Revision of the basal Triassic dicynodont Vinceria andina (Therapsida, Dicynodontia) of Argentina

DOMNANOVICH, NADIA; MARSICANO, CLAUDIA

San Juan

Jornada; XXII Jornadas Argentinas de Paleontología de Vertebrados; 2006

The Middle Triassic taxon Vinceria andina Bonaparte corresponds to a small-sized dicynodont that was exhumed in levels of the Middle Triassic Cerro de las Cabras Formation (Mendoza, Argentina). It was originally included in the cosmopolitan Kannemeyeriidae although, in more recent phylogenetic analyses of known representatives of Triassic dicynodonts, Vinceria is, instead, related with taxa from China, Tanzania, and Russia, in the basal family Shansiodontidae. Nevertheless, the internal relationships of this basal group of Middle Triassic dicynodonts is poorly understood mainly because the lack of accurate descriptions of the known specimens. Moreover, a recent evaluation of the kannemeyeriids from South Africa has proposed that Vinceria is a junior synonym of Kannemeyeria and thus, not a valid taxon. A revision of the taxonomic status of the Argentinian dicynodonts is currently undergoing. Preliminary results confirms previous assumptions that Vinceria andina is a valid taxon. Also, the studied material exhibit several characters in the skull, as the equal size of the preorbital (plus orbital) and postorbital regions, the wide and blunt snout, the structure of the intertemporal bar, the robust zygomatic arches and postorbital bars, that closely related it with the Shansiodontidae and clearly distinguished Vinceria from Kannemeyeria and its relatives.