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Oldest records of the Late Triassic theropod dinosaur Coelophysis bauri

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Lucas, S.G. and Spielmann, J.A., eds., 2007, The Global Triassic. New Mexico Museum of Natural History and Science Bulletin 41.
OLDEST RECORDS OF THE LATE TRIASSSIC
THEROPOD DINOSAUR COELOPHYSIS BAURI
JUSTIN A. SPIELMANN1, SPENCER G. LUCAS1, LARRY F. RINEHART1,
ADRIAN P. HUNT1, ANDREW B. HECKERT2 AND ROBERT M. SULLIVAN3
1 New Mexico Museum of Natural History and Science, 1801 Mountain Road NW, Albuquerque, NM 87104-1375;
2 Department of Geology, Appalachian State University, ASU Box 32067, Boone, NC 28608-2067;
3 Section of Paleontology and Geology, State Museum of Pennsylvania, 300 North Street, Harrisburg, PA 17120
Abstract— Coelophysis bauri is a well-known theropod dinosaur from the Upper Triassic of the southwestern
United States. Prior to this study, it was only known from extensive remains from the Whitaker quarry, in the Rock
Point Formation, of north-central New Mexico. Here, we document fossils of C. bauri from the Upper Triassic
Snyder quarry, north-central New Mexico and from the Petrified Forest National Park. Both of these new records
are from the Painted Desert Member of the Petrified Forest Formation, stratigraphically below the Rock Point
Formation. This extends the biostratigraphic range of C. bauri to the early Revueltian (early-middle Norian)
through the Apachean (late Norian-?Rhaetian). Thus, C. bauri is no longer an index taxon of the Apachean land-
vertebrate faunachron.
INTRODUCTION
Coelophysis bauri, one of the best-known Late Triassic dino-
saurs, has been known from a single locality, the Whitaker quarry at
Ghost Ranch, New Mexico (e.g., Colbert, 1989) (Fig. 1). Here, we de-
scribe and photographically illustrate specimens referable to C. bauri
from the Upper Triassic (Revueltian) Snyder quarry, north-central New
Mexico, compare these specimens with another C. bauri fossil described
from broadly correlative strata in the Petrified Forest National Park of
Arizona (Padian, 1986) and summarize the biostratigraphic range of C.
bauri based on these additional specimens. In this paper, NMMNH =
New Mexico Museum of Natural History and Science, Albuquerque and
UCMP = University of California Museum of Paleontology, Berkeley.
PREVIOUS STUDIES
Coelophysis bauri is one of the best, if not the best, known Trias-
sic dinosaurs and has been the subject of numerous publications for more
than 100 years. In this section we highlight key works that are relevant to
our discussion. These include the initial naming of Coelophysis bauri, the
publication of the Ghost Ranch specimens, the Rioarribasaurus vs.
Coelophysis controversy and the taxonomic relationship of C. bauri to
Megapnosaurus (=“Syntarsus”).
In 1881, David Baldwin, while collecting for Edward Drinker
Cope, discovered small theropod dinosaur fossils at three localities in the
Upper Triassic strata of northern New Mexico; one locality was noted
as “Gallina Canyon” and the other two localities as “Arroyo Seco.” After
studying these specimens, Cope published two papers on the material.
The first (Cope, 1887a) described two new species that Cope assigned
to Marsh’s genus Coelurus. C. longicollis, the larger of the two, was
named based on one vertebra from each of the cervical, dorsal and caudal
series, plus a femur. The other species, C. bauri, was based on a cervical
vertebra, a sacrum and a distal femur. The second paper (Cope, 1887b)
was a review of North American Triassic vertebrates, in which Cope
revised his interpretation of the C. longicollis and C. bauri material as
distinct taxa, instead referring it to the European genus Tanystropheus
(then perceived as a dinosaur, not a protorosaur). In this same publica-
tion, Cope named a third species, T. willistoni, that was smaller than the
other two. This species was named based on an incomplete acetabular
border and a single dorsal centrum. Neither of the two Cope publications
included illustrations or locality information, nor were specimen num-
bers or types designated. In 1889, Cope removed T. longicollis, T. bauri
and T. willistoni from the genus Tanystropheus, based on the morphology
of the neural canals of the centra, and gave these three species the new
generic name Coelophysis (Cope, 1889).
Later work by Huene (1915) recognized the three species of
Coelophysis, primarily by size differences, and while he illustrated the
material for the first time, he, like Cope, neither provided specimen
numbers nor designated any types. It fell to Hay (1930) to designate
Coelophysis bauri as the type species of Coelophysis; C. bauri was
selected because the other two species were judged to be undiagnostic.
The other species were synonymized with C. bauri by Colbert (1947).
Colbert (1947) initially described a massive bonebed of complete
articulated and disarticulated skeletons of a small theropod from Ghost
Ranch, Rio Arriba County, New Mexico. This quarry became known by
a variety of names, including the Ghost Ranch quarry, the Coelophysis
quarry and the Whitaker quarry (after the initial discoverer of the site).
Colbert (1947) referred to the theropods from that quarry as Coelophysis,
but provided no justification for his assignment. Colbert (1964)
rediagnosed Coelophysis bauri based on the Ghost Ranch material, fol-
lowed later by a complete osteology (Colbert, 1989). Subsequently, he
(Colbert, 1990) described variation in C. bauri, again based solely on the
Ghost Ranch sample.
In his monographic description of the large, Early Jurassic
coelophysoid Dilophosaurus, Welles (1984) designated lectotypes for
Coelophysis bauri and C. longicollis, and provided Longosaurus as a
new generic name for C. longicollis, thus creating the binomial
Longosaurus longicollis. Colbert (1989) also designated a lectotype for
C. bauri, apparently unaware of the lectotype designation in Welles’
FIGURE 1. Index map showing the distribution of Coelophysis fossil localities
in Arizona, New Mexico and Texas. Biostratigraphic subdivision after Lucas
(1998). Abbreviations: GR – Ghost Ranch and SQ – Snyder quarry.
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(1984) previous work.
Padian (1986) was the first to point out discrepancies between
Cope’s holotype material of Coelophysis and the Ghost Ranch theropod.
Specifically, Padian (1986) noted that of the 24 characters used by Colbert
(1964) to diagnosis Coelophysis bauri, only eight can be assessed in
Cope’s syntypes. Hunt and Lucas (1991) expanded upon this line of
reasoning by noting that the lectotypes of C. bauri and Longosaurus
longicollis designated by Welles (1984) were ineligible to become lecto-
types because the designated material was not part of the original syntypes.
Thus, Hunt and Lucas (1991) affirmed the validity of the lectotype for
C. bauri that Colbert (1989) had proposed. In addition, they designated
a lectotype for C. willistoni, the only remaining of Cope’s species for
which a lectotype had not yet been designated. Summarily, Hunt and
Lucas (1991) pointed out that none of the lectotypes of Cope’s initial
three species of Coelophysis were in any way diagnostic below the level
of Theropoda indet. and that “[n]one of the Whitaker quarry material
should ever have been assigned to Coelophysis” (p. 195). Thus, they
proposed a new generic and specific name for the Whitaker quarry mate-
rial, Rioarribasaurus colberti. In addition, they noted (p. 195) that an
attempt to “petition the International Commission on Zoological No-
menclature to conserve the name Coelophysis bauri, by designating a
neotype, would be met with rejection, simply because the type material
of the taxon is extant.”
