The umbilicus is very 

small and has a maximum diameter of 4.7 mm and a ratio of 0.04 of the shell diameter. The umbilical wall is 

steep, and the umbilical shoulder is narrowly rounded. 

The shell has a slender cross section with the greatest 

width near the umbilicus. A thickness ratio of 0.29 percent is indicated for the base of the body chamber at a 

diameter of 83 mm.

Fifteen sinuous ribs are present on the last one-half 

of the phragmocone. About every third rib extends to 

the umbilicus. On the inner one-half of the flank, the 

longer ribs are straight, rectiradiate, and very weak, 

but on the outer one-half, each rib becomes stronger, 

curves backward and then forward and disappears at 

or near the edge of the venter. Secondary ribs arise at 

midflank and follow the curvature of the other ribs. 

The ribs reappear very faintly in the sulcate venter, 

which they cross at right angles. All ribs weaken at the 

base of the body chamber and gradually disappear.

The suture (fig. 16C) of the neotype very closely 

resembles that of Herrick and Johnson's type. Parts of 

the external sutures of two other specimens are also 

shown in figure 16.

The presence of small elongate tubercules on the 

edge of the venter was noted by Herrick and Johnson. 

These are not present on the visible whorl of the 

neotype. They are clearly visible, however, on a smaller 

specimen (pi. 19, fig. 10), where they are small, clavate, 

closely spaced, and alined with the ribs. On the same 

specimen, but at a larger diameter, the tubercles 

gradually fuse with one another to form a keel on each 

edge of the venter.

Herrick and Johnson's type came from a unit of septarian limestone concretions in the Mancos Shale in 

the Rio Puerco valley in southern Sandoval County. 

Our specimens are from the same area (fig. 1, Iocs. 

27, 32), where they were associated with Hoplitoides 

sandovalensis.

The specimen from Cuchillo Parado, Chihuahua, 

Mexico, figured by Kummel and Decker (1954, p. 317, 

pi. 33, figs. 1, 2; text figs. 7A, 10) as "Hoplitoides" cf. 

"H. " munieri Pervinquiere is probably Herrickiceras 

costatum. The Mexican specimen has ribs crossing the 

sulcate venter, and the first-lateral saddle of the external suture is broader than the lateral lobe.

Types.—Neotype USNM 275940, hypotypes USNM 

275941, 275942.

5 mm

5 mm

10 mm

FIGURE 16. External sutures of Herrickiceras costatum (Herrick 

and Johnson). A, Hypotype USNM 275941 (pi. 19, figs. 10-12) at 

a diameter of 32 mm, from USGS Mesozoic locality D10469 (text 

fig. 1, loc. 32). B, Hypotype USNM 275942 (pi. 19, figs. 13-15) at a 

diameter of 71 mm, from the same locality. C, Neotype USNM 

275940 (pi. 19, figs. 16-18) at a whorl height of 33 mm, from 

USGS Mesozoic locality D10508 (fig. 1, loc. 27). Heavy lines mark 

middle of venter.

AGE RELATIONSHIPS OF COILOPOCERATIDAE

Most species of the Coilopoceratidae in New Mexico 

are known only from local areas and this complicates 

their age relationships. The general sequence, from 

oldest to youngest, of Hoplitoides cf. H. koeneni, H. 

sandovalensis, Coilopoceras springeri, C. colleti, and 

C. inflatum, seems well established, but local populations within the species of Coilopoceras are somewhat 

uncertain.

The oldest species, Hoplitoides cf. H. koeneni and H. 

cf. H. wohltmanni, occur with Collignoniceras 

woollgari woollgari, which permits a correlation with 

the zone of C woollgari in Europe. Inasmuch as C. 

woollgari also occurs in west Texas and northern Mexico (as Selwynoceras mexicanum of Powell, 1963,
24 UPPER CRETACEOUS AMMONITE FAMILY COILOPOCERATIDAE HYATT, WESTERN INTERIOR, U.S.

p. 1225), a correlation with rocks in these areas is indicated. Watinoceras cobbani Collignon (1966, p. 36, 

pi. 19, figs. 8,8a, 8b) was collected by us from beds containing C. woollgari woollgari in Socorro County. This 

species of Watinoceras is found in the Moroccan zone 

of Benueites benueensis and Watinoceras guentheri of 

Collignon (1966, p. 67), which suggests an age equivalent to that of the Hoplitoides from New Mexico. Collignon considered this zone as middle Turonian. 

