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An associated dentition and calcified vertebral centra of the Late Cretaceous elasmobranch, Ptychodus anonymus Williston 1900


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The associated remains of a ptychodontid shark, Ptychodus anonymus Williston 1900, were recovered by the authors from the Smoky Hill Chalk Member (Late Cretaceous; late Coniacian) of the Niobrara Chalk Formation of western Kansas. Preserved elements included 208 teeth, five vertebral centra, fragments of centra and calcified cartilage, and oral (pharyngeal) denticles. The presence of calcified vertebral centra indicate that Ptychodus is a neoselachian shark and not a hybodont as previously reported. Whereas individual teeth of the genus Ptychodus are relatively common fossils in Late Cretaceous marine sediments, reasonably complete dentitions and preserved soft tissues are rare, and few have been reported in the literature. Most of the Ptychodus teeth that have been documented previously from the Niobrara Chalk have not included accurate stratigraphic information. In addition to reporting the associated dentition, calcified vertebral centra and oral denticles of Ptychodus anonymus, we also review the fauna association of the specimen and the history of the genus in North America.
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Paludicola 4(4):125-136 June 2004
by the Rochester Institute of Vertebrate Paleontology
An associated dentition and calcified vertebral centra of the
Late Cretaceous elasmobranch, Ptychodus anonymus Williston 1900
Michael J. Everhart
and Tom Caggiano
1-Sternberg Museum of Natural History, Hays, KS 67601. 2-145 Hayrick Lane, Commack, NY 11725
The associated remains of a ptychodontid shark, Ptychodus anonymus Williston 1900, were recovered by the authors from
the Smoky Hill Chalk Member (Late Cretaceous; late Coniacian) of the Niobrara Chalk Formation of western Kansas.
Preserved elements included 208 teeth, five vertebral centra, fragments of centra and calcified cartilage, and oral (pharyngeal)
denticles. The presence of calcified vertebral centra indicate that Ptychodus is a neoselachian shark and not a hybodont as
previously reported. Whereas individual teeth of the genus Ptychodus are relatively common fossils in Late Cretaceous marine
sediments, reasonably complete dentitions and preserved soft tissues are rare, and few have been reported in the literature. Most
of the Ptychodus teeth that have been documented previously from the Niobrara Chalk have not included accurate stratigraphic
information. In addition to reporting the associated dentition, calcified vertebral centra and oral denticles of Ptychodus
anonymus, we also review the fauna association of the specimen and the history of the genus in North America.
Ptychodus is a genus of extinct durophagous
sharks whose remains are found in Late Cretaceous
marine sediments around the world. The unusual teeth
of ptychodontid sharks were first described by Agassiz
(1833-1844) from the English chalk. Leidy (1868) was
the first to report on the discovery of Ptychodus teeth
from the "Cretaceous series" of western Kansas when
he described a single, damaged tooth (Ptychodus
occidentalis) from "a few miles east of Fort Hays,
Kansas." At about the same time, Dr. George M.
Sternberg collected Ptychodus mortoni teeth from the
Niobrara Chalk of western Kansas, which were later
figured by Leidy (1873). Cope (1874, p. 47-48; 1875,
p. 294) listed five species of Ptychodus from different
stratigraphic horizons in Kansas: P. janewayi, P.
polygyrus, P. occidentalis, P. mortoni and P. whipplei.
However, while most of Cope’s specimens are
assumed to be curated in the American Museum of
Natural History, his name is not associated with any
Ptychodus material currently in the AMNH collection.
Another early collector in Kansas, B. F. Mudge (1876,
p. 217) noted that the “teeth of Selachians are quite
common. At one locality, over 400 were collected in an
area of 30 inches, and apparently from the jaws of one
individual – a Ptychodus – and all in excellent
preservation.” Mudge’s specimens were most likely
maintained in the museum of the Kansas Academy of
Science but, according to Skelton (1996), the entire
KAS collection was moved and dispersed about 1915,
and the museum was never reconstituted.
Unfortunately, except for the small P. occidentalis
tooth described by Leidy (1868), there is no further
record of the fate of these early Kansas specimens.
Williston (1900, Pl. 29, fig. 5-8, 16-18, 20-22, 24)
described two new species of Ptychodus (P. martini
and P. anonymus) from the Smoky Hill Chalk and
published the first photographs of the teeth of seven
species (Ptychodus mortoni, P. martini, P. occidentalis,
P. anonymus, P. polygyrus, P. whipplei and P.
janewayi) from western Kansas. The discovery of a
well-preserved specimen of P. mortoni, including
calcified centra, was reported by Stewart (1980) but the
specimen has not been further described. Stewart
(1990) reported only three species (P. mortoni, P.
martini and P. anonymus) from the Smoky Hill Chalk
and proposed the first stratigraphic distribution of
ptychodontids in that member, suggesting that they are
limited stratigraphically to the lower third of the
member (late Coniacian – early Santonian). Although
many additional specimens of this genus have been
recovered in Kansas during the last one hundred years,
little information has been added to the literature since
Williston (1900).
This paper describes the fragmentary remains of a
Ptychodus anonymus specimen (AMNH 19553)
collected by the authors from western Kansas in 1995,
and donated to the American Museum of Natural
History (AMNH).
PALUDICOLA, VOL. 4, NO. 4, 2004
Locality and Stratigraphy--AMNH 19
553 was
discovered in the Smoky Hill Chalk Member of the
Niobrara Formation in southeastern Gove County,
Kansas, about five miles south of Castle Rock. The
exact locality is on record at the American Museum of
Natural History. The remains were located about 3 m
above the uppermost bed of bioturbulated chalk in
Hattin's (1982) Marker Unit 3, and 32 m above the
contact with the underlying Fort Hays Limestone
(Figure 1). The top of the Fort Hays Limestone is
exposed along the Smoky Hill River less than two
miles to the southeast. The specimen occurred near the
upper limits of Stewart's (1990) biostratigraphic zone
of Protosphyraena perniciosa, just below the base of
the zone of Spinaptychus n. sp. and would be late
Coniacian in age.