Even though Hunt and Lucas (1991) provided a “by-the-book”
argument, frequently citing the International Code of Zoological Nomen-
clature, which was supplemented by support from Sullivan (1993, 1994,
1995) and Huber (1994), a petition for the designation of a neotype of
Coelophysis bauri from the Ghost Ranch material was submitted to the
International Commission on Zoological Nomenclature (ICZN) by Colbert
et al. (1992). They disputed the claim of Hunt and Lucas (1991) that the
stratigraphic level of the Ghost Ranch quarry was demonstrably differ-
ent than the level that yielded the holotype material of C. bauri; they
also noted that individual bones of the Ghost Ranch material are identical
to those of the holotype of C. bauri and that the name Coelophysis bauri
is well entrenched in the literature, both technical and popular, and in the
public consciousness. Sullivan et al. (1996) addressed these observa-
tions, demonstrating that the Ghost Ranch sample comes from a distinct
horizon, with dramatically different preservation than the original mate-
rial collected by Baldwin. The resultant decision of the ICZN (1996) was
to designate a neotype of C. bauri from the Ghost Ranch material – this
was accomplished by making the holotype of R. colberti the neotype of
C. bauri – rendering Rioarribasaurus colberti a junior objective syn-
onym of Coelophysis bauri.
Raath (1969) named and described “Syntarsus” (=Megapnosaurus)
rhodesiensis based on an incomplete articulated skeleton, lacking the
skull and cervical vertebrae, from the Early Jurassic Forest Sandstone
Formation near Bulawayo, Zimbabwe (then Rhodesia). Raath (1969)
compared “S.rhodesiensis to Coelophysis bauri and was struck by the
similarity between the two taxa. However, he did note a handful of minor
differences, mostly confined to the hip and tarsus. Additional work by
Raath (1977) provided further description of numerous “S.rhodesiensis
specimens, and allowed for a better comparison between “S.rhodesiensis
and C. bauri. Raath (1977, table 19) noted further differences between
the skulls and forelimbs of the two taxa (reiterated by Colbert [1989]); he
subsequently detailed the variation present in the African specimens
(Raath, 1990).
In addition, Rowe (1989) and Tykoski (1998) described a new
species of “Syntarsus,” “S. kayentakatae, from the Early Jurassic
Kayenta Formation of Arizona. Over the years the close taxonomic
association between “Syntarsus” and Coelophysis has only grown closer
with numerous differences between the taxa being resolved as more speci-
mens are examined. Paul (1988, 1993) was the first to suggest that “S.
rhodesiensis and C. bauri be placed in the same genus. Downs (2000)
further reiterated the synonymy of the two genera based on his analysis
of the Ghost Ranch material. Ivie et al. (2001) pointed out that the
generic name Syntarsus was preoccupied by a beetle and proposed the
generic name Megapnosaurus (“big dead lizard”) for the theropod.
Bristowe and Raath (2004) recently placed both species of “Syntarsus
in the genus Coelophysis, although they remain listed separately in
Tykoski and Rowe (2004). Smith and Merrill (2006) found significant
morphometric variation between Coelophysis and “Syntarsus,” and ar-
gued that the two genera should not be synonymized. In addition, they
noted variation within the Whitaker quarry sample, which they inter-
preted as a result of sexual dimorphism. This assertion thus counters the
claim by Smith (1997) that the variation within the Whitaker sample
could have systematic significance. The one generally agreed on feature
between Bristow and Raath (2004) and Smith and Merrill (2006) is that
Coelophysis bauri is more closely related to “S.rhodesiensis then either
is to “S.kayentakatae. Thus, Coelophysis currently contains two spe-
cies, C. bauri (the type species) and C. rhodesiensis; and Megapnosaurus
(= “Syntarsus”) kayentakatae is a closely related taxon (Tykoski, 2005;
Ezcurra, 2006; Ezcurra and Novas, 2006).
Hunt et al. (1998) named a fragmentary coelophysid Camposaurus
arizonensis (originally described by Lucas et al. [1992]), for ceratosaurian
postcrania from the Placerias quarry in the Bluewater Creek Formation
of east-central Arizona. Some workers (e.g., Long and Murry, 1995;
Irmis, 2005) consider this material indistinguishable from Coelophysis,
whereas others recognize it as a valid, distinct taxon (Tykoski and Rowe,
2004; Heckert et al., 2005), a position we follow here.
Sullivan and Lucas (1999) built upon Sullivan et al. (1996) and
described a new theropod, Eucoelophysis baldwini, from exposures of
the Painted Desert Member of the Petrified Forest Formation in the
vicinity of Orphan Mesa. They also referred one of the specimens (a
proximal pubis) originally collected by Baldwin to this taxon. Subse-
quently, Heckert et al. (2000, 2003) referred abundant theropod material
from the Snyder quarry, at the same stratigraphic horizon some distance
(~2 mi) to the west, to Eucoelophysis sp. based on the similar morphol-
ogy of the tibia and fibula, but refrained from referring them to E. baldwini,
largely because of differences in the femur. Ezcurra (2006) recently re-
described Eucoelophysis as a non-dinosaurian dinosauriform, but agreed
that the Snyder material described by Heckert et al. (2000; and thus by
extension Heckert et al., 2003) is distinct from E. baldwini.
SNYDER QUARRY MATERIAL
The Snyder quarry is a bone bed in the upper part of the Painted
Desert Member of the Petrified Forest Formation a few km from Ghost
Ranch, in north-central New Mexico (Zeigler et al., 2003) (Fig. 1).
Phytosaurs dominate the Snyder quarry assemblage, but theropod fos-
sils also are present.
Heckert et al. (2000, 2003) provided a preliminary discussion of
the theropod material from the Snyder Quarry. Here, we expand on their
summary and describe additional material that has been prepared since
that publication. We agree with Heckert et al. (2000, 2003) that there are
two distinct size grades of theropod represented within the Snyder quarry
assemblage, one significantly larger than the other. However, we con-
clude that the material of the smaller theropod is attributable to the
theropod dinosaur Coelophysis bauri, not Eucoelophysis baldwini, which
is now considered a non-dinosaurian dinosauriform (Ezcurra, 2006). In
addition, Ezcurra (2006) noted that the Snyder quarry material more
closely resembles dinosaurs than the dinosauriform Eucoelophysis. Spe-
cifically, he assigned it to Coelophysoidea indet., cf. Coelophysidae
based on the following synapomorphies of the Coelophysoidea: pre-
maxillary body craniocaudally lengthened, heterodont premaxilla, pre-
maxillary nasal process forms more than half of the rostrodorsal narial
border, subnarial gap, rostral end of the maxillary alveolar border sharply
upturned and cervical vertebrae craniocaudally elongated. Additionally,
Ezcurra (2006) noted that the alveolar ridge defining the ventral margin of
the antorbital fossa indicates a close relationship of the Snyder quarry
small theropod skull to Liliensternus, and the square rostral end of the
antorbital fossa resembles Zupaysaurus (Ezcurra and Novas, 2005) and
386
members of the Coelophysidae (sensu Rauhut, 2003).
Theropoda Indet.
Much of the theropod fossil material recovered from the Snyder
quarry consists of isolated ribs, centra and miscellaneous bone frag-
ments. However, only the centra may be identifiable to Theropoda indet.
due to neural arch morphology, whereas the rest can only be identified to
Reptilia indet., Tetrapoda indet. or Vertebrata indet. Here, we focus only
on the more diagnostic elements.