Among the ammonites from this zone in Morocco is 

the species Proplacenticeras zaharense Collignon 

(1966, p. 33, pi. 18, figs. 5-9), which has a sulcate 

venter and an umbilicus too narrow for Proplacenticeras. The species may well be a Hoplitoides much 

like the ones from New Mexico.

Hoplitoides sandovalensis and Herrickiceras 

costatum occur in a very limited area in the Rio Puerco 

valley. Seven of the 10 collections containing H. sandovalensis include specimens of Spathites puercoensis 

(Herrick and Johnson). A few collections include 

Prionocyclus hyatti (Stanton) or Shuparoceras. The 

zone cannot be correlated outside the Rio Puerco area.

The collection of Coilopoceras springeri from the Rio 

Puerco valley (D3670, fig. 1, loc. 7) that consists 

dominantly of smooth or nearly smooth specimens 

resembles Hoplitoides sandovalensis in this respect. 

Associated fossils include Inoceramus howelli White, 

Prionocyclus hyatti (Stanton), and a fragment of 

Shuparoceras. The collection is probably slightly 

younger than those containing H. sandovalensis.

Collections from the Semilla Sandstone Member of 

the Mancos Shale contain a Coilopoceras referred to C. 

springeri. These specimens have sutures like those 

from locality D3670, but the shells tend to be more ornamented, foreshadowing C. colleti. Associated fossils 

include Inoceramus howelli and Prionocyclus hyatti.

Coilopoceras colleti from the Carthage area is 

associated with Prionocyclus macombi Meek and 

Lopha bellaplicata novimexicana Kauffman. Coilopoceras colleti from the Llaves area (D4395, fig. 1, loc. 3) 

is associated also with P. macombi, but the Lopha is 

absent and its place taken by Inoceramus aff. /. 

dimidius White. Collection D4395 came from 3 m 

below the base of beds containing Lopha lugubris (Conrad). The collections from the Carthage and Llaves 

area may be the same age or, possibly, that from 

Llaves may be slightly younger.

Coilopoceras inflatum at localities D10636 and 

D10644 near Oscura (fig. 1, Iocs. 54, 56) is found with 

Lopha lugubris, Prionocyclus macombi, and Inoceramus dimidius White. A rare occurrence of the ammonite Hourcquia in this collection may provide a 

means of international correlation. Hourcquia has been 

described only from Madagascar (Collignon, 1965a, p.

77-82, pi. 411-413) and Japan (Matsumoto, 1970, p. 

310-314, pi. 49, fig. 2a-d, text figs. 4, 5) and possibly 

France (de Grossouvre, 1893, p. 51, pi. 2, fig. 6a, b). The 

type of the genus, H. mirabilis Collignon, is from 

the upper Turonian zone of Coilopoceras requieni 

(d'Orbigny) and Romaniceras deveriai (d'Orbigny) according to Collignon (1965a, p. 78).

The youngest of the Western Interior Coilopoceratidae may be C. inflatum in the D Cross Mountain-Cebollita Mesa area (fig. 1, Iocs. 40-44) where the 

species is associated with Prionocyclus wyomingensis 

Meek.

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INDEX

[Italic page numbers indicate major references]

Abstract..............

Aconeceras ...........

africanum, Coilopoceras

Algeria, Coilopoceras ..

Hoplitoides .......

Angola, Coilopoceras .. 

autenriethi, Hoplitoides

B

Bauchioceras .....................

bellaplicata novimexicana, Lopha . 

benueensis, Benneites ............

Benueites benueensis ............

bipartitus, Hoplitoides gibbosulus 

brasiliensis, Coilopoceras .........

Brazil, Coilopoceras..............

Hoplitoides .................

California, Coilopoceras .....................

Cameroon, Hoplitoides ......................

Canadian River locality .....................

Carlile Shale ...............................

Cebollita Mesa .............................

