A carcharodontosaurid tooth from “Boca de Forno” Ravine of the Itapecuru Formation, Parnaíba Basin, Maranhão, Brazil

Abstract

Carcharodontosauridae forms a clade of medium-to very large-sized (6–14 m long) allosauroid theropods mostly restricted to the Early and mid-Cretaceous with an almost global distribution, and characterized by deep and narrow ornamented skulls and strongly compressed ziphodont teeth. In