Small Theropod
The smaller of the two theropods initially described by Heckert et
al. (2000) is represented by an incomplete skull with associated cervical
vertebrae (NMMNH P-30852) (Figs. 2, 3A-D), two incomplete skel-
etons (NMMNH P-29047 and NMMNH P-31661) (Figs. 3E-F, 4, 6E-
I), a set of associated hindlimbs (NMMMH P-29046) (Figs. 5D-M, 6A-
D) and several isolated hindlimb elements (NMMNH P-31293, P-54617
through P-54620) (Figs. 5A-C, N-O). These specimens are summarized
in Tables 1 and 2, with metrics of each specimen in Appendix. Specimens
NMMMNH P-29046, P-29047, P-30852 and P-31661 were all found in
close proximity to each other (within ~2m laterally), but repetition of
elements (especially left tibiae) indicates the presence of at least three
individuals of similar size.
NMMNH P-30852
NMMNH P-30852 is an incomplete skull that includes the left
premaxilla, the left maxilla, left lacrimal, left prefrontal, most of both
lower jaws and two articulated anterior cervical vertebrae, probably
cervicals three and four (Figs. 2, 3A-F). This specimen also provides a
rare opportunity to examine the internal surfaces of the various skull
elements of Coelophysis, as much of the Ghost Ranch material has only
the external surfaces of the cranial bones exposed.
The left premaxilla is complete and roughly triangular, with a very
thin nasal process projecting posteriorly and a more robust maxillary
process. The narial fossa is present where the two processes meet,
which also demarcates the anterior margin of the external nares. Four
tooth sockets are preserved, the third of which houses an unerupted
tooth, whereas the other teeth are incomplete.
The left maxilla is incomplete and is missing its posterior portion.
The nearly complete ascending process of the anterior maxilla is triangu-
lar. Much of the posterior maxilla is very fragmentary, preserving only
the portion directly above the tooth row. Ten teeth, in various states of
completeness, are present. The total number of tooth sockets cannot be
assessed due to mediolateral crushing of the specimen. The length of the
maxilla, as preserved, is ~101 mm.
The left lacrimal (Fig. 3E-F) is complete and has an inverted L-
shape. The posterodorsal margin of the element is slightly curved, not
linear. A low ridge on the lateral surface of its jugal process extends
dorsally, curves and continues anteriorly on the dorsal process of the
lacrimal, demarcating the posterodorsal margin of the external antorbital
fossa. A small elliptical opening is present on the medial side of the
maxillary process. A triangular depression is present on the medial side
of the base of the jugal process. Notably, the length of the base of the
lacrimal is greater than 30% of the height of the ascending process.
A disarticulated right postorbital is attached to an amalgamation
of lower jaw elements, so it can only be seen in lateral view. Overall, it is
roughly T-shaped, with the jugal process slanted anteroventrally. A ven-
trally-projecting triangular process is present on the medial side of the
confluence of the frontal, squamosal and jugal processes of the postor-
bital.
The mandibles are both present, but incomplete. The right jaw
preserves more of the tooth row and is more complete posteriorly but is
missing its anterior tip. The left lower jaw preserves the anterior tip, but
is missing its posterior one-third. Both exhibit little crushing in compari-
son to the right maxilla.
The left lower jaw preserves an incomplete dentary, portions of
the angular, surangular and ?splenial. However, as preserved, it is diffi-
cult to discern the sutures between the dentary, angular and surangular. In
the left dentary, 20 tooth sockets are preserved, 12 of which bear teeth;
portions of the anterior dentary are obscured by the right maxilla, so
presumably there are one or two tooth sockets that are not visible.
Anteriorly, the left dentary is relatively short and elliptical in
cross-section, with the long axis oriented dorsoventrally, whereas poste-
riorly the dentary thickens dorsoventrally. All that is preserved of the
posterior end of the lower jaws is their ventral margins. An unbroken,
slightly curved dorsal margin in this area preserves the ventral margin of
the external mandibular fenestra. The ?splenial has been displaced dor-
sally and is sharply triangular and concave in lateral view.
TABLE 1. Coelophysis bauri specimens from the Snyder quarry (NMMNH
locality 3845) described in the text.
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FIGURE 2. A-D, NMMNH P-30852, Coelophysis bauri, incomplete and partially disarticulated skull. A-B, photograph and line drawing of skull in left
lateral view. C-D, photograph and line drawing of skull in right lateral view. Teeth are darkened. Abbreviations: an, angular; ?cb, ?ceratobranchial; d,
dentary; en, external nares; mf, mandibular fenestra; mx, maxilla; mx ap, ascending process of maxilla; po, postorbital; po jp, jugal process of postorbital;
pmx, premaxilla; pmx mp, maxillary process of premaxilla; pmx np, nasal process of the premaxilla;?pre, prearticular; ?sp, splenial; t, isolated tooth.
388
The right dentary preserves 17 readily discernable alveoli; some
of the posteriormost sockets are not visible. Of the 17 sockets, 10 are
tooth-bearing. The anterior dentary is either complete to the symphysis
of the lower jaws or nearly so. The posterior portion is missing.
The ?angular is rotated dorsally from its natural position, its me-
dial surface (Fig. 2A-B). The element is triangular with a long pointed
process extending anteriorly and a dorsal expansion of the element pos-
teriorly. If correctly interpreted, the relatively smooth edge along the
dorsal margin of the ?angular forms the ventral border of the internal
mandibular fenestra.
A pair of elongate, mediolaterally compressed elements with
slightly expanded posterior ends are present below the lower jaws. Heckert
et al. (2003) identified these elements as ?ceratobranchials and we concur
with their tentative interpretation, because this pair of elements is posi-
tioned where the ceratobranchials would have been in vivo (Colbert,
1989, fig. 47A).
Two cervical vertebrae, associated with the skull, are articulated
and nearly complete, missing only their neural spines, the right
postzygapophysis of the posterior vertebra and portions of the cervical
ribs (Fig. 3A-B). Both are amphicoelous with the anterior articular sur-
faces angled anteriorly, have elongate triangular pre- and
postzygapophyses and elliptical caudal fossa on the lateral sides of the
centra that deepen posteriorly. The orientation of laminae
(centrodiapophyseal and ventral lamina) in these vertebrae are identical
to the morphology of Coelophysis bauri and Liliensternus liliensterni
(Ezcurra and Cuny, 2007, fig. 1). In addition, the posterior vertebra has
an accessory canal slightly above and running parallel to the neural canal.
This can only be seen in posterior view, because the anterior end of the
posterior vertebra is obscured by the articulated postzygapophyses of
the vertebra immediately anterior to it. Such accessory canals are also
present in the Ghost Ranch sample of Coelophysis bauri and were dis-
cussed extensively (as “lateral tunnels” by Colbert (1989, p. 78-80)).
The cervical ribs are preserved in a block of matrix beneath the centra.
The anterior vertebra is missing both the articular ends of the cervical
ribs, although an element on the right side of the vertebrae may be a
disarticulated anterior cervical rib. The left cervical rib of the posteriormost
vertebra has a complete anterior articular surface in articulation. Both
cervical ribs are extremely elongate, with those of the anterior vertebra
extending posteriorly beyond the posterior vertebra.
NMMNH P-29047
NMMNH P-29047 is an incomplete right pelvis and hindlimb
that includes an incomplete right ilium, incomplete right ischium, proxi-
mal left tibia, left fibula missing its distal end and five manual and pedal
elements (Figs. 4F-J, 6E-I).
