Yeneen houssayi gen. et sp. nov. and an overview of the sauropod titanosaurian diversity from Cerro Overo – La Invernada area (Bajo de la Carpa Formation, Santonian), North Patagonia, Argentina

The fossil record of titanosaur sauropods for the Upper Cretaceous of the Neuquén Basin is remarkably extensive. However, for the Bajo de la Carpa Formation (Santonian) only five nominate species are recorded (Rinconsaurus caudamirus, Bonitasaura salgadoi, Traukutitan eocaudata, Overosaurus paradasorum, and Inawentu oslatus), the latter two coming from the Cerro Overo-La Invernada (CO-LI) area. Here we present a new titanosaur sauropod from La Invernada, Yeneen houssayi gen. et sp. nov. (MAU-Pv-LI-538). The new species is characterised by a series of distinctive features in dorsal, sacral and caudal vertebrae. Phylogenetic analysis indicates that Yeneen is closely related to Narambuenatitan and Overosaurus, as a basal member of an unnominated clade (called ‘Clade A’) of derived non-lithostrotian saltasauroids. The evidence provided by the Cerro Overo – La Invernada sauropod titanosaur fauna suggests that, during the Santonian, species diversity was relatively high and that at least two lineages coexisted: Collossosauria and Saltasauroidea. This finding makes the CO-LI area the one with the greatest diversity of titanosaurs for the Santonian of the Neuquén basin (as it is also for abelisaurid theropods), which makes it an exceptional area to understand the evolution of dinosaur faunas for this period.