A new giant basal titanosaur sauropod in the Upper Cretaceous (Coniacian) of the Neuquén Basin, Argentina

Abstract

A new basal sauropod titanosaur, Kaijutitan maui gen. et sp. nov., is described. The holotype of this species, which comes from the Sierra Barrosa Formation (upper Coniacian, Upper Cretaceous), consists of cranial, axial, and appendicular elements presenting an unique combination of plesiomorphic and apomorphic characters. The most notable characteristic observed in Kaijutitan is the presence of anterior cervical vertebrae with bifid neural spines, a condition that would have evolved several times among sauropods. The phylogenetic analysis places Kaijutitan as a basal titanosaur, the sister taxon of Epachthosaurus + Eutitanosauria. The new species supports the coexistence, in the Late Cretaceous (Turonian-Santonian), of basal titanosaurs and eutitanosaurian sauropods, at least in Patagonia.