The incomplete right ilium (Fig. 4F-H) preserves much of the
FIGURE 3. A-F, NMMNH P-30852, Coelophysis bauri. A-D, cervical vertebrae in A, left lateral, B, right lateral, C, dorsal and D, anterior views. E-F, left
lacrimal in E, medial and F, lateral views. G-H, NMMNH P-31661, Coelophysis bauri, left scapulocoracoid in G, lateral and H, medial views. Abbreviations:
ap, acromial process; cf, coracoid foramen; gl, glenoid; sb, scapular blade.
389
acetabular region (both ischial and pubic peduncles and the supra-ac-
etabular crest), but the iliac blade is missing. The anterior margin of the
pubic peduncle is also missing, as is the anterior portion of the supra-
acetabular crest. The supra-acetabular crest extends from a buttress pos-
terior to the acetabulum to a point relatively low on the pubic peduncle.
This creates a dorsal “hood” over the acetabulum, a feature also seen in
UCMP 129618 (see below). In ventral view, the acetabulum is suboval;
the anterior acetabulum is slightly wider mediolaterally than the poste-
rior portion.
The single right ischium (Fig. 4I-J) is nearly complete except for
minor fragments missing from its ventral margin the acetabulum. The
iliac articular facet is subtriangular. The acetabular facet (or antitrochanter)
is subrectangular and oriented anterodorsally. The pubic facet is triangu-
lar. When articulated with the ilium, nearly the entire acetabulum can be
delineated: overall, it is elliptical, with the long axis oriented dorsoven-
trally. The shaft of the ischium is straight, projects posteroventrally and
is triangular in cross-section with a circular lateral edge. The rugose
medial margin of the ischial shaft demonstrates the articulation of the left
and right ischia. The shaft terminates at a small, convex expansion that
appears lunate in distal view.
The proximal left tibia (Fig. 6E-G) is broken below the level of the
fibular crest. In proximal view, the tibia is subtriangular anteriorly and
rectangular posteriorly. There is a slight depression on the medial margin
of the proximal tibia; just lateral to this depression is a groove for the
reception of the proximal fibula. The cnemial crest is prominent and
concave medially, and a distinct groove extends down the shaft from this
concavity. A distinct notch is present on the posterior margin of the
proximal end of the tibia; an identical notch is present on UCMP 129618
(see below). The fibular crest extends down the proximal quarter of the
shaft, and the site of articulation with the fibula extends laterally from
the fibular crest as a pyramidal process that is oriented posteriorly. A
single nutrient foramen is present just below and posterior to the level of
the fibular crest.
The left fibula lacks much of the shaft and its distal end (Fig. 6H-
I). In cross section, the proximal fibula is a rounded rectangle that thins
anteroposteriorly along the length of the shaft. On the medial side of the
fibula is a process extending anteroventrally from the posterior edge of
the proximal end that articulates with the fibular crest of the tibia.
The various manual and pedal elements include a complete, elon-
gate metacarpal IV, the distal end of a metatarsal, a complete elongate
proximal phalanx, a complete, stout, distal phalanx and a curved terminal
manual phalanx. These bones do not differ from the same elements in the
Ghost Ranch specimens of Coelophysis bauri (Colbert, 1989).
NMMNH P-31661
NMMNH P-31661 comprises parts of a skeleton that consists of
numerous cervical rib and rib fragments, a partial left scapulocoracoid, a
right radius, an incomplete sacrum, a metacarpal and a terminal pedal
phalanx (Figs. 3G-H, 4A-E). These fragments were all collected from a
single small jacket, so we consider them associated and to represent a
single individual.
Most of the cervical ribs and rib fragments preserve the articular
facets and the anterior portions of the rib. Most notable is a prominent
anterior expansion of the anterior cervical rib.
The left scapulocoracoid (Fig. 3G-H) is incomplete, missing por-
tions of its anterior margin and most of the scapular blade, though the
glenoid is well preserved. In addition, no suture between the scapula and
coracoid can be distinguished. The posterior-facing glenoid is saddle
shaped, with the ventromedial margin slightly downturned. The pyrami-
dal acromial process lies just ventral to the glenoid, projecting laterally
from the element. A ridge runs from the acromial process anteriorly. A
moderately-sized coracoid foramen is present, at approximately the level
of the ventral margin of the glenoid. In medial view, the coracoid is
concave.
The right radius is complete. The proximal radius is elliptical,
with the long-axis oriented anteroposteriorly. The radial shaft is also
elliptical, though the anteroposterior edges taper to a point. The distal
radius is subcircular and has its long axis oriented mediolaterally.
The incomplete sacrum (Fig. 4A-E) includes all five centra ex-
pected in a coelophysoid, though in varying degrees of completeness.
The first centrum has none of its neural arch preserved. The second
centrum includes an incomplete neural arch. The third centrum includes
a complete neural arch, the base of the neural spine and portions of the
right transverse process. The fourth includes a complete neural arch and
the base of the neural spine and the fifth preserves a complete neural
FIGURE 4. A-E, NMMNH P-31661, Coelophysis bauri, incomplete sacrum
in A, right lateral, B, ventral, C, left lateral views, D, anterior view of first
sacral vertebra and E, posterior view of fifth sacral vertebra. F-J, NMMNH
P-29047, Coelophysis bauri. F-H, incomplete right ilium in F, lateral, G,
medial and H, ventral views. I-J, right ischium in I, lateral and J, medial
views. In A-C, the vertebrae are numbered. Abbreviations: ace, acetabulum;
af, acetabular facet; if, iliac facet; ip, ischial peduncle; pf, pubic facet; pp,
pubic peduncle; sup, supra-acetabular crest.
390
arch, the base of the neural spine and a complete right transverse process.
All the left transverse processes are missing, whereas the portions of the
medial ilium are still adhered to the incomplete right transverse processes
of the third through fifth vertebrae. All the centra are nearly rectangular in
ventral view and slightly waisted. The anterior articular surface of the
first centrum and the posterior articular surface of the fifth centrum are
circular and suggest that the sacral vertebrae are amphicoelous. The first
through fourth centra are seamlessly fused, whereas the fifth is adhered
but demarcated by a distinct line. Colbert (1989) documented this condi-
tion in large individuals of Coelophysis bauri. Comparison with the
NMMNH Whitaker quarry material shows this to be common in small
C. bauri individuals as well.
The single metacarpal is likely from the right manus, based on the
orientation of its distal end. Its proximal end is rectangular and expanded
compared to the thinner shaft of the element, which is circular in cross-
section. The distal end of the metacarpal has two distinct condyles; the
lateral is larger and extends more distally than the medial. The single
ungual is not highly curved, as are terminal manual phalanges, so it
appears to pertain to the pes. In proximal view, the phalanx is subtriangular.
Along either side of the distal two-thirds of the phalanx is a groove just
above the ventral surface. These elements are exactly as Colbert (1989)
described them in Coelophysis bauri.
NMMNH P-29046
Four hindlimb elements – two femora, a left tibia and a proximal
left fibula – were found in association, and are proportionate to each
other in size, so we consider them to belong to a single individual (Figs.
5D-M, 6A-D). The left femur (Fig. 5J-M) is virtually complete, with a
slightly offset break midway along the shaft, and lacking only a portion
of the medial distal condyle. The right femur is broken near its distal end,
although based on comparisons to the left femur, very little of the ele-
ment is actually missing. The left tibia is complete, although the shaft is
interrupted by two diagenetic fractures that give the element an artificial
kinked appearance overall.