Cenomanian age, Coilopoceras ...............

chispaense, Coilopoceras ........... 5, 11,16, 17,

chispaense, Glebsoceras .....................

Choffaticeras ...............................

cobbani, Watinoceras .......................

Coilopoceras .................................

africanum ..............................

brasiliensis .............................

chispaense .................... 5,11,16,17,

colleti ..................... 1, 6, 11, 12, 13,

16, 19, 20, 

pis. 1, 3, 5, 6,

definition ..............................

discoideum..............................

distribution ............................

duartei .................................

eaglefordense ...................... 11, 16,

grossouvrei ............................

haugi ..................................

indiduraense ...........................

inflatum................... 1,11,12, 19, 20,

23, 24; pis. 1, 

13,14,15,16,17,

jenski ..................................

lucianoi ................................

mauryae ...............................

multicostatum ..........................

newelli .................................

novimexicanum .................... 11,13,

origin ..................................

requieni ................................

requienianum ...........................

scindiae ................................

sergipensis 

sinaiense ..

Page

1

5

12

12

6

12

5, 6

6

24

24

24

5, 6

21

12

12 

5,6 

17 

17 

20 

12

20,21

16

6, 11

13, 24

1, 5, 6 

12 

21

20, 21

14, 15,

23, 24;

7,8,9 

11 

21 

12 

16

17,20 

21

12, 21 

16

,21,22 

,11,12

18, 20 

21 

21 

21

20

21

14,15

12

24

21

21

21

21

Coilopoceras—Continued Page

springeri................... 1, 5, 11, 12, 13, 16, 17

18,19, 20, 23, 24;

pis. 1, 3, 6,10,18,19

zihoricum .............................. 11

Coilopoceratidae, definition.................. 5

colleti, Coilopoceras ............. 1, 6,11,12,13,14, 15

16,19, 20, 23, 24;

pis. 1,3, 5, 6, 7, 8,9

Collignoniceras woollgari.................... 6

woottgari ........................ 7,13, 23, 24

Colombia, Coilopoceras ..................... 12

Hoplitoides ............................ 6

Colorado, Coilopoceras ...................... 12

Coniacian age, Coilopoceras ................. 12

Hoplitoidea ............................ 6

costata, Placenticeras ....................... 1

costatum, Herrickiceras .............. 22, 23, 24, pi. 19

Placenticeras ........................... 22

costatus, Hoplitoides ingens ................. 5

crassicostatus, Hoplitoides .................. 5, 6

D

D-Cross Tongue, Mancos Shale .............. 20

depressus, Mammites ....................... 7, 13

deveriai Romaniceras ....................... 24

dimidius, Inoceramus ....................... 22, 24

discordeum, Coilopoceras.................... 21

Donenriquoceras ........................... 22

duartei, Coilopoceras........................ 16

E, F, G

eaglefordense, Coilopoceras ............. 11, 16, 17, 20

Ecuador, Coilopoceras ...................... 12

Egypt, Hoplitoides ......................... 6

France, Coilopoceras . 

Hourcquia ......

Fossil localities ......

gibbosula, Pulchellia ..........

gibbosulus, Hoplitoides .......

bipartitus, Hoplitoides ....

makurdiensis, Hoplitoides . Glebosoceras .................

glebosum ................

glebosum, Glebosoceras .......

Glebsoceras chispaense ......

grossouvrei, Coilopoceras ....

guentheri, Watinoceras........

