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The distribution of the enigmatic reptile Vancleavea in the Upper Triassic Chinle Group of the Western United States
... Referred specimens: NMMNH P-36150, morphotype B osteoderm (Fig. 28C); NMMNH P-37451, right ilium ( Fig. 28A-B Description: NMMNH P-36150 and all the YPM specimens were included in the Vancleavea campi referred specimen list of Nesbitt et al. (2009). Spielmann et al. (2006a) included illustration and brief description of NMMNH P-36150 (Fig. 28C), following Hunt et al. (2002Hunt et al. ( , 2005. Based on the more complete V. campi specimen described by Nesbitt et al. (2009), NMMNH P-36150 is a morphotype B osteoderm from the ventral region of the carapace. ...
... It also includes the sphenodont Whitakersaurus, the archosauriform Vancleavea, at least one drepanosaur, a rauisuchian skeleton (cf. Postosuchus), the sphenosuchian Hesperosuchus, the chatterjeeid Shuvosaurus (= Effigia) and the phytosaur Redondasaurus (e.g., Hunt and Lucas, 1993a;Clark et al., 2000;Harris and Downs, 2002;Hungerbühler, 2002;Hunt et al., 2002;Lucas et al., 2003Lucas et al., , 2005Rinehart et al., 2004;Nesbitt, 2007;Heckert et al., 2008;Renesto et al., 2009). It should be noted that the Redondasaurus "bermani" specimen was collected just above the main level of the Whitaker quarry, during overburden removal (David Berman pers. ...
... Whereas some authors have questioned the validity of this taxon (e.g., Long andMurry 1995), others (e.g., Hungerbühler 2002;Spielmann et al., 2006) recognize it as valid, which, combined with its stratigraphic distribution, validates its utility as an index taxon of the Apachean land-vertebrate faunachron (Lucas, 1998;Lucas et al., 2007b). 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). ...
... Subsequently, Small and Downs (2002) referred to this fossil as an unusual archosauriform, but made no more precise identification. Hunt et al. (2002) identified it as Vancleavea campi, a taxon previously known from an incomplete postcranium that includes very specialized and distinctive osteoderms (e.g., Long and Murry, 1995;Hunt et al., 2005). A complete description of RHM GR 138 was recently published ). ...
... Vancleavea campi was first described from an incomplete postcranial skeleton (Murry and Long 1989) and has proven to be abundant in the Late Triassic of the southwestern United States (Hunt et al. 2002(Hunt et al. , 2005Parker and Barton 2008;Parker and Martz 2011). More recently discovered specimens, including a complete skeleton, have revealed the truly bizarre morphology of this taxon, with several adaptations for a semi-aquatic lifestyle (Small and Downs 2002;Nesbitt et al. 2009a). ...
Trace fossils such as bite marks provide rare, direct evidence of animal behavior, including predator-prey interactions. We present an osteoderm of the aetosaur Typothorax coccinarum from the Late Triassic Chinle Formation of Arizona with several punctures and scores, interpreted here as bite marks, preserved as evidence of predation/scavenging by a large carnivore. The marks include a single bite producing four subparallel fusiform pits on the ventral surface and several additional marks, including striated scores, on the dorsal surface. These traces are described and compared with known contemporaneous carnivorous taxa to determine the source of the bite marks. Some Triassic carnivores, including theropod dinosaurs can be ruled out because of tooth shape and serration densities. Phytosaurs and large paracrocodylomorphs remain as likely candidates based on tooth morphology. Although some phytosaur teeth are too rounded to produce the marks seen in this specimen, we demonstrate that the more lingually flattened teeth typically found in the posterior section of the snout are sufficiently mediolaterally compressed to produce a fusiform pit. A protective function for aetosaur osteoderms cannot be confirmed presently, but the extensive carapace these bones formed would have been a major barrier to both scavengers and active predators and may preserve more feeding/predation traces than previously thought. The bite marks described herein support the hypothesis that aetosaurs were prey items of large archosauromorphs, expanding our understanding of the complex, and seemingly carnivore dominated Late Triassic terrestrial ecosystems of North America.
... Case made a small collection here that he catalogued as UMMP (University of Michigan Museum of Paleontology) 7441. UMMP 7441 is a collection of fragmentary specimens that Case identified as "fragments, limb bones, vertebrae, etc. of small phytosaurs" but that actually encompasses at least seven taxa, including Vancleavea (Hunt et al., 2002). UMMP 7441 also includes the proximal left femur of a crurotarsan. ...
