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UNIVERSITY OF
ILLINOIS LIBRARY
AT’ URBANA-CHAMPAIGN
GEOLOGY

JONI I

Vv

FIELDIANA
Geology

Published by Field Museum of Natural History

New Series, No. 4 August 4, 1980

Amphibia and Reptilia
from the Campanian of New Mexico

JUDY GAIL ARMSTRONG-ZIEGLER
FIELD MUSEUM OF NATURAL HISTORY

ABSTRACT

A washing and screening process has resulted in recovery of more
than 7,000 vertebrate fossils from four sites in the late Cretaceous
Fruitland Formation, northwestern New Mexico. At least 48 genera
are represented (see Armstrong-Ziegler, 1978, for complete vertebrate
faunal listing). Only the Amphibia and Reptilia are described in this
report.

On the basis of total taxonomic content, the Fruitland Formation
fauna is closest to, but slightly younger than, that from the Campanian
Judith River Formation of Montana. An Upper Campanian age is
therefore assigned to the Fruitland Formation. Faunal comparisons
also indicate that the Fruitland Formation fauna is slightly older than
the Maestrichtian Lance and Hell Creek Formations of Wyoming and
Montana. The four sites studied in the Fruitland represent three aqua-
tic subenvironments of deposition: upland river, upland stream, and
lowland river. Both freshwater and terrestrial forms appear in varying
proportions in all three of these subenvironments. In addition, brackish
water forms appear in the lowland river subenvironment.

INTRODUCTION

The Fruitland Formation, first described by Bauer (1916), was
named after the town of Fruitland, N.M., on the San Juan River, where
outcrops of the formation are particularly well exposed. The unit at
Bauer’s type locality, N29N R1SW, is 73.5 m. thick. Other extensive

Library of Congress Catalog Card No.: 80-66380 ye
US ISSN 0096-2651 aN,
Accepted, fe pubkie
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yi FIELDIANA: GEOLOGY

exposures of the Fruitland Formation occur on the northwestern,
western, and southern borders of the San Juan Basin, which extend
from northwestern New Mexico into southwestern Colorado. In New
Mexico and Colorado, north of the San Juan River, the formation is
consistently thicker, ranging up to 161.5 m. as seen on the La Plata
River near the New Mexico-Colorado boundary. South of the San Juan
River, the formation ranges between 76 and 107 m. in thickness. In
Bauer’s section of ‘“‘Cottonwood Arroyo’’ (T26N R16W), the Fruitland
Formation is 100 m. thick; this section is near the three localities (A, B,
and C) included in this study.

The Upper Cretaceous sequence of stratigraphic units in the area of
this study consists, from bottom to top, of the Lewis Shale, the Pic-
tured Cliffs Sandstone, the Fruitland Formation, and the Kirtland
Shale. The beds of the Fruitland Formation, deposited under both
freshwater and brackish water conditions, include mudstones,
siltstones, crossbedded sandstones, and coal. Individual beds are
highly lenticular and of limited lateral extent.

The Upper Cretaceous rock units of the San Juan Basin represent
extensive transgressive-regressive cycles of deposition. These rock
units were deposited in and near a late Cretaceous epicontinental sea
that extended from the Gulf of Mexico to the Arctic Ocean. Lying on
the west margin of this sea, the basin was intermittently above and
below sea level as the sea advanced and retreated during late Cretace-
ous times. As this sea regressed for the last time, the Fruitland Forma-
tion was formed through swamp, fluviatile, floodplain, and lacustrine
deposition that occurred shoreward on top of the Pictured Cliffs
Sandstone. Fassett & Hinds (1971) have contributed a detailed consid-
eration of the Fruitland’s areal and stratigraphic extent, of its lithology,
and of its mode of deposition.

Fossils are numerous and varied in the Fruitland. The fauna contains
terrestrial, freshwater, and brackish water forms, including vertebrates
and invertebrates. The flora consists of a variety of both angiosperms
and gymnosperms.

Since 1962, Dr. W. A. Clemens, Department of Paleontology, Uni-
versity of California, Berkeley, has made collections of fossil verteb-
rates from Hunter’s Wash (Fruitland and Kirtland Formations) in the
southwestern part of the basin. He published a preliminary paper on
the mammals (Clemens, 1973) and intends to do further studies here
and also on the mammals collected by myself and associates.

In the summer of 1975, Dr. E. Lindsay of the University of Arizona
investigated the magnetic stratigraphy of the San Juan Basin in New

ARMSTRONG-ZIEGLER: CAMPANIAN AMPHIBIANS & REPTILES 3

Mexico. During this time, he collected some microvertebrate material
from the Fruitland at locality UALP 75137, which is in SE 4, SE %,
Sec. 34, T24N, RI3W, Alamo Mesa West, 72’ Quadrangle. The
stratigraphic position of this locality is 30.5 m. above the University of
Kansas locality number 43 (Clemens and Eaton field trip, 1962). Both
mammal and lower vertebrate fossils were obtained from this locality,
and a number of identifiable specimens were sent to me. Dr. Clemens is
conducting a study of the mammal specimens of this collection, and the
present paper includes descriptions of the amphibian and reptilian
specimens.

From June 12-24, 1974, Mr. W. J. Breed and Dr. L. G. Marshall and
associates from the Department of Geology, Museum of Northern
Arizona, conducted and reported on an initial survey of the paleon-
tological resources on Navajo Tribal Lands leased by Western
Gasification Company for a coal company, Utah International, near
Burnham, San Juan County, New Mexico. Two microvertebrate lo-
calities were found by Mr. D. Lawler of this party and were given field
numbers 88 and 93 (Marshall Field Notes, M.N.A. 1974). A third lo-
cality, HW#24 (= UCMP V-72090), discovered by Mr. H. Wagner,
University of California, Berkeley, in April and May, 1972, was re-
located and given the number 16 (Marshall Field Notes M.N.A., 1974).

In this paper, these localities are referred to by the MNA locality
numbers as follows: #16=A, #88=B, and #93=C. Each locality is in
T26N, R16W, and their exact positions follow:

Locality A: 108° 29’ 10” W longitude
36° 31’ 18” N latitude
Locality B: 108° 30’ 49” W longitude
36° 29’ 10” N latitude
Locality C: 108° 32' 6” W longitude
36° 29’ 18” N latitude
During the summer of 1974, while employed as an assistant preparator
for the Geology Department, Museum of Northern Arizona, I became
involved in the field and laboratory work for the preliminary paleon-
tological survey of this area. With the aid of MNA personnel, I col-
lected seven burlap bags of matrix and seven and one-half bags of
anthill concentrate on August 14-15, 1974, from microvertebrate Lo-
cality A.

The following summer, I again returned to the Museum of Northern
Arizona. Locality B was visited the weekend of June 25-27, 1975, at
which time material was collected and stratigraphic notes were taken.
From June 28 to August 22, 1975, screen washing was carried on, anda

4 FIELDIANA: GEOLOGY

preliminary report of my progress was given at the Four Corners
Geological Symposium at MNA. A final field trip, the weekend of
August 22-24, was made with the aid of Mr. D. Gnidovec, Mr. M.
Zavada, and Ms. T. Kreklau, and collections of matrix were made from
Locality C. Zavada, a graduate student at Arizona State University,
made a collection of plant megafossils at this time; he later informed me
that eight species, heretofore unknown from the Fruitland, were ac-
quired from this site.

The present report describes only the amphibian and reptilian por-
tions of the total lower vertebrate assemblage. The fish component of
the fauna and certain invertebrates, important as environmental in-
dicators, will be described in a separate paper. A preliminary paper
describing a new species of snake and a complete material listing for
the vertebrates of the Fruitland has been submitted to the Journal of
Paleontology. In subsequent sections of this report, the total as-
semblage from the Fruitland is compared with the following major
studies: Lance Formation of Wyoming (Estes, 1964; Clemens, 1964);
Hell Creek and Judith River Formations of Montana (Sloan & Van
Valen, 1965; Estes et al., 1969; Sahni, 1972); Milk River Formation of
Alberta, Canada (Russell, 1935); Fruitland and Kirtland Formations of
New Mexico (Clemens, 1973; Reeside, 1924; Stanton, 1916; Gilmore,
1916; Knowlton, 1916).

Comparison of the total assemblage from the three sites and
Lindsay’s site with other faunas has provided evidence for assigning a
more definitive age than ‘‘Late Cretaceous’ to the Fruitland For-
maiton. Zoogeographical interpretations, leading from comparisons
among these assemblages, have provided a more complete picture of
the biota that existed along an epicontinental seaway that ranged from
Mexico to Canada during late Cretaceous times. In addition, study of
the fauna and comparisons with other fossil and recent faunas have led
to a better understanding of the paleoenvironment of deposition and of
paleoclimatic conditions. Some conclusions are drawn about the
paleoecology of this thanatocoenotic assemblage of land and aquatic
fossil forms by comparing them with analogous extant ecological com-
munities.

