New theropod fauna from the Upper Cretaceous (Huincul Formation) of Northwestern Patagonia, Argentina

Abstract

The present contribution describes theropod remains coming from the Huincul Formation (Neuquén Group; Cenomanian-Turonian; Upper Cretaceous) at a single locality located in northwestern Río Negro province, Patagonia, Argentina. This theropod association is composed of abelisauroids, two different-sized carcharodontosaurid allosauroids, a coelurosaur of uncertain relationships, a megaraptoran tyrannosauroid, and a possible unenlagiid paravian. Two new theropod genera and species are here described. The new carcharodontosaurid is based on an isolated postorbital bone bearing a unique prominence above the orbital brow. The new megaraptoran of uncertain affinities is described on the basis of a partially articulated tail and sacral vertebra. A new taxon is characterized by having notably elongate and highly pneumatic sacral and caudal vertebrae. It shows a large number of similarities with the African taxa Deltadromeus and Baharisaurus. These genera probably constitute a still poorly known clade of megaraptoran tyrannosauroids different from the Megaraptoridae. These findings support that Patagonia is a key place for understanding theropod evolution in Gondwana.