A NEW SOUTH AMERICAN ORNITHOPOD DINOSAUR FROM THE SANTONIN BAJO DE LA CARPA FORMATION (NEUQUÉN PROVINCE, ARGENTINA)

PENÉLOPE CRUZADO CABALLERO ; JUAN GASCA; LEONARDO S. FILIPPI; IGNACIO CERDA; ALBERTO GARRIDO

Congreso; 75 Annual Meeting Society of Vertebrate Paleontology; 2018

In the last decade, the Argentinian ornithopod record?which includes eight described species?has been increased with the discovery of new and diverse bone remains coming from the Late Cretaceous. The area near the village of Rincón de los Sauces (Neuquén Province) presents rich fossiliferous outcrops that have provided new ornithopod remains. These bones come from two units: Plottier and Bajo de la Carpa formations. In the latter, several isolated postcranial bones and a partial articulated skeleton (MAU-Pv-CO-596) have been found. MAU-Pv-CO-596 comes from the Cerro Overo site (Santonian, Late Cretaceous). The skeleton preserves five posterior cervical vertebrae and three of its corresponding ribs, the most anterior six vertebrae and seven left ribs of the dorsal series, the two scapulae, coracoids and sternal plates, four intercostal plates as well as the right forelimb including humerus, radius, ulna and nearly complete manus (excluding some distal phalanges). The skeleton corresponds to a medium-bodied ornithopod with a gracile general appearance. Histological analysis suggests that the specimen was sexually mature but not a fully grown individual. Some distinctive characters present in MAU-Pv-CO-596 such as strongly bowed humeral shaft and weakly developed deltopectoral crest are shared with other South American basal ornithopods. A phylogenetic analysis including MAUPv- CO-596 within a large ornithischian dataset has been performed. The results recover anunnamed clade with several South American ornithopods, including MAU-Pv-CO-596placed as the sister taxon of the clade composed of Talenkauen and Macrogyphosaurus.