Ammonite Faunas of the 

Sarten Sandstone (Cretaceous), 

Luna County, New Mexico

U.S. GEOLOGICAL SURVEY BULLETIN 1641-B

Ammonite Faunas of the 

Sarten Sandstone (Cretaceous), 

Luna County, New Mexico

By WILLIAM A. COBBAN

Three ammonite faunas 

of low diversity are 

described from rocks of 

late Albian to early 

Cenomanian age

Contributions to Paleontology

U.S. GEOLOGICAL SURVEY BULLETIN 1641-B
DEPARTMENT OF THE INTERIOR 

DONALD PAUL MODEL, Secretary

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1987

For sale by the

Books and Open-File Reports Section

U.S. Geological Survey

Federal Center

Box 25425

Denver, CO 80225

Library of Congress Cataloging in Publication Data

Cobban, William Aubrey, 1916-

Ammonite faunas of the Sarten sandstone (Cretaceous), Luna County,

New Mexico. 

(Contributions to paleontology) (U.S. Geological Survey Bulletin ;

1641-B)

Bibliography: p. 

Includes index.

Supt. of Docs. No.: I 19.3:1641-6 

1. Ammonoidea. 2. Paleontology Cretaceous. 3. Paleontology New

Mexico Luna County. 

I. Title. II. Series. III. Series: U.S. Geological Survey bulletin ;

1641-B.

QE75.B9 no. 1641-B 557.3 s 86-600106 

[QE807.A5] [564'.53]
CONTENTS

Abstract 1

Introduction 1

Localities of collections 2

Ammonite faunas of the Sarten Sandstone 2

Distribution of the ammonite faunas in New Mexico and Texas

Age of the Sarten Sandstone 4

Systematic descriptions 5

Family Pachydiscidae Spath, 1922 5

Genus Eopachydiscus Wright, 1955 5

Eopachydiscus marcianus (Shumard) 5 

Family Brancoceratidae Spath, 1934 6

Subfamily Mortoniceratinae Spath, 1925 6 

Genus Mortoniceras Meek, 1876 6

Mortoniceras equidistans (Cragin) 6 

Mortoniceras aff. M. leonense (Conrad) 8 

Mortoniceras sp. 8 

Subgenus Drakeoceras Young, 1957 8 

Mortoniceras (Drakeoceras} sp. 9 

Family Acanthoceratidae Hyatt, 1900 9 

Genus Mantelliceras Hyatt, 1903 9

Mantelliceras sp. 9 

Family Engonoceratidae Hyatt, 1900 10

Genus Engonoceras Neumayr and Uhlig, 1881 10 

Engonoceras belviderense (Cragin) 10 

Engonoceras sp. 10 

Family Turrilitidae Meek, 1876 10

Genus Turrilites Lamarck, 1801 10

Turrilites aff. T. costatus Lamarck 10 

References cited 11 

Index 15

PLATES

1. Eopachydiscus, Engonoceras, and Mortoniceras.

2. Eopachydiscus, Mortoniceras, and Turrilites.

3. Mortoniceras and Eopachydiscus.

4. Mantelliceras, Engonoceras, and Mortoniceras.

5. Mortoniceras.

FIGURE

1. Map showing outcrops of Sarten Sandstone and localities of ammonite collections 1

Contents Bill
TABLES

1. Localities at which ammonites were collected 2

2. Upper Albian-lower Cenomanian ammonite zonation in Texas

3. Upper Albian ammonite zonation in southern England 5

4. Upper Albian ammonite zonations proposed recently 5

BIV Contents
CONTRIBUTIONS TO PALEONTOLOGY

Ammonite Faunas of the Sarten Sandstone 

(Cretaceous), Luna County, New Mexico

By William A. Cobban

Abstract

Three ammonite faunas of low diversity occur in 

the Sarten Sandstone of the Cooke Range, New Mexico. 

Mortoniceras equidistans (Cragin) and Eopachydiscus 

marcianus (Shumard), of middle late Albian age, characterize the oldest fauna, which is found a little below the 

middle of the formation. Mortoniceras (Drakeoceras) sp. 

and Engonoceras belviderense (Cragin) occur in the next 

younger Albian fauna, about in the middle of the Sarten. 

Fragments of a robust, sparsely ribbed Mantelliceras of 

early Cenomanian age and a single specimen of Turrilites 

aff. T. costatus Lamarck were found at the top of the 

Sarten.

The oldest fauna is also known from the Smeltertown Formation of Strain (1968) near El Paso, Texas. 

Farther east in Texas, this fauna is restricted to the Duck 

Creek Formation. The middle (Drakeoceras) fauna of the 

Sarten Sandstone is probably the age equivalent of some 

part of the Fort Worth Limestone of north and north-central Texas. Ammonites and the associated bivalves at the 

top of the Sarten suggest an age equivalent of the Buda 

Limestone of Texas.

INTRODUCTION

The Sarten Sandstone was named by Darton (1916, 

p. 19, 43) for outcrops on Sarten Ridge (now Rattlesnake 

Ridge) in the Cooke Range north of Deming, N. Mex. 

(fig. 1). From limy beds a little below the middle of the 

formation, Darton collected marine fossils which were determined as Early Cretaceous in age by T. W. Stanton 

(in Darton, 1916, p. 43). Two collections were made by 

Darton, one on Sarten Ridge and the other on Fluorite 

Ridge (fig. 1). These collections contained 12 species of 

bivalves and 3 species of gastropods, but no ammonites. 

Stanton (in Darton, 1916, p. 44) stated that the fossils 

"represent the forms of the Washita group of the Comanche series and show about the same fauna! facies as 

that found in the marginal deposits of southern Kansas 

and near Tucumcari, N. Mex." The lists of fossils were 

published again by Darton (1917) and later repeated by 

Jicha (1954, p. 26). Nothing further has been written regarding the fauna of the Sarten Sandstone.

In recent years personnel of the U.S. Geological 

Survey and New Mexico Bureau of Mines and Mineral 

Resources have made collections of fossils from the Sartff 

*/D11759

/ 32

R 9W R 8W

2 MILES 

J

0123 

I I I I 

KILOMETERS

Figure 1. Map showing outcrops of Sarten Sandstone 

(patterned) and localities of ammonite collections. Sarten 

outcrops from demons (1982).

ten Sandstone in the Cooke Range. Some of these collections contain certain ammonites that permit a refined age 

assignment and correlation of the Sarten. Although most 

of the ammonites consist of fragments, representative 

specimens are described and illustrated in this report because of their importance in dating and correlating the 

Sarten Sandstone.

All specimens illustrated in this report are in the 

National Museum of Natural History in Washington,

Introduction B1
D.C., and have USNM catalog numbers. Plaster casts of 

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

Survey's Mesozoic invertebrate fossil collections at the 

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

Mexico Bureau of Mines and Mineral Resources, Socorro, 

N. Mex. Robert E. Burkholder of the U.S. Geological 

Survey made the photographs. Thomas Hyatt of Deming, 

N. Mex., kindly allowed access to the localities where 

collections were made. Dr. W. J. Kennedy, Oxford University, England, gave helpful advice concerning ammonites from the top of the Sarten Sandstone.

LOCALITIES OF COLLECTIONS

The ammonites described or recorded in this report 

came from nine localities. These localities are shown on 

figure 1, and data concerning the localities, stratigraphic 

positions in the Sarten Sandstone, and collectors are given 

in table 1.

AMMONITE FAUNAS OF THE 

SARTEN SANDSTONE

Ammonites were collected from three levels in the 

Sarten Sandstone. The oldest and largest collection came 

from a limy unit below the middle of the formation, where 

fragments of ammonites occur as uncrushed internal molds 

of limestone. Some molds have oyster encrustations. Mortoniceras equidistans (Cragin) is the dominant species of 

mollusks in these limy beds. Other genera include Engonoceras sp. and Eopachydiscus, the latter represented 

by E. marcianus (Shumard).

Sandy beds about 24 m above the fossiliferous limy 

beds have septarian limestone concretions that contain occasional fragments of Mortoniceras and Engonoceras. The 

specimens of Mortoniceras are distorted and poorly preserved; because they are bituberculate, they are assignable 

to the subgenus Drakeoceras.

The uppermost meter of the Sarten consists of sandy 

nodular limestone that contains a few internal molds of 

fossil mollusks as well as fragments of shells of large 

Exogyra. Most of the fossils seem characteristic of the 

Buda Limestone of Texas and Mexico. Six of the seven 

specimens of ammonites collected represent a sparsely ribbed, robust Mantelliceras that has affinities with M. 

budaense Adkins (1931, p. 41, pi. 2, fig. 3; pi. 4, fig. 

10). Adkins' holotype came from the top of the Buda 

Limestone near Austin, Texas. Mantelliceras budaense 

has been regarded as a questionable synonym of the English M. cantianwn Spath (1926, p. 82) by Matsumoto, 

Muramoto, and Takahashi (1969, p. 256) and as a more 

definite synonym by Kennedy (1971, p. 56), Young 

(1979, p. 21), and Mancini (1982, p. 253). Mantelliceras 

cantianum, however, seems more densely ribbed than M. 

budaense and has more discrete lower lateral tubercles.

