Phylogenetic relationships of the Triassic theropod Zupaysaurus rougieri from NW Argentina

EZCURRA, M. D.; NOVAS, F. E.

Historical Biology

Taylor & Francis

Lugar: London; Año: 2007 vol. 19 p. 35 - 72

1029-2381

The anatomy and phylogenetic relationships of the Upper Triassic theropod Zupaysaurus rougieri are reviewed. This taxon isrepresented by a nearly complete skull and fragmentary postcranial remains recovered from the Los Colorados Formation(Norian), NWArgentina. Originally, Zupaysaurus rougieri was considered a basal member of the Tetanurae, but its anatomyclosely resembles that of the Coelophysoidea, supporting its nesting within this theropodan subclade. Thus reinterpreted,Zupaysaurus represents the first record of coelophysoids in South America. Phylogenetic analyses perfomed in this studydepict Zupaysaurus as a non-coelophysid coelophysoid. Autopomorphic traits of Zupaysaurus include: maxillary-jugal ventralmargin forming an obtuse angle in lateral view, tibia with a very deep and caudally open caudal fossa for the reception of anastragalar caudal process. Within the phylogenetic context outlined here, the derived features shared with Tetanurae (e.g.maxillary fenestra, caudally forked ascending ramus of the maxilla) are better interpreted as homoplasies rather than tetanuranderived features.