LOCALITIES

Localities A, B, and C apparently lie within the upper 15.2 m. of the
Fruitland Formation. This stratigraphic position was determined
through field comparisons of the strata with descriptions of lithology
and maps of the Fruitland Formation in the area of the localities pro-
vided by Bauer (1916) and Fassett & Hinds (1971). Figure 1 shows the

Teahies ae . ee 4 Cc Ironstone
cis (ee a ee ere nodule
: oman’ Cc Fossil horizon
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t '
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’ Sandstone
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—— —————————EE—

Re Poe —WA Yt OS
B

Fic. 1. Sections of the Fruitland Formation from Sites A, B, and C, New Mexico.

6 FIELDIANA: GEOLOGY

positions of the fossil horizons in generalized stratigraphic columns of
the sections exposed at the three localities.

Locality A contains one productive horizon consisting of two cal-
careous fossiliferous lenses outcropping about 3 m. apart (fig. 2). Ten
burlap feed bags of matrix were collected from this locality. In addition
to the excavated matrix, five and a half bags of anthill material were
collected from four separate anthills, located 137 m. north and north-
west of locality A. These recent fossiliferous anthills were formed by
the small red ant, Pogonomyrmex, the same genus that formed the
fossiliferous Bug Creek Anthills of the Hell Creek Formation in Mon-
tana. Some anthills formed by a larger black ant species were sampled
but yielded no fossil material; the rock particles transported by these
ants are considerably smaller than the sand grains and fossil fragments
transported by Pogonomyrmex.

Locality B contains two fossil horizons, each of which has a lateral
extent of about 4.5 m. (fig. 2). Six burlap feed bags of excavated matrix
were collected at this locality, together with specimens picked from the
surface.

Locality C contains two fossil horizons whose exposures encircle a
small hillock approximately 4.5 m. in diameter. The lower fossil hori-
zon on the hillock has a second outcropping 3 m. due north of it at
ground level (fig. 2). The beds exhibit a general 4° dip to the east. The
shale bed shown for Locality C in Figure 3 contains an abundance of
plant mega-fossils, including angiosperms and gymnosperms. Six bur-
lap feed bags of matrix were collected from Locality C.

These three localities are strikingly similar in lithology and appear-
ance. Differential weathering has given them a vuggy look, with
‘‘toadstools’’ capped by resistant siltstones (fig. 2) and sandstones
resting on pinnacles of the more easily weathered shales and
mudstones.

Lindsay (written comm., 1976) describes the lithologic character of
Locality UALP 75137: ‘‘fossiliferous siltstone, light tan, poorly sorted,
with a few lignite fragments. The locality is the surface of a round
knob, underlain by a white concretionary sandstone, about 4.5 m. thick
that overlies a thick (about 3-3.5 m.) black carbonaceous, relatively
continuous siltstone.’’ Locality UALP 75137 is about 30.5 m. above
the Kansas University Locality 43. On the Alamo Mesa West Quad-
rangle (seven and one-half series) topographic map, Locality UALP
75137 is in SE%4, SE", sec. 34, T24N, R13W (Lindsay, written comm.,
1976). Lindsay’s crew collected ten sacks of matrix at this locality.

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ARMSTRONG-ZIEGLER: CAMPANIAN AMPHIBIANS & REPTILES 9

MATERIALS AND METHODS

The bone concentrations occur in calcareous sandstone lenses and
consist mainly of disassociated and fragmentary elements. Much of the
material was eroded by transportation before burial. Approximately
6,092 identifiable specimens were collected from Locality A; 1,544
from Locality B; and 426 from Locality C. About 33% of the specimens
from Locality A, 40% from Locality B, and 36% from Locality C are
gar-pike scales. Obviously, these high percentages of gar scales do not
reflect the actual abundance of the gar-pike, Lepisosteus, because a
gar-pike contains many hundreds of scales.

The washing and screening process as developed by Hibbard (1949),
Clemens (1973), and McKenna (1962) was employed to concentrate
and reduce the matrix for hand sorting. The screen boxes were con-
structed according to McKenna (1962). For his Locality UALP 75137,
Lindsay used tandem screen boxes, the inner box with one-sixteenth-
inch mesh size and the outer box with a one-twenty-fifth-inch mesh
size, to process 10 bags of matrix two or three times in water without
the use of chemicals. The smallest identifiable specimen sent to me by
Lindsay is a fragmentary lizard osteoscute approximately 1.0 mm. in
width.

Due to the calcareous nature of the matrix from Locality A, diluted
formic acid, as recommended by Sahni (1972), was used to dis-
aggregate the matrix before it was washed. The other localities (B and
C) produced matrix containing more clay and other particles of small
size that made disaggregation by washing difficult to accomplish be-
cause of the clinging properties of these particles. A chemical separa-
tion using Amine 220 and Methyl Amyl Alcohol as recommended by
Lund (1970) was tried on the matrix from these localities, but it was
discovered that the same results could be obtained just as effectively
and with less expense by dry screening the matrix after the initial wet
screening. It is possible that valuable information concerning the envi-
ronment of deposition could be obtained by doing a grain size and
mineral analysis on the matrix; however, such a sedimentological
treatment is beyond the scope of the present research.

Opposite:

Fic. 3. (Left) Diagrammatic paleogeographic map showing the subenvironments of
deposition for sites A, B, C, and D. (Right) Past Pictured Cliffs Sea’s shorelines showing
sites A, B, C, and D in relation to them. After Fasset & Hinds (1971, p. 14, fig. 7, p. 37).

10 FIELDIANA: GEOLOGY

INVERTEBRATES

A tubular pelecypod, Teredina neomexicana (Family Pholadidae) is
found at Localities A, B, and C. Distinctive fossil molds of insect
burrows and crab claws occur at Locality C.

VERTEBRATES
Order Salientia
Family Discoglossidae
Scotiophryne pustulosa Estes, 1969b. Plate la,b.

Referred specimen.—MNA P1. 1625 fragmentary posterior portion
of left maxilla.

Locality.—MNA A.

Description.—Specimen P1. 1625 is a fragment of the posterior por-
tion of a left maxilla that exhibits prominent pustulate sculpturing on its
lateral surface. On the medial surface there is a distinct pterygoid pro-
cess and, dorsally, an expansion and notch for the squamosal. The
teeth are small and closely spaced (i.e., five/mm.) Specimen Pl. 1625
corresponds closely with the holotype (MCZ 3626) from the Lance
Formation described by Estes (1969b, p. 4, fig. 2c).

Discussion.—Recovery of specimen Pl. 1625 from the Fruitland
Formation expands the geographic range for Scotiophryne pustolosa
from Montana to New Mexico during Late Cretaceous times. The
stratigraphic range of this species now extends from the Campanian
Fruitland Formation into the Middle Paleocene as established by its
occurrence in the Tongue River Formation of Montana (Estes, 1969b).
In addition to the Fruitland and Tongue River Formation, S. pustolosa
has also been recorded from the Lance Formation of Wyoming and
Hell Creek Formation of Montana (Estes, 1969b).

Family Pelobatidae
?Eopelobates sp. Plate Ic,d.

Referred specimen.—UALP No. 75137-A, fragmentary posterior
portion of a left maxilla.
Locality. —UALP 75137.

Description.—Both ends of this right maxilla are broken, but the
distinctive slope of the dorsal border for the orbit is evident, supporting
the assumption that it is from the posterior portion of the maxilla. The
lateral surface has prominent sculpturing, consisting of shallow de-
pressions bounded by ridges extending from halfway down the outer

j i j 1 1 4 1

PLATE 1. Each scale is in millimeters, a, b, Scotiophryne pustulosa Estes, 1969c, MNA
Pl. 1625, maxilla: a, labial view, b, lingual view; c, d, ?Eopelobates sp., VALP 754137-A,
left maxilla: c, labial view; d, lingual view; e, Opisthotriton kayi Auffenberg, 1961, UALP
75137-0, right dentary, labial view; f, g, Cuttysarkus mcnallyi Estes, 1964, UALP 75137-C,
right dentary: f, labial view, g, lingual view.

11

12 FIELDIANA: GEOLOGY

surface of the maxilla. This sculpturing is confined to the posterior
portion of the fragment, leaving both the ventral one half and anterior
regions of the maxilla smooth. The posteroventral smooth surface is
separated from the sculpture above by a long furrow. The medial sur-
face has a strong dental gutter and attachment spaces for 12 teeth in a
distance of 3.0 mm.

