Material postcraneano de Proterochampsa barrionuevoi Reig 1959 (Diapsida: Archosauriformes) del Triásico Superior del centro-oeste de Argentina

TROTTEYN, MARÍA JIMENA

AMEGHINIANA

ASOCIACION PALEONTOLOGICA ARGENTINA

Año: 2011 vol. 48 p. 424 - 446

0002-7014

Proterochampsids are members of the clade Archosauriformes, a group distinguished from others because of its depressed skulls transversely expanded at the posterior end, narrow and longitudinally long snout, nares located close to the midline, absence of postfrontals, and presence of an assymmetric pes. The family Proterochampsidae includes five genera recorded in Triassic formations of Argentina and Brazil. In this family is included the Argentinean species Proterochampsa barrionuevoi Reig, from the Late Triassic Ischigualasto Formation. This taxon was known from skulls and cervical vertebrae, but the rest of the postcranium remained unknown until now. Herein, a new and almost complete specimen of Proterochampsa barrionuevoi is described in detail (PVSJ 606). The specimen includes skull, complete vertebral series, scapulae, coracoids, pelvic girdle, right humerus, right radius and ulna, both femora, and complete right hindlimb. An emended diagnosis considering neurocranial features –semilunar depression ventrolaterally exposed, basisphenoidal fossa surround by a rostrolateraly V-shaped ridge with convex branches– is provided. The features distinguishing P. barrionuevoi from the Brazilian species P. nodosa are: snout becoming narrow anteriorly in a less gradual manner than in P. nodosa, lower occiput, nares lanceolate with narrow anterior and posterior ends, and frontal less irregular that in P. nodosa.