... Nevertheless, it also includes scales of redfieldiid and coelacanthid fishes, sphenodont jaw fragments, a rauisuchian skeleton (cf. Postosuchus), a skeleton of the archosaur Vancleavea, a skull, skeleton and other fossils of the sphenosuchian Hesperosuchus and skulls of the phytosaur Redondasaurus Clark et al., 2000;Hungerbühler, 2002;Hunt et al., 2002;Rinehart et al., 2004). ...
The early evolution of archosauromorphs during the Permo-Triassic constitutes an excellent empirical case study to shed light on evolutionary radiations in deep time and the timing and processes of recovery of terrestrial faunas after a mass extinction. However, macroevolutionary studies of early archosauromorphs are currently limited by poor knowledge of their phylogenetic relationships. In particular, one of the main early archosauromorph groups that need an exhaustive phylogenetic study is “Proterosuchia,” which as historically conceived includes members of both Proterosuchidae and Erythrosuchidae. A new data matrix composed of 96 separate taxa (several of them not included in a quantitative phylogenetic analysis before) and 600 osteological characters was assembled and analysed to generate a comprehensive higher-level phylogenetic hypothesis of basal archosauromorphs and shed light on the species-level interrelationships of taxa historically identified as proterosuchian archosauriforms. The results of the analysis using maximum parsimony include a polyphyletic “Prolacertiformes” and “Protorosauria,” in which the Permian
Aenigmastropheus
and
Protorosaurus
are the most basal archosauromorphs. The enigmatic choristoderans are either found as the sister-taxa of all other lepidosauromorphs or archosauromorphs, but consistently placed within Sauria. Prolacertids, rhynchosaurs, allokotosaurians and tanystropheids are the major successive sister clades of Archosauriformes. The Early Triassic
Tasmaniosaurus
is recovered as the sister-taxon of Archosauriformes. Proterosuchidae is unambiguosly restricted to five species that occur immediately after and before the Permo-Triassic boundary, thus implying that they are a short-lived “disaster” clade. Erythrosuchidae is composed of eight nominal species that occur during the Early and Middle Triassic. “Proterosuchia” is polyphyletic, in which erythrosuchids are more closely related to
Euparkeria
and more crownward archosauriforms than to proterosuchids, and several species are found widespread along the archosauromorph tree, some being nested within Archosauria (e.g., “
Chasmatosaurus ultimus
,”
Youngosuchus
). Doswelliids and proterochampsids are recovered as more closely related to each other than to other archosauromorphs, forming a large clade (Proterochampsia) of semi-aquatic to aquatic forms that includes the bizarre genus
Vancleavea
.
Euparkeria
is one of the sister-taxa of the clade composed of proterochampsians and archosaurs. The putative Indian archosaur
Yarasuchus
is recovered in a polytomy with
Euparkeria
and more crownward archosauriforms, and as more closely related to the Russian
Dongusuchus
than to other species. Phytosaurs are recovered as the sister-taxa of all other pseudosuchians, thus being nested within Archosauria.
The Triassic vertebrate paleontological record of New Mexico includes important assemblages of tetrapod fossils from both the Middle Triassic Moenkopi Formation and the Upper Triassic Chinle Group. The Anton Chico Member of the Moenkopi Formation preserves primarily temnospondyl amphibian body fossils, but the record of reptiles comprises both sparse body fossil assemblages and more abundant track assemblages, mostly of chirotheriid reptiles. A bonebed accumulation of temnospondyls assigned to Eocyclotosaurus appetolatus is particularly notable. The Upper Triassic Chinle Group in New Mexico preserves an array of vertebrate faunal assemblages that represent the entirety of Chinle “time,” and includes numerous bonebeds of Revueltian age as well as the best records of Apachean vertebrates in the American West. These include the characteristic assemblages of the Revueltian and Apachean land-vertebrate faunachrons.
Vancleavea campi is an unusual archosauriform taxon present throughout the Adamanian-Apachean interval of the Chinle Group. We photographically illustrate and redescribe the holotype from the Adamanian (latest Carnian) Blue Mesa Member of the Petrified Forest Formation at Petrified Forest National Park. Vancleavea campi displays apomorphies that include tall, narrow osteoderms with a bifurcate base and a smooth surface texture and smooth, flat osteoderms with a dorsal ridge, as well as the combination of these derived-aspect osteoderms with underived-aspect limb and girdle elements. Vancleavea has aquatic adaptations including dorsally-directed (non-terminal) external nares, an elongate body with short limbs and upright-standing osteoderms (sculling tail), although many specimens of this taxon are found in association with terrestrial faunas.
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