Faunal Association--The
inoceramids, Volvice-
ramus grandis and Pl
atyceramus platinus, and the
ostreid, Pseudoperna congesta, are the most common
macroinvertebrates in this zone. Fragments of the
rudist, Durania maxima, are found occasionally, as are
pen fragments of the squid, Tusoteuthis longa. The
remains of vertebrates collected by the authors from
this locality include: (Elasmobranchs) Cretoxyrhina
mantelli, Cretolamna appendiculata, Squalicorax
falcatus, Ptychodus mortoni, P. anonymus, P. martini,
P. polygyrus; (Teleosts) Protosphyraena perniciosa, P.
nitida, Xiphactinus audax, Ichthyodectes ctenodon,
Gillicus arcuatus, Saurodon leanus, Pachyrhizodus
caninus, P. minimus, Cimolichthys nepaholica,
Enchodus petrosus, E. gladiolus, Martinichthys brevis,
and Thryptodus zittelli; (Reptilia) Tylosaurus
nepaeolicus and other unidentified mosasaur remains.
Associated teeth of Ptychodu
s martini
and Everhart, 1999) and the lamniform shark,
Scapanorhynchus raphiodon (Hamm and Shimada,
2002) were also recently documented from the same
exposure. Nicholls (1988) reported a nearly complete
specimen of the marine turtle, Toxochelys latiremis,
from a site further east in the same section. The
fragmentary skull of a polycotylid plesiosaur was
reported by Everhart (2003) from the same
stratigraphic interval approximately 4 miles to the
southwest. A more comprehensive listing of vertebrate
species was provided by Stewart (1990) from this and
other biostratigraphic zones in the Smoky Hill Chalk.
AMNH 19553 consists of portions of the upper
d lower dentitio
ns of a ptychodontid shark totaling
201 teeth, five nearly complete vertebral centra (54 mm
diameter), several centra fragments, calcified cartilage,
oral denticles, and two associated teeth of the
anacoracid shark, Squalicorax falcatus.
AMNH 19553 was discovered in April, 1995, by
us (TC) while on a field trip in southeastern
Gove County, Kansas. Numerous teeth were located as
float in a small gully at the edge of a shallow valley in
the Smoky Hill River drainage. The loose teeth were
followed up slope to where additional remains were
eroding from the chalk. Unfortunately, only a few teeth
remained in situ. The matrix surrounding those teeth,
however, yielded five articulated vertebral centra,
several fragments of centra, and some debris that
appeared to be composed of calcified cartilage. A
quantity of the surrounding matrix was collected and
the area was searched for any additional remains.
A portion of the matrix recovered from around the
men was pr
ocessed with dilute acetic acid by J. D.
Stewart (Los Angeles County Museum of Natural
History –LACMNH). More than 150 oral (pharyngeal)
denticles were recovered from this matrix sample along
with several teeth of Cimolichthys nepaholica and
Enchodus sp., and scales of Paraliodesmus gaudagnii
(Stewart, pers. comm., 1995). Seven of the 208 teeth
recovered from the specimen are curated as LACMNH
138527 to provide providence for the oral denticles
collected by Stewart.
The AMNH specimen includes fourteen large,
medial teeth that range in size from 19
mm by 18 mm mesial–distally to 25 mm by 23 mm
labial-lingually. The labial margins of these tooth
crowns are convex and the lingual margins are concave
(Figure 2). The labial edge of each crown sits on a
shelf formed in the lingual margin of the preceding
crown (Figure 3). AMNH 19553 preserves a single
tooth from the symphysial tooth row in the upper jaw
that measures 9 mm mesial–distally and 8 mm labial-
lingually (Figure 4). The root of this tooth is overhung
by the crown shelf at the labial edge and compares well
with the upper jaw medial tooth figured by Woodward
(1887, Pl. 10, fig. 11). The remaining teeth in the
specimen are asymmetrical. The larger lateral teeth,
positioned adjacent to the medials, range in size from
20 mm by 14 mm to 24 mm by 20 mm. Intermediate
lateral teeth range from 18 mm by 14 mm to 14 mm by
9 mm. Posterior teeth (defined as those teeth at the
distal edges of each jaw plate) range from 13 mm by 11
mm to 12 m by 8 mm. Crown height is greatly
diminished in the most distal teeth. In occlusal view,
the crown morphology changes dramatically
mesodistally and the cusp becomes more offset
The roots are not centered und
er the cr
owns of the
teeth in this specimen. On medial teeth, the crown shelf
is centered in a mesial-distal direction. The root is
almost flush with the lingual edge of the crown shelf,
while the crown shelf overhangs the root at the labial
edge. The roots tend to be flush at the mesial and
lingual sides of the asymmetrical teeth that make up the
Paludicola 4(4):125-136 June 2004
by the Rochester Institute of Vertebrate Paleontology
FIGURE 1. A generalized stratigraphic column of Late Cretaceous rocks in Kansas showing the temporal range of the genus Ptychodus, and the
approximate stratigraphic occurrence of AMNH 19553. (Adapted from Shimada, 1996)
PALUDICOLA, VOL. 4, NO. 4, 2004
FIGURE 2. An occlusal view of a medial tooth from the lower jaw of Ptychodus anonymus (AMNH 19553). Labial is to the top of the photograph.
Note the ornamentation in the marginal area surrounding the crown and the shelf formed on the posterior side of the crown. (Scale = mm)
FIGURE 3. An occlusal view of two medial teeth from the lower jaw of AMNH 19553 showing the articulation of the protuberance on the labial
edge of the following tooth with the shelf formed in the lingual notch of the leading tooth in the row. Anterior is to the left. (Scale = mm)
Paludicola 4(4):125-136 June 2004
by the Rochester Institute of Vertebrate Paleontology
lateral and posterior sections of the jaw plate, and the
crown shelf overhangs on the labial and distal sides.
The roots contain numerous foramina just below the
crown – root contact.
Approximately 10% of the teeth in this specimen
show visible wear facets on the apex of the crown.
None exhibit the extreme wear in evidence on some
ptychodontid teeth (Authors pers. observations).
Twelve of the teeth are incompletely formed
replacement teeth (Figure 5). Most of these are hollow
crowns with the enamel in various stages of
completion. Several, however, are more developed and
are partially filled with the dentine that would
eventually have formed the bilobate root. These crowns
would have been located in the most lingual (posterior)
positions in the tooth rows. Similar replacement teeth
have been observed by the authors in other associated
Ptychodus tooth sets (FHSM VP-2222, VP-2223 and
VP-14854). Traces of wear were first reported and
figured by Woodard (1887, p. 126-127; Pl. 10, fig. 13).
