A new procolophonoid (Reptilia, Parareptilia) from the Upper Permian of Uruguay

Abstract

ABSTRACT Piniosaurus magnidentis gen. et sp. nov., a latest Permian procolophonoid reptile from the Buena Vista Formation of Uruguay, is described and its relationships are considered. The new taxon is characterized by the absence of a lateral maxillary depression, a premaxilla with a dorsally expanded maxillary process, a maxilla-premaxillary junction almost straight and marked by a shallow, but well-defined step that displaces the premaxillary alveolar margin slightly medially with respect to the maxillary tooth row, and the presence of a large conical, fang-like palatine tooth, which is positioned next to the suture with the vomer. The transitional nature of Pintosaurus is reflected in the retention of several plesiomorphic features that contrast with the presence of synapomorphies that are shared with procolophonids. A phylogenetic analysis suggests a basal position for Piniosaurus within Procolophonoidea, either as the sister taxon of a clade that includes Coletta and procolophonids or as the sister taxon of Coletta itself. The results of our phylogenetic analysis, together with the Permian age of Piniosaurus, are consonant with the hypothesis of a Gondwanan origin of Procolophonoidea.