12

24

2

5

5 

5, 6

6

5, 6

11

11

16

21

24

H

haugi, Coilopoceras ......................... 12, 21

Herrickiceras............................... 1

costatum ........................ 22, 23, 24; pi. 19

definition .............................. 22

(Hoplites), Neoptychites lentiformis .......... 5

wohltmanni ............................ 5, 9

Hoplitoides ................................ 1

autenriethi ............................. 5, 6

crassicostatus .......................... 5, 6

distribution ............................ 6

gibbosulus ............................. 5

bipartitus .......................... 5, 6

makurdiensis ....................... 6

hourcqui ............................... 11

ingens .................................. 6, 9, 11

costatus ............................ 5

laevis .............................. 5, 6

nodifer ............................. 5

koeneni .................... 5, 6, 7,12, 23; pis. 1, 3

latesellatus ............................. 5, 6

munieri ................................ 22, 23

origin .................................. 6

sandovalensis ................. 6, 8, 11, 13, 22, 23,

24; pis. 23,4,11,18 

solgeri ................................. 5, 6

wilsingi ................................ 5, 6

wohltmanni ................. 5, 6, 7, 8,12, 23; pi. 1

hourcqui, Hoplitoides ....................... 11

Hourcquia mirabilis ........................ 24

howelli, Inoceramus ......................... 17, 24

hyatti, Prionocyclus ............... 6, 11, 12,13,17, 24

I

Imlayites .................................. 22

India, Coilopoceras ......................... 12

indiduraense, Coilopoceras .................. 16

inflatum, Coilopoceras ......... 1, 11, 12, 19, 20, 21, 22,

23, 24; pis. 1,11,12,

13,14,15, 16,17,18, 20

ingens, Hoplitoides .......................... 6, 9, 11

Neoptychites ........................... 5, 6

costatus, Hoplitoides .................... 5

laevis, Hoplitoides ...................... 5, 6

nodifer, Hoplitoides ..................... 5

Inoceramus dimidius ....................... 22, 24

howelli................................. 17, 24

Israel, Coilopoceras ......................... 12

Hoplitoides ............................ 6

J, K, L

Japan, Hourcquia .. 

jenski, Coilopoceras . 

Jordan, Hoplitoides .

24

21

6

koeneni, Hoplitoides ............ 5, 6, 7, 12, 23, pis. 1, 3

... 5, 6

... 5, 6

... 12

... 6

... 5

... 12

... 11

... 11

Limestone concretions, Mancos Shale ........ 11, 23

Lincoln County, N. Mex. .................... 20

laevis, Hoplitoides ingens ..........

latesellatus, Hoplitoides ............

Lebanon, Coilopoceras .............

Hoplitoides ...................

lentiformis, Neoptychites (Hoplites) . 

leonhardianum, Paralenticeras ......

Leoniceras quassi ..................

segne

27
28 INDEX

Localities, fossil................

Lopha bettaplicata novimexicana. 

lugubris ....................

lucianoi, Coilopoceras ...........

lugubris, Lopha ................

M

macombi, Prionocyclus..................... 12,

Madagascar, Coilopoceras...................

Hoptttoides ............................

Hourcquia .............................

makurdiensis, Hoptttoides gibbosulus ........

Mammites depressus .......................

Mancos shale...............................

D-Cross Tongue ........................

limestone concretions ...................

Semilla Sandstone Member............. 13,

Tres Hermanos Sandstone Member.......

mauryae, Coilopoceras ......................

mexicanum, Selwynoceras ...................

Mexico, Coilopoceras .......................

Herrickiceras ...........................

Hoptttoides ............................

mirabilis, Hourcquia ........................

multicostatum, Coilopoceras.................

Mungo River locality, Hoptttoides............

munieri, Hoptttoides ........................

N, O

Page

2

24

24

21

24

15,24

12

6

24

6

7, 13

17

20

11,23

17,24

7, 13

21

23

12

23

6

24

20

5

22,23

........... 5, 6

........... 5

........... 5, 9

........... 12

............ 21

............ 12

............ 5,6

............ 5

novimexicanum, Coilopoceras ........... 11, 13, 14, 15

Lopha bellapttcata ...................... 24

Neoptychites ingens .......

(Hoplites) lentiformis ... 

wohltmanni .......

New Mexico, Coilopoceras .. 

newelli, Coilopoceras .......

Nigeria, Coilopoceras ......

Hoptttoides ...........

nodifer, Hoptttoides ingens .

Oscura area, N. Mex. . 20

Paralenticeras leonhardianum ...............

Peru, Coilopoceras ..........................

Hoptttoides ............................

Placenticeras costata .......................

costatum ...............................

Prionocyclus hyatti ............... 6, 11, 12,13,

macombi .............................. 12,

wyomingensis ..........................