Five circular centra were recovered in partial
articulation (Figure 6) from the site along with
numerous fragments. The centra were extremely fragile
and were not prepared prior to donation. All of the
centra are fractured and none are 100 percent complete.
The centra measure 54 mm in diameter and are 4 mm
thick. Concentric layers of calcified cartilage are
visible on the edges of fractures. The surface of each
centrum exhibits fine grooves which radiate outward
from the center. Foramina are not apparent, and
openings for the basidorsal / basiventral cartilages were
not observed. Stewart (1980) reported slightly larger
(63-63 mm), compressed centra in association with a
Ptychodus mortoni specimen (KUVP 59041) in the
collection of the University of Kansas. An examination
of the KUVP 59041 remains in 2004 by one of us
(MJE) located only three partial vertebrae (Figure 7).
These fragments are similar in structure and surface
detail to the centra from the AMNH specimen. The
calcified centra from both specimens conform closely
to the asterospondylic type figured by Cappetta (1987,
fig. 9C). Although Cappetta (Ibid.) and others have
suggested that Ptychodus is a hybodont on the basis of
the similarities in the dentitions, the presence of
calcified centra indicates that it is instead a
neoselachian, as are all modern sharks and rays.
Additional work is required on more complete
specimens, such as KUVP 59041, to further define the
systematic relationships.
Cappetta (1987, p. 21) noted that “the inside of
the mouth is also covered, in many selachians, by
numerous mucous membrane denticles,” but did not
provide a description. Oral (pharyngeal), denticles
were collected from the matrix around AMNH 19553
by Stewart (pers. comm., 1995), and in addition, a
small number were recovered by the authors from the
matrix adhering to inside of the hollow tooth crowns of
some of the partially formed replacement teeth. The
hollow underside of these replacement teeth apparently
served as traps for denticles as the specimen decayed.
The denticles measure just over 1 mm in length and 0.5
mm in maximum width across the cusp (Figure 8), and
appear to be composed of an enamel-like material. The
cusps are inflated and exhibit from one to three lobes.
The smooth upper surface of the cusp contrasts
markedly with the highly ornamented dermal denticles
of various shark species (Cappetta, 1987, fig. 31). The
opposite end tapers to a point and would appear to be
the portion that anchored the denticle into the epithelial
lining of the mouth. We were also able to collect
similar oral denticles from the replacement teeth of a
second P. anonymus specimen (FHSM VP-14854)
recovered near the same locality as AMNH 19553 in
1999 (Everhart, et al., 2003).
Two teeth of the shark Squalicorax falcatus were
discovered in close association with the AMNH 19553
specimen, suggesting possible scavenging of the
Ptychodus remains. Squalicorax is well documented as
a scavenger of vertebrate remains in the Late
Cretaceous Western Interior Sea and Gulf Coast areas
(Schwimmer, et al., 1997). While no direct evidence of
scavenging was apparent on the AMNH 19553
specimen, it is unusual to otherwise find the remains of
two vertebrate species in such close association in the
Smoky Hill Chalk. It is uncertain if the teleost remains
recovered from the matrix by Stewart (pers. comm.,
1995) are associated with the specimen or are simply a
part of the normal detritus which had accumulated on
the sea floor.
Class Chondrichthyes Huxley, 1880
Subclass Elasmobranchii Bonaparte, 1838
Cohort Euselachii Hay, 1902
Subcohort Neoselachii Compagno 1977
Order incertae sedis
Family Ptychodontidae Jaekel, 1898
Genus Ptychodus Agassiz, 1835
Ptychodus anonymus Williston 1900
Discussion--Woodard (1887, p. 128) noted that
the dentition of Ptychodus “is that of a true Ray, and
does not bear the slightest resemblance to that of the
Cestraciont Sharks.” While the Family Ptychodontidae
has more recently been included in the Superfamily
Hybodontoidea Zangerl, 1981 (Cappetta, 1987; Welton
and Farish, 1993, and others), Stewart (1980)
suggested that “…that all living sharks and rays
(including Heterodontus) are members of the
monophyletic Neoselachii, united by synapomorphies
including the presence of calcified centra. Since
Paludicola 4(4):125-136 June 2004
by the Rochester Institute of Vertebrate Paleontology
FIGURE 4. A) Labial views of a medial tooth from the upper jaw (upper left), and B) a medial tooth from the lower jaw. (Scale = mm)
FIGURE 5: Oblique views of two of the replacement tooth crowns recovered in association with AMNH 19553. These crowns demonstrate that the
enamel of the tooth is completed prior to the formation of the bilobate root. (Scale = mm)
FIGURE 6: Two of the five calcified vertebral centra collected in association with AMNH 19553. The presence of calcified centra places Ptychodus
in the Neoselachii with modern sharks and rays. The diameter of each vertebra is approximately 54 mm.
FIGURE 7: Three fragmentary vertebrae from the Ptychodus mortoni specimen (KUVP 59041) reported by Stewart (1980). (Scale = cm)
PALUDICOLA, VOL. 4, NO. 4, 2004
Ptychodus shares this derived state, it must be regarded
as a neoselachian and not as a hybodont …”
conclusion was based on calcified centra found in a
relatively complete specimen Ptychodus mortoni which
is now in the University of Kansas collection (KUVP
59041). Cappetta (1987, p. 37) acknowledged
Stewart’s comments, but noted that “it cannot be
excluded that calcified centra appeared parallely in
very specialized hybodonts like Ptychodus.”
Unfortunately, KUVP 59041 has not been described
further. Stewart’s (1980) suggestion is followed here
while the authors note that additional refinement is
necessary regarding the placement of the Family
Ptychodontidae within the Neoselachii.
odontids are recognized most readily by
r rounded, sub-rectangular teeth that are arranged in
parallel, interlocking rows to form a pavement on the
upper and lower jaws. According to Kauffman (1972),
this feeding mechanism apparently evolved in response
to a durophagous diet. Most workers divide Ptychodus
teeth into morphological types based on crown
development: low, intermediate and high (Welton and
Farish 1993). P. anonymus falls into the high crowned
type. All species exhibit transverse enameloid ridges,
except for P. mortoni whose ridges radiate in all
directions from the center of the cusp. Ptychodontid
teeth also exhibit distinctive ornamentation on the
marginal areas around the crown (Figure 2). The crown
shape, transverse ridges and marginal ornamentation
are the diagnostic features used to distinguish among
the various species. In all species, the enameloid crown
extends over the low, weakly bilobate root.