Table 1 . Localities at which ammonites were collected

U.S. Geological

Survey Mesozoic

locality

Collector, year of collection, description of 

locality, and stratigraphic position

D6830 E. R. Landis and W. A. Cobban, 1968; 

J. R. Wright and S. C. Hook, 1977; E. 

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

A. Cobban, 1978. SW/4SW/4 sec. 29, 

T. 21 S., R. 8 W. From very light gray 

weathering, hard, nodular limestone 

below middle of Sarten Sandstone. 

D6833 E. R. Landis and W. A. Cobban, 1968. 

Same area as D6830. From gray- and 

brown-weathering septarian limestone 

concretions 73 feet1 (22.3 m) above 

D6830

D10104 E. R. Landis, S. C. Hook, and W. A. 

Cobban, 1976; J. R. Wright, D. E. 

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

1977; R. R. Cobban, S. C. Hook, and 

W. A. Cobban, 1980. NW/4NW/4 sec. 

18, T. 21 S., R. 8 W. From sandy, 

nodular limestone at top of Sarten Sandstone.

D10183 Richard Naff and S. C. Hook, 1977. 

NE'/4 NW/4NW/4 sec. 7, T. 21 S., R. 

8 W. From orange-weathering, sandy, 

nodular limestone in lower part of Sarten Sandstone.

D10184 Richard Naff, J. R. Wright, S. C. Hook, 

and W. A. Cobban, 1977. NW'ANWV^ 

sec. 7, T. 21 S., R. 8 W. From lightgray-weathering nodular limestone about 

31 feet (9.5 m) above D10183 and same 

stratigraphic position as D6830.

D10481 E. A. Merewether, S. C. Hook, and W. 

A. Cobban, 1978. SE!/4NW'/4SE'/4 sec. 

36, T. 21 S., R. 9 W. From brownweathering limestone about stratigraphic 

position of D6833.

D10495 W. A. Cobban, 1978. NWV^NW1/* sec. 

18, T. 21 S., R. 8 W. From sandy, 

nodular limestone at top of Sarten Sandstone.

D10520 S. C. Hook and W. A. Cobban, 1978. 

SE'/4NW'/4 sec. 1, T.22 S., R. 9 W. 

From light-gray nodular limestone at 

same stratigraphic position as D6830. 

D11759 S. C. Hook, 1982. NW'ASW'ANW^ sec. 

32, T. 21 S., R. 8 W. From light-gray 

nodular limestone at same stratigraphic 

position as D6830

'Principal units of measurement in this report are metric. However, measurements originally 

made in inch-pound units are given in those units, followed by metric equivalents in parentheses.

The holotype of M. cantianum (Sharpe, 1856, pi. 18, 

figs. 1, 2) has 33 ribs per whorl, whereas the holotype 

of M. budaense has 25 or 26. In addition, M. cantianum

B2 Ammonite Faunas of the Sarten Sandstone, New Mexico
is probably an older species than M. budaense. Kennedy 

(1969, 1970, 1971) has recognized for the lower Cenomanian of England a zone of Mantelliceras mantelli (J. Sowerby), which is divisible into a lower Hypoturrilites carcitanensis (Matheron) assemblage, a medial Mantelliceras 

saxbii (Sharpe) assemblage, and an upper Mantelliceras 

gr. dixoni Spath assemblage. The lower assemblage contains M. cantianum and other species of Mantelliceras; 

the medial assembly contains occasional M. cantianum 

and other species; and the upper assemblage contains M. 

gr. dixoni, M. aff. souaillonense (Renz), M. lymense 

(Spath) and rare M. cf. mantelli as well as the first appearance of Turrilites costatus Lamarck and T. 

scheuchzerianus Bosc. Inasmuch as Turrilites aff. T. costatus was also found with Mantelliceras at the top of the 

Sarten, the age of these Sarten ammonites seems to be 

high in the early Cenomanian and probably equivalent to 

Kennedy's Mantelliceras gr. dixoni assemblage.

The Buda Limestone of Texas has not been zoned 

in detail, although four ammonite zones have been recognized in the lower Cenomanian part of the underlying 

Gray son Formation (Mancini, 1979). Young (1967a, p. 

67-70) assigned the Buda to the zone of Budaiceras hyatti 

and noted that "the main diagnostic fossils of the Buda 

Limestone are of the ammonite genera Budaiceras and 

Faraudiella. The ammonites are so rare in the Buda that 

a zonation has not yet been possible. However, 99 percent 

of the ammonites from Hays, Travis, and Williamson 

Counties are from the lower member, and not over a half 

dozen specimens are known from the upper member" 

(Young, 1967b, p. 28). Budaiceras seems to occur mostly 

in the lower and middle parts of the Buda (Young, 1959, 

p. 79; Martin, 1967, p. 295), although Young (1979, p. 

87-89) has noted it in the upper part at a few localities. 

Mantelliceras, however, seems to occur only in the upper 

part of the Buda (Adkins, 1931, p. 42; Reaser, 1970, 

p. 80, fig. 11; Young, 1979, p. 88, 89).

The thin, sandy, nodular limestone unit at the top 

of the Sarten Sandstone in the Cooke Range is probably 

resting disconformably on a sandstone equivalent of the 

Anapra Sandstone (Strain, 1976, p. 81) of the El Paso 

area, where the Anapra is a 172-foot-thick, thick-bedded 

quartz sandstone that contains partings of siliceous shale. 

In the El Paso area, the Del Rio Clay separates the Anapra 

Sandstone from the Buda Limestone (Strain, 1976, p. 81). 

A disconformity at the base of the Buda equivalent in 

the Cooke Range is not surprising inasmuch as the Buda 

is known to rest disconformably on the Del Rio Clay or 

on older parts of the Washita Group at places in west-central and southwest Texas (for example, Brand and Deford, 

1958, p. 385; Hazzard, 1959; DeFord and Haenggi, 1970, 

fig. 7; Moore, 1969, fig. 4; Rose, 1972, p. 23, 43, pi. 

4, text fig. 34). In part of south-central Texas, the upper 

part of the Buda rests disconformably on the lower part 

(Martin, 1967, p. 290, 298, figs. 2, 4).

The sandy nodular limestone bed at the top of the 

Sarten contains the following molluscan fauna (USGS 

Mesozoic locality D10104):

Syncyclonema sp.

Neithea (Neithea) texana (Roemer)

Lima shumardi Shuttuck

Exogyra clarki Shuttuck

E. whitneyi (Bose)

Pterotrigonia (Scabrotrigonia) sp.

Stearnsia sp.

Protocardial sp.

Granocardium (Criocardium) budaense (Shuttuck)

Artica? compacta (White)

Homomya cf. H. budaensis Whitney

Turritella cf. T. semiatimgranulata Roemer

T. sp.

Tylostoma harrisi Whitney

Mantelliceras sp.

Turrilites aff. T. costatus Lamarck

Cymatoceras sp.

DISTRIBUTION OF THE AMMONITE FAUNAS 

IN NEW MEXICO AND TEXAS

The Eopachydiscus marcianus-Mortoniceras equidistans fauna in the lower part of the Sarten Sandstone 

can be readily correlated with similar faunas in southern 

New Mexico and in Trans-Pecos Texas. Farther east in 

Texas, Young (1967a) has shown the position of this zone 

(divided into a zone of E. brazosensis overlain by a zone 

of Pervinquieria equidistans) in regard to formations in 

south-central Texas, north-central Texas, north Texas, the 

High Plains, upper Concho and Llano River drainages, 

Fort Stockton quadrangle (Pecos County), and Cienega 

quadrangle (Presidio County). Perhaps the best known of 

the formations that contain this fauna is the Duck Creek 

Formation of north-central and north Texas. Eopachydiscus marcianus occurs abundantly in the lower part of this 

formation. Mortoniceras equidistans occurs with E. marcianus, but ranges higher than it.

Bose (1910, p. 16-30) divided the Cretaceous rocks 

into 11 lithologic units, numbered from the base upward, 

on the Sierra de Cristo Rey uplift, which lies astride the 

international boundary between the United States and 

Mexico just west of El Paso, Texas. Strain (1968; 1976) 

gave new formal names to five of these units and applied 

names established elsewhere to four of the other units. 

Bose's unit number 4 (Capas con Schloenbachia nodosa, 

n. sp.), named Smeltertown Formation by Strain, contains 

Eopachydiscus marcianus and Mortoniceras equidistans 

(Bose's Schloenbachia trinodosa), of early-middle Sarten 

age. Bose did not record Eopachydiscus, but specimens 

have been found in the Smeltertown Formation at the type 

locality of the Smeltertown (USGS Mesozoic locality 

D10474).

Distribution of Ammonite Faunas B3
In Trans-Pecos Texas, the E. marcianus-M. 

equidistans fauna has been recorded from the Fort 

Stockton and Kent areas and from the Eagle Mountains 

farther southwest. The Fort Stockton area in Pecos 

County, about 200 miles (322 km) east-southeast of El 

Paso, has yielded many ammonites from rocks assigned 

to the Duck Creek Formation by Adkins (1927, p. 44). 