Proplacenticeras pseudoplacenta ............ 11,

zaharense ..............................

pseudoplacenta, Proplacenticeras ........... 11,

Pseudotissotia segnis .......................

Pseudotissotiidae...........................

puercoensis, Spathites .................. 11, 13,

Pulchettia gibbosula ........................

Page

12

12

6

1

22

17,24

15,24

22, 24

12,17

24

12, 17

11

6

17,24

Q.R

quassi, Leoniceras

requieni, Coilopoceras ..............

requienianum, Coilopoceras.........

Rio del Piano locality...............

Rio Ruerco valley, Sandoval County. 

rioensis, Spathites .................

Romaniceras deveriai ..............

San Juan Basin.............................

Sandoval County, N. Mex., Herrickiceras ......

Hoptttoides ............................

sandovalensis, Hoptttoides .......... 6,8, 11,13,

24; pis. 2, 3,4, 

Scaphites warreni ..........................

Schloenbachiids ............................

schweinfurthi, Tissotia ......................

scindiae, Coilopoceras .......................

segne, Leoniceras ...........................

segnis, Pseudotissotia ......................

Selwynoceras mexicanum ...................

Semilla Sandstone Member, Mancos Shale... 13, 

sergipensis, Coilopoceras ....................

Shuparoceras ....................... 11, 13, 17,

sinaiense, Coilopoceras ......................

socorroense, Tragodesmoceras ...............

24

21

17

23

13

24

17

23

8

22,23

11,18

12,22

12

11

21

11

11

23

17,24

21

19,24

21

12

solgeri, Hoptttoides ......................... 5, 6

Spain, Hoptttoides.......................... 6

Spathites puercoensis .................. 11, 13, 17, 24

rioensis ................................ 13

springeri, Coilopoceras .......... 1, 5,11, 12,13, 16, 17,

18,19, 20, 23, 24; 

pis. 1,3, 6,10,18,19

T, V

Tethyan belt, Coilopoceras ..................

Hoptttoides ............................

Tethyan region .............................

Texas, Coilopoceras .........................

Tissotia schweinfurthi ......................

Tragodesmoceras socorroense ...............

Tres Hermanos Sandstone Member, Mancos 

Shale...........................

Trinidad, Coilopoceras ......................

Hoptttoides ............................

Tunisia, Hoptttoides ........................

Valencia County, N. Mex.

Venezuela, Coilopoceras ..

Hoptttoides .........

12

6

1

12

11

12

7, 13

12

20

12

W, Z

warreni, Scaphites .......................... 12, 22

Watinoceras- cobbani ........................ 13, 24

quentheri .............................. 24

wilsingi, Hoptttoides ........................ 5, 6

wohltmanni, Hoptttoides ......... 5,6, 7, 8,12, 23; pi. 1

Neoptychites (Hoptttes) ................. 5, 9

woollgari, Colttgnoniceras ................... 6

woottgari ........................ 7,13, 23, 24

woollgari, Colttgnoniceras ............ 7, 13, 23, 24

Wrightoceras .............................. 6

Wyoming, Coilopoceras ..................... 12

wyomingensis, Prionocyclus ................. 22, 24

zaharense, Proplacenticeras 

zihoricum, Coilopoceras ....

i U S. GOVERNMENT PRINTING OFFICE- I98O
PLATES 1-21

Contact photographs of the plates in this report are available, at cost, from the U.S. Geological Survey Photographic Library, Federal Center,

Denver, Colorado 80225.
PLATE 1

[All figures natural size]

FIGURES 1, 2. Hoplitoides cf. H. koeneni Solger (p. 6).

Figured specimen USNM 252968, from USGS Mesozoic locality D10260 (text fig. 1, loc. 48). See plate 3, figures 4, 5, for

inner whorl, text figure 2 for whorl section, and text figure 3-4 for suture. 

3, 4. Hoplitoides cf. H. wohltmanni (von Koenen) (p. 7).

Hypotype USNM 252969, from USGS Mesozoic locality D5773 (text fig. 1, loc. 45). See text figure 4 for suture. 

5, 6. Coilopoceras springeri Hyatt (p. 16).

Hypotype USNM 275906, from USGS Mesozoic locality D3884 (text fig. 1, loc. 10). 