As clarification, consistent with Wooda
rd (1887)
and Dibley (1911), the term row indicates a labio-
lingual column of teeth. The lower dentition has a
medial row that contains the largest teeth in the
dentition (Woodward, 1887, 129; Dibley, 1911, p.
263), while the opposing medial row of the upper
dentition contains relatively small medial (symphysial)
teeth flanked by rows of larger teeth that collectively
form a furrow for the medial row of large lower teeth
to fit into. The small medial row teeth in the upper jaw
are symmetrical (Figure 3A) as are the teeth in medial
row in the lower jaw. The ptychodontid dentition
displays monognathic heterodonty in that the tooth
shape changes from mesial to distal along the dental
series. The teeth become more asymmetrical toward
the lateral rows. This condition has also been reported
in P. whipplei (Welton and Farish, 1993) and P.
occidentalis (Cicimurri (2001).
Teeth of the genus Ptych
odus are
known from
Late Cretaceous marine sediments of every continent
except Australia (Cappetta, 1987, p. 38). In North
America, the genus has been reported from numerous
localities within the extent of the Western Interior Sea.
The largest number of ptychodontid species has been
reported from Texas (Welton and Farrish, 1993) but
they are also well known from Kansas (Leidy, 1868,
1873; Cope, 1874, 1875; Mudge, 1876; Williston,
1900; Stewart, 1980, 1990; Shimada, 1993; Shimada
and Martin, 1993; Everhart, et al., 2003; Shimada and
Everhart, 2003), Alabama (Morton, 1842; Applegate,
1970), Georgia (Case and Schwimmer, 1988),
Mississippi (Manning and Dockery, 1992), South
Dakota (Cappetta, 1973), Arizona (Williamson, et al.,
1993), New Mexico (Williamson, et al., 1990), Utah
(this paper), Wyoming (Evetts, 1979; Cicimurri, 2004)
and Canada (Case, et al., 1990). Stewart (1988)
reported the first North American occurrence from
P. anonymus
has a more restricted ge
range and is apparently limited to the Western Interior
Sea of North America. The type locality was originally
described by Williston (1900, p. 241) as being from
"Walnut Creek" and "probably" from the "Benton" of
Kansas. Hattin (1982) noted that the Benton Formation
is an obsolete term that originally included the
Graneros Shale, Greenhorn Limestone and Carlile
Shale, and thus is middle Cenomanian through middle
Turonian in age. Exposures of rocks of this age in
Kansas are generally restricted to the north-central part
of the state. The only "Walnut Creeks" in north-central
Kansas are in Norton, Phillips and Jewell counties. The
Smoky Hill Chalk Member crops out occasionally in
Norton and Phillips counties but there are no
documented exposures of the "Benton" there. In Jewell
County, there is a Walnut Creek near the town of Burr
Oak, west of Mankato, KS. Exposures in the area
include the basal Fort Hays Limestone and the Carlile
Shale. This area is most likely close to the locality of
Williston's type specimen of P. anonymus. If so, the
material would be middle Turonian to early Coniacian
in age.
Whereas the genus Pt
has a temporal
range from the Albian into the early Campanian
(MacLeod and Slaughter, 1980), P. anonymus has been
documented only from the middle Cenomanian through
the late Coniacian. Meyer (1974) and Welton and
Farish (1993) indicate that P. anonymus occurs
commonly in the Cenomanian and Turonian of Texas.
Lucas, et al. (1988) and Wolberg (1985) documented
the species from the latest Cenomanian and the
Turonian of New Mexico respectively. It is also known
from the late Cenomanian-middle Turonian Tropic
Shale of Utah as well (M. Graffam, pers. comm., 1999;
J. Bourdon, pers. comm., 1999). Parkin, et al. (2002)
reported P. anonymus from the Greenhorn Limestone
(middle Cenomanian) of Colorado. Cicimurri (2001,
2004) documented the species from the late
Cenomanian – Turonian of South Dakota. In his
discussion of Niobrara Formation vertebrate
stratigraphy, Stewart (1990) noted that P. anonymus
Paludicola 4(4):125-136 June 2004
by the Rochester Institute of Vertebrate Paleontology
FIGURE 8: (Left to right) Occlusal, lateral and basal views of an oral (pharyngeal) denticle recovered from the remains of AMNH 19553. These
denticles formed a protective lining in the throat of the shark. (Scale = mm)
and Graneros Shale (middle Cenomanian) of Russell
County (Everhart, 2004, pers. observation).
was known from the Greenhorn and Carlile formations
of Kansas, and stated that the range of the taxon
extended upward into the biostratigraphic zones of
Protosphyraena perniciosa and Spinaptychus n. sp. in
the lower Smoky Hill Chalk. These zones include the
stratigraphic Marker Units 1-5 of Hattin (1982) and
encompass late Coniacian through early Santonian
time. AMNH 19553 would represent a relatively late
occurrence of the species.
Williston (1900) described the teeth of Ptychodus
anonymus as having "broadly conical crowns" and
"very distinctly reticulate marginal areas", with
"transverse ridges not reaching the rims of the crowns."
Although Williston (1900) did not specify the number
of ridges as a diagnostic feature in his description, 12
ridges are discernable on the tooth shown as figure 7 of
Plate XXIX. Most of the other photographs of the other
teeth are not clear enough to count, however, the tooth
shown as figure 8 appears to have 7 ridges. Meyer
(1974) noted that the subspecies Ptychodus anonymus
anonymus from the Kamp Ranch Member (Turonian)
of the Arcadia Park Shale of Texas exhibited fewer
transverse ridges and noted the same concentric pattern
on the marginal area as is observed on AMNH 19553.
Specimens figured by Lucas et al. (1988, fig. 13A-D)
also display a variation in the number of ridges. Welton
and Farrish (1993, p. 57) indicate that the "crown is
moderately inflated; cusp conical, high and rounded;
transition from cusp to marginal area smooth, not
angular; approximately 12 fine transverse ridges extend
across apex, down sides of cusp, then divide and curl
around as they enter marginal area; margin narrow with
bumpy granular pattern, not crossed by transverse
ridges in marginal area; root anaulacorhizous;
histology osteodont." The teeth of AMNH 19553
match these descriptions in all aspects of tooth shape.
