A new ornithopod dinosaur from the Santonian of Northern Patagonia (Rincón de los Sauces, Argentina)

Abstract

In recent decades, the Argentinian ornithopod record – which includes eight species that have been described – has increased as a result of the discovery of diverse new bone remains from the Upper Cretaceous. The area near the town of Rincón de los Sauces (Neuquén Province) presents rich fossiliferous outcrops that have provided new ornithopod remains. These bones are from two units: the 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. The holotype of Mahuidacursor lipanglef gen. et sp. nov. (MAU-Pv-CO-596) comes from the Cerro Overo site (Santonian, Upper Cretaceous). The skeleton preserves elements from the cervical and dorsal series, the pectoral girdle and the right forelimb. It corresponds to a medium-bodied ornithopod with a gracile general appearance. Histological analysis suggests that the specimen was a sexually mature but not fully grown individual. Some distinctive characters present in Mahuidacursor, such as the strongly bowed humeral shaft and the weakly developed deltopectoral crest, are shared with other South American basal ornithopods. A phylogenetic analysis including Mahuidacursor within a large ornithischian dataset was performed. The results show Mahuidacursor to be a basal ornithopod recovered within a polytomy along with Notohypsilophodon and the clade Elasmaria (Talenkauen + Macrogryphosaurus).