Eopachydiscus marcianus is represented by ammonites 

identified by Adkins as Desmoceras brazoense and D. 

laevicaniculatus, and Mortoniceras equidistans is represented by ammonites identified as Pervinquieria equidistans, P. kiliani, and P. whitei.

In the Kent area, about 140 miles (225 km) eastsoutheast of El Paso, Brand and DeFord (1958, p. 381) 

recorded E. marcianus (as E. brazoense and E. 

laevicaniculum) from the lower part of their Levinson 

Member of the Boracho Limestone, and M. equidistans 

(as Pervinquieria equidistans) slightly higher.

The Eagle Mountain area southwest of Kent and 

about 100 miles (160 km) southeast of El Paso has also 

yielded E. marcianus and M. equidistans. Underwood 

(1963, p. 9, 10) recorded E. marcianus (as E. cf. E. 

brazoense) and M. equidistans (as Pervinquieria equidistans) from the lower part of the Espy Formation of Huffmgton (1943, p. 1005).

In addition to the Cooke Range and El Paso area, 

the E. marcianus-M. equidistans fauna has been found 

in the Tucumcari area in the northeast part of New 

Mexico. Stanton (1928, p. 407) recorded Pervinquieria 

trinodosa [M. equidistans] from beds now assigned to the 

Mesa Rica Sandstone in the Tucumcari area. Undescribed 

USGS collections made later from the Mesa Rica Sandstone in this area include excellent examples of E. marcianus and M. equidistans.

AGE OF THE SARTEN SANDSTONE

The Washita Group of Texas, to which Stanton (in 

Darton, 1916, p. 44) equated the Sarten Sandstone, includes upper Albian and lower Cenomanian rocks. The 

ages and correlations of the ammonite faunas of the Sarten 

can be determined best by comparing them to the better 

known ammonite faunas of Texas, as well as to those 

of the Anglo-Paris basin.

Young (1972, p. 7) established a sequence of seven 

ammonite zones for upper Albian rocks of Texas based 

on species of Manuaniceras, Adkinsites, Eopachydiscus, 

Pervinquieria, Drakeoceras, and Mortoniceras. Above 

this sequence, Young and Powell (1976, fig. 2) recognized five zones of lower Cenomanian ammonites based 

on species of Plesioturrilites, Graysonites, Budaiceras, 

and Forbesiceras. The Texas zonation of these authors 

is shown in table 2.

Spath (1923, p. 73; 1926; 1942, p. 671-673) proposed for the upper Albian of southern England two ammonite zones and six subzones based on species of Mortoniceras, Stoliczkaia, Hysteroceras, Callihoplites, and 

Arrhaphoceras (table 3). Problems concerning Spath's zonation have been summarized by Cooper and Kennedy 

(1979, p. 298, 299), who adopted some suggestions for 

changes advocated by Owen (1975) and Breistroffer 

(1940; 1947). Cooper and Kennedy's zonation is shown 

in table 4 together with a later proposal by Amedro (1980, 

p. 239-244).

Table 2. Upper Albian-iower Cenomanian ammonite 

zonation in Texas

Substage

Lower Cenomanian

Upper Albian

Zone

Forbesiceras brundrettei (Young)

Budaiceras hyatti (Shattuck)

Graysonites lozoi Young

Graysonites adkinsi Young

Plesioturrilites brazosensis (Roemer)

Drakeoceras drakei Young

Mortoniceras wintoni (Adkins)

Drakeoceras lasswitzi Young

Pervinquieria equidistans (Cragin)

Eopachydiscus brazosensis (Shumard)

Adkinsites bravoensis (Bose)

Manuaniceras powelli Young

Kennedy (1969, table 1) recognized for the early 

Cenomanian of southern England a Mantelliceras mantelli 

Zone with three assemblages, which from oldest to 

youngest include the Hypoturrilites carcitanensis assemblage, the Mantelliceras saxbii assemblage, and Mantelliceras gr. dixoni assemblage. These assemblages were 

not considered as subzones because the faunas were 

mostly at discrete stratigraphic positions separated by 

largely unfossiliferous beds.

The ammonite fauna from below the middle of the 

Sarten Sandstone includes Eopachydiscus marcianus and 

Mortoniceras equidistans. Inasmuch as E. brazoensis 

(Shumard, 1860) is a synonym of E. marcianus 

(Shumard, 1854), the fauna embraces the Texas middle 

upper Albian zones of E. brazoensis and Pervinquieria 

[Mortoniceras] equidistans of Young (1972, p. 7). 

Eopachydiscus marcianus has not been recorded from 

Europe, but M. kiliani (Lasswitz, 1904), a synonym of 

M. equidistans (Cragin, 1893), has been figured by Spath 

(1932, p. 408, pi. 38, figs. 1, 2; pi. 42, fig. 1; pi. 47, 

fig. 1) from his M. aequatoriale and Arrhaphoceras substuderi subzones of the upper Albian.

B4 Ammonite Faunas of the Sarten Sandstone, New Mexico
Table 3. Upper Albian ammonite zonation in southern England

Substage Zone Subzone

Stoliczkaia dispar (d'Orbigny)

Upper Albian

Mortoniceras inflation (J. Sowerby)

Stoliczkaia dispar (d'Orbigny) and 

Mortoniceras perinflatum (Spath)

Arrhaphoceras substuderi Spath

Mortoniceras aequatoriale (Kossmat)

Callihoplites auritus (J. Sowerby)

Hysteroceras varicosum (J. de C. Sowerby)

Hysteroceras orbignyi (Spath)

Table 4. Upper Albian ammonite zonations proposed recently

Cooper and Kennedy (1979)

Zone

Stoliczkaia dispar

Mortoniceras inflatum

Subzone

Mortoniceras (Durnovarites) perinflatum

Stoliczkaia (Faraudiella) blancheti

Callihoplites auritus

Hysteroceras varicosum

Hysteroceras orbignyi

Am6dro (1980)

Assemblage-zone

Pervinquieria perinflata

Pervinquieria fallax

Pervinquieria inflata

Pervinquieria pricei

The poorly preserved Mortoniceras (Drakeoceras) 

fragments higher in the Sarten cannot be placed in any 

specific zone of the Texas late Albian sequence of 

Drakeoceras. Inasmuch as the fragments were collected 

not far above the beds containing M. equidistans, they 

may lie in Young's Drakeoceras lasswitzi Zone, which 

in north and north-central Texas includes the upper part 

of the Duck Creek Formation and the overlying Fort 

Worth Limestone and Weno Formation.

As noted earlier, the fauna at the top of the Sarten 

is of early Cenomanian age, about the age of the Buda 

Limestone.

SYSTEMATIC DESCRIPTIONS

Family PACHYDISCTDAE Spath, 1922 

Genus EOPACHYDISCUS Wright, 1955

Type species. Pachydiscus laevicaniculatus Lasswitz, 

1904.

This genus includes large, compressed to inflated, 

fairly involute ammonites that have rounded flanks and

a venter with constrictions and sparse thick ribs. Suture 

is characterized by a trifid lateral lobe (L) and numerous 

auxiliaries, all minutely frilled. The genus is mainly of 

late Albian age.

Eopachydiscus marcianus (Shumard)

Plate 1, figures 1-6; plate 2, figure 1; plate 3, figure 11

1854. Ammonites marcianus Shumard, p. 183, pi. 4, fig. 5.

1860. Ammonites brazoensis Shumard, p. 594.

1893. Pachydiscus brazoensis (Shumard). Cragin, p. 236, pi. 

44, fig. 3.

1894a. Pachydiscus marcianus (Shumard). Cragin, p. 54 (footnote).

1904. Pachydiscus laevicaniculatus F. Roemer manuscript. 

Lasswitz, p. 236, pi. 15, fig. 2; text figs. 8, 9.

1919 [1920]. Desmoceras brazoense (Shumard). Adkins and 

Winton, p. 35, pi. 2, figs. 1, 2.

1919 [1920]. Desmoceras sp. A. Adkins and Winton, p. 35, 

pi. 2, fig. 3.

1923. Pachydiscusl sp. Reeside, p. 205, pi. 49, fig. 1.

Systematic Descriptions 65
1925. Desmoceras brazoense (Shumard). Bullard, pi. 20, 

figs. 1, 2.

1925. Desmoceras brazoense (Shumard). Winton, pi. 4, fig. 

1.

1926. Desmoceras brazoense (Shumard). Bullard, pi. 16, fig.

1.

1927. Desmoceras brazoense (Shumard). Adkins, pi. 6, fig.

2.

1927. Desmoceras laevicaniculatum (Roemer). Adkins, pi. 6, 

fig. 1.

1927. Desmoceras brazoense (Shumard). Bybee and Bullard, 

pl. 4, fig. 1.

1928. Desmoceras! brazoense (Shumard). Adkins, p. 220,

pl. 9, fig. 2. 

1928. Desmoceras! laevicaniculatum (Roemer). Adkins, p.

220, pl. 9, fig. 1.