However, the teeth exhibit only 5 to 7 fairly coarse
transverse ridges, which extend downward, but not
completely to the bottom of the cusp. The marginal
area has a distinct pattern of fine, irregularly concentric
lines. Tooth ornamentation, including the number of
The number of Ptychodus species has increased
significantly since they were first described by Agassiz
(1833-1844). Because of this, and the poorly
understood relationships between these species, the
genus is certainly in need of further study and revision.
Many species of ptychodontids have one or more
subspecies (Dibley, 1911; Meyer, 1974). According to
Dibley, (1911), P. decurrens has four subspecies.
Meyer (1974) listed two sub-species for P. anonymus.
According to Meyer (Ibid.), Williston's original form is
now P. anonymus anonymus. It is joined by a smaller,
more primitive subspecies P. anonymus blechroconus.
Furthermore, Meyer (Ibid.) suggested that a transition
occurred over time from P. decurrens bifurcus to P.
anonymus blechroconus to P. anonymus anonymus.
However, Cicimurri (pers. comm., 2004) noted that the
large specimen of P. decurrens figured by Meyer is
more likely a high crowned P. occidentalis. Meyer
(1974) also indicated an apparent transition occurred
from the low to the high crowned species between the
Cenomanian and the Coniacian, and concluded that P.
decurrens is the most primitive form based on its low
crown height. The earliest occurrence of P. decurrens
in Kansas is near the contact of the Dakota Sandstone
PALUDICOLA, VOL. 4, NO. 4, 2004
transverse ridges, is similar to the description that
Welton an
d Farrish (Ibid.) provide for Ptychodus
mammillaris. However, the teeth of AMNH 19553 do
not exhibit the characteristic flattening of the crown
observed in P. mammillaris. Welton and Farris (1993)
disagreed with the suggestion by Herman (1977) that
P. anonymus is a subspecies of P. mammillaris. It
appears that AMNH 19553 has affinities of both
species, which would tend to support Herman’s
argument. Considering the amount of variation in tooth
morphology that has been reported, P. anonymus
appears to be a transitional form that clearly needs
more study.
AMNH 19553 is significant because: 1) it is the
ost com
plete set of remains of Ptychodus anonymus
yet described, including calcified vertebral centra,
replacement teeth and oral denticles; 2) the presence of
calcified centra indicates that ptychodontids are
neoselachians, and not hybodonts; 3) it is associated
with accurate stratigraphic information; and 4) it was
recovered near the upper end of the temporal range of
this species in the Western Interior Sea. In addition,
this specimen provides useful data on the temporal
distribution and diversity of the late Coniacian fauna in
the Western Interior Sea during the Late Cretaceous.
We thank Don Albin, Utica, KS, for allowing
access to the
locality; J. D. Stew
art, Los Angeles
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... vertebral centra, portions of mineralized cartilages and placoid scales (e.g. Everhart and Caggiano, 2004;Shimada et al., 2009Shimada et al., , 2010Amadori et al., 2020a;Jambura and Kriwet, 2020). ...
... †Ptychodus was a ubiquitous elasmobranch, as its associated and isolated teeth are widely reported from the Upper Cretaceous of Africa, Asia, Europe and North and South America (e.g. Antunes and Cappetta, 2002;Dutheil and Ackermann, 2004;Everhart and Caggiano, 2004;Cappetta, 2012;Shimada, 2012;Diedrich, 2013;Vullo and Courville, 2014;Hamm, 2017Hamm, , 2019Hamm, , 2020Amadori et al., 2019bAmadori et al., , 2020a. The dentition of †Ptychodus consists of teeth that are arranged in antero-posteriorly directed dental rows to form maxillary and mandibular tooth plates exhibiting different degrees of dignathic heterodonty (see Woodward, 1887Woodward, , 1904Woodward, , 1912Williston, 1900a, b;Shimada, 2012;Amadori et al., 2019bAmadori et al., , 2020a. ...
... Woodward (1904) and Shimada et al. (2009) documented lower dentitions of both low-crowned and high-crowned †Ptychodus species that still are articulated with the Meckel's cartilages. According to these articulated findings, the lower dentition of †Ptychodus exhibits a symphyseal row composed of the largest teeth within the dental plate, while teeth decrease in size laterally (see also Woodward, 1887Woodward, , 1912Williston, 1900a, b;Everhart and Caggiano, 2004;Shimada, 2012;Diedrich, 2013;Amadori et al., 2020a, b;Hamm, 2020). The articulated tooth set PIMUZ A/I 5056 (Fig. 4) described here allows a detailed assessment of the lower dental plate of †P. ...
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The first articulated dentition of †Ptychodus from Africa is described herein. The specimen, likely coming from the Turonian of the Asfla area (Goulmima region, southeastern Morocco), exhibits a well-preserved lower dental plate of a second-level predator. A new species, †P. maghrebianus sp. nov., is erected herein based on this durophagous dentition characterised by imbricated cuspidate teeth. We employed for the first time in †Ptychodus multiple quantitative analyses and statistical parametric and non-parametric tests to process biometrical data taken from articulated, associated and isolated teeth. The quantitative approach (morphospace analysis) is exploited herein to support the traditional taxonomic identification (qualitative examination) of †P. maghrebianus sp. nov. and to separate it from the similar cuspidate species, †P. mortoni. Morphospace reconstructions confirm a marked lower dental heterodonty (mesio-distal patterns) for both species. The analysis protocol employed here also allows assigning indeterminate teeth as belonging to †P. mortoni. The reconstruction of the entire lower dental plate of †P. maghrebianus sp. nov. shows a cuspidate dentition probably able to reduce tooth damages when crushing thin-shelled prey. Both dental morphologies and tooth wear patterns suggest a peculiar food processing and a diet mainly consisting of bivalves, decapods and small fish for this durophagous predator. Trophic reconstructions of the Turonian ichthyofauna inhabiting the middle to outer ramp environment of the Asfla area emphasize that †P. maghrebianus sp. nov. and the batoid †Tingitanius most likely represented second-level consumers, whereas the sclerorhynchiforms †Asflapristis and †Ptychotrygon represented third-level predators. Top positions within the food web were occupied by larger predaceous elasmobranchs (e.g., †Squalicorax).