The femora are mirror images of each other, but otherwise identi-
cal. Each has a prominent greater trochanter that is confluent with the
femoral head. The head has a hooked appearance, with a sulcus, visible in
proximal view, for the capitular ligament. The hooked appearance of the
femoral head differs from the femur illustrated by Colbert (1989, fig. 80),
however, many consider Colbert’s illustration to be of a non-dinosaurian
archosaur (J. Harris, pers. commun.). The anterior (“lesser”) trochanter
is triangular, robust (compare with Raath, 1977, figs. 15-16) and extends
along the anterior surface of the shaft. A trochanteric shelf separates the
anterior trochanter and the proximal femoral shaft. This shelf wraps
laterally around the shaft to its posterolateral edge. The fourth tro-
chanter, situated on the posterior shaft, begins just below the level of the
terminus of the trochanteric shelf and extends distally to above the mid-
point of the shaft. Overall, the femoral shaft is subtriangular in cross
section. Distally, the tibiofibular crest is subtriangular and extends pos-
teriorly from the lateral condyle. A prominent medial epicondyle is present
as a prominent groove running along the distal shaft to meet the distal end
of the femur.
The proximal tibia (Fig. 6A-D) is very similar to those described
above for NMMNH P-29047, including the cleft along the posterior
margin of the proximal end and the flange on the medial side of the
proximal shaft for articulation with the fibula. The distal tibia is rhom-
FIGURE 5. A-C, NMMNH P-54620, Coelophysis bauri, large right femur missing distal condyles in A, anterior, B, posterior and C, medial views. D-M,
NMMNH P-29046, Coelophysis bauri. D-I, right femur in D, G anterior, E, H, posterior, F, proximal and G, distal views. J-M, left femur in J, anterior,
K, posterior, L, proximal and M, distal views. N-O, NMMNH P-54618, Coelophysis bauri, distal right femur in N, anterior and O, distal views.
Abbreviations: at, anterior trochanter; cl, sulcus for capitular ligament; ft, fourth trochanter; me, medial epicondyle; tfc, tibiofibular crest; ts, trochanteric
shelf.
391
boidal in distal view. A process on its anterior side for the recepetion of
the astragalocalcaneum runs ventrolaterally. A prominent lateral expan-
sion is present, giving the distal tibia a rectangular shape in anterior view.
A ridge is also present on the posterior surface. None of the tibiae and
fibulae examined in this study are fused to each other; such fusion is
variable in Coelophysis bauri according to Colbert (1989, p. 107).
The proximal left fibula is morphologically identical to the same
element of P-29047 described above, although it is slightly smaller.
Isolated Hindlimb Elements
The other isolated limb elements from the Snyder quarry consist
of femora and tibiae in various stages of completeness (Tables 1-2).
Of these, one deserves special mention: NMMNH P-54620, a
large right femur missing its distal condyles (Fig. 5A-C). This femur is
considerably larger than all the other material referred to the small
theropod. The length of this element is 235 mm, as preserved. While this
specimen stands out as the largest representative element of the smaller
theropod from the Snyder quarry sample, and equivalent in size to UCMP
129618, it is nevertheless slightly smaller than some of the largest
Coelophysis bauri femora from the Ghost Ranch quarry (the largest of
which we are aware is a ~240 mm long femur in the State Museum of
Pennsylvania block).
Referral to a Single Taxon
We consider these records to all pertain to a single taxon based on
the similarity of like elements, especially the tibiae of NMMNH P-
29047 and NMMNH P-29046, the similarity in overall size and the
various features that are identical to Coelophysis bauri (see below), and
fall well within the range of variation others have documented in
coelophysoid theropods, including C. bauri (Colbert, 1990), C.
rhodesiensis (Raath, 1990) and Megapnosaurus kayentakatae (Tykoski,
1998).
Large Theropod
The larger of the two theropod taxa represented in the quarry,
originally noted by Heckert et al. (2000), is represented by a single
element, NMMNH P-29168, a fused right tibia and fibula with most of
FIGURE 6. A-D, NMMNH P-29046, Coelophysis bauri, left tibia in A, medial, B, lateral, C, proximal and D, distal views. E-I, NMMNH P-29047,
Coelophysis bauri. E-G, proximal left tibia in E, proximal, F, lateral and G, posterior views. H-I, left fibula in H, proximal and I, medial views. J-O,
NMMNH P-29168, large Snyder quarry coelophysoid, fused right tibia/fibula in J, K, posterior, L, M, anterior, N, proximal and O, distal views.
Abbreviations: ac, astragalocalcaneum; ap, ascending process of astragalus; fc, fibular crest; cn, cnemial crest; lp, lateral process of distal tibia.
392
their shafts missing (Fig. 6J-O). The proximal tibia does not have the
cleft along the posterior margin as seen in the smaller individual dis-
cussed above, but it does have a prominent cnemial crest. The fibula is
fused to the lateral condyle of the proximal tibia. The distal tibia and
fibula are fused to the astragalocalcaneum. This fusion is extensive: the
ascending process of the astragalus is barely discernable on the anterior
distal tibia. Just lateral to this process is a prominent groove oriented
ventrolaterally. Also, whereas the distal tibia does have a lateral process,
it does not extend beyond the level of the shaft, and so is not nearly as
extensive as the same feature in the small theropod. We consider this
specimen Coelophysoid indet. based on the presence of a deep fossa on
the craniolateral surface of the ascending process of the astragalus.
COMPARISON OF THE SNYDER THEROPOD MATERIAL
WITH UCMP 129618
Padian (1986) described UCMP 129618, an incomplete skeleton
of a theropod dinosaur, from the Painted Desert Member of the Petrified
Forest Formation, Chinle Group, of the Petrified Forest National Park,
Arizona (UCMP locality V82250). The skeleton includes one dorsal and
one anterior caudal centrum, an incomplete right pelvis (Fig. 7), an in-
complete left ischium, fragmentary femora (Figs. 8-9), both tibiae (Fig.
10), a left fibula (Fig. 10B-E) and right distal tarsals, metatarsals and
phalanges. The specimen was collected in the southwestern portion of
the northern half of Petrified Forest National Park, near Lacey Point at a
location that subsequently came to be known informally as “Dinosaur
Hill.” Fossils from Dinosaur Hill come from the uppermost Kachina
Point Bed and the fine-grained sediments immediately overlying it (Heckert
and Lucas, 2002).
Padian (1986) identified the skeleton as Coelophysis bauri based
on comparisons to Cope’s syntypes of C. bauri, not the neotype. When
comparing UCMP 129618 to the Ghost Ranch material, Padian (1986,
p. 56) noted that “there are differences between the Ghost Ranch and
Petrified Forest specimens that may require taxonomic reevaluation when
full descriptions of the former are published.” With the Ghost Ranch
material now serving as the neotype of C. bauri it is worth reviewing the
comparison to see if Padian’s (1986) initial concerns were warranted.
Padian (1986) was not the only one to have doubts about the assignment
of the UCMP 129618 to C. bauri: Long and Murry (1995) also noted
that UCMP 129618 is “considerably different from the Ghost Ranch
specimens” (p. 187) but did not provide any specific differences. Heckert
and Lucas (1998) considered UCMP 129618 an indeterminate ceratosaur.
Hunt et al. (1998) noted that the presence of an obturator foramen, a
feature that Padian (1986) cited specifically as distinguishing UCMP
129618 from the Ghost Ranch Coelophysis material, was in fact shared
by both taxa. Thus, while many workers have noted a general difference
between the Ghost Ranch Coelophysis material and UCMP 129618, no
specific differences have been enumerated in the literature. In contrast to
these other studies, we find numerous similarities between Coelophysis
and UCMP 129618.