Discussion.—This specimen is questionably referred to the genus
Eopelobates. The sculpture present on the maxilla is similar to the
sculpture on the squamosal of UCMP 55707 (Estes, 1964, p. 59, fig.
31b) from the Lance Formation, Wyoming, defined at that time as
‘‘near Hylidae’’ but later redefined (Estes, 1970) as being possible
?Eopelobates sp. or ‘‘a related pelobatid perhaps nearer to the dis-
coglossids.’’ Estes mentions that a fragment of maxilla, AMNH 8133,
is now known from the Lance with sculpture similar to the squamosal,
UCMP 55707, but it has not been described or figured. Estes’ (1970)
account of the different species of Eopelobates notes a similar
sculpture pattern seen on UALP 75137-A, but he does not specifically
state whether the sculpturing covered the entire maxilla or only parts of
it. Drawings of E. anthracinus and E. guthriei (Estes, 1970, figs. 8, 14)
suggest a narrow smooth surface of bone immediately dorsal to the
teeth. Since only the dorsal half of the posterior portion of the maxilla
recovered from the Fruitland is covered with sculpturing, its reference
to Eopelobates can only be provisional. The Fruitland specimen may
prove more closely related to Miopelobates robustus (Bolkay, 1913)
from the Lower Pliocene of Poland and Hungary, which exhibits
sculpturing only on the posterior portion of its maxilla and, in addition,
has a ‘‘bifurcated furrow’’ possibly homologous with the furrow seen
along the ventromedial border of the sculpture on UALP 75137-A.
Bolkay does not indicate if the ventral half of the posterior portion of
the maxilla of Miopelobates is free of sculpture.

Sahni (1972, p. 347, figs. 7L, M) described a discoglossid maxilla
(designated specimen C) from the Campanian Judith River Formation,
Montana, which possesses sculpture pattern and size similar to UALP
75137-A and also exhibits a ventral border free of sculpture. In com-
paring sculpture pattern and relative size between the maxilla (C) from
the Judith River, the squamosal, UCMP 55707, from the Lance, and
the specimens of Eopelobates (Estes, 1970), similarities are clear and,
therefore, it seems certain Sahni’s maxilla (C) is referable to the
pelobatids instead of the discoglossids. Without more material, it is
impossible at this point to assign the fragmentary maxilla from the
Fruitland to Eopelobates or any other pelobatid genus with certainty.
However, UALP 75137-A is, beyond doubt, a Late Cretaceous

ARMSTRONG-ZIEGLER: CAMPANIAN AMPHIBIANS & REPTILES 13

pelobatid with close taxonomic affinity (sculpture pattern and ventral
border free of sculpturing) to the maxilla (C) from the Campanian
Judith River Formation of Montana.

Family Prosirenidae
Prodesmodon ?copei Estes, 1964

Referred specimens.—UALP 75137-Y, right premaxilla; 75137-Z,
fragmentary premaxilla; 75137-aa, dorsal vertebra; 75137-bb, frag-
mentary dorsal vertebra; 75137-cc, fragmentary left dentary; 75137-dd,
fragmentary right dentary; 75137-ee, fragmentary left dentary;
75137-ff, fragmentary maxilla. MNA Pl. 1644, fragmentary ?cervical
vertebra.

Localities. —UALP 75137 and MNA A.

Description.—The referred specimens of these various skeletal ele-
ments from the Fruitland Formation are identical through all of their
features to their counterparts in the hypodigm from the Lance Forma-
tion described by Estes (1964, p. 88-92). Diagnostic characteristics for
the elements cited above include: vertebrae with completely hemis-
pherical ball-and-socket condyles and cotyles; nasal process on inter-
nal surface of premaxilla excavated by deep pit set off by two distinct
septae, one in medial position by midline and the other lateral to it;
broad supradental shelf internal and dorsal to tooth row on maxilla;
external surface of maxilla pitted; dentaries joined by strong symphysi-
sial union marked by prominently interdigitating lobes; dentary,
maxillary, and premaxillary teeth nonpedicellate and with compressed,
faintly spatulate crowns.

Discussion.—Specimen MNA PI. 1644 is questionably a fragmentary
cervical vertebra of Prodesmodon copei. Although the completely
hemispherical condyle and the small size of the specimen are indicative
of this genus (Estes, 1964, p. 88), it has basapophyses that extend
anteriorly beyond the midpoint of the centrum. This latter character
was formerly believed to be definitive of another small Late Cretaceous
salamander species, Opisthotriton kayi, and was one of the characters
used to distinguish O. kayi from P. copei. Estes (1969c, p. 88), how-
ever, has recently concluded that basapophyses are highly variable
structures; therefore, I feel that the hemispherical condyle and small
size are probably sufficient to allot this specimen and similar vertebrae
to P. copei rather than O. kayi. If Pl. 1644 is from P. copei, it is likely a
cervical vertebra, because cervical vertebrae of O. kayi exhibit simi-
larly elongate basapophyses. Estes (1964, p. 88), considering P. copei,
notes that the basapophyseal keels on cervical vertebrae in his

14 FIELDIANA: GEOLOGY

hypodigm do not extend as far as the midpoint of the centrum; this may
constitute a specific distinction of the Lance Formation form from the
Fruitland Formation form. Acquisition of additional vertebral material,
derived from other portions of the vertebral column, is needed to verify
the conspecificity of the Prodesmodon from New Mexico with P. copei
from Wyoming. Maestrichtian occurrences of P. copei include the Hell
Creek Formation of Montana (Estes et al., 1969) and the Lance For-
mation of Wyoming (Estes, 1964). Campanian occurrences include the
Judith River Formation of Montana (Sahni, 1972) as well as the Fruit-
land Formation of New Mexico (this study).

Family Batrachosauroididae
Opisthotriton kayi Auffenberg, 1961. Plate le.

Referred specimen.—UALP Nos.: 75137-O, fragment of right den-
tary; 75137-P, fragmentary cervical vertebra; 75137-Q, fragment of
vertebra; 75137-R, fragment of vertebra; 75137-S, fragment of ver-
tebra; 75137-T, fragment of vertebra.

Locality. —UALP 75137.

Description.—Specimen 75137-P, the fragmentary cervical vertebra
of Opisthotriton kayi has a circular cotyle that appears to be completely
hollow, with no ossification in its deepest part. It has prominent ven-
troposterior basapophyses and a distinct median keel. The neural arch
is low and dorsally flattened and carries the broken base of the neural
spine. The zygapophyses are slightly oblique to the horizontal.

The fragmentary right dentary, 75137-O, exhibits a smooth external
bone surface and contains nine badly broken and medially crushed
teeth. The labial surface is strongly concave in the lateroposterior area,
and on the lateroventral surface there is a prominent ridge for the
attachment of the intermandibularis muscle.

All of these scattered characters of the fragmentary vertebrae and
right dentary agree in detail with Estes’ (1964, 1969a) accounts of O.
kayi.

Discussion.—Estes (1969a, p. 230) placed O. kayi in a new family,
Batrachosauroididae, along with genus Batrachosauroides. Following
Estes, the fragmentary cervical vertebra is referable to Opisthotriton
rather than Batrachosauroides because it shows the greater flattening
of the neural arch and the stronger development and more posterior
position of the basapophyses.

Opisthotriton kayi has been reported from the Maestrichtian Hell
Creek and Lance Formation of Montana (Estes et al., 1969), and

ARMSTRONG-ZIEGLER: CAMPANIAN AMPHIBIANS & REPTILES 15

Wyoming (Estes, 1964, 1969b; Auffenberg, 1961). Elsewhere, material
representative of the genus is known from the Late Paleocene Polecat
Bench Formation (Silver Coulee beds), Park County, Wyoming (Jep-
sen, 1940; Gilmore, 1942, p. 166).

Order Urodela
Family incertae sedis
Cuttysarkus menallyi Estes, 1964. Plate If,g.

Referred specimens.—UALP Nos.: 75137-C, right dentary; 75137-J,
right dentary; 75137-B fragment of dentary; 75137-hh, fragment of
dentary; 75137-gg, fragment of dentary.

Locality. —UALP 75137.

Description.—The dentaries recovered from the Fruitland agree in
detail with Estes’ (1964, pp. 139, 140) descriptions of this peculiar
form. Diagnostic characters of the dentaries used by Estes include:
short, subtriangular overall shape; meckelian fossa triangular, closed
anteriorly and broadly open posteriorly; external surface smooth with-
out foramina; teeth pleurodont and recurved posteriorly. The most
complete specimen on hand, 75137-C, exhibits 13 teeth, three of which
are complete to the tips.

Discussion.—Cuttysarkus mcnallyi was placed tentatively in the
Order Sauria by Estes (1964, p. 140) on the basis of two reptilian
characteristics: deep pleurodont tooth attachment and lack of a dental
gutter. He also noted that two features, the smooth, imperforate exter-
nal surface of the jaw and the broad, triangular, posteriorly expanded
meckelian fossa were reminiscent of some of the urodeles. Estes et al.
(1969, p. 22), in a second account of C. mcnallyi, suggested that the
absence of maxillae for the species was indicative of a larval salaman-
der condition.

In addition to the Urodelian characters cited above, the fact that
deeply pleurodont teeth are not necessarily confined to the Reptilia
[many salamanders (see table 1), including two late Cretaceous genera
Opisthotriton and Prodesmodon, exhibit this condition] serves to
further support the conclusion that the dentaries of C. mcnallyi belong
to a larval salamander rather than a lizard.

On the basis of the above observations, I reassign Cuttysarkus to the
Order Urodela. Dr. Richard Estes, San Diego State University, and
Mr. Bruce Naylor, University of Alberta, are separately working on
Cuttysarkus’ relationship to different Urodelan families.