... Ptychodus is an extinct genus of durophagous elasmobranchs mostly known by dental and, more rarely, skeletal remains (e.g., vertebral centra, portion of mineralized cartilages and placoid scales; MacLeod, 1982;Everhart and Caggiano, 2004;Shimada et al., 2009Shimada et al., , 2010. Associated and isolated teeth of Ptychodus are common in the Upper Cretaceous of Africa, Asia, Europe and North and South America (e.g., Cappetta, 2012;Shimada, 2012;Hamm, 2017). ...
... Recently, Shimada et al. (2009) described the replacement teeth in an articulated specimen of a high-crowned Ptychodus species for the first time and also discussed some palaeobiological issues, such as body size and feeding specialization (see also Shimada, 2012). Ptychodus species are commonly regarded to be durophagous predators able to feed mainly on hard-shelled macroinvertebrates (e.g., Amadori et al., 2019;Canavari, 1916;Cappetta, 2012;Casier, 1953;Diedrich, 2013;Everhart, 2017;Everhart and Caggiano, 2004;Fossa-Mancini, 1921;Kauffman, 1972;Quenstedt, 1885;Shimada, 2012;Williston, 1900aWilliston, , 1900bWolberg, 1985). ...
... Woodward (1887,1904) suggested that the upper symphyseal teeth of Ptychodus are small in size, while the lower symphyseal ones are large (see also Shimada et al., 2009). Later, several authors followed this interpretation (e.g., Williston, 1900a, b;Dibley, 1911;Malecki, 1980;Everhart and Caggiano, 2004;Shimada, 2012;Hamm, 2017), while others (e.g., Canavari, 1916;Fossa-Mancini, 1921;MacLeod, 1982;Welton and Farish, 1993) erroneously interpreted this reconstruction by inverting the position of the dental plates. ...
Dental and skeletal remains of Ptychodus mediterraneus from the Upper Cretaceous Scaglia Rossa Formation of northeastern Italy are described and discussed herein, together with isolated teeth of P. latissimus and P. polygyrus from the English Chalk of Sussex, southern England. The redescription of the holotype of Ptychodus mediterraneus and lectotype fixations for P. latissimus and P. polygyrus allow the systematic reassessment of the three low–crowned Ptychodus species. In addition, these taxa are compared with other morphologically similar species, such as P. martini and P. marginalis. Micropalaeontological analyses suggest a Turonian age for the low–crowned P. mediterraneus. Based on articulated tooth sets of P. mediterraneus, the pavement–like dentitions of this durophagous taxon are reconstructed herein, revealing a marked dignathic heterodonty. Imbricated dentitions observed in articulated specimens of Ptychodus mediterraneus also suggest broad distributions of bite–induced load on tooth plates; the dental features of this low–crowned durophagous shark indicate a high specialization for grinding thick–shelled bivalves (e.g., inoceramids and rudists). Fragments of cranial mineralized cartilages (e.g., a ‘V–shaped’ jaw portion) and asterospondylic vertebral centra of P. mediterraneus are consistent to those commonly occurring in fusiform sharks. Evidences of scavenging on Ptychodus recorded on cartilages and tooth–bioerosion are also reported herein. Moreover, a posterior–to–anterior tooth replacement is hypothesized for Ptychodus based on the abrasion patterns observed in articulated dental sets. New insights on the palaeoecology and palaeobiology of Ptychodus are also provided.
... The genus was highly diverse with species exhibiting varied tooth morphologies from low to high crowns, with multiple tooth ridges being parallel or radiating and a marginal area of varying widths and ornamentation patterns. Although associated and articulated specimens have been found (Dibley 1911;MacLeod 1982;Everhart and Caggiano 2004;Hamm 2008;Shimada et al. 2009Shimada et al. , 2010Hamm 2010aHamm , 2010bShimada 2012) they are uncommon occurrences. Because of this, the majority of species are described solely on isolated teeth. ...
... This wide stratigraphic interval and the aerial extent that these units are exposed at the surface makes the type locality very difficult to verify. Everhart and Caggiano (2004) One could be easily be ascribed to a new species but is not, as it appears to represent a continuous lineage of increased crown height and thicker ridge development, not yet reaching the broad and flat-topped P. mammillaris tooth form. ...
... Six other specimens representing three species of Ptychodus from the Western Interior Seaway have vertebrae associated with dental remains. These include P. occidentalis (UNSM 123607) from the middle Cenomanianearly Turonian Greenhorn Limestone (Shimada et al. 2009), P. rugosus AMNH 19553 (Everhart andCaggiano 2004;Hamm 2010) and P. mortoni KUVP 59041 (Stewart 1980;Hamm 2008) (Woodward 1889) and a partial skeleton referred to P. mediterraneus (I-17376) from the Turonian of Italy, which is now considered to be conspecific with P. latissimus (Canavari 1916;Hamm 2008;Diedrich 2013). The vertebrae associated with SMP-SMU 69004-690012 and KUVP 59041 measure 64 and 62.5 mm respectively and are interpreted to be from the trunk region. ...
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Isolated tooth specimens of the Late Cretaceous shark Ptychodus anonymus Williston 1900 are common occurrences in the Cenomanian and Turonian deposits throughout the Western Interior Seaway. Reported here is an association of 58 teeth of P. anonymus (FHSM VP-19170) recovered from the Jetmore Member of the Greenhorn Formation (Late Cenomanian) in Mitchell County, Kansas. This specimen is significant as it represents the first occurrence of an associated dentition of this species. A single vertebra was also collected, which makes this the stratigraphically oldest occurrence of Ptychodus with associated post cranial remains. This tooth set consists of teeth from seven tooth file positions to the right and left side of a central medial file. This specimen demonstrates the complete heterodonty pattern in the dentition of P. anonymus, clarifying the morphological variations that exist in isolated teeth ascribed to the species. This specimen provides additional clues to determine the ordinal taxonomic classification of the family.
... 6752.98 Ptychodus Agassiz, 1834 Ptychodus (dal greco "πτυχή", piega, e "ὀδούς", dente = "dente con pieghe"; Agassiz, 1842) è un genere di pesci cartilaginei estinti del Cretaceo che, insieme al genere Heteroptychodus, fa parte della famiglia Ptychodontidae (Chondrichthyes, Elasmobranchii;Cuny, 2008;Cappetta, 2012). Ptychodus è noto principalmente attraverso denti isolati, provenienti da rocce dell'Albiano-Campaniano di America, Europa, Africa e Asia (Everhart & Caggiano, 2004;Cappetta, 2012;Verma et al., 2012). I denti in generale presentano una corona squadrata e massiccia ricoperta da simil-smalto, con una cuspide generalmente arrotondata o appiattita, attraversata da creste parallele o radiali. ...