7, 8. Coilopoceras colleti Hyatt (p, 13).

Small specimen showing unusual dense and flexuous ribbing. Hypotype USNM 275886 from USGS Mesozoic locality

17632 (text fig. 1, loc. 2). 

9-11. Coilopoceras inflation Cobban and Hook, n. sp. (p. 19).

Paratype USNM 275921, from USGS Mesozoic locality D2055 (text fig. 1, loc. 40).
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1192 PLATE 1

11

HOPLITOIDES AND COILOPOCERAS
PLATE 2

[All figures natural size]

FIGURES 1-11. Hoplitoides sandovalensis Cobban and Hook, n. sp. (p. 8).

1-3. Paratype USNM 275878, from USGS Mesozoic locality 15947 (text fig. 1, loc. 29). 

4, 5. Paratype USNM 275879, from USGS Mesozoic locality 15925 (text fig. 1, loc. 28). 

6, 7. Holotype USNM 275877, from USGS Mesozoic locality 15947 (text fig. 1, loc. 29).

8-10. Paratype USNM 275880, from USGS Mesozoic locality 15799 (text fig. 1, loc. 30). See text figure ID for suture. 

11. Paratype USNM 275881, from USGS Mesozoic locality 15797 (text fig. 1, loc. 34). See plate 3, figures 15, 16 for 

other views.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1192 PLATE 2

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HOPLITOIDES
PLATE 3

[All figures natural size]

FIGURES 1-3. Coilopocerascolletillyatt(p. 13).

Hypotype USNM 275887, from USGS Mesozoic locality D3702 (text fig. 1, loc. 41). 

4, 5. Hoplitoides cf. H. koeneni Solger (p. 6).

Views of the inner whorls of the specimen shown on plate 1, figures 1, 2. Figured specimen USNM 252968. 

6-8, 12-16. Hoplitoides sandovalensis Cobban and Hook, n. sp. (p. 8).

6-8. Paratype USNM 275882, from USGS Mesozoic locality 15947 (text fig. 1, loc. 29).

12-14. Paratype USNM 275883, from USGS Mesozoic locality 3672 (text fig. 1, loc. 31). See text figure IB for suture. 

15, 16. Paratype USNM 275881, from USGS Mesozoic locality 15797 (text fig. 1, loc. 34). See text figure 7A for suture. 

9-11. Coilopoceras springeri Hyatt (p. 16).

Hypotype USNM 275907, from USGS Mesozoic locality D3670 (text fig. 1, loc. 6). See text figure 11.B for suture.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1192 PLATE 3

16

COILOPOCERAS AND HOPLITOIDES
PLATE 4

[Figure natural size]

Hoplitoides sandovalensis Cobban and Hook, n. sp. (p. 8).

Side view of paratype USNM 257884, from USGS Mesozoic locality D10508 (text fig. 1, loc. 27). See plate 11, figure 1 for front view, and 

text figure 7C for suture.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1192 PLATE 4

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PLATE 5

[All figures natural size]

FIGURES 1-15. Coilopoceras colleti Hyatt (p. 13).

1-3. Hypotype USNM 275888, from USGS Mesozoic locality D10354 (text fig. 1, loc. 51).

4-6. Hypotype USNM 275889, from the same locality.

7-9. Hypotype USNM 275890, from USGS Mesozoic locality D4395 (text fig. 1, loc. 3).

10. Hypotype USNM 275891, from USGS Mesozoic locality D10630 (text fig. 1, loc. 53). 

11, 12. Hypotype USNM 275892, from USGS Mesozoic locality D4395 (text fig. 1, loc. 3).

13. Hypotype USNM 275893, from USGS Mesozoic locality D10354 (text fig. 1, loc. 51). 

14, 15. Hypotype USNM 275894, from the same locality as figure 13. See text figure WA for the suture.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1192 PLATE 5

13

COILOPOCERAS
PLATE 6

[All figures natural size]

FIGURES 1-8. Coilopoceras colleti Hyatt (p. 13).

1-3. Hypotype USNM 275896, from USGS Mesozoic locality D10354 (text fig. 1, loc. 51). 

4, 5. Hypotype USNM 275897, from the same locality.

6-8. Hypotype USNM 275898, from USGS Mesozoic locality D4395 (text fig. 1, loc. 31). 

9, 10. Coilopoceras springeri Hyatt (p. 16).

Hypotype USNM 278122, from the type locality of C springeri along Rio del Piano at USGS Mesozoic locality D10739 

(text fig. 1, loc. 59).
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1192 PLATE 6
PLATE 7

[All figures natural size]

FIGURES 1-9. Coilopoceras colleti Hyatt (p. 13).

From USGS Mesozoic locality D4395 (text fig. 1, loc. 3). 

1, 2. HypotypeUSNM 275900. 

3, 4. Hypotype USNM 275901. 

5, 6. HypotypeUSNM 275902. 

7-9. Hypotype USNM 275903.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1192 PLATE 7

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COILOPOCERAS
PLATE 8

[Figure about seven-tenths natural size]

Coilopoceras colleti Hyatt (p. 13).

Side view of hypotype USNM 275904, from USGS Mesozoic locality D10354 (text fig. 1, loc. 51). See plate 9 for end views of this large 

adult and text figure 9 for cross section.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1192 PLATE 8

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PLATE 9

[Figures about seven-tenths natural size]

Coilopoceras colleti Hyatt (p. 13).

End views of hypotype USNM 275904, from USGS Mesozoic locality D10354 (text fig. 1, loc. 51). See plate 8 for side view and text figure 

9 for cross section.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1192 PLATE 9

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COILOPOCERAS
PLATE 10

[All figures natural size]

FIGURES 1-8. Coilopoceras springeri Hyatt (p. 16).

From type locality of Semilla Sandstone Member of Mancos Shale at USGS Mesozoic locality 28873 (text fig. 1, loc. 13). 

1, 2. HypotypeUSNM 275908. 

3-5. Hypotype USNM 275909. 

6-8. Hypotype USNM 275910.
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PROFESSIONAL PAPER 1192 PLATE 10 

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PLATE 11

[Figure 1 natural size; figure 2 slightly smaller than natural size]

FIGURE 1. Hoplitoides sandovalensis Cobban and Hook, n. sp. (p. 8).

Paratype USNM 275884, from USGS Mesozoic locality D10508 (text fig. 1, loc. 27). See plate 4 for side view and text figure

7C for suture. 

2. Coilopoceras inflatum Cobban and Hook, n. sp. (p. 19).

Sectional view of the holotype USNM 275920, from USGS Mesozoic locality D2055 (text fig. 1, loc. 40). See text figure 15A 

for suture.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1192 PLATE 11

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HOPLITOIDES AND COILOPOCERAS
PLATE 12

[Figure about three-fourths natural size]

Coilopoceras inflatum Cobban and Hook, n. sp. (p. 19).

Side view of paratype USNM 275922, from USGS Mesozoic locality D10321 (text fig. 1, loc. 38). See plate 13, figure 2, for end view and 

text figure 144 for cross section.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1192 PLATE 12

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PLATE 13

[Both figures reduced]

FIGURES 1, 2. Coilopoceras inflatum Cobban and Hook, n. sp. (p. 19).

1. Paratype USNM 275923, from USGS Mesozoic locality D10634 (text fig. 1, loc. 22). See plate 14 for side view.

2. Paratype USNM 275922, from USGS Mesozoic locality D10321 (text fig. 1, loc. 38). See plate 12 for side view.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1192 PLATE 13

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COILOPOCERAS
PLATE 14

[Figure about six-tenths natural size]

Coilopoceras inflatum Cobban and Hook, n. sp. (p. 19).

Side view of paratype USNM 275923, from USGS Mesozoic locality D10534 (text fig. 1, loc. 22). See plate 13, figure 1, for end view and 

text figure 14C for whorl section. This huge specimen was collected by L. F. Gunther, Brigham City, Utah.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1192 PLATE 14

COILOPOCERAS
PLATE 15

[Figure natural size]

Coilopoceras inflatum Cobban and Hook, n. sp. (p. 19). 

Paratype USNM 275924, from USGS Mesozoic locality D10299 (text fig. 1, loc. 43). See plate 16, figures 1 and 2, for end views.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1192 PLATE 15

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PLATE 16

[All figures natural size]

FIGURES 1-3. Coilopoceras inflatum Cobban and Hook, n. sp. (p. 78).

1, 2. Paratype USNM 275924, from USGS Mesozoic locality D10299 (text fig. 1, loc. 43). See plate 15 for side view. 

3. Rear view of slender paratype USNM 275925, from USGS Mesozoic locality D7066 (text fig. 1, loc. 42).
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1192 PLATE 16

COILOPOCERAS
PLATE 17

[All figures natural size]

Coilopoceras inflation Cobban and Hook, n. sp. (p. 19). 

Paratype USNM 275926, from USGS Mesozoic locality D7066 (text fig. 1, loc. 42), that has unusual dense ribbing.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1192 PLATE 17

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PLATE 18

[All figures natural size]

FIGURES 1-3, 11-13. Coilopoceras inflation Cobban and Hook, n. sp. (p. 19).

1-3. Paratype USNM 275927, from USGS Mesozoic locality D10644 (text fig. 1, loc. 55). 

11-13. Paratype USNM 275928, from USGS Mesozoic locality 26203 (text fig. 1, loc. 44). 

4-6. Hoplitoides sandovalensis Cobban and Hook, n. sp. (p. 8).

Paratype USNM 275885, from USGS Mesozoic locality D10508 (text fig. 1, loc. 27). See text figure 6 for cross

section. 

7-10. Coilopoceras springeri Hyatt (p. 16).

7, 8. Hypotype USNM 275911, from USGS Mesozoic locality 22873 (text fig. 1, loc. 13). This unusual specimen

resembles C. cotteti Hyatt in its umbilical bullae and lateral ribs. 

9, 10. Hypotype USNM 275912, from USGS Mesozoic locality D4014 (text fig. 1, loc. 11).
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1192 PLATE 18

i3

COILOPOCERAS AND HOPLITOIDES
PLATE 19

[All figures natural size except as indicated]

FIGURES 10-18. Coilopoceras springeri Hyatt (p. 16).

1-3. Hypotype USNM 275913, from USGS Mesozoic locality 28873 (text fig. 1, loc. 13). 

4-6. Hypotype USNM 275914, from USGS Mesozoic locality D10575 (text fig. 1, loc. 21). 

7-9. Hypotype USNM 275915, from USGS Mesozoic locality D3884 (text fig. 1, loc. 10). 

10-18. Herrickiceras costatum (Herrick and Johnson) (p. 23).

10-12. Hypotype USNM 275941, from USGS Mesozoic locality D10469 (text fig. 1, loc. 32). See text figure 16A for

suture.

13-15. Hypotype USNM 275942, from the same locality. See text figure WB for suture. 

16-18. Neotype USNM 275940, from USGS Mesozoic locality D10508 (text fig. 1, loc. 27). See text figure 16C for suture.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1192 PLATE 19

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COILOPOCERAS AND HERRICKICERAS
PLATE 20

[All figures natural size]

FIGURES 1-16. Coilopoceras inflatum Cobban and Hook, n. sp. (p. 19).

From USGS Mesozoic locality D10636 (text fig. 1, loc. 54).

1,2. ParatypeUSNM 275929.

3-5. Paratype USNM 275930.

6-8. Paratype USNM 275931.

9-10. Paratype USNM 275932.

12, 13. Paratype USNM 275933.

14-16. Paratype USNM 275934.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1192 PLATE 20

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PLATE 21

[All figures natural size]

FIGURES 1-5. Coilopoceras inflation Cobban and Hook, n. sp. (p. 19).

1, 3. Paratype USNM 275935, from USGS Mesozoic locality D10636 (text fig. 1, loc. 54).

2. Paratype USNM 275936, from USGS Mesozoic locality D10638 (text fig. 1, loc. 41).

4, 5. Paratype USNM 275937, from USGS Mesozoic locality D10644 (text fig. 1, loc. 55).
GEOLOGICAL SURVEY PROFESSIONAL PAPER 1192 PLATE 21

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COILOPOCERAS