16 FIELDIANA: GEOLOGY

Order Testudinata
Family Dermatemydidae
Adocus sp.

Referred specimen.—MNaA PI. 1646, isolated carapace and plastron
fragments.

Localities.—MNA Localities A and C.

Description.—The ornamentation on these specimens consists of
regular rows of shallow pits that have three rows of pits in a S-mm. line
or Six or seven per centimeter. The thickness of these fragments is 0.5
cm. (=5 mm.).

Discussion.—Adocus vigoratus from the Paleocene Ojo Alamo
Sandstone in New Mexico was erected by Hay (1910) on the basis of
carapace and plastron characters alone. The material at hand corre-
sponds with Hay’s description of the sculpture pattern on these speci-
mens, but I feel that sculpture pattern similarities alone do not provide
sufficient basis for definite assignment of this material to A. vigoratus.

Another species, Adocus ?lineolatus [sic] nominated by Cope (1875)
for material from Colorado was tentatively defined on the basis of more
finely pitted sculpture (four to five rows of pits in a 5-mm. line) than
typical of A. vigoratus. Later, Gilmore (1916) reported A. ?/ineolatus
from the Fruitland Formation. The sculpture pattern variations seen
between A. vigoratus and A. ?lineolatus could well signify individual or
ontogenic differences rather than a species separation. Until cranial
remains are recovered in association with these carapace and plastron
elements, a proper assessment of the validity of these described
species will be difficult to make.

Adocus sp. also occurs in the Maestrichtian Hell Creek Formation of
Montana (Estes et al., 1969).

Compsemys sp. Leidy
Referred specimen.—MNA PI. 1648, carapace fragment.

Locality.—MNA Locality A.

Description.—The present specimen exhibits the closely set, flat-
topped pustulae typical of carapace sculpture for this genus.

Discussion.—Gilmore (1916) reported carapace fragments of Comp-
semys sp. from the Paleocene Ojo Alamo Sandstone of New Mexico.
Late Cretaceous occurrences of the genus include C. victa (Estes et al.,
1969) from the Maestrichtian Lance and Hell Creek Formations of
Wyoming and Montana and Compsemys sp. (Russell, 1935) from the
Campanian Milk River Formation of Alberta. Since many described

ARMSTRONG-ZIEGLER: CAMPANIAN AMPHIBIANS & REPTILES 17

species of Compsemys have similar sculpture patterns, this character
alone is insufficient for species identification.

?Basilemys sp.
Referred specimens.—MNA PI. 1647, shell fragments.

Locality.—MNA Locality A.

Description.—These shell fragments are 1 cm. in thickness and have
a very coarse, exaggerated sculpture pattern consisting of pits 1 cm. in
diameter spaced approximately 1 cm. apart.

Discussion.—The fragments are questionably referred to Basilemys
on the basis of large relative size. Basilemys sp. (Estes et al., 1969, pp.
17, 18) from the Maestrichtian Lance and Hell Creek Formations also
exhibits pitted sculpture, but here, the pattern is on a finer scale; the
pits, although circular, are both smaller in diameter and more closely
spaced, with three to four occupying each square centimeter.

Other specimens ascribed to this genus resemble the form from the
Lance and Hell Creek Formations rather than the present material
from the Fruitland Formation in the above noted distinction in
sculpture pattern. These include B. nobilis (Gilmore, 1916) from the
Paleocene Ojo Alamo Sandstone of New Mexico, Basilemys sp. (Gil-
more, 1916; Sahni, 1972) from the Campanian Judith River Formation
of Montana, and Basilemys sp. (Russell, 1935) from the Campanian
Mile River Formation of Alberta. Perhaps the present material repre-
sents a new genus and species of the family, but more diagnostic
material is needed before it is identified further.

Family Trionychidae
Trionyx sp.

Referred specimen.—MNA PI. 1629, plastron and carapace frag-
ments.

Locality.—MNA Locality A.

Description.—These specimens have a honeycomb pattern of
sculpture in which small irregular pits give the appearance of being
uniformly punched into the bone. Interlocking ridges surround each
pit.

Discussion.—Webb (1962) states that the presence or absence of a
prenuchal bone does not constitute sufficient grounds for a separation
of Aspideretes from Trionyx. Therefore, the present material and simi-
lar material from the Fruitland Formation found by Gilmore (1916) and
described by him as Aspideretes austerus are now allocated to Trionyx
(Cope, 1875). It is not generally conceded that the sculpture pattern in

18 FIELDIANA: GEOLOGY

trionychids is of dubious taxonomic significance at the species level
(Estes, 1964, p. 98). In the absence of other more definitive skeletal
material, the Trionyx remains from the Fruitland Formation cannot
be allocated to a species.

Order Sauria
Family Tetidae
Leptochamops Estes, 1964

Leptochamops denticulatus (Gilmore, 1928). Plate 2d.

Chamops denticulatus Gilmore, 1928, p. 26.
Leptochamops denticulatus Estes, 1964, p. 110.

Referred specimens.—UALP Nos.: 75137-E, fragments of left den-
tary; 75137-K, fragment of right dentary; 75137-D, fragment of dentary;
75137-L, fragment of ?dentary; 75137-M, maxillary fragment; 75137-N,
maxillary fragment.

Locality. —UALP 75137.

Description.—Estes (1964, p. 110) erected a new genus Lep-
tochamops, for Chamops denticulatus Gilmore (1928), removing this
species from the genus Chamops, the type species of which is
Chamops segnis (Marsh, 1892). The principal criteria for this action
were the following features of L. denticulatus: greater restriction of the
anterior portion of the meckelian fossa; concave lateral border of the
dentary; enlargement of the dentary for the coronoid articulation; more
numerous teeth; cusp form; and heterodonty through the tooth row on
some specimens. Estes (1964, p. 113) points out that, among recent
teiids, each of these characters is subject to variation but, taken to-
gether, they represent a degree of morphologic divergence from
Marsh’s species that necessitates separation at the generic level.

The most complete and diagnostic dentary in the collection at hand is
specimen No. UALP 75137-K, which comprises much of the anterior
portion of a right ramus and which clearly shows the restriction of the
meckelian groove in this region. The lateral border of the dentary is
slightly concave. All the teeth are tricuspid and subpleurodont, closely
matching those on the dentary illustrated by Estes (1964, fig. 50). Many
of the tooth crowns have a black shaft capped by a sharply contrasting
light brown occlusal surface. The teeth project about one-half of their
height above the parapet of the jaw. A heterodont condition (variability
in height and diameter of individual teeth on one specimen) can be seen
on the dentary fragment, UALP 75137-D, Plate 2d. As Estes (1964, p.
112) surmises, heterodonty in the genus appears to be a function of size

PLATE 2. Each scale is in millimeters. a, b, cf. Gerrhonotus sp., UALP 75137-F,
fragmentary left dentary: a, labial view, b, lingual view; c, anguid osteoscute; d, Lep-
tochamops denticulatus (Gilmore, 1928), UALP 75137-D, dentary, fragment lingual view,
x30; e, Chamops segnis Marsh, 1892a, MNA PI. 1613, dentary fragment, lingual view.

19

20 FIELDIANA: GEOLOGY

and also of region of the dentary or maxilla preserved, so it is not
surprising to find that only one of six fragmentary specimens in the
present collection displays this condition.

The maxilla of L. denticulatus is distinguished from the dentary by
an elongated flange that represents a portion of the deep dorsoventral
border of the bone. The two fragmentary specimens, Nos. UALP
75137-M and 75137-N, share tricuspid, subpleurodont, bicolored teeth
that extend about one-half their height over the parapet of the deep
dorsoventral border of the bone. Homotaxy with these is thus assured.

Discussion.—The presence of Leptochamops in the Fruitland For-
mation of New Mexico represents the southernmost known occurrence
of this genus. Elsewhere, it has been reported from the Lance Forma-
tion, Wyoming, Estes (1964); Hell Creek Formation, Montana, Estes et
al. (1969); and Judith River Formation, Montana, Sahni (1972). The
Hell Creek and Lance Formations are both Maestrichtian in age, and
the Judith River Formation is slightly older, being Campanian. Two
other teiid genera, Meniscognathus and Haptosphenus, described by
Estes (1964) from the Lance Formation have not yet been identified
from the Fruitland Formation. These two genera are also found in the
Hell Creek Formation (Estes et al., 1969) but are conspicuously absent
in the fauna from the older Judith River Formation.

Chamops segnis Marsh, 1892a. Plate 2e.

Iguanavus teres Marsh (1892a, p. 451).
Lanceosaurus hatcheri Gilmore (1928, p. 160).
Lanceosaurus compressus Gilmore (1928, p. 161).
Alethesaurus quadratus Gilmore (1928, p. 162).

Referred specimen.—MNaA PI. 1613, fragment of dentary.
Locality.—MNA Locality A.

