New information on the braincase and mandible of Coahomasuchus (Archosauria: Aetosauria) from the Otischalkian (Carnian) of Texas

DESOJO, J.B; HECKERT, A.

NEUES JAHRBUCH FUR GEOLOGIE UND PALAONTOLOGIE-ABHANDLUNGEN

E. Schweizerbart'sche Verlagsbuchhandlung, Science Publishers

Lugar: Stuttgart; Año: 2004 vol. 2004 p. 605 - 616

0077-7749

The aetosaur genus Coahomasuchus Heckert & Lucas, 1999 is known from a ingle specimen from the Colorado City Formation (Upper Triassic: Late Carnian) of the Chinle Group. New data on the braincase and mandible, as well as a revised diagnosis, are presented. The preserved braincase region includes all or parts of the parasphenoid, basisphenoid, basioccipital, and opisthotic, all of which are described here. The preserved mandible includes a small fragment of the dentary, splenial, angular, surangular, articular, and prearticular. This new cranial description is intended to provide more information on this taxon for future studies on the interrelationships of the Aetosauria. We document that some characters used to discriminate some aetosaurian taxa, such as the presence or absence of a ventral depression on the basisphenoid and a laterally exposed splenial, should not be used in future phylogenetic analyses of aetosaurs.