Fortunately, all the major elements that comprise UCMP 129618
– the incomplete hip, femora, tibiae and fibula – are also represented in
the various incomplete skeletons of the small Snyder theropod. The ilia
of both animals have prominent supra-acetabular crests that give their
acetabula a “hooded” appearance. The proximal femora are identical,
sharing a hooked greater trochanter, a triangular anterior trochanter, a
trochanteric shelf that wraps laterally around the femoral shaft and a
sulcus for the capitular ligament. Likewise, the distal femora are also
similar, with prominent, subtriangular tibiofibular crests and prominent
medial epicondyles. The tibiae share the following characteristics: a notch
along the posterior margin of the proximal tibia, prominent cnemial crest
and rhomboid distal tibia with rectangular lateral projection. The fibulae
of UCMP 129618 and the small Snyder theropod are also similar. These
features shared by both taxa are present in the coelophysoids Liliensternus
liliensterni, Coelophysis rhodesiensis and Coelophysis bauri. In addi-
tion, given the close temporal and geographic distribution of these taxa, it
is most parsimonious to assign both to the same taxon.
COMPARISONS WITH COELOPHYSIS BAURI
Utilizing recent phylogenetic analyses of basal theropods (Ezcurra,
2006; Ezcurra and Novas, 2006), examination of Coelophysis bauri ma-
terial from the NMMNH Ghost Ranch quarry block, plus published
descriptions of C. bauri (Colbert, 1989), we compared the small Snyder
theropod and UCMP 129618 to C. bauri. Here, we compare these
theropods to other Late Triassic basal theropods, based on the diagnoses
provided by Ezcurra (2006) and Ezcurra and Novas (2006).
The following characteristics, listed by Ezcurra (2006) and Ezcurra
and Novas (2006) as unambiguous apomorphies of coelophysoids are
possessed by the Snyder/UCMP theropod: angle between rostral margin
and alveolar margin of premaxilla equal or less than 40° (19° in NMMNH
P-30852); presence of a ventral process at the caudal end of premaxiallary
body (which we refer to above as the maxillary process of the premax-
illa); absence of a subnairal foramen; axial diapophysis present; postaxial
cervical neural spines dorsoventrally low; articulation facet of pubic
penduncle of ilium with pronounced kink and cranial part facing almost
entirely cranially. Of note is that the rostral end of the dentary does not
appear to be dorsally expanded; a feature that argues against the Snyder/
UCMP theropod being a coelophysoid. But, since the dentaries of
NMMNH P-30852 are incomplete this is likely the cause of this anoma-
lous feature, especially given the presence of various apomorphies pos-
sessed by the Snyder/UCMP theropod that are characteristic of more
exclusive clades within Coelophysoidea.
The following characteristics are listed by Ezcurra (2006) and
Ezcurra and Novas (2006) as unambiguous apomorphies of the
Coelophysidae (consisting of Coelophysis and Megapnosaurus [=
Syntarsus”]) also possessed by the Snyder/UCMP theropod:
mediolateral width of anterior end of dentary equal to that of caudal part,
caudoventral process of the coracoid tapering and projected beyond the
caudal margin of the glenoid fossa, supraacetabular crest and lateral brevis
fossa continuous as a well developed ridge, with non-distinct separation
between both structures.
The Snyder/UCMP theropod possesses the following character-
istics, listed by Ezcurra (2006) and Ezcurra and Novas (2006) as unam-
biguous apomorphies of Coelophysis: absence of promaxillary foramen,
rostral process of postorbital at about the same level as or slightly higher
than the squamosal process, resulting in a T-shaped postorbital. The
angle of the ascending process of the maxilla in NMMNH P-30852 is
~36° as preserved, although the anterior end of the maxilla in NMMNH
P-30852 is not visible and thus would increase the length of the maxilla,
consequently reducing the angle of the ascending process. This is an
important feature since Ezcurra (2006) and Ezcurra and Novas (2006)
list an angle of the ascending process of the maxilla less than 35° as an
apomorphy of Coelophysis.
Bristowe and Raath (2004) used the width of the base of the
vertical ramus of the lacrimal, being greater than 30% of its height as a
characteristic distinguishing Coelophysis bauri from C. rhodesiensis (al-
though this feature is also present in Eoraptor, Megapnosaurus (=
Syntarsus”) kayentakatae and Zupaysaurus). The presence of this char-
acter in the Snyder/UCMP theropod demonstrates that this material can
be identified to C. bauri. This is the most logical result given that C.
bauri is the only coelophysid reported from Upper Triassic strata in
North America. In addition to the strict character analysis, side-by-side
comparisons of Coelophysis bauri and the Snyder/UCMP theropod show
that they are identical, as noted throughout the description above.
Table 2 demonstrates that all the material discussed above per-
tains to basal theropods, while some material (NMMNH P-29046 and
P-54167l; UCMP 129618) can be identified to the genus Coelophysis.
Only NMMNH P-30852 can be definitively identified as Coelophysis
bauri. However, parsimony would dictate that all the basal theropod
393
FIGURE 7. A-B, UCMP 129618, Coelophysis bauri, partial right pelvis in A, lateral and B, medial view. Note centrum (c) adhered to medial ilium.
394
FIGURE 8. A-I, UCMP 129618, Coelophysis bauri, proximal femora. A-D, right proximal femur in A, anterior, B, posterior, C, medial and D, lateral
views. E-I, left proximal femur in E, proximal, F, anterior, G, posterior, H, medial and I, lateral views.
material from the Snyder quarry is assignable to a single taxon. We be-
lieve it is most parsimonious to assign this material to Coelophysis bauri
because none of the aforementioned taxa, other than Coelophysis and
Camposaurus, existed in the Late Triassic of North America as far as is
currently known.
THE BIOSTRATIGRAPHIC RANGE OF COELOPHYSIS BAURI
Coleophysis bauri was previously known only from the Ghost
Ranch Whitaker quarry, Rio Arriba County, New Mexico, in the Rock
Point Formation. The Rock Point Formation is of Apachean age (late
395
FIGURE 9. A-H, UCMP 129618, Coelophysis bauri, distal femora. A-D, left distal femur in A, posterolateral, B, medial, C, lateral and D, proximal views.
E-H, right distal femur in E, anterior, F, posterior, G, medial and H, distal views.
396
FIGURE 10. A-I, UCMP 129618, Coelophysis bauri, tibiae and fibula. A-E, left tibia and fibula in A, lateral, B, anterior, C, posterior, D, proximal and E,
distal views. F-I, right tibia in F, medial, G, lateral, H, proximal and I, distal views.
397
TABLE 2. Specimens discussed in the text, with list of diagnostic characters and taxon to which the individual specimen can be identified.
Norian-Rhaetian?) (Lucas and Tanner, 2007). The presence of the
phytosaur Redondasaurus in the Whitaker quarry fauna (Rinehart et al.,
2004) demonstrates that the assemblage pertains to the Apachean land-
vertebrate faunachron (lvf) of Lucas and Hunt (1993).
The Snyder quarry is stratigraphically lower than the Whitaker
quarry. It is in the upper part of the Painted Desert Member of the
Petrified Forest Formation (Lucas et al., 2003, 2005). The fauna of the
Snyder quarry includes the aetosaur Typothorax coccinarum and the
phytosaur Pseudopalatus buceros, both of which indicate a Revueltian
(early-middle Norian) age (Heckert et al., 2005).