... Tra i primi a notare la scarsa affi nità degli Ptychodus con i batoidei vi furono Fossa-Mancini (1921) e Casier (1953; successivamente gran parte degli autori inserì il genere negli ibodontiformi (Patterson, 1966;Applegate, 1970;Herman, 1977;Welton & Farish, 1993;Antunes & Cappetta, 2002). Nel 1980 Stewart ipotizzò che la calcifi cazione della parte centrale delle vertebre di Ptychodus potesse indicare l'appartenenza di questo taxon ai Neoselachii (Everhart & Caggiano, 2004;Blanco-Pinon et al., 2007;Hamm, 2008;Verma et al., 2012;Hamm, 2017), piuttosto che agli ibodontiformi. Studi istologici sullo smalto dei denti hanno inizialmente confermato la presunta affi nità tra Ptychodus e ibodontiformi (Cuny, 2008), ma recenti analisi sullo smaltoide (simil-smalto, tipico degli elasmobranchi) di Ptychodus sembrano aver chiarito la controversia, evidenziando una struttura complessa del tutto assimilabile a quella dei Neoselachii (Hoffman et al., 2016). ...
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Isolated and associated teeth referred to Ptychodus decurrens Agassiz, 1838 and P. cf. latissimus Agassiz, 1835 (Condritti, Elasmobranchi), are described and figured herein. The material, mostly coming from the Trentino region, is housed in the Paleontological Collection of the Museo Civico di Rovereto (Trento, northern Italy). Based on the described morphologies, the original position of the teeth within the mandibular and maxillary dental plates was established. The ornamentations and abrasions observed on the crown of the fossils under study also seem to indicate different adaptations to the durophagy, confirming the hypothesis of a diet consisting mainly of shell-covered prey.
... It is predominantly known from Cretaceous deposits of North America, Europe, Africa, and Asia with a fossil range from the Albian to the Campanian (e.g., Cappetta, 2012). The remains typically consist of isolated teeth and associated or articulated dental plates; there are also rare reports of mineralized cartilaginous elements mostly consisting of scattered vertebral centra and jaw rami (Woodward, 1887(Woodward, , 1912Niedzẃiedzki and Kalina, 2003;Everhart and Caggiano, 2004;Cappetta, 2012;Amadori et al., 2020a;Hamm, 2020a). In general, the heterodont, 'pavementlike' dentitions of Ptychodus are composed by variously ornamented molariform teeth (durophagous adaptations), which characterize this elasmobranch predator (Woodward, 1912;Cappetta, 2012;Shimada, 2012;Amadori et al., 2020aAmadori et al., , 2020bAmadori et al., , 2022. ...
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Isolated teeth belonging to the genus Ptychodus Agassiz, 1834 (Chondrichthyes; Elasmobranchii) from the Upper Cretaceous of the Ryazan and Moscow Oblast regions (European Russia) are described and discussed in detail herein. The taxonomic composition of the Ptychodus assemblage from the Ryazan region is very diverse including the first records of the cuspidate species P. altior and P. anonymus, which thus is largely consistent with those from other contemporaneous European localities. Ptychodus ubiquitously inhabited epicontinental seas of Europe during most of the Cretaceous with the most diverse assemblages coming from southern England, northern Italy, Belgium, and European Russia. Additionally, the material documented here from the Cenomanian of Varavinsky ravine area (Moscow Oblast) represents the northernmost occurrence of Ptychodus hitherto reported from Europe. It is evident that the Late Cretaceous shallow seas of the Russian platform represented a crucial pathway for the dispersal of Ptychodus from the European peri-Tethys to the eastern margins of the Neo-Tethyan Ocean. The Albian-Campanian records of Ptychodus from Europe indicate that its dominance in the peri-Tethys persisted for most of its evolutionary history. A local temperature drop across most of the European shallow seas probably contributed to the narrowing of its geographic range in the peri-Tethyan seas towards the end of the Mesozoic Era. The fossil remains of Ptychodus documented herein are accordingly of utmost importance for better understanding the taxonomic composition of Russian fossil ichthyofaunas and also inform about the dispersal of Ptychodus towards western and eastern peri-Tethyan seas during the Late Cretaceous.
... Ptychodus Agassiz, 1834 is a genus of Cretaceous elasmobranchs ranging from the Albian to the Campanian with worldwide distribution (Woodward, 1912;Cappetta, 2012). The fossil record of this enigmatic predator mainly includes isolated teeth, very rare associated, but also articulated dentitions and mineralized cartilaginous elements (Nicolis, 1889;Woodward, 1889;Tan, 1949;MacLeod, 1982;Everhart & Caggiano, 2004;Shimada et al., 2010;Cappetta, 2012;Shimada, 2012;Diedrich, 2013;Hamm, 2017;Amadori et al., 2019aAmadori et al., , 2019bAmadori et al., , 2020Jambura & Kriwet, 2020). Ptychodus possessed polygonal, molariform teeth arranged in dental plates suitable for crushing shelled preys (Williston, 1900a(Williston, , 1900bWoodward, 1912;Cappetta, 2012;Shimada, 2012;Diedrich, 2013;Amadori et al., 2019bAmadori et al., , 2020. ...
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Associated and isolated teeth of the extinct elasmobranch Ptychodus latissimus Agassiz, 1835 from the Upper Cretaceous Scaglia Rossa pelagic limestone of northern Italy are described and discussed here in detail for the first time. The dentition of this widely distributed species consists of low-crowned molariform teeth that exhibit marked and strong occlusal ornamentations suitable for crushing hard-shelled prey. The associated tooth sets and isolated teeth analyzed here are heterogeneous in size and crown outline, but unambiguously belong to a single species. Re-examination of this Italian material consisting of ca. 30 specimens mostly coming from historical collections allows for a rigorous assessment of the intraspecific variability of P. latissimus, including the identification of three different tooth “morphotypes” based on their positions within the jaws. The relatively flat crowns and occlusal sharp and thick ridges indicate a high adaptation for crushing hard-shelled prey in P. latissimus indicating that the durophagous adaptations of this species were certainly more pronounced than in all other species of Ptychodus. We hypothesize that P. latissimus was a third-level predator occupying habitats with abundant thickshelled prey, such as inoceramid bivalves and ammonites.
