A COMPLETE ABELISAURID (THEROPODA) PELVIS FROM NEUQUÉN PROVINCE, ARGENTINA.

CORIA, R. A.; PAULINA CARABAJAL, A.

San Juan

Congreso; IV Congreso Latinoamericano de paleontología de vertebrados; 2011

Museo de Ciencias Naturales, Universidad Nacional de San Juan

The Abelisauridae are a typical group of Gondwanan theropods, whose higher diversity lies so far on the Patagonian record that spans from the Cenomanian (Candeleros Fm) up to the Maastrichtian (La Colonia Fm). In Neuquén Province, the outcrops of Neuquén Group have yielded abelisaurid remains virtually throughout the entire section. The identified taxa include Ekrixinatosaurus Calvo et al. 2004 (Candeleros Fm), Ilokesia Coria & Salgado 1998 and Scorpiovenator Canale et al. 2008 (Huincul Fm), and Abelisaurus Bonaparte & Novas 1985 and Aucasaurus Coria et al. 2002 (Anacleto Fm.). Here we report the complete sacrum and pelvic elements of a medium-size theropod specimen (MCF-PVPH-820) recovered from Huincul Formation’s sandstones (Cenomanian, Upper Cretaceous). The specimen represents an adult individual based on the fully fused pelvic elements, and exhibits a combination of several features observed in most Abelisauridae (i.e. Abelisaurus, Carnotaurus, Majungasaurus, Aucasaurus)  such as a low iliac blade, slightly dorsoventrally expanded pre and postacetabular processes, pubis with closed obturator foramen, broad brevis shelf and a sinsacrum composed by six vertebrae.  Like in Carnotaurus and Aucasaurus, the dorsal edge of the ilium is straight, unlike the convex condition described for Skorpiovenator (Canale et al., 2008). Unlike Carnotaurus and Skorpiovenator, the preacetabular process bears an anterior projection dorsally placed and the ventral border is rather convex, and the ilium seems to be dorsoventrally narrower. Based on the size, MCF-PVPH-820 matches with the holotype specimen of Ilokelesia, although spite the similar stratigraphic provenance, the lack of overlapping elements (Coria and Salgado, 2000) impedes a certain comparison with that form.