UCMP 129618 was recovered from strata low in the Painted
Desert Member of the Petrified Forest Formation, Petrified Forest Na-
tional Park, Arizona (Heckert and Lucas, 2002). This record of
Coelophysis bauri, like the Snyder quarry record, also is Revueltian.
These additional records extend the biostratigraphic range of
Coelophysis bauri from Apachean to early Revueltian (Fig. 11). This
indicates that the temporal range of C. bauri encompasses much of
Norian time. Thus, the biostratigraphic utility of C. bauri is reduced, and
it is no longer an index fossil of the Apachean (e.g., Lucas, 1998).
ACKNOWLEDGMENTS
The late John Estep photographed UCMP 129618. Numerous
volunteers of the New Mexico Museum of Natural History and Science
helped in the excavation and preparation of the Snyder quarry material.
Martin D. Ezcurra and Jerry D. Harris provided reviews that improved
the manuscript.
398
FIGURE 11. Biostratigraphic distribution of Coelophysis bauri occurrences in the southwestern USA. See text for discussion.
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Measurements (in mm) of selected elements from the Snyder quarry Coelophysis bauri sample and UCMP 129618. In reference to proximal and distal limb
bones, the length is an anteroposterior measurement, whereas the width is a mediolateral measurement. Midshaft diameter is midshaft length/midshaft
width. Abbreviations: AP = as preserved; NA = not applicable, indicating a feature is not preserved in a specimen; NM = not measured, the feature is present
but due to preservation cannot be measured; * = based on metrics in Padian (1986); ** = measurements of NMMNH C-3086 a cast of the right ilium,
proximal and distal femora, both tibiae and left fibula of UCMP 129618.
APPENDIX
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... Fibula of Sanjuansaurus is slightly bowed anterolaterally (Alcober & Martínez 2010). More similar to Velocipes is proximal part of fibula referred to Coelophysis bauri by Spielmann et al. (2007a), which is strongly asymmetrical in lateral view, with curvature of anterior and posterior margins very similar to Velocipes. It differs, however, in being more rectangular in proximal view, in contrast to triangular (comma-shaped) shape of Velocipes. ...
... 51;Hutchinson 2002, fig. 2c;Spielmann et al. 2007a, fig. 6 H). ...
... 6 H). Similar to Velocipes is a theropod skeleton described by Padian (1986), which was referred questionably to Coelophysis (for a review, see Nesbitt et al. 2007 andSpielmann et al. 2007a), but is larger and more robust than Ghost Ranch material and similar to 'Gojirasaurus' in tibial proportions (Padian 1986;Nesbitt et al. 2007;Spielmann et al. 2007a). Its fibula may bear prominent attachment site for M. iliofibularis, but this condition may be a Downloaded by [University of Wroclawski] at 03:08 06 November 2017 ...
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The so-called historical Polish discoveries of Triassic ‘dinosaurs’ have been repeatedly cited in papers and popular science books. Here, we re-evaluate each historical and purported Triassic dinosaur find from Poland. Additionaly, we describe several supposed ‘dinosaur’ bones collected by Polish geologists but only briefly mentioned: in regional geological journals, on collection labels, or in field notes. We attempt to assign all investigated specimens to the least inclusive taxon possible. Our revision indicates that part of this material represents non-dinosaur archosauromorph taxa. Most of the analysed specimens are fragmentary bones or isolated teeth and are indistinguishable from skeletal elements described from other well-known Triassic archosauromorph taxa. We conclude that fossils of dinosauriforms are present in the Upper Triassic of Silesia and Holy Cross Mountains. New analysis of Velocipes guerichi von Huene, 1932 holotype specimen from Kocury shows that it is the proximal part of fibula of a medium-sized theropod (or even neotheropod). Formally undescribed part of dinosauriform limb bone from the Holy Cross Mountains and V. guerichi from Silesia are the only identifiable dinosauromorph skeletal remains recognised in the Polish Triassic discovered prior to the description of Silesaurus opolensis Dzik, 2003 from the Upper Carnian of Krasiejów.
... Unfortunately, the other vertebrates from the Coelophysis quarry do not provide a precise age within the Late Triassic, as all of the fish, Hesperosuchus, Postosuchus, and Vancleavea have long temporal ranges (e.g., Huber et al., 1993;Long and Murry 1995;Lucas 1997;Milner et al., 2006;Hunt et al., 2002Hunt et al., , 2005. Coelophysoid theropods are extremely difficult to identify at the generic level and have a stratigraphic range from the Carnian to the Hettangian (early Late Triassic to Early Jurassic) (Heckert and Lucas, 2000;Tykoski and Rowe, 2004;Spielmann et al., 2007). Shuvosaurus okeeffeae and Whitakersaurus bermani have only been found at the Coelophysis quarry, and thus are not biostratigraphically useful, and other records of Shuvosaurus (S. inexpectatus) are from strata of older, Revueltian, age in West Texas (Lucas et al., 2007a). ...
... We thus attempt here to extract growth, allometry, variation, age and mass distribution, and survivorship information from our database of the Ghost Ranch population of Coelophysis bauri. This study is intended to reflect the characteristics of this single population, so data from other Coelophysis occurrences (e.g., Spielmann et al., 2007) are not included in the analysis. ...
... The specimen possesses a pronounced fibular crest on the lateral side of the tibia that extends up to the proximal end of the tibia and ends distally as a bulbous expansion ( Figure 3F). This same expansion appears in Allosaurus fragilis, Dilophosaurus wetherilli, Megalosaurus bucklandi (OUMNH J.13575) and Piatnitzkysaurus floersi, inter alia, but is not present in Coelophysis bauri (e.g., NMMNH P-29046, Spielmann et al., 2007) or the contemporaneous Sarcosaurus woodi (WARMS G668, WARMS G680; Ezcurra et al., 2020). Parallel to this is a sharp proximodistally oriented crest on the lateral margin of the proximal end of the tibia. ...
... The fibular crest in particular is diagnostic, extending well into the proximal end of the tibia on BELUM K12493. This is the basal condition for theropods and is present in coelophysoids (Spielmann et al., 2007), dilophosaurids (Welles, 1984), other averostran-line taxa such as Sarcosaurus (Ezcurra et al., 2020), as well as ceratosaurians (Madsen and Welles, 2000;O'Connor, 2007). Among tetanurans only some megalosauroids are known to possess such a proximally extended fibular crest (Benson, 2010a;Madsen, 1976;Malafaia et al., 2018). ...
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Several specimens from the Lias Group (Lower Jurassic) of Northern Ireland have been suspected as dinosaurian in origin. Bone histology and morphology demonstrates that two of these, both from the same locality in Co. Antrim, demonstrably are from dinosaurs. We interpret one as the proximal end of the left femur of a basal thyreophoran ornithischian, and tentatively assign it to cf. Scelidosaurus. The other is the proximal part of the left tibia of an indeterminate neotheropod, perhaps a member of the averostran-line similar to Sarcosaurus, or a megalosauroid. These are the first dinosaur remains reported from anywhere in Ireland and some of the most westerly in Europe, and they are among only a small number of dinosaurs known from the Hettangian Stage. Two additional specimens are no longer considered to be from dinosaurs. We interpret one as a surangular or mandible fragment from a large marine reptile, perhaps an ichthyosaur or pliosaur; the other is a polygonal fragment of Paleocene basalt.