Description.—Estes (1964, pp. 102, 103) has provided an excellent
description of the dentary of Chamops segnis. Some of Estes’ diagnos-
tic characters used to identify the above fragmentary specimen include:
tooth crowns wrinkled, tricuspid lingually and grooved labially; sub-
pleurodont teeth projecting two-thirds of their height over the parapet
of the jaw; medial curvature of the jaw; expanded splenial; and medial
curvature of dorsal and ventral borders of dentary.

Discussion.—Chamops segnis and Leptochamops denticulatus rep-
resent the first two teiid genera to be reported from the Campanian
Fruitland Formation. Other Campanian occurrences of C. segnis in-
clude the Judith River Formation of Montana (Sahni, 1972) and the
Wapiti Formation of Canada (Sternberg, 1951). Maestrichtian occur-

ARMSTRONG-ZIEGLER: CAMPANIAN AMPHIBIANS & REPTILES 21

rences include the Lance Formation of Wyoming (Estes, 1964) and the
Hell Creek Formation of Montana (Estes et al., 1969).

Family Anguidae
Genus and species indet. Plate 2c.

Referred specimens. —UALP 75137-h, four complete lateral body
osteoscutes and 50 fragmentary osteoscutes.

Locality. —UALP 75137.

Description.—All of the complete lateral body osteoscutes are rec-
tangular in shape. Each is sculptured over one-half of its external sur-
face with irregular pits and ridges, and a flat gliding surface occupies
the other half. There is no evidence of lateral suturing or of a keel on
any of the osteoscutes. The length of a complete osteoscute is ca. 3.5
mm., and the width is ca. 2 mm. The dentaries of both Gerrhonotus and
Pancelosaurus occur in the Lance Formation; Meszoely (1970, p. 105)
assigned the above defined osteoscutes to Pancelosaurus instead of
Gerrhonotus on the basis of the greater abundance of skull remains of
Pancelosaurus relative to Gerrhonotus. This criterion of relative abun-
dance used by Meszoely does not seem sufficient reason to assign these
osteoscutes to either Pancelosaurus or Gerrhonotus. Further, it cannot
be applied to the osteoscutes from the Fruitland (identical to those
illustrated by Meszoely) because Gerrhonotus dentary fragments occur
in the Fruitland, but no Pancelosaurus cranial remains have been re-
corded to date. Until more extensive material has been recovered from
the Fruitland or elsewhere, the generic identification of these osteo-
scutes will remain uncertain.

Subfamily Gerrhonotinae
cf. Gerrhonotus sp. Plate 2a, b.

Referred specimens.—UALP Nos.: 75137-F, fragment of left den-
tary; 75137-G, fragment of left dentary.

Locality. —UALP 75137.

Description.—The teeth are pleurodont and slightly recurved post-
eriorly, projecting one-half of their height over the parapet of the jaw.
Specimen 75137-F shows the characters of the tooth crown unique to
Gerrhonotus as established by Estes (1964, p. 124). These characters
include tooth crown striated to varying degrees lingually and labially
and lingual and labial vertical grooves that separate the crown of the
tooth into two separate cusps, of which the posterior is larger. The
grooves dividing the crown are not present on the teeth of the smaller

22 FIELDIANA: GEOLOGY

specimen, 75137-G; following the comparative work of Estes (p. 124),
this specimen, thereby, probably derives from the anterior portion of
the dentary of an adult specimen or from any portion of the dentary of a
juvenile.

Discussion.—Occurrence of Gerrhonotus in the Campanian Fruit-
land Formation constitutes the second late Cretaceous record of this
still extant genus; the first is the Maestrichtian Lance Formation of
Wyoming (Estes, 1964). Gerrhonotus is absent in the Maestrichtian
Hell Creek and Campanian Judith River Formations of Montana, two
faunas generally similar to that of the Fruitland in overall composition.
Prior to these late Cretaceous records for Gerrhonotus, fossil remains
were limited to the ?Eocene Four Mile local fauna, northwest Colorado
(McKenna, 1960, p. 10), and the Miocene Niobrara River local fauna,
Nebraska (Estes, 1964, p. 123). The recent species of Gerrhonotus are
widely distributed over North and Central America.

Order Serpentes
Family Aniliidae
Genus Coniophis Marsh, 1892

Coniophis cosgriffii n. sp. (Armstrong-Ziegler, March, 1978, J. Paleon-
tol.)

Order Crocodilia

Family Crocodylidae
Subfamily Crocodylinae
Leidyosuchus sp. Lambe, 1907
Referred specimens.—MNA No. Pl. 1428, several isolated teeth.

Localities.—MNA sites A and C.

Description.—These Fruitland Formation teeth are stout and con-
ical, and their anterior and posterior blade-like ridges do not lie in the
same longitudinal plane but, rather, are offset somewhat medially. The
inner surfaces of all of the teeth are less convex than the outer surfaces,
but both surfaces are completely smooth, lacking striations.

Discussion.—These teeth resemble the teeth of the genus
Leidyosuchus, a form characterized by small teeth in the following
literature: by Lambe (1907) and Sahni (1972) for Leidyosuchus
canadensis from the Campanian Oldman and Judith River Formations
of Alberta and Montana; by Leidy (1856) for synonym of L. canaden-
sis, Crocodylus humilis, from the Judith River Formation of Montana;

ARMSTRONG-ZIEGLER: CAMPANIAN AMPHIBIANS & REPTILES 23

by Gilmore (1910) and Estes (1964) for L. sternbergi from the Maes-
trichtian Lance and Hell Creek Formations of Wyoming and Montana;
and by Russell (1935) for L. sternbergi from the Campanian Milk River
Formation of Alberta.

Previously, crocodilian teeth from the Kirtland Shale and Fruitland
Formation were identified as Crocodylus sp. by Reeside (1924). As
Lambe (1907) has demonstrated, all Cretaceous Crocodylus should be
placed in synonymy with Leidyosuchus. Therefore, the Fruitland For-
mation form is now identified as Leidyosuchus sp.

?Thoracosaurus sp. Cope, 1875

Referred specimens.—MNA PI. 1628, isolated teeth.
Locality.—MNA Locality A.

Description.—Teeth from the front of the mouth are strongly re-
curved and conical, bearing longitudinal striations on the crowns.
Teeth from the posterior part of the mouth have crowns that are robust
and rounded, with fewer, more widely spaced striations. All the teeth
have ridges separating their lateral from their medial surfaces.

Discussion.—The first record of this genus was reported by Cope in
1875 from the Cretaceous of New Jersey, at which time he placed the
species Thoracosaurus neocesariensis in the subfamily Alligatorinae
on the basis of well-preserved and complete cranial elements. Re-
cently, DeKay (in Estes, 1970) placed this species in the subfamily
Crocodylinae, and Estes (1970) further notes its presence in the Hell
Creek Formation of Montana.

Subfamily Alligatorinae
Brachychampsa sp. Gilmore, 1911

Referred specimens.—MNA PI. 1445, isolated teeth.
Localities. —-MNA Localities A, B, and C.

Description.—The referred teeth are slightly recurved, with short,
rounded, wrinkled crowns that have slight ridges on both their anterior
and posterior edges.

Discussion.—Brachychampsa sp. teeth were recorded from the
Kirtland Shale in New Mexico by Gilmore (1916), who based his
identification on the similarities of his specimens with teeth of
Brachychampsa montana from the Hell Creek Formation of Montana
(Gilmore, 1911). Other Cretaceous records for the genus include:
Brachychampsa sp. (Estes, 1964), Lance Formation of Wyoming; B.
perrugosa (Cope, 1874), Arapahoe Formation of Colorado; B. per-

24 FIELDIANA: GEOLOGY

rugosa (Lambe, 1902), Oldman Formation of Alberta; B. montana
(Sahni, 1972), Judith River Formation of Montana.

Order Saurischia
Suborder Theropoda
Infraorder Coelurosauria
Family Coeluridae

Paronychodon lacustris Cope, 1876. Plate 3d.
Tripriodon caperatus Marsh (1889, pl. 3, figs. 18-33).
Zapsalis abradens Cope (1876, p. 345).
Referred specimens.—MNA PI. 1627, several isolated teeth.
Locality.—MNA Locality A.

Description.—Each of these recurved, laterally compressed teeth
bears two to four longitudinal striations on its internal surface and is
smooth or striated (two to four ridges) on its external surface. Accord-
ing to Estes et al. (1969, p. 25), the teeth with flattened external sur-
faces may be from the anterior part of the tooth row, and those without
this condition may have had a posterior position.

Discussion.—Paronychodon lacustris teeth have been recovered
from the Maestrichtian Hell Creek and Lance Formations of Montana
(Estes et al., 1969) and Wyoming (Estes, 1964). Campanian occur-
rences other than the Fruitland Formation include the Judith River
Formation of Montana (Sahni, 1972) and the Milk River Formation of
Alberta (Russell, 1935).

Family ?Coeluridae. Plate 3a.

Specimens.—MNA PI. 1624, several isolated teeth.
Locality. —MNA Locality A.

