A new species of the aetosaur Typothorax (Archosauria: Stagonolepididae) from the Upper Triassic of east-central New Mexico.

ASU Author/Contributor (non-ASU co-authors, if there are any, appear on document)
Andrew B. Heckert Ph.D., Assistant Professor of Geology (Creator)
Institution
Appalachian State University (ASU )
Web Site: http://www.library.appstate.edu/

Abstract: We describe an incomplete skeleton of a new species of the aetosaur Typothorax, T.antiquum, from the Los Esteros Member of the Santa Rosa Formation near Lamy, Santa Fe County, New Mexico. Features that diagnose T. antiquum from the type and only other species of Typothorax, T. coccinarum Cope, are the relatively narrow paramedian scutes (width: length ratio ~2-3), coarser and less dense pitting on the dorsal paramedian scutes, more pronounced radial ridges on the dorsal lateral scutes, and a more robust ilium, with more prominent and thicker peduncles, lateral buttress and iliac blade. We also refer incomplete scutes and scute fragments from the Garita Creek Formation in east-central New Mexico to T. antiquum. Typothorax scutes from the overlying Trujillo Formation in east-central New Mexico pertain to T.coccinarum and are the stratigraphically lowest occurrence (LO) of that taxon. The LO of T. antiquum is older (Adamanian: latest Carnian) than the LO of the much more common T. coccinarum (Revueltian: early-mid Norian). T. antiquum is a relatively rare Adamanian aetosaur and thus has limited biochronological utility. The morphology and temporal distribution of Typothorax species suggests they represent a single, anagenetic lineage, with T. antiquum directly ancestral to T. coccinarum.

Additional Information

Publication
Lucas, S.G., Heckert, A.B., and Hunt, A.P., (2002) A new species of the aetosaur Typothorax (Archosauria: Stagonolepididae) from the Upper Triassic of east-central New Mexico. New Mexico Museum of Natural History and Science Bulletin 21, p. 221-234. (ISSN 1524-4156) Archived in NC DOCKS with permission of the editor. The version of record is available at: http://econtent.unm.edu/
Language: English
Date: 2002