... The author reports that it is relatively common, however, for the last sacral of the series to be non-fused, or in some cases, the last two. Concerning the neural spines, Coelophysis and Megapnosaurus also present considerable variation, with specimens showing free spines (Spielmann et al., 2007), and others with the five spines forming a single fused bar, as in some Ornithischia (Griffin, 2018). Although some authors (Colbert, 1989;Rinehart et al., 2009) suggested that variation in the degree of sacral spines fusion may be evidence of sexual dimorphism, the presence of intermediate stages reinforces at least some ontogenetic control (Griffin, 2018;Griffin & Nesbitt, 2016;Raath, 1990). ...
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Full-text available
The fusion of the sacrum occurs in the major dinosaur lineages, i.e. ornithischians, theropods, and sauropodomorphs, but it is unclear if this trait is a common ancestral condition, or if it evolved independently in each lineage, or even how or if it is related to ontogeny. In addition, the order in which the different structures of the sacrum are fused, s well as the causes that lead to this co-ossification, are poorly understood. Herein, we escribed the oldest record of fused sacral vertebrae within dinosaurs, based on two primordial sacral vertebrae from the Late Triassic of Candelária Sequence, southern Brazil. We used computed microtomography (micro-CT) to analyze the extent of vertebral fusion, which revealed that it occurred only between the centra. We also assessed the occurrence of sacral fusion in Dinosauria and close relatives. The degree of fusion observed in representatives of the major dinosaur lineages suggested that there may be a sequential pattern of fusion of the elements of the sacrum, more clearly observed in Sauropodomorpha. Our analyses suggest that primordial sacral vertebrae fuse earlier in the lineage (as seen in Norian sauropodomorphs). Intervertebral fusion is observed to encompass progressively more vertebral units as sauropodomorphs evolve, reaching up to five or more fully fused sacrals in Neosauropoda. Furthermore, the new specimen described here indicates that the fusion of sacral elements occurred early in the evolution of dinosaurs. Factors such as ontogeny and the increase in body size, combined with the incorporation of vertebrae to the sacrum may have a significant role in the process and in the variation of sacral fusion observed.
... However, using an explicitly apomorphy-based approach to specimen identification, Nesbitt et al. (2007) concluded that dinosaurs were much less common and diverse in Late Triassic strata in North America than originally posited. Earlier reports (Long & Murry, 1995) were, for the most part, based on skeletal remains that are either inadequate for definitive identification or indistinguishable from corresponding bones in the only well-documented Late Triassic theropod taxon from North America, Coelophysis bauri Cope, 1887 (also see: Spielmann et al., 2007). Nesbitt et al. (2007) showed that none of the currently known Triassic dinosaurian remains from North America can definitely be assigned to Sauropodomorpha. ...
Article
The early evolution of dinosaurs is documented by abundant postcranial material, but cranial material is much rarer and comparisons of cranial features among early dinosaurs are limited to only a few specimens. Here, we fully detail the osteology of the unusual early-diverging dinosaur Daemonosaurus chauliodus from the latest Triassic Coelophysis Quarry in northern New Mexico, USA. The taxon possesses a unique and curious suite of character states present in a variety of early dinosaurs, and the morphology of D. chauliodus appears to link the morphology of Herrerasaurus with that of later diverging eusaurichians. Our phylogenetic analyses places D. chauliodus at the base of dinosaurs and our interpretation of the unusual mix of character states of D. chauliodus does not lead to a firm conclusion about its nearest relationships or its implications for the evolution of character state transitions at the base of Dinosauria. The combination of character states of D. chauliodus should not be ignored in future considerations of character evolution in early dinosaurs. As one of the last members of the earliest radiation of saurischians in the Carnian–early Norian, D. chauliodus demonstrates that members of the original diversification of dinosaurs survived until nearly the end of the Triassic Period.
... The Late Triassic is marked by the first appearance of mammals, dinosaurs, lepidosaurs, pterosaurs, turtles, crocodiles, and lissamphibians (Benton, 2004), of which the dinosaurs became one of the most important tetrapod groups of Mesozoic terrestrial ecosystems (Nesbitt et al., 2009;Ezcurra, 2012). Sporadic occurrences of the Late Triassic dinosaurs are known mostly from the different stratigraphic horizons of the Gondwanan countries such as Argentina, Brazil, South Africa, and India (Nesbitt et al., 2009;Ezcurra, 2012;Sereno, 2012), though basal forms are also known from Germany, Switzerland, France, England, and North America (Sander, 1992;Nesbitt et al., 2007;Spielmann et al., 2007;Rinehart et al., 2009). Most of these Late Triassic dinosaurs were quadrupedal and facultatively bipedal, small in size ranging from 2 to 9 m in body length and were essentially omnivores and herbivores (Brusatte et al., 2010;Langer et al., 2010;Galton, 2014;Baron et al., 2017). ...
Article
The Late Triassic Tiki Formation has yielded five isolated nearly complete claws or ungual phalanges from a fossil locality, which are described in detail and compared with other Late Triassic tetrapods. Of these, four ungual phalanges are slender, asymmetric, ventrally recurved, transversely compressed, and contain deep collateral grooves on either side, a low median keel on the proximal articular surface and a prominent proximoventral flexor tubercle showing their high similarity to the theropod dinosaurs. The remaining claw is unlike that of any theropods in terms of high robusticity and near symmetry. However, as in dinosaurs it is ventrally recurved and contains deep lateral grooves, a small flexor tubercle, lateromedially extended proximal articular surface with a distinct median keel and is considered as belonging to an indeterminate dinosaur. Although it is not possible to ascertain whether the unguals belong to a single taxon or multiple taxa, this new find points towards the presence of small dinosaurs in the Late Triassic Tiki fauna.
... Hayden (H2, H3, H4), Canjilon (UCMP V2816) and Snyder (NMMNH L-3845) quarries have produced various basal theropod and neotheropod specimens (e.g. Hunt & Lucas 1989;Heckert et al. 2003;Lucas et al. 2003;Irmis et al. 2007;Nesbitt et al. 2007;Spielmann et al. 2007;Nesbitt & Stocker 2008;Nesbitt et al. 2009;Whiteside et al. 2015). The uppermost quarry of the Chinle Formation with dinosaur fossils is the Whitaker Quarry (NMMNH L-3115) which is placed in the overlying 'Upper Siltstone' Member (e.g. ...
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Three small and gracile jaw fragments are recovered from the Boren Quarry, one of the lowest fossil quarries of the Upper Triassic Dockum Group of Texas. The specimens are referred to archosauromorphs, where the morphology of the dentary and teeth of two specimens resemble what is observed in basal saurischians. Growing numbers of early dinosaur fossils from the lowest quarries of the Dockum Group of Texas which correspond to the lowermost Norian raises doubts concerning early dinosaur dispersal during the late Carnian-early Norian interval and the first occurrence of North American dinosaurs which might have happened earlier than previously suggested.
Article
In the early 1990s a theropod dinosaur found close to the Triassic-Jurassic boundary of France was assigned to a second species of the genus Liliensternus: L. airelensis (Moon Airel Formation). This contribution reveals that common features that purportedly unite “L.” airelensis with L. liliensterni are more widely distributed among coelophysoids and basal dinosaurs than it was thought. A cladistic analysis reveals that “L.” airelensis is more closely related to the Coelophysidae than to L. liliensterni. A feature that supports this systematic arrangement includes a supraacetabular crest forming a well-developed ridge continuous with the lateral margin of the brevis fossa, with nondistinct notch between both structures. The new genus Lophostropheus, gen. nov., is therefore erected to include the species L. airelensis. Thus, the new combination Lophostropheus airelensis is proposed.