Description.—These possibly coelurosaurid teeth are recurved, with
smooth anterior edges and serrate posterior edges.

Discussion.—Unfortunately, these teeth do not possess features
allowing generic determination. Estes (1964) and Estes et al. (1969)
described similar teeth from Lance and Hell Creek Formations and
noted that they resembled those of Velociraptor mongoliensis (Osborn,
1924, p. 1, fig. 1) from the Djadochta Formation, Central Mongolia.
However, in shape and size, they also resemble teeth of such other
coelurid genera as Chirostenotes from the Campanian Oldman Forma-
tion and Coelophysis from the upper Triassic at Ghost Ranch, New
Mexico (Estes et al., 1969, p. 25).

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26 FIELDIANA: GEOLOGY

Infraorder ?Deinonychosauria
Family ?Dromaeosauridae. Plate 3b.

Specimens.—MNA PI. 1645, several isolated teeth.
Locality.—MNA Locality A.

Description.—These short-crowned, compressed teeth are serrated
on both anterior and posterior edges with the sets of serrations lying on
the same longitudinal plane. There are 30 to 40 serrations per 5 mm. on
the anterior edge and 20 to 30 on the posterior edge. Recurvature
among these teeth ranges from slight to pronounced.

Discussion.—The specimens at hand closely resemble a number of
specimens from other late Cretaceous deposits. These, listed by unit
and by their various taxonomic allocations are: the Maestrichtian Hell
Creek Formation of Montana, Dromaeosauridae? (Estes et al., 1969,
pl. 1, C); the Maestrichtian Lance Formation of Wyoming, cf. Dryp-
tosaurus sp. (Estes, 1964, p. 144); the Campanian Judith River Forma-
tion of Montana, Dromaeosaurus albertensis (Sahni, 1972, p. 359); the
Campanian Milk River Formation of Alberta, cf. Dromaeosaurus sp.
(Russell, 1935, fig. 7); and the Judith River Formation of Montana,
Laelaps (Cope, 1876). Laelaps tooth types have often been included in
Dryptosaurus (e.g., Estes, 1964). However, Colbert and Russell (1969),
in a revision of the family, surmised that Laelaps might, with better
reasons, be included with the dromaeosaurs.

The teeth from the Fruitland Formation do not fall into any of the
ranges of tooth serration number cited from the various taxa of the
group by Colbert and Russell (1969, p. 39, 40). Further, the teeth of the
Fruitland Formation form differ from the premaxillary and maxillary
teeth of Dromaeosaurus albertensis in two seemingly significant re-
spects. First, the serrations on the anterior and posterior edges of the
latter are equally developed, with approximately 16 serrations per 5
mm. Second, the anterior serrated edge on a tooth of D. albertensis is
offset somewhat medially relative to the posterior edge rather than
lying in the same longitudinal plane as in the Fruitland form. These
differences serve to exclude the present material from Dromaeosaurus
(Laelaps) but do not provide sufficient basis for the nomination of a
new genus to include them. Therefore, in the absence of more defini-
tive criteria, they can only be included with question in the family
Dromaeosauridae.

Family Deinodontidae

Deinodon horridus Leidy, 1856. Plate 3e.
Aublysodon misandus Leidy, 1868, p. 198.

ARMSTRONG-ZIEGLER: CAMPANIAN AMPHIBIANS & REPTILES Dy

A. lateralis Cope, 1876, p. 248.

Laelaps incrassatus Cope, 1876, p. 248, 341.
L. hazenianus Cope, 1876, p. 343.
Ornithomimus grandis Marsh, 1890, p. 85.
Dryptosaurus kenabekides Hay, 1899, p. 348.
Gorgosaurus libratus Lambe, 1914, 13.

Referred specimens.—MNA PI. 1623, three isolated teeth.
Locality.—MNA Locality A.

Description.—The largest and most complete specimen has a length
of 64 mm., a width at the base of 25 mm., and is compressed linguola-
bially, with a wear facet on one surface. Both anterior and posterior
edges are serrated.

Discussion.—Deinodon horridus has been recorded from the Maes-
trichtian Hell Creek Formation of Montana (Estes et al., 1969). In
addition to the present material, Campanian occurrences include the
Judith River Formation of Montana (Sahni, 1972) and the Oldman
Formation of Alberta (Lambe, 1914).

Order Ornithischia
Suborder Ornithopoda
Family ?Pachycephalosauridae. Plate 3c.

Specimen.—MNA PI. 1642, isolated tooth.
Locality.—MNA Locality B.

Description.—This slightly compressed tooth crown has serrations
on both anterior and posterior borders, with a distinct constriction at
its junction with the root. Although much of the root is broken off,
enough remains to show that it ventrally continues the triangular out-
line initiated by the crown.

Discussion.—This specimen resembles teeth from the Lance, Hell
Creek, and Judith River Formations in the characters of the crown.
However, all of these possess a cylindrical root in contrast to the
triangular root of the present form. Therefore, it is with reservation
that I assign the Fruitland tooth to the family Pachycephalosauridae on
the basis of tooth crown similarities to all previously described teeth of
forms assigned to this family.

Estes (1964) and Estes et al. (1969) designated the Lance form as cf.
Pachycephalosaurus sp. and referred the Hell Creek form with ques-
tion to the family Pachycephalosauridae. Sahni (1972) assigns his
Judith River form with question to the pachycephalosaur, Stegoceras
validus, founded for material from the Oldman Formation by Lambe
(1902).

28 FIELDIANA: GEOLOGY

Family Hadrosauridae
Kritosaurus navajovius Brown, 1910. Plate 3f, g.

Referred specimens.—MNA PI. 1626, several isolated teeth.
Locality.—MNA Locality B.

Description and discussion.—Kritosaurus navajovius is represented
in the collection from Locality B by both maxillary teeth with smooth
borders and mandibular teeth with papillate borders. This species was
originally described for material from the Kirtland Shale and Fruitland
Formation of New Mexico by Brown (1910). Other occurrences of the
genus Kritosaurus are in the Campanian Judith River Formation of
Montana (Sahni, 1972) and Campanian Oldman and Milk River Forma-
tions of Alberta (Russell, 1935).

PALEOECOLOGY AND PALEOGEOGRAPHY

The Fruitland Formation is a continental sequence deposited on top
of the marine Pictured Cliffs Sandstone when the epicontinental sea-
way that formed the latter retreated from the area. The sediments
composing the Fruitland were derived from eroding highlands to the
southwest and were transported by rivers and streams flowing in a
northeasterly direction toward the Pictured Cliffs Sea. Deposition oc-
curred under environmental conditions typical for late Creataceous
deposits in western North America; the climatic regime was moist and
subtropical, and the detrital material accumulated in a lowland flood-
plain setting. The same general regime is represented by such units as
the Lance, Hell Creek, and Judith River Formations; and the gulf
coastal plain of the southeastern United States constitutes a modern
analogue. Interpretations of the faunas at four localities in the Fruitland
Formation together with their geographic locations in relation to the
ancient shorelines as established by Fassett and Hinds (1971, p. 14, fig.
3) has led to the distinction of three subenvironments: lowland river,
upland river, and upland stream.

The subenvironment at Localities B and C, as interpreted both from
the assemblages that they have produced and from their position on
Fassett and Hind’s paleogeographic map (1971, p. 14, fig. 3), represents
two variants of the general lowland river subenvironment. Total faunal
content at Locality B favors an estuarine regime. Included in the as-
semblage are 11 taxa of fish, three taxa of dinosaurs, and one abundant
pelecypod. Six of the fish are elasmobranchs. Two of these,
Myledaphus sp. and Ischyrhiza sp., belong to genera whose living rep-
resentatives prefer brackish or estuarine conditions but have been

ARMSTRONG-ZIEGLER: CAMPANIAN AMPHIBIANS & REPTILES 29

identified in freshwater fossil deposits. Although the two species of
Squatirhina and the one species of Lonchidion have no recent record of
nonmarine habitation, they also have been identified in freshwater fos-
sil assemblages. Only the mackerel shark, /surus (Oxyrhina), is limited
to marine waters in the modern fauna and to marine fossil assemblages.
The osteichthyan component at Locality B is comprised of forms
whose living representatives are found in large, slow Mississippi-like
rivers and also in brackish-marine bays. Included in this group are
Acipenser, Paleopsephurus, Amia, Lepisosteus, and Paralbula.

Teredina neomexicana, a tubular pelecypod, is abundant at Locality
B. In morphology, this species resembles the living shipworm, Teredo,
a pelecypod found burrowing into wood debris along the Atlantic
coastal regions of the United States.

The dinosaurs consist of the small terrestrial saurischian,
Paronychodon, and two ornithischians, a pachycephalosaurid and a
duck-billed semiaquatic form Kritosaurus.

