NEW INFORMATION ABOUT THE ANATOMY AND PHYLOGENETIC RELATIONSHIPS OF SKORPIOVENATOR BUSTINGORRYI CANALE ET AL. (THEROPODA, CERATOSAURIA) FROM THE UPPER CRETACEOUS OF NEUQUÉN PROVINCE, PATAGONIA, ARGENTINA

CANALE JUAN IGNACIO; NOVAS, FERNANDO EMILIO

Dallas

Congreso; 75th Society of Vertebrate Paleontology Meeting; 2015

Society of Vertebrate Paleontology

Skorpiovenator bustingorryi Canale et al. (MMCh PV 48) from the Huincul Formation (Cenomanian) of Neuquén province, Patagonia, Argentina is one of the best-represented abelisauroid theropods ever found. After years of technical preparation we conducted an osteological analysis of the specimen, allowing the recognition of many anatomical cranial and postcranial traits. As in other ceratosaurs, the opening for basisphenoid recess is teardrop-shaped. A trait shared with other abelisaurids like Carnotaurus and Majungasaurus is the presence of a slight median bulge ventrally pronounced on the posteroventral surface of basioccipital. As in Carnotaurus and Abelisaurus the tips of paraoccipital processes are dorsolaterally projected, contrasting with the laterally projected processes seen in Majungasaurus. The anterodorsal border of the neural spine of the axis is convex as in Carnotaurus, different from the slightly concave condition in Majungasaurus. The ventral margin of the mid-sacral centra is strongly dorsally arched, as in Carnotaurus, contrasting with the straight margin observed in Rajasaurus. The femoral fourth trochanter is a moderately elevated crest as in Ekrixinatosaurus and Aucasaurus, but not the strongly reduced process observed in Rahiolisaurus and Majungasaurus. The popliteal fossa of femur is traversed by infrapopliteal ridge between medial condyle and tibiofibular crest, as in Carnotaurus, Quilmesaurus and Ekrixinatosaurus, contrasting to the smooth condition seen in Rajasaurus. Metatarsal III is T-shaped in proximal view, as in Aucasaurus, lacking the strong caudal buttress seen in Majungasaurus and Rahiolisaurus. We incorporated the revised scorings of the holotype and other South American abelisaurids (220 modified scorings in total) in an existing matrix of 40 taxa and 326 morphological characters. The analysis was run in TNT (1.1), giving 20 MPT´s of 742 steps. A consensus tree was obtained, excluding the highly fragmentary and poorly known Tarascosaurus, "Pourcieux" and "La Boucharde" abelisaurids. Skorpiovenator was recovered deeply nested in a small clade of other Cenomanian-Turonian abelisaurids from Patagonia (including Ilokelesia and Ekrixinatosaurus), sister group of Carnotaurini. Notably, all the South American abelisaurids are recovered as members of the clade Brachyrostra, with the Indian-Malagasian Majungasaurinae as its sister group.Project supported by PICT-2012-Nº 2906 of ANPCyT ( to J.I.C.)