Aetosaurs (Archosauria:Stagonolepididae) from the Upper Triassic (Revueltian) Snyder Quarry

ASU Author/Contributor (non-ASU co-authors, if there are any, appear on document)
Andrew B. Heckert Ph.D., Professor (Creator)
Appalachian State University (ASU )
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Abstract: Two species of aetosaurs are known from the Snyder quarry (NMMNH locality 3845): Typothorax coccinarum Cope and Desmatosuchus chamaensis Zeigler, Heckert, and Lucas. Both are represented entirely by postcrania, principally osteoderms (scutes), but also by isolated limb bones. Aetosaur fossils at the Snyder quarry are, like most of the vertebrates found there, not articulated. However, clusters of scutes, presumably each from a single carapace, are associated. Typothorax coccinarum is an index fossil of the Revueltian landvertebrate faunachron (lvf) and its presence was expected at the Snyder quarry, as it is known from correlative strata throughout the Chama basin locally and the southwestern U.S.A. regionally. The Snyder quarry is the type locality of D. chamaensis, which is considerably less common than T. coccinarum, and presently known from only one other locality. Some specimens we tentatively assign to D. chamaensis resemble lateral scutes of Paratypothorax, but we have not found any paramedian scutes of Paratypothorax at the Snyder quarry, so we refrain from identifying them as Paratypothorax. Specimens of both Typothorax and Desmatosuchus from the Snyder quarry yield insight into the anatomy of these taxa. Desmatosuchus chamaensis is clearly a species of Desmatosuchus, but is also one of the most distinctive aetosaurs known. Both species of aetosaur from the Snyder quarry appear to be anagenetic descendants from more primitive members of the same genus, D. chamaensis from D. haplocerus (Cope) and T. coccinarum from T. antiquum Lucas, Heckert, and Hunt.

Additional Information

Heckert, A.B., Zeigler, K.E., and Lucas, S.G., (2003) Aetosaurs (Archosauria:Stagonolepididae) from the Upper Triassic (Revueltian) Snyder Quarry. New Mexico: New Mexico Museum of Natural History and Science Bulletin 24 (Paleontology and Geology of the Upper Triassic (Revueltian) Snyder Quarry, New Mexico) p. 115-126. (ISSN 1524-4156) Archived in NC DOCKS with permission of the editor. The version of record is available at:
Language: English
Date: 2003

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