The presence of the estuarine marine, Hybodus, at Locality B
suggests a deposit very proximal to the Pictured Cliffs Sea. The ab-
sence of amphibians and small semiaquatic reptiles further strenthens
the interpretation of the locality as a large river mouth on the shore of
the Pictured Cliffs Sea because the somewhat saline water of this type
of locale would have excluded them. Most of the fish included in the
assemblage were forms adapted to and living at the locality. The di-
nosaur teeth present in the assemblage represent forms that were
adapted to and living at the locality. The dinosaur teeth present in the
assemblage were massive enough to have survived transport from
more inland areas, whereas the delicate skeletal elements of anurans,
urodeles, and squamatans would have been destroyed in transit.
Moreover, it is possible that some of the dinosaurs lived at or near the
locality. This is particularly likely for the duckbill, Kritosaurus.

Locality C lies somewhat inland from Locality B, as evidenced by the
slightly different composition of its produced faunal assemblage. The
overall correspondence, however, is great enough to include it with
Locality B in the general lowland river subenvironment. The
euryhaline fish, Squatirhina, Myledaphus, Amia, Lepisosteus, and
Paralbula, occur at this site together with the crocodilians,
Leidyosuchus and Brachychampsa. Although this association is am-
biguous for purposes of interpreting the living environment, the abun-
dance of the tubular pelecypod, Teredina, serves to confirm a near-
coastal position for Locality C. As noted in the discussion of Locality
B, Teredina was found in association with a marine shark, /surus. This

30 FIELDIANA: GEOLOGY

occurrence reflects the preference of this fossil pelecypod for saline or
estuarine conditions.

What appear to be insect burrows in the form of tubes arranged in a
semi-symmetrical fashion and crab claws were also collected at Lo-
cality C. These provide only limited evidence relevant to environmen-
tal interpretations because neither can be identified as to genus or
species. They suggest shallow water at the point of deposition, perhaps
a sand bar or muddy bank at the mouth of a large river. The abundance
of large fish such as the alligator gar and bowfin at Locality C support
the conclusion that the general area of deposition was a large river.

Essentially, then, the faunal community of the lowland river sub-
environment represented by Localities B and C is characterized by a
mixture of euryhaline and marine vertebrates and by the presence of
some fish of considerable size.

Locality A represents an upland river subenvironment. In addition to
fish that show no preference between fresh and brackish water, the
assemblage from this locality includes exclusively freshwater fish to-
gether with amphibians and turtles. No exclusively marine vertebrates
are present. As in the case of the assemblages from Localities B and C,
the presence of large fish suggests a broad, deep river. In addition to
the general character of the suite of lower vertebrates, the abundance
of marsupials and multituberculates in the assemblage from Locality A
suggests a more upland locality of deposition. Two partial shell frag-
ments of Teredina were recovered from this locality so that one may
infer that Teredina was adapted to both freshwater or marine environ-
ments but prefers the latter habitat.

Locality D (=UALP 75137) is the farthest removed from the
shoreline of the Pictured Cliffs Sea and represents a small body of
water, either a stream or pond, in the more upland regions to the
southwest. The recovered assemblage includes only freshwater and
terrestrial vertebrates. There are two small fish—the hybodont, Lon-
chidion, and a form related to the recent freshwater drum, Platacodon.
Aquatic or semiaquatic amphibians are abundant and include: an am-
phiumid, C. mcnallyi; two salamanders, P. copei and O. kayi; and a
frog, ?Eopelobates sp. The reptiles include three lizards and one
crocodilian. One of the lizards, the teiid, Leptochamops, may have
been semiaquatic. The two anguids are cf. Gerrhonotus and a generi-
cally and specifically indeterminate form represented by
Pancelosaurus-like osteoscutes. The crocodilian is known only from
osteoscutes of uncertain allocation. They may pertain to either
Leidysuchus, Thoracosaurus, or Brachychampsa. As might be ex-

ARMSTRONG-ZIEGLER: CAMPANIAN AMPHIBIANS & REPTILES 31

pected, no evidence of the tubular pelecypod, Teredina, was recorded
from this site (Lindsay, written comm., 1976).

Using electric log data to correlate the isopachal intervals between
the radioactively dated Huerfanito Bentonite Bed of the Lewis Shale to
the top of the Pictured Cliffs Sandstone, Fassett and Hinds (1971)
inferred the approximate successive shorelines of the Pictured Cliffs
Sea. Figure 3 shows these shorelines in relationship to the geographical
positions of the vertebrate localities. Localities B and C were indeed
closest to the shoreline. Locality A lies somewhat inland, and Locality
D was the most distal from the Pictured Cliffs Sea. This type of corre-
lation has exciting implications for further paleoenvironmental work in
the San Juan Basin. Theoretically, if one were to collect microverte-
brates along one of these ‘‘past shorelines,’’ time-equivalent samples
from similar ecologic niches would be obtained. The probable envi-
ronments of deposition for Localities A, B, C, and D are shown in
Figure 3, a revised version of the diagrammatic paleogeographic map
compiled by Fassett and Hinds (1971, p. 37).

The vertebrate localities probably vary somewhat in age, with Lo-
cality A the youngest, Localities B and C intermediate in age, and
Locality D the oldest; the intervals separating them, however, are
probably not extensive. The differences in composition among the as-
semblages collected from them, therefore, are sure to reflect dif-
ferences among contemporary living environments rather than evolu-
tionary changes caused by the lapse of time.

In the following section, the four localities in the Fruitland will be
considered together and separately in making comparisons with other
faunas to the north.

BIOSTRATIGRAPHY

Cobban (1973) computed a potassium-argon date for the lower part
of the Fruitland Formation as 75 + 2 million years. By synthesizing this
date with the Western Interior Ammonite Zones, he was able to
estimate that both the Kirtland Shale and Fruitland Formation were
deposited in the Upper Campanian between 72 and 73 million years ago
(Cobban, 1973, p. 151). On the basis of his palynological work on
samples from the Fruitland Formation, Tschudy in Fassett and Hinds
(1971) also assigns a Late Campanian age to this unit. Zavada (written
comm., 1976) disagrees with Tschudy’s determination and, on the basis
of samples from Locality C and other localities in the Fruitland, assigns
an Early Maestrichtian rather than Late Campanian age to the de-
posits.

32 FIELDIANA: GEOLOGY

The diversity contained in the vertebrate fauna of the Fruitland For-
mation of New Mexico is comparable to that from the Campanian
Judith River Formation; both contain some 48 genera of vertebrates.
The recovered vertebrate assemblages from the Maestrichtian Lance
and Hell Creek Formations of Wyoming and Montana are notably
larger, containing 75 and 78 genera, respectively. This greater di-
versity, no doubt, reflects the more intensive and prolonged collecting
that has been accomplished at localities in these units. Table 1 is a
listing of all lower vertebrate genera occurring in the principal Late
Cretaceous vertebrate-bearing units of the western parts of the United
States and Canada. Table 2 is a summary of this data, showing the
percentage of taxonomic resemblance between the faunas of the Fruit-
land, Judith River, Lance, and Hell Creek Formations. An inspection
of this reveals that there is close taxonomic correspondence between
the Lance and Hell Creek faunas, but that the Fruitland and Judith
River faunas are divergent in part from the Lance-Hell Creek complex.
A portion of this divergence is identical for Fruitland and Judith River
faunas, but it should be noted that these units diverge from each other
in the areas of several important taxonomic groups. There is, in total,
greater correspondence of the Fruitland fauna with the Judith River
fauna than with the Lance or Hell Creek faunas. There is, however,
less correspondence between the Fruitland and Judith River faunas

TABLE 1. Extant salamanders which exhibit deeply pleurodont teeth.

Amphiuma means Cryptobranchus alleghanensis
Necturus maculosus Desmognathus fuscus
Salamandra maculosa Gyrinophilus porphyriticus
Megalobatrachus japonicus Ambystoma maculatum

TABLE 2. Percentage of correlations* based on taxonomic re-
semblances between four major late Cretaceous Faunas.

No. of
Faunas common genera _— Percentage
‘Lance and Hell Creek 47 71%
Judith River and Fruitland 33 50%
Judith River and Lance 33 50%
Judith River and Hell Creek 33 50%
Fruitland and Lance 30 45%
Fruitland and Hell Creek Si 48%

*Either the two formations both have a given genera (positive
correlation) or both do not (negative correlation).

ARMSTRONG-ZIEGLER: CAMPANIAN AMPHIBIANS & REPTILES 33

than between the Lance and Hell Creek faunas. This general
taxonomic comparison, then, is in accord with the interpretation, de-
rived from pollen analysis (Tschudy in Fassett and Hind, 1971) and
from ammonite stratigraphy and radiometric dating (Cobban, 1973),
that the Fruitland Formation was deposited in Late Campanian time.

A portion of the taxonomic divergence between the Fruitland and
Judith River assemblages is certain to reflect differences in the envi-
ronments of deposition represented in the two units. Within this cate-
gory, some of the marine and euryhaline fish present in the collections
from Localities B and C, Lonchidion, Squatirhina, and Ischyrhiza, are
particularly notable. All three of these also occur in the Lance and Hell
Creek faunas but are conspicuously absent from the Judith River col-
lections. This strongly suggests the absence of the littoral zone facies
from the Judith River vertebrate-bearing deposits rather than a faunal
distinction indicative of differing stratigraphic positions.

