The prefrontal of Rinconsaurus caudamirus (Sauropoda, Titanosauria) as a crocodyliform ilium

Abstract The holotype of the titanosaur sauropod Rinconsaurus caudamirus, from the Bajo de la Carpa Formation (Santonian, Upper Cretaceous, Neuquen Group), is based on an articulated series of 13 anterior-middle to middle posterior caudal vertebrae and two illia, in addition to cranial, axial and appendicular elements corresponding to several individuals. One of the skull elements originally identified as a prefrontal (MAU-Pv-CRS-102), is reinterpreted here as a mesoeucrocodylian right ilium, likely belonging to Pehuenchesuchus enderi, a crocodyliform found in the same quarry. Therefore, this element is excluded from the Rinconsaurus type materials, adding a new element to Pehuenchesuchus and increasing the knowledge of its anatomy.