1928. Desmoceras! marcianum (Shumard). Adkins, p. 221. 

1955. Eopachydiscus laevicaniculatus (Lasswitz, ex Roemer

manuscript). Wright, p. 570.

1955. Eopachydiscus brazoensis (Shumard). Wright, p. 571. 

1955. Eopachydiscus marcianus (Shumard). Wright, p. 571. 

1957b. Eopachydiscus laevicaniculatus (Lasswitz). Wright, p.

L377, fig. 493. 

1960. Eopachydiscus brazoense (Shumard). Perkins, pl. 10,

fig- 1.

The holotype of Ammonites marcianus Shumard 

(1854), which was never illustrated, may be lost. This 

specimen was a small, poorly preserved juvenile. Lasswitz 

(1904, pl. 15, fig. 2; text figs. 8, 9) was the first person 

to illustrate a good specimen. His drawings show a slender phragmocone about 130 mm in diameter with an umbilical ratio of 0.21. Whorl section is oval with the greatest width at the lower part of the flank. The venter is 

narrowly rounded. A very narrowly rounded shoulder 

sharply defines the umbilicus. Six prorsiradiate to rectiradiate constrictions cross the flank and venter of the 

last half whorl. These constrictions and the bounding ribs 

are a little sinuous and arch forward on crossing the venter. One to three weaker secondary ribs are present on 

the outer half of the flank between each pair of constrictions.

Eopachydiscus marcianus attains a large size (Adkins and Winton, 1919, pl. 2, fig. 2). Cragin (1893, p. 

237) mentioned that some specimens attain a diameter of 

about 2 feet (610 mm), and have whorl heights exceeding 

8 inches (200 mm).

The types of Ammonites marcianus Shumard, A. 

brazoensis Shumard, and Pachydiscus laevicaniculatus 

Roemer came from the lower part of the Duck Creek 

Limestone in south-central and north-central Texas (Adkins, 1928, p. 220, 221), where E. marcianus occurs in 

such abundance as to be used in constructing gate posts 

and flower bed borders (Winton and Adkins, 1919, pl. 

4, fig. 2).

Parts of 10 pachydiscids from locality D6830 can 

be assigned to E. marcianus. The smallest specimen (pl. 

1, figs. 3, 6) has an estimated diameter of about 43 mm.

Its whorls are well rounded and about as high as wide. 

The inner whorls are poorly preserved, but the last half 

of the outer whorl has about five constrictions crossing 

the outer part of the flanks and venter. A strong, thick 

rib arising from an umbilical bulla trends straight across 

the flank and venter and bounds one side of a constriction. 

This individual also has on the last half whorl five strong, 

straight ribs that begin from umbilical bullae. The rest 

of the specimens consist of larger fragments of only parts 

of whorls. As the whorls increase in size, they become 

higher than wide, and the venter becomes narrowly 

rounded. The largest fragment is part of a septate whorl 

that had an estimated height of 150 mm. At that large 

size, broad, low ribs are present on the outer half of the 

flank, but they disappear on the venter. Fragments of two 

other septate specimens, which have whorl heights of 97 

and 110 mm, have sinuous constrictions and low ribs 

arching forward on crossing the venter. Whorl sections 

are typical of the species at these diameters (pl. 2, fig. 

1).

Types. Hypotypes, USNM 363030-363034.

Family BRANCOCERATTOAE Spath, 1934 

Subfamily MORTONICERATINAE Spath, 1925 

Genus MORTONICERAS Meek, 1876

Type species. Ammonites vespertinus Morton, 1834.

This genus, proposed by Meek (1876, p. 448), has 

been broadly interpreted to include fairly evolute keeled 

ammonites that have squarish to rectangular whorl sections and ornament of bituberculate, trituberculate, or 

quadrituberculate ribs. Some forms have, in addition, spiral ornament. Rostrate apertures are common. Suture usually has rather deeply indented lobes and saddles; the E/L 

saddle is broad and bifid, and L is narrower and bifid 

or irregularly trifid.

Mortoniceras equidistans (Cragin)

Plate 1, figure 8; plate 2, figures 5, 6; plate 3, figures 4, 5; 

plate 5, figures 1-8.

1893. Schloenbachia leonensis Conrad var. equidistans Cragin, p. 241. >

1904. Schloenbachia kiliani Lasswitz, p. 245, pl. 19, fig. 1; 

text fig. 6.

1907. Mortoniceras inflatum (Sowerby) var. kiliani Lasswitz? 

Pervinquiere, p. 246.

1910. Schloenbachia whitei Bose, p. 63, pl. 1, figs. 6-9.

1910. Schloenbachia trinodosa Bose, p. 78, pl. 9, fig. 4; 

pl. 10, figs. 1-4.

1922. Inflaticeras [Subschloenbachia] kiliani (Lasswitz). 

Spath, p. 102.

1923. Inflaticeras kiliani (Lasswitz). Spath, p. 76.

B6 Ammonite Faunas of the Sarten Sandstone, New Mexico
1925. Schloenbachia (Inflaticeras) trinodosum Boese. Diener,

p. 139. 

1925. Schloenbachia (Inflaticeras) whitei Boese. Diener,

p. 139.

1925. Gauthiericeras kiliani (Lasswitz). Diener, p. 153. 

1925. Inflaticeras kiliani (Lasswitz). Spath, p. 183. 

1925. Inflaticeras trinodosum (Bose). Spath, p. 183. 

1927. Pervinquieria kiliani (Lasswitz). Adkins, pi. 3, fig. 4.

1927. Schloenbachia trinodosa Bose. Bybee and Bullard, 

pi. 4, fig. 3.

1928. Prohysteroceras whitei (Bose). Adkins, p. 229.

1928. Pervinquieria kiliani (Lasswitz). Adkins, p. 233,

pi. 5, fig. 4. 

1928. Pervinquieria n. sp. 4. Adkins, p. 234, pi. 10,

fig. 1.

1928. Pervinquieria trinodosa (Bose). Adkins, p. 234. 

1932. Mortoniceras (Pervinquieria) kiliani (Lasswitz). Spath,

p. 408, pi. 38, figs. 1, 2; pi. 42, fig. 1; pi. 47, fig.

1; text fig. 14C. 

1934. Prohysteroceras (Goodhallites) whitei (Bose). Spath,

p. 446. 

1940. Pervinquieria kiliani (Lasswitz). Breistroffer, p. 75,

138. 

1940. Pervinquieria kiliani var. alstonensis Breistroffer,

p. 138, 139. 

1940. Pervinquieria fallax var. kilianiformis Breistroffer,

p. 140.

1942. Pervinquieria kiliani (Lasswitz). Haas, p. 94. 

1947. Neoharpoceras (Goodhallites) withei (sic) Bose. Breistroffer, p. 66.

1947. Pervinquieria kiliani (Lasswitz). Breistroffer, p. 66. 

1955. Mortoniceras (Mortoniceras) kiliani (Lasswitz). Reyment, p. 33, pi. 5, fig. 3.

1957. Pervinquieria kiliani (Lasswitz). Young, p. 3. 

1957. Goodhallites whitei (Bose). Young, p. 19. 

1967a. Pervinquieria equidistans (Cragin). Young, p. 67-69. 

1967b. Pervinquieria equidistans (Cragin). Young, p. 27.

The species equidistans was originally described as 

Schloenbachia leonensis Conrad var. equidistans Cragin 

(1893, p. 241). The variety was briefly described as having ribs bearing "three coarse, equidistantly placed nodes: 

umbilical, intermediate, and ventro-lateral, of which the 

last-named is particularly large and prominent and, with 

the corresponding nodes of other ribs, gives to the venter 

a decidedly squarish, instead of the ordinary rounded appearance." Cragin did not illustrate the type. A single extant specimen in the Cragin collections at Colorado College, Colorado Springs, Colo., may be the holotype. This 

keeled specimen, 169 mm in diameter, has an umbilical 

ratio of 0.42 and a squarish whorl section a little higher 

than wide. Ornament consists of prorsiradiate ribs that 

have equispaced umbilical, lateral, and ventrolateral tubercles. Ribs are slightly sinuous on the penultimate whorl, 

where they number 35. On the outer whorl, ribs are 

straight and number 22. Ventrolateral tubercles on the

outer whorl are large and nodate to slightly clavate. Faint 

spiral ornament is present on the outer whorl.

The ammonite from Texas described as Schloenbachia kiliani Lasswitz (1904, p. 245, pi. 19, fig. 1; text 

fig. 6) can be interpreted as the inner whorls of the 

species M. equidistans. Lasswitz's type has a diameter 

of 94 mm, an umbilical ratio of 0.36, and a squarish 

whorl section a little higher than wide. Ornament consists 

of 40 slightly sinuous trituberculate ribs that have faint 

spiral ornament on the ventrolateral shoulder. Young 

(1967b, p. 27) regarded Lasswitz's species as a synonym 

of M. equidistans.