The following discussion is a commentary on the more important
taxonomic similarities and differences among the assemblages from the
four Late Cretaceous units that, in total, yield a Campanian strati-
graphic position for the Fruitland Formation vertebrate fauna. As will be
shown, many of the faunal differences between the Campanian Judith
River and Fruitland faunas on the one hand and the Maestrichtian
Lance and Hell Creek faunas on the other are indicative of evolu-
tionary changes that occurred in the composition of the terrestrial and
freshwater vertebrate fauna during Late Cretaceous time. In this con-
sideration, it is recognized that an indeterminate portion of the dif-
ferences between the faunas is due to less intensive collection in the
Campanian units. However, within a number of the important groups
of vertebrates represented in all of the faunas, it seems fairly certain
that the observed differences in assemblage composition reflect
genuine and stratigraphically important differences that existed in the
living faunas.

The Judith River fauna appears to reflect solely an upland river set-
ting because it contains only freshwater and terrestrial vertebrate re-
mains. As expected, the fish component of this fauna is most compara-
ble with the fish component from Locality A (also an upland river
assemblage). Both contain Myledaphus, Amia (Kindleia), Lepisosteus,
and ?Paralbula. The Fruitland fauna at Locality A contains Acipenser,
absent from the Judith River fauna, but lacks Belonostomus, present in
the latter. This difference may well constitute a change in faunal com-
position, perhaps even an incident of ecologic replacement, that oc-
curred through the passage of time. The fish assemblages from Lo-

34 FIELDIANA: GEOLOGY

calities B, C, and D are very different from the Judith River complex
because they include the various elasmobranch species adapted to
marine and brackish water conditions. On the other hand, the fish
assemblages of Locality B, C, and D closely resemble those from the
Lance and Hell Creek Formations but are conspicuously absent from
the older Judith River and Milk River Formations as well as from the
Fruitland Formation.

Among the Anura, the Fruitland has a pelobatid, ?Eopelobates, in
common with the Judith River assemblage. This was linitially de-
scribed from the Judith River Formations as ‘‘Discoglossid type C’’
(Sahni, 1972). In addition to ?7Eopelobates, the Fruitland fauna shares
Scotiophyrne pustulosa with both the Lance and Hell Creek faunas.
However, the Lance and Hell Creek faunas contain cf. Barbourula, a
form absent from the Judith River and Fruitland faunas. Among the
Urodela, the Fruitland assemblage shares two genera (Prodesmodon,
Opisthotriton) in common with the Judith River assemblage and three
genera (Prodesmodon, Opisthotriton, and Cuttysarkus) in common
with the Hell Creek and Lance assemblages. The Judith River, Lance,
and Hell Creek faunas also contain three genera (Habrosaurus,
Scapherpeton, and Lisserpeton) not in the Fruitland fauna, which
could reflect less intensive collecting in the latter or, perhaps, a re-
gional rather than stratigraphic variation.

Of the four turtle genera from the Fruitland, two (Basilemys and
Trionyx) are found in the Judith River fauna, three (Compsemys,
Basilemys, and Trionyx) are found in the Lance fauna, and three
(Adocus, Compsemys, and Trionyx) are found in the Hell Creek fauna.
In addition to these, one additional chelonian genus, Eubaena, is com-
mon to the Lance and Hell Creek faunas but is missing from all of the
earlier faunas. Because Adocus and Basilemys are easily confused,
perhaps a closer review of the turtle fragments collected from the Milk
River and Judith River faunas, using Estes’ criteria for distinguishing
these two genera, might show that these earlier Campanian units
shared Adocus as well as Basilemys with the Fruitland Formation.

An Eosuchian, Champsosaurus sp., is present in the Maestrichtian
Lance and Hell Creek Formations (Estes et al., 1969) and the Campa-
nian Edmonton and Judith River Formations (Sahni, 1972) but, thus
far, no remains of this form have been discovered in the Fruitland
Formation. There are three crocodilians (Leidyosuchus,
Thoracosaurus, and Brachychampsa) present in the Fruitland fauna,
and all of these are found in the Hell Creek fauna as well (Estes et al.,
1969). Two of them (Leidyosuchus and Brachychampsa) are found in

ARMSTRONG-ZIEGLER: CAMPANIAN AMPHIBIANS & REPTILES 35

the Judith River (Sahni, 1972) and Lance faunas (Estes, 1964) as well.
The New aniliid snake, Coniophis cosgriffi, from the Fruitland For-
mation (Armstrong-Ziegler, 1978) is probably also represented in the
Hell Creek fauna by an unidentified fragmentary vertebra (see Estes et
al., 1969, p. 23, fig. 4). Another snake, Coniophis, is recorded from
both the Lance and Hell Creek Formations (Estes et al., 1969). Thus
far, no snake remains have been recovered from the Judith River For-
mation fauna (Sahni, 1972).

The Fruitland fauna shares two teiids, Chamops segnis and Lep-
tochamops denticulatus, with the Judith River fauna (Sahni, 1972). In
addition to these, the Hell Creek fauna also has Haptosphenus placo-
don and Peneteius aquilonius, with only the latter occurring in the
Lance fauna (Estes et al., 1969). One and, perhaps, two different an-
guids are present in the Fruitland collections—i.e., cf. Gerrhonotus
and gen. et sp. indet. represented by Pancelosaurus-like osteoscutes.
Both of these are described in accounts from the Lance fauna (Estes,

- 1964), but only the latter, in accounts of the Hell Creek fauna (Estes et

al., 1969). The Judith River Formation (Sahni, 1972) entirely lacks
anguids; therefore, the family may have been totally absent from North
America during the earlier Campanian. Three additional lizards absent
in the Fruitland Formation (Parasaniwa, Paraderma, and Exostinus)
are common to the Lance, Hell Creek, and Judith River faunas; and
two additional lizards (Palaeosaniwa and Colpodontosaurus) are
common only to the Lance and Hell Creek faunas. One scincid, Con-
togenys sloani, is reported only from the Hell Creek fauna.

A comparison among the dinosaurian records for the Lance, Hell
Creek, Judith River, and Fruitland Formations yields few items of
possible stratigraphic significance because it portrays, for the most
part, dissimilarities due to ecologic facies differences (i.e., Triceratops
vs. Pentaceratops distributions) and similarities due to long-ranging
genera (i.e., Paronychodon). However, one exception to this gener-
ality appears to be the presence of Kritosaurus in the Judith River
(Sahni, 1972) and Fruitland faunas as well as other Campanian deposits
such as those of the Oldman and Milk River Formations (Russell, 1935)
and its conspicuous absence in the Maestrichtian Lance and Hell Creek
Formations. This record constitutes yet another taxonomic datum in
support of closer time correspondence of the Fruitland Formation with
the older units of Montana and Alberta. Further support for this con-
clusion is derived from the presence of Anatosaurus, Triceratops, and
Tyrannosaurus in the Lance and Hell Creek faunas (Estes, 1964; and
Estes et al., 1969) and their absence in the older Judith River (Sahni,
1972) and Fruitland faunas.

36 FIELDIANA: GEOLOGY

Clemens (written comm., 1976) has identified the following mamma-
lian material from my Fruitland localities, A, B, and C:

?Mesodma sp. Based on part of a Ps. 7New multituberculate(s): The
M2 differs from Mesodma in the irregular development of cusps.
The Ps differs from Mesodma in that the slope of the anterior edge
is not parallel with the roots, and there is a great distance between
the first and second serrations. A.

?Essonodon sp. The configuration of cusps and basins on this molar
are somewhat Essonodon-like. A.

Cimolodon sp., new species, with smaller bulbous cusps than found
in C. nitidus. A.

Eucosmodontid, a new genus and new species. A, B.

Alphadon cf. marshi. Represented by an upper molar lacking only
the parastyle. This tooth might be the M? or M? of A. marshi;
however, its crown could be a bit too bulbous to be referable to
that species. The differences are not great. C. |

?Peradectes sp. The talonid of a molar shows Peradectes-like
characters that include a small hypoconulid and its separation
from the entoconid. A.

This material and Clemens’ (1973) former work on Fruitland mam-
mals still supports his original contention that the unique character of
the Fruitland mammalian faunal complex reflects an intermediacy in
age between Maestrichtian and Campanian assemblages (Clemens,
1973, p. 164).

From a consideration of the total fossil content of the Fruitland
Formation, including vertebrate, invertebrate, and pollen taxa, it
seems most reasonable to assume an Upper Campanian age for the unit
because the evidence points toward a closer affinity with the Campa-
nian Judith River Formation than with the Maestrichtian Lance and
Hell Creek Formations. This affinity is evident despite obvious
ecologic facies differences existing, in part, between the two units and
the relatively small amounts of collecting (and, thus, incomplete sam-
pling) that have been accomplished in the two. Certain taxa, as dis-
cussed above, signify an age for the Fruitland Formation that is only
slightly younger than that of the typical Campanian units.

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