Two new pleurodiran turtles from the Portezuelo Formation (Upper Cretaceous) of northern Patagonia, Argentina

The chelonian fauna of the Portezuelo Formation (Turonian-Coniacian), outcropping at Sierra del Portezuelo (Neuquen province, Argentina), is reported. Two new taxa of pleurodiran turtles are described. One of them is Prochelidella portezuelae new species, a short-necked chelid closely related to extinct species of the Lohan Cura (Albian), Candeleros (Cenomanian), and Bajo Barreal (Turonian) formations from northwestern and central Patagonia, and to the extant species of the genus Acanthochelys. The other is Portezueloemys patagonica new genus and species, a member of the epifamily Podocnemidoidea, and is considered the sister group of the family Podocnemididae. This discovery confirms the coexistence in northwestern Patagonia of a north gondwanan component (Pelomedusoides) and a south gondwanan element (Chelidae) during the Turonian-Coniacian.