A New Titanosaur Sauropod from the Upper Cretaceous of Patagonia, NeuquéN Province, Argentina

Abstract

A new titanosaur sauropod from the Upper Cretaceous of Neuquen is described, Choconsaurus baileywillisi gen. et sp. nov. The species is represented by a nearly complete series of dorsal vertebrae as well as other parts of the skeleton. The material comes from the locality of Villa El Chocon and stratigraphically from the Huincul Formation, whose age has been estimated as upper Cenomanian. The new taxon presents many autapomorphic features, including the presence of a small notch on the dorsal margin of the posterior articular surface of the cervical centra, accessory articulations lateral to the hyposphene, which are more developed in the anterior dorsal vertebrae, midand posterior dorsal vertebrae with an accessory lamina placed between the posterior centrodiapophyseal and the accessory posterior centrodiapophyseal laminae, and a hyposphene on anterior caudal vertebrae. Phylogenetic analysis recovers Choconsaurus baileywillisi as a non-eutitanosaur titanosaur, taxa that are well represented in the lower Upper Cretaceous of Patagonia. Choconsaurus baileywillisi is, to date, the most complete non-eutitanosaur titanosaur.