A Late Cretaceous lizard assemblage from the Allen Formation, northern Patagonia, Argentina

Lizards are poorly known from the Mesozoic of South America, including several specimens from the Lower and Upper Cretaceous of Brazil, and only a few from the Upper Cretaceous of Patagonia. Here, we describe a new lizard assemblage from a single bone-bearing level in the Allen Formation (upper Campanian – lower Maastrichtian), cropping out at the Cerro Tortuga locality, Río Negro Province, northern Patagonia, Argentina. We recognise the presence of three different taxa, all of them represented by partially isolated maxillae, belonging to different lizard lineages: pleurodontan Iguania; Teiioidea; and possibly Scincoidea. These specimens support the presence of a quite diverse lizard assemblage during the Late Cretaceous in southern South America, suggesting that their absence in other Cretaceous deposits from Patagonia represents preservational and/or sampling bias. The taxonomic diversity also points to a broad ecological diversity, because the three taxa strongly differ in their dental morphology and inferred dietary habits. The assemblage from Cerro Tortuga indicates that lizards, along with snakes and sphenodontians, were an important component of the Late Cretaceous lepidosaurian fauna of South America and, likely, Gondwana.