... When Agassiz originally described P. polygyrus he also described three other species, P. concentricus, P. sulcatus, and P. marginalis, all of which he considered to be related to P. polygyrus. Malecki (1980) considered P. marginalis to be a sub-species of P. polygyrus, and since this observation, reports of P. marginalis from Cenomanian and Turonian deposits in North America have been referred to P. polygyrus (Welton and Farish, 1993;Cicimurri, 1998Cicimurri, , 2004Hamm, 2003;Everhart et al., 2003;Everhart and Caggiano, 2004;Shimada and Fielitz, 2006). Taxonomic assignment of material from the Cenomanian and Turonian of Europe and North America should be referred to P. marginalis (Hamm, 2010). ...
... The wide and flat molariform teeth of Ptychodus (e.g., P. decurrens, P. latissimus and P. polygyrus) are commonly regarded as durophagous feeding adaptations and benthic, thick-shelled macroinvertebrates are traditionally considered target preys of Ptychodus (e.g., Compagno, 2002;Everhart and Caggiano, 2004;Everhart, 2005;Cappetta, 2012;Shimada, 2012;Kolmann et al., 2014). A few possible lines of evidence supporting this assumption are represented by putative tooth marks on inoceramid bivalves (Kauffman, 1972). ...
Dental remains of the elasmobranch Ptychodus from the Upper Cretaceous of northeastern Italy are described herein. This material, consisting of two slabs containing a partially associated tooth set and additional detached teeth with similar morphological features, derives from different lithozones of the Scaglia Rossa Formation, known as the ʻlastameʼ and ʻPietra di Castellavazzoʼ. All of these teeth are characterized by an unusual high and narrow cusp. The tooth set exhibits elements with different morphologies although they are clearly referable to a single taxon. Based on the species-specific characters of the teeth and according to the Principle of Priority of the International Code of Zoological Nomenclature, we propose herein to resurrect the species Ptychodus altior Agassiz, 1835 as a valid taxon that can easily be separated from P. rugosus Dixon, 1850. Moreover, we designate a neotype of Ptychodus altior Agassiz, 1835 since the type series seemingly is lost. Although similarly developed cusps are observed also in the species Ptychodus rugosus Dixon, 1850 and P. whipplei Marcou, 1858, the material described herein is assigned to Ptychodus altior because of the presence of a narrow cusp with smooth lateral cusp faces. The narrow high-cusped morphology characterizing this species probably indicates a different target prey compared to low-crowned congeneric species. Ptychodus altior is solely known from the Turonian-Coniacian of Europe; we review the distribution and paleobiogeography of this species, extending its range to the Angola region. The fossils described herein represent the first record of Ptychodus altior from Italy and significantly contribute to the knowledge of this species and, more generally, of the paleobiodiversity of the genus Ptychodus in the central Tethys area.
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Due to their cartilaginous endoskeleton and the continuous tooth replacement, the chon-drichthyan fossil record predominantly consists of isolated teeth, which offer diagnostic features for taxonomic identifications, but only provide very limited information of an organism's life history. In contrast, the calcified vertebral centra of elasmobranchs (sharks, skates and rays) yield important information about ecological and biological traits that can be utilized for constructing age-structured population dynamic models of extant species and palaeoecolo-gical reconstructions of such aspects in extinct groups. Here, we describe two large shark vertebrae from the Santonian (Upper Cretaceous) of Spain, which show a unique combination of characters (asterospondylic calcification pattern, with concentric lamellae and numerous parallel bands that are oriented perpendicular) that is only known from ptychodontid sharks, a distinct, extinct group of giant durophagous sharks of the Cretaceous era. Based on linear regression models for large extant sharks a total length between 430 and 707cm was estimated for the examined specimen. Our results indicate that ptychodontid sharks were large viviparous animals, with slow growth rates, matured very late and, therefore, show typical traits for K-selected species. These traits combined with a highly specialized feeding ecology might have played a crucial role for the success but also, eventually, extinction of this group.
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Tooth remains of the elasmobranch Ptychodus are common in Late Cretaceous marine in both nearshore and deep water deposits worldwide. Although they are typically found as isolated tooth specimens, associated or articulated specimens are very rare. Described here is the first occurrence of an associated tooth set of the Late Cretaceous ptychodontiform shark P. mammillaris (FHSM VP-17989) from the Pfeifer Shale Member (lower middle Turonian) of the Greenhorn Limestone in Russell County, Kansas. The specimen consists of 47 teeth and represents the earliest stratigraphic occurrence of the species in the Western Interior Seaway. Although found disarticulated, this tooth set consists of teeth from eight different tooth file positions which demonstrates the heterodonty within the dentition. This specimen is unique because it is the earliest occurrence of the species and possesses the largest lower medial file teeth of P. mammillaris found in North America to date.
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A Campanian fish assemblage is described from the uppermost Blufftown Formation in weste chondrichthyan and eight osteichthyan taxa are identified, virtually all for the first time from the region. The s a transitional zone between the Atlantic and eastern Gulf of Mexico Coastal Plain Provinces during the Late Cr faunal relationships with both.
Twenty-three elasmobranch taxa have been recovered from the Upper Cretaceous Carlile Shale (Middle Turonian to Early Coniacian) of the Black Hills region of South Dakota and Wyoming. The oldest unit, the Pool Creek Member, represents marine shoreface depositional environments and contains a selachian assemblage composed predominantly of pelagic predators (Carcharias, Cretodus, Cretolamna, Cretoxyrhina, Johnlongia, Scapanorhynchus, Squalicorax). Rocks from the lower part of the overlying Turner Sandy Member represent shallow-water environments influenced by wave-generated and tidal currents. Moderately diverse elasmobranch assemblages recovered from these rocks contain a preponderance of benthic taxa (Cantioscyllium, Chiloscyllium, Ischyrhiza, Pseudohypolophus, Ptychodus, Ptychotrygon, Rhinobatos, Sclerorhynchus). Only one taxon, Ptychodus latissimus, has thus far been recovered from the Sage Breaks Shale Member, which was deposited in an offshore, shelf-depth, open marine environment.