Reassessment of theropod material from Pichasca, Northern Chile: Presence of Abelisauridae (Theropoda: Ceratosauria) from the Quebrada La Totora Beds (Albian - Turonian)

The South American fossil record of abelisaurids (Ceratosauria: Abelisauridae) theropods is relatively abundant and diverse in Cretaceous rocks, particularly in Brazil and Argentina. However, little is known about the presence of this clade in other regions of the continent. In this work, a theropod tooth collected from Cretaceous beds in Pichasca Natural Monument, Coquimbo region, Northern Chile, is comprehensively re-studied through morphological and morphometrical analysis. Additionally, the geological provenance of the specimen is revised, based on novel stratigraphic information from the locality. Morphological traits, including the crown shape, crown attributes, denticule morphology of the mesial and distal carina, and the enamel texture are consistent with abelisaurids affinities for the studied specimen, which is thus referred to here as Abelisauridae indet. The geological provenance of the specimen is assigned to the Quebrada La Totora Beds, a unit where fossil-bearing rocks can be constrained to the upper Albian-Turonian lapse. This is the first report of Abelisauridae in Chile and the first record of the clade in the southwestern margin of South America. The presence of abelisaurids in this mid-latitude region can be potentially relevant for understanding the biogeography of the group during the Late Cretaceous.