Two ammonites from the Ciudad Juarez area, 

Chihuahua, Mexico, described by Bose (1910) as Schloenbachia whitei and S. trinodosa, can also be included as 

synonyms of M. equidistans. The holotype of S. whitei 

(Bose, 1910, pi. 1, figs. 6-9) is half a whorl of a phragmocone about 84 mm in diameter. Whorl section is higher 

than wide and subrectangular with flattened flanks and 

venter. Greatest width is at the umbilical shoulder. A low 

keel is present. Ornament consists of closely spaced prorsiradiate sinuous ribs rising from umbilical bullae or from 

a position low on the flanks. All ribs are accentuated at 

the ventrolateral shoulder, where they bend forward onto 

the venter. The external suture (Bose, 1910, pi. 1, fig. 

8) has a broad, bifid E/L saddle and a narrower, bifid, 

rectangular L. The specimen came from rocks now assigned to the Smeltertown Formation in the Ciudad Juarez 

area, Chihuahua, Mexico (Strain, 1976, p. 78, 79).

Several specimens consisting of half a whorl or 

more, as well as fragments of 30 other specimens from 

USGS Mesozoic locality D6830, reveal that Bose's 

holotype of Schloenbachia whitei can be interpreted as 

the inner whorls of the form Bose named Schloenbachia 

trinodosa. The latter was based on two large phragmocones that have whorls higher than wide and are ornamented by prorsiradiate closely spaced to moderately 

spaced trinodose ribs. The change in ornament from that 

of forms like the holotype of S. whitei to that of S. 

trinodosa can be seen best on a specimen from locality 

D6830 (pi. 1, fig. 8). This individual consists of an adult 

phragmocone with part of the body chamber present. The 

early part of the outer septate whorl has flattened flanks 

ornamented by closely spaced prorsiradiate sinuous ribs 

numbering 28 per half whorl. These ribs rise from umbilical bullae or from a position low on the flanks. Each 

rib is accentuated at the ventrolateral shoulder. On the 

later part of the last septate whorl, ribs become more 

widely spaced and straighter, and a bullate tubercle arises 

on each at the middle of the flank. Whorl height at the 

base of the body chamber is about 55 mm. Several other 

specimens in the collections are septate at whorl heights 

of 50-60 mm. Sutures of the specimens from locality 

D6830 are like that of the holotype of Bose's Schloenbachia whitei.

Systematic Descriptions B7
The juvenile closely spaced flexuous ribs of M. 

equidistans are much like those of the species described 

as Schloenbachia burckhardti by Bose (1910, p. 61, pi. 

1, figs. 1, 2, 4, 5), but the latter has an entirely different 

suture characterized by a long narrow L.

The inner whorls of M. equidistans in their compressed, flat flanks and closely spaced, sinuous, weakly 

bituberculate ribs closely resemble the inner whorls of 

Prohysteroceras Spath (1921, p. 286), especially the subgenus Goodhallites Spath (1932, p. 381). Most species 

of Mortoniceras have inner whorls ornamented by fewer, 

stronger, and straighter ribs, but some species have 

densely and sinuously ribbed inner whorls, such as M. 

fissicostatum Spath (1932, p. 396), and M. sp. ex gr. 

pricei (Spath) as figured by Renz (1971, pi. 11, figs. 

3a, b).

In addition to the specimens from locality D6830, 

several specimens were found at localities D 10 184 and 

D11759.

. Hypotypes, USNM 363039-363044.

Mortoniceras aff. M. leonense (Conrad)

Plate 3, figures 1, 2, 6-10, 12, 13

Many fragments of robust ammonites from USGS 

Mesozoic localities D6830 and D6832 have affinities with 

Mortoniceras leonense (Conrad, 1857, p. 160, pi. 16, fig. 

2a-d). Conrad's holotype, described as Ammonites 

leonensis, came from unnamed rocks near Leon Springs, 

Pecos County, Texas, which Adkins (1927, p. 67) later 

assigned to the Duck Creek Limestone.

Mortoniceras leonense is characterized by its 

squarish whorl section, sparse ribbing, and prominent umbilical and ventrolateral tubercles. The type (USNM 9878) 

is in the National Museum of Natural History, 

Washington, D.C. A plaster cast of the type shows it 

to consist of a whorl and a half of a phragmocone that 

has a diameter of about 83 mm and an umbilical ratio 

of 0.43. On the outer whorl, 21 straight, rectiradiate ribs 

bear strong, nodate inner ventrolateral tubercles. Umbilical tubercles are strong and nodate, and number 13 per 

whorl. Ribs alternate in length on the younger third of 

the outer whorl, where the long ones arise from the umbilical tubercles, and the shorter ones begin near the middle 

of the flank. On the rest of the outer whorl, most ribs 

arise in pairs from the umbilical tubercles. Weak midflank tubercles are present on several ribs on the younger 

half of the last whorl.

Several specimens from the Sarten Sandstone that 

have affinities with M . leonense consist of parts of whorls 

comparable in size to those of Conrad's holotype. The 

smallest specimen is half a whorl 41.5 mm in diameter

that has an umbilical ratio of 0.40 and ornament of weak, 

straight ribs and 7 strong nodate umbilical tubercles and 

12 strong inner ventrolateral tubercles (pi. 3, figs. 6, 7). 

A little larger specimen (pi. 3, figs. 1, 2) of 57 mm 

diameter has 25 ventrolateral and 13 umbilical tubercles 

on the outer whorl. Another specimen (pi. 3, figs. 8-10), 

consisting of parts of two whorls, has an umbilical ratio 

of 0.38 at a diameter of 57.5 mm for the smaller whorl. 

At this diameter 15 ventrolateral tubercles and 8 umbilical 

tubercles are present per half whorl. A fourth specimen 

(not illustrated) has 17 ventrolateral tubercles and about 

9 umbilical tubercles per half whorl at a diameter of 89 

mm. Weak mid-flank tubercles first appear on the Sarten 

specimens at some diameter near 50 mm. These specimens from the Sarten Sandstone differ from the holotype 

of M. leonense mainly in having more ribs and tubercles.

Fragments of large, robust ammonites from USGS 

Mesozoic localities D6830, D10184, and D10520, may 

represent parts of adults of Mortoniceras aff. M. leonense. 

These fragments have squarish whorl sections and 

trinodose ribs (pi. 3, figs. 12, 13). Several septate fragments have whorl heights of more than 50 mm. Ribs, 

which are rectiradiate to prorsiradiate, have equal-spaced 

nodate umbilical, lateral, and ventrolateral tubercles, of 

which the last is usually the largest.

Figured specimens. USNM 363046-363049.

Mortoniceras sp.

Plate 4, figures 14, 15

A phragmocone from USGS Mesozoic locality 

D6830 resembles Mortoniceras equidistans in having 

trituberculate ribs, but the specimen is more involute, and 

the ribbing is sparser. The specimen consists of parts of 

two whorls. Ribs per half whorl are estimated at 16 or 

17 for the inner whorl and 9 or 10 for the outer whorl.

Figured specimen. USNM 363045.

Submenus DRAKEOCERAS Young, 1957

Type species. Drakeoceras drakei Young, 1957.

Young (1957, p. 19) proposed Drakeoceras for 

moderately evolute keeled ammonites that have densely 

ribbed inner whorls and more sparsely ribbed outer 

whorls. Ribs on the outer whorls have umbilical tubercles 

and usually double ventrolateral tubercles. Although 

Young erected Drakeoceras as a genus, ammonites of this

B8 Ammonite Faunas of the Sarten Sandstone, New Mexico
type seem to fall within the scope of Mortoniceras as 

suggested by Matsumoto (1960, p. 38).

Mortoniceras (Drakeoceras) sp.

Plate 2, figures 2, 3; plate 3, figure 3; plate 4, figure 13

An impression of a small part of a whorl and parts 

of distorted whorls of two other individuals from locality 

D6833 represent a species of Mortoniceras characterized 

by finely ribbed inner whorls and sparsely ribbed outer 

whorls. About 12 or 13 ribs are present per half whorl 

at diameters of 110-120 mm. At this size, ribs consist 

of primaries separated by one or two secondaries. 

Primaries rise from strong umbilical tubercles, and secondaries appear low on the flanks. All ribs bear nodate ventrolateral tubercles, some of which consist of a double 

tubercle. The impressed area on the dorsum of one of 

the specimens reveals a densely ribbed venter on which 

the ribs are bent forward sharply as chevrons (pi. 3, fig. 

3).

Owing to their fragmentary condition or to their 

great distortion, none of the specimens can be assigned 

with certainty to any described species. The lateral 

impression of one specimen (pi. 4, fig. 13) has ornament 

suggestive of the side view of Mortoniceras 

(Drakeoceras) lasswitzi (Young, 1957, pi. 5, fig. 5). The 

densely ribbed venter of the inner whorl of another specimen (pi. 3, fig. 3) is like the venter of M. (D.) dellense 

(Young, 1957, pi. 10, fig. 5) at a comparable diameter.

Figured specimens. USNM 363050-363052.

Family ACANTHOCERATTDAE Hyatt, 190O 

Genus MANTELLICERAS Hyatt, 19O3

Type species. Ammonites mantelli J. Sowerby, 1814.

Kennedy (1971, p. 49, 50) summarized this genus 

as "Medium-sized (rarely large) ammonites, evolute and 

inflated to involute and compressed, usually with umbilical, lower lateral, lower and upper ventro-lateral tubercles 

on long ribs, alternating with short ribs with lower lateral 

and lower and upper ventro-lateral tubercles at some stage 

in the ontogeny. Some forms lose all but the upper ventrolateral tubercles early in their ontogeny and may become 

non-tuberculate when adult. Venter typically raised, but 

a siphonal tubercle is never developed. Suture-line relatively simple, with moderately subdivided rectangular 

bifid elements."

This early Cenomanian genus has a world-wide distribution.

Mantelliceras sp.

Plate 4, figures 1-10

Parts of six specimens from the top of the Sarten 

Sandstone represent a robust, rather sparsely ribbed 

species of Mantelliceras. Most consist of less than half 

a septate whorl (pi. 4, figs. 1-10). All are stout and have 

whorl sections about as wide as high with broadly rounded 

to flattened flanks. Ribs are strong, straight, mostly rectiradiate, and of alternate long and short lengths. They 

number about 15 per half whorl. All specimens have bullate umbilical tubercles and nodate inner and outer ventrolateral tubercles of which the outer rise above the venter and are the stronger. On the large specimens, the inner 

ventrolateral tubercles weaken and disappear. The two 

smallest specimens have occasional very weak lateral 

tubercles. Sutures are poorly preserved.

Sparsely ribbed mantelliceratids may be characteristic of a high position in the lower Cenomanian. Kennedy 

(1971, pis. 20-22) illustrated several sparsely ribbed 

forms from the upper part of the lower Cenomanian of 

England. These specimens were referred to as Mantelliceras gr. dixoni Spath, M. tenue Spath, and M. aff. 

souaillonense (Renz).

Of the American species of Mantelliceras, M. 

budaense Adkins (1931, p. 41, pi. 2, fig. 3, pi. 4, fig. 

10) resembles the fragments from the Sarten Sandstone 

in its robust form and sparse ribbing. The holotype of 

M. budaense, the only specimen described, came from 

the Buda Limestone near Austin, Texas. The specimen 

consists of about a third of a whorl of body chamber 

and the last septate whorl. Diameter of the type is 87 

mm, and the umbilical ratio is 0.32. The body chamber 

is a little broader than high with broadly rounded flanks. 

Matsumoto (1960, fig. 3A) has shown a sketch of the 

whorl section. Ornament consists of rectiradiate to slightly 

prorsiradiate, strong, rounded, straight ribs that alternate 

in length and number 25 on the last complete whorl. 

Larger ribs arise from umbilical bullae, and all ribs have 

inner and outer nodate ventrolateral tubercles. In contrast 

to the ornament on the Sarten specimens, the inner ventrolateral tubercles on the holotype persist to a larger diameter. Young and Powell (1976, p. xxv.4, pi. 7, figs. 

10, 12) and Young (1979, p. 16, 20, 21, 89) considered 

M. budaense as a synonym of M. cantianum Spath.

European species of Mantelliceras that lose the 

inner ventrolateral tubercles at a small diameter similar 

to that of the Sarten specimens include M. couloni (d'Orbigny, 1850, p. 147) and M. costatum (Mantell, 1822, 

p. 113, pi. 21, fig. 9). These species, however, are more 

densely ribbed than the Sarten species at comparable diameters.

Figured specimens . USNM 363035-363038.

Systematic Descriptions B9
Family ENGONOCERATTOAE Hyatt, 19OO 

Genus ENGONOCERAS Neumayr and Unlig, 1881

Type species. Ammonites pierdenalis von Buch, 1849.

Engonoceras includes involute, compressed shells 

with flat or sulcate venter. Ribs are flexuous to straight 

and usually flattened on the outer part of the flank. Nodate 

to bullate umbilical and mid-flank tubercles may be present as well as ventrolateral clavi arranged alternately 

across the venter. Suture is simple with mostly entire saddles. The genus has a range of middle Albian to early 

Cenomanian.

Engonoceras belviderense (Cragin)

Plate 1, figure 7

1890. Ammonites belviderei Cragin, p. 75 (not described).

1894b. Ammonites belviderensis Cragin. Cragin, pi. 1, figs. 

3-5 (not described).

1895. Sphenodiscus belviderensis (Cragin). Cragin, p. 369.

1898. Engonoceras belviderensis (Cragin). Bohm, p. 192.

1900. Buchiceras (Sphenodiscus) belviderensis (Cragin). Cragin, p. 27.

1900. Buchiceras (Sphenodiscus) belviderensis var. monscomancheanus Cragin, p. 29, pi. 1, fig. 5.

1900. Buchiceras (Sphenodiscus) belviderensis var. clavatus 

Cragin, p. 30, pi. 2, figs. 1-3.

1900. Buchiceras (Sphenodiscus) belviderensis var. uddeni 

Cragin, p. 30, pi. 1, figs. 3, 4.

1900. Buchiceras (Sphenodiscus) belviderensis var. mentorianus Cragin, p. 31, pi. 1, figs. 6, 7.

1903. Engonoceras belviderense (Cragin). Hyatt, p. 158, pi. 

18, figs. 4, 5.

1903. Engonoceras uddeni (Cragin). Hyatt, p. 159, pi. 18, 

figs. 1-6.

1924. Engonoceras belviderensis (Cragin). Twenhofel, p. 87, 

pi. 11, figs. 1-4.

1928. Engonoceras belviderense var. mons-comancheanum 

(Cragin). Adkins, p. 262.

1928. Engonoceras belviderense var. clavatum (Cragin). Adkins, p. 212.

1970. Engonoceras belviderense (Cragin). Scott, p. 83.

Scott (1970, p. 83) has drawn attention to the variation within this species. Most names applied to the species 

were based on small variations in the suture. Specimens 

assigned to the species by Cragin are slender and weakly 

ornamented.

A single impression of part of a whorl from locality 

D6833 can be assigned to Engonoceras belviderense. The 

impression has a flat flank and narrow, flat venter. Umbilical bullae are present, but ornament other than sinuous 

growth striae is absent.

Type. Hypotype, USNM 363053.

Engonoceras sp.

Plate 4, figures 11, 12

Fragments of two moderately large poorly preserved 

engonoceratids are present in the collection from locality 

D6830. Each is represented by less than half a whorl of 

specimens that had diameters of about 68-70 mm. Both 

specimens are robust, and have broad, flat venters bounded by alternate broad clavi numbering about 10 per whorl. 

Umbilical bullae number four per half whorl. Only bits 

of sutures are visible.

Figured specimen. USNM 363054.

Family TURRHJTIDAE Meek, 1876 

Genus TURRELITES Lamarck, 18O1

Type species. Turrilites costatus Lamarck, 1801.

This helical genus is characterized by its tightly 

coiled spire that has an acute apical angle and is ornamented by ribs which may have three or four rows of 

equal numbers of tubercles. The genus may be confined 

to the Cenomanian.

Turrilites aff. T. costatus Lamarck

Plate 2, figure 4

A well-preserved turrilitid of four whorls was found 

at the contact of the Sarten Sandstone and the overlying 

Colorado Formation. The specimen was in a sandy, limy 

nodule that contained a few small chert pebbles. Inasmuch 

as the base of the Colorado Formation at this locality is 

a pebbly sandstone or a thin conglomerate, the question 

arises concerning the source of the turrilitid. Limestone 

nodules at the top of the Sarten are also sandy. Inasmuch 

as other fossils were not observed in the basal Colorado 

conglomerate, I am assuming the limy nodule containing 

the turrilitid was either at the very top of the Sarten or 

reworked into the base of the Colorado.

The turrilitid is an internal mold 96 mm high with 

an apical angle of 19°. Ornament consists of 22 strong, 

narrow, curved ribs on each whorl. On the middle of the 

whorls, the ribbing is interrupted by a narrow sulcus that 

may be pathologic.

Of the species of Turrilites, the Sarten specimen 

seems nearest to T. costatus Lamarck (1801, p. 102). Apical angle and rib density are similar to those of T. costatus. Turrilites costatus, however, has a more pronounced interruption in the ribbing a little below the middle of the flank as well as another interruption at the base, 

and the ribs between the two interruptions are nodelike.

Figured specimen. USNM 363055.

B10 Ammonite Faunas of the Sarten Sandstone, New Mexico
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References Cited B13

INDEX

[Italic page numbers indicate major references]

Acanthoceratidae ................ 9

Access to collecting localities ........ 2

adkinsi, Graysonites .............. 4

Adkinsites ..................... 4

bravoensis ................... 4

Advice concerning Sarten Sandstone

ammonites ............... 2

aequatoriale, Mortoniceras .......... 4

Age of Sarten Sandstone ........... 4

alstonensis, Pervinquieria kiliani ...... 1

Ammonite faunas of New Mexico and Texas 3 

Ammonite zone for early Cenomanian of

southern England ........... 4

Ammonite zones for upper Albian and

Cenomanian rocks of Texas .... 4

for upper Albian of southern England . 4 

Ammonites belviderei ............ 10

belviderensis ................. 10

brazoensis ................... 5

leonensis .................... 8

mantelli ..................... 9

marcianus ................... 5

pierdenalis .................. 10

vespertinus ................... 6

Ammonites from Ciudad Juarez, Mexico . 7

from lower Cenomanian of England . . 9

Anapra Sandstone ................ 3

Anglo-Paris basin ................ 4

Arrhaphoceras .................. 4

substuderi ................... 4

Artica compacta ................. 3

auritus, Callihoplites .............. 5

B

belviderei, Ammonites ............ 10

belviderense, Engonoceras ..... 10, pi. 1

clavatum, Engonoceras .......... 10

mons-comancheanum, Engonoceras . . 10 

belviderensis, Ammonites .......... 10

Buchiceras (Sphenodiscus) ........ 10

clavatus .................. 10

mentorianus ............... 10

mons-comancheanus .......... 10

uddeni ................... 10

Engonoceras ................. 10

Sphenodiscus ................ 10

blancheti, Stoliczkaia (Faraudielld) .... 5

Boracho Limestone, Levinson Member . . 4 

Bose, E., Cretaceous lithologic units of . 3 

Brancoceratidae ................. 6

bravoensis, Adkinsites ............. 4

brazoense, Desmoceras .......... 4, 5

Eopachydiscus .............. 4, 6

brazoensis, Ammonites ............. 5

Eopachydiscus .............. 4, 6

Pachydiscus .................. 5

brazosensis, Eopachydiscus ........ 3, 4

Plesioturrilites ................ 4

brundrettei, Forbesiceras ........... 4

Buchiceras (Sphenodiscus) belviderensis . 10 

clavatus .................. 10

mentorianus ............... 10

mons-comancheanus .......... 10

uddeni ................... 10

Buda Limestone ............... 2, 9

budaense, Granocardium (Criocardium) . 3 

Mantelliceras ............... 2, 9

budaensis, Homomya ............. 3

Budaiceras .................. 3, 4

Ayorti .................... 3, 4

burckhardti, Schloenbachia .......... 8

Callihoplites ................... 4

auritus ..................... 5

cantianum, Mantelliceras ......... 2, 9

carcitanensis, Hypoturrilites ....... 3, 4

c/arfa', Exogyra ................. 3

clavatum, Engonoceras belviderense ... 10 

clavatus, Buchiceras (Sphenodiscus)

belviderensis ............. 10

Cobban, R.R., collector ........... 2

Collecting locality, access .......... 2

Colorado Formation ............. 10

compacta, Artica ................ 3

Cooke Range .................. 1

costatum, Mantelliceras ............ 9

costatus, Turrilites ........ 3, 10, pi. 2

couloni, Mantelliceras ............. 9

(Criocardium) budaense, Granocardium . 3 

Cymatoceras sp ................. 3

D

Del Rio Clay .................. 3

dellense, Mortoniceras (Drakeoceras) ... 9 

Descriptions, systematic ............ 5

Desmoceras brazoense ........... 4, 5

laevicaniculatum ............... 6

laevicaniculatus ................ 4

marcianum ................... 6

sp. A ...................... 5

dispar, Stoliczkaia ............... 5

dixoni, Mantelliceras .......... 3, 4, 9

drakei, Drakeoceras .............. 4

Drakeoceras ............. 2, 4, 5, 8

drakei ...................... 4

lasswitzi .................... 4

(Drakeoceras), Mortoniceras .... 5, pi. 2

dellense ..................... 9

lasswitzi .................... 9

sp ............... 9, pi. 3, pi. 4

Duck Creek Formation .......... 3, 4

Duck Creek Limestone ............ 8

(Durnovarites) perinflatum, Mortoniceras . 5

Engonoceras .................. 10

belviderense ............. 10, pi. 1

clavatum ................. 10

mons-comancheanum .......... 10

belviderensis ................. 10

uddeni .................... 10

sp ................. 2, 10, pi. 3

Engonoceratidae ................ 10

Eopachydiscus .............. 2, 4, 5

brazoense ................. 4, 6

brazoensis ................. 4, 6

brazosensis ................ 3, 4

laevicaniculatus ................ 6

laevicaniculum ................ 4

marcianus ... 2, 3, 4, 5, pis. 1, 2, 3

Eopachydiscus marcianus Mortoniceras

equidistans fauna ........... 3

in northeast New Mexico ......... 4

in Texas .................... 3

in Trans-Pecos Texas ............ 4

equidistans, Mortoniceras .... 2, 3, 4, 6,

8, pis. 1, 2, 3,5 

Pervinquieria ............... 3, 4

[Mortoniceras] ............... 4

Schloenbachia leonensis .......... 6

Espy Formation ................. 4

Exogyra ...................... 2

clarki ...................... 3

whitneyi .................... 3

F, G

fallax, Pervinquieria .............. 5

kilianiformis, Pervinquieria ........ 1

Faraudiella .................... 3

(Faraudielld} blancheti, Stoliczkaia .... 5

Faunas, ammonite, of New Mexico and

Texas .................. 3

fissicostatum, Mortoniceras .......... 8

Fluorite Ridge .................. 1

Forbesiceras ................... 4

brundrettei ................... 4

Fort Worth Limestone ............. 5

Gauthiericeras kiliani ............. 7

Goodhallites whitei ............... 1

(Goodhallites) withei, Neoharpoceras ... 7

whitei, Prohysteroceras ........... 1

Granocardium (Criocardium) budaense . . 3

Grayson Formation ............... 3

Graysonites .................... 4

adkinsi ..................... 4

lozoi ....................... 4

H-K

harrisi, Tylostoma ............... 3

Homomya budaensis .............. 3

Hook, S.C., collector ............. 2

Index B15
hyatti, Budaiceras ............. 3, 4

Hypoturrilites carcitanensis ........ 3, 4

Hysteroceras ................. 3, 4

orbignyi .................... 5

varicosum ................... 5

inflata, Pervinquieria ............. 5

Inflaticeras kiliani ............... 6

trinodosum ................... 1

[Subschloenbachia] kiliani ......... 6

(Inflaticeras) trinodosum, Schloenbachia . 1

whitei, Schloenbachia ............ 1

inflatum, Mortoniceras ............ 5

kiliani, Mortoniceras ............ 6

kiliani, Gauthiericeras ............. 7

Inflaticeras ................... 6

[Subschloenbachia] ............ 6

Mortoniceras ................. 4

(Mortoniceras) ............... 7

(Pervinquieria) ............... 1

Mortoniceras inflatum ........... 6

Pervinquieria ............... 4, 7

Schloenbachia ................. 6

alstonensis, Pervinquieria ......... 7

kilianiformis, Pervinquieria fallax ..... 7

laevicaniculatum, Desmoceras ........ 6

laevicaniculatus, Desmoceras ........ 4

Eopachydiscus ................ 6

Pachydiscus .................. 5

laevicaniculum, Eopachydiscus ....... 4

Landis, E.R., collector ............ 2

lasswitzi, Drakeoceras ............. 4

Mortoniceras (Drakeoceras) ........ 9

leonense, Mortoniceras ....... 8, pi. 3

leonensis, Ammonites ............. 8

equidistans, Schloenbachia ........ 6

Levinson Member of Boracho Limestone . 4

Lima shumardi ................. 3

lozoi, Graysonites ............... 4

lymense, Mantelliceras ............ 3

M

mantelli, Ammonites .............. 9

Mantelliceras ............... 3, 4

Mantelliceras ................. 2, 9

budaense .................. 2, 9

cantianum ................. 2, 9

costatum .................... 9

couloni ..................... 9

dixoni .................. 3, 4, 9

lymense ..................... 3

mantelli ................... 3, 4

saxbii .................... 3, 4

souaillonense ............... 3, 9

tenw£ ...................... 9

sp ................... 9, pi. 3

Manuaniceras .................. 4

powelli ..................... 4

marcianum, Desmoceras ........... 6

marcianus, Ammonites ............. 5

Eopachydiscus .2, 3, 4, 5, pis. 1, 2, 3 

Pachydiscus .................. 5

mentorianus, Buchiceras (Sphenodiscus)

belviderensis ............. 10

Merewether, E.A., collector ......... 2

Mesa Rica Sandstone ............. 4

Mexico .................... 2, 7

mons-comancheanum, Engonoceras

belviderense ............. 10

mons-comancheanus, Buchiceras

(Sphenodiscus) belviderensis ... 10 

Mortoniceras ............... 2, 4, 6

aequatoriale .................. 4

equidistans .......... 2, 3, 4, 6, 8,

pis. 1,2, 3, 5 

fissicostatum .................. 8

inflatum .................... 5

kiliani .................... 6

kiliani ...................... 4

leonense ............... 8, pi. 3

perinflatum .................. 5

pricei ...................... 8

wintoni ..................... 4

sp ................... 8, pi. 4

(Drakeoceras) .......... 2, 5, pi. 2

dellense ................... 9

lasswitzi ................... 9

sp .............. 9, pi. 3, pi. 4

(Durnovarites) perinflatum ......... 5

(Mortoniceras) kiliani ............ 7

(Pervinquieria) kiliani ........... 1

(Mortoniceras) kiliani, Mortoniceras .... 7

{Mortoniceras] equidistans, Pervinquieria . 4

Mortoniceratinae ................. 6

N, O

Naff, Richard, collector ............ 2

Neithea (Neithea) texana ........... 3

(Neithea) texana, Neithea .......... 3

Neoharpoceras (Goodhallites) withei .... 7

nodosa, Schloenbachia ............ 3

orbignyi, Hysteroceras ............. 5

P-R

Pachydiscidae .......

Pachydiscus brazoensis .

laevicaniculatus .....

marcianus ........

sp

......... 5

......... 5

......... 5

......... 5

......... 5

perinflata, Pervinquieria ........... 5

perinflatum, Mortoniceras .......... 5

(Durnovarites) ............... 5

Pervinquieria ................. 4

Pervinquieria equidistans ......... 3, 4

fallax ...................... 5

kilianiformis ................ 1

inflata ...................... 5

kiliani .................... 4, 1

alstonensis ................. 1

perinflata .................... 5

pricei ...................... 5

trinodosa .................... 4

whitei ...................... 4

n. sp. 4 .................... 7

[Mortoniceras] equidistans ......... 4

(Pervinquieria) kiliani, Mortoniceras ... 7

Photographing of specimens ......... 2

pierdenalis, Ammonites ........... 10

Plesioturrilites .................. 4

brazosensis .................. 4

powelli, Manuaniceras ............. 4

pricei, Mortoniceras .............. 8

Pervinquieria ................. 5

Prohysteroceras whitei ............. 1

(Goodhallites) whitei ............ 1

Protocardia sp ................. 3

Pterotrigonia (Scabrotrigonia) sp ...... 3

Rattlesnake Ridge ................ 1

Sarten Ridge ................... 1

saxbii, Mantelliceras ............ 3, 4

(Scabrotrigonia) sp., Pterotrigonia ... 3, 4 

scheuchzerianus, Turrilites .......... 3

Schloenbachia burckhardti .......... 8

kiliani ...................... 6

leonensis equidistans ............ 6

nodosa ..................... 3

trinodosa .................. 3, 6

whitei ...................... 6

(Inflaticeras) trinodosum .......... 1

whitei .................... 1

semiatimgranulata, Turritella ........ 3

shumardi, Lima ................. 3

Sierra de Cristo Rey uplift, Bose's

lithologic units on .......... 3

Smeltertown Formation ............ 3

souaillonense, Mantelliceras ....... 3, 9

Sphenodiscus belviderensis ......... 10

(Sphenodiscus) belviderensis, Buchiceras 10 

clavatus .................. 10

mentorianus ............... 10

mons-comancheanus .......... 10

uddeni ................... 10

Stanton, T.W., quoted ............ 1

Stearnsia sp ................... 3

Stoliczkaia .................... 4

dispar ...................... 5

(Faraudiella) blancheti ........... 5

[Subschloenbachia] kiliani, Inflaticeras . . 6 

substuderi, Arrhaphoceras .......... 4

Syncyclonema sp ................ 3

Systematic descriptions ............ 5

T-Z

Tabet, D.E., collector ............. 2

tenue, Mantelliceras .............. 9

texana, Neithea (Neithea) .......... 3

Texas, Buda Limestone of .......... 2

trinodosa, Pervinquieria .......... 4, 7

Schloenbachia ............... 3, 6

trinodosum, Inflaticeras ............ 1

Schloenbachia (Inflaticeras) ........ 1

Turrilites .................... 10

costatus .............. 3, 10, pi. 2

scheuchzerianus ................ 3

Turrilitidae ................... 10

B16 Ammonite Faunas of the Sarten Sandstone, New Mexico
Turritella semiatimgranulata ......... 3 Washita Group ............... 1, 3 Schloenbachia ................. 6

sp ........................ 3 of Texas, upper Albian and (Inflaticeras) ................ 1

Tylostoma harrisi ................ 3 Cenomanian rocks in ........ 4

uddeni, Buchiceras (Sphenodiscus) Weno Formation ................ 5 wMtneyi, Exogyra ............... 3

belviderensis ............. 10 whitei, Goodhallites .............. 1 wintoni> Mortoniceras ............. 4

Engonoceras ................. 10 Pervinquieria ................. 4 withei, Neoharpoceras (Goodhallites) ... 7

varicosum, Hysteroceras ........... 5 Prohysteroceras ................ 1 Wright, J.R., collector ............ 2

vespertinus, Ammonites ............ 6 (Goodhallites) ............... 7 Young, Keith, quoted ............. 3

£ U.S. GOVERNMENT PRINTING OFFICE: 1987 773-047/46,024 REGION NO. 8 Index B17

PLATES 1-5

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

[AH figures natural size. Localities shown on figure I in text]

Figures 1-6. Eopachydiscus marcianus (Shumard) (p. 5).

From USGS Mesozoic locality D6830.

1,2. Hypotype USNM 363030.

3,6. Hypotype USNM 363031.

4, 5. Hypotype USNM 363032.

7. Engonoceras belviderense (Cragin) (p. 10).

Hypotype USNM 363053, from USGS Mesozoic locality D6833. 

Lateral view with venter on left.

8. Mortoniceras equidistans (Cragin) (p. 6).

Hypotype USNM 363039, from USGS Mesozoic locality D6830. 

See plate 5, figure 8, for rear view.
US. GEOLOGICAL SURVEY BULLETIN 1641-B PLATE 1

EOPACHYDISCUS, ENGONOCERAS, AND MORTONICERAS
PLATE 2

[All figures natural size. Localities shown on figure 1 in text]

Figure 1. Eopachydiscus marcianus (Shumard) (p. 5).

Hypotype USNM 363033, from USGS Mesozoic locality D6830. 

2, 3. Mortoniceras (Drakeoceras) sp. (p. 9).

Figured specimen USNM 363050, from USGS Mesozoic locality D6833. 

4. Turrilites aff. T. costatus Lamarck (p. 10).

Figured specimen USNM 363055, from USGS Mesozoic locality D10495. 

5,6. Mortoniceras equidistans (Cragin) (p. 6).

Hypotype USNM 363040, from USGS Mesozoic locality D6830.
U.S. GEOLOGICAL SURVEY BULLETIN 1641-B PLATE 2

EOPACHYDISCUS, MORTONICERAS, AND TURRILITES
PLATE 3

[All figures natural size. Localities shown on figure 1 in text]

Figures 1, 2, 6-10, 12, 13. Mortoniceras aff. M. leonense (Conrad) (p. 8).

1, 2. Figured specimen USNM 363046, from USGS Mesozoic locality D6830.

6, 7. Figured specimen USNM 363047, from USGS Mesozoic locality D6832.

8-10. Figured specimen USNM 363048, from USGS Mesozoic locality D6830.

12, 13. Figured specimen USNM 363049, from USGS Mesozoic locality D6830.

3. Mortoniceras (Drakeoceras) sp. (p. 9).

Latex cast of the venter of the inner whorls. Figured specimen USNM 363052, from USGS Mesozoic locality D6833. 

4, 5. Mortoniceras equidistans (Cragin) (p. 6).

Hypotype USNM 363041, from USGS Mesozoic locality D6830. 

11. Eopachydiscus marcianus (Shumard) (p. 5).

Hypoiype USNM 363034, from USGS Mesozoic locality D6830.
BULLETIN 1641-B PLATE 3

MORTONICERAS AND EOPACHYDISCUS
PLATE 4

[All figures natural size. Localities shown on figure 1 in text]

Figures 1-10. Mantelliceras sp. (p. 9).

From USGS Mesozoic locality D10104.

1,2. Figured specimen USNM 363035.

3, 4. Figured specimen USNM 363036.

5, 8-10. Figured specimen USNM 363037.

6, 7. Figured specimen USNM 363038.

11, 12. Engonoceras sp. (p. 10).

Figured specimen USNM 363054, from USGS Mesozoic locality D6830. 

13. Mortoniceras (Drakeoceras) sp. (p. 9).

Figured specimen USNM 363051, from USGS Mesozoic locality D6833. 

14, 15. Mortoniceras sp. (p. 8).

Figured specimen USNM 363045, from USGS Mesozoic locality D6830.
U.S. GEOLOGICAL SURVEY BULLETIN 1641-B PLATE 4

14 15 

MANTELLICERAS, ENGONOCERAS, AND MORTONICERAS
PLATE 5

[AH figures natural size. Locality shown on figure 1 in text]

Figures 1-8. Mortoniceras equidistans (Cragin) (p. 6).

From USGS Mesozoic locality D6830.

1-3. Hypotype USNM 363042.

4, 5. Hypotype USNM 363043.

6, 7. Hypotype USNM 363044.

8. Hypotype USNM 363039. See plate 1, figure 8, for side view.
U.S. GEOLOGICAL SURVEY BULLETIN 1641 -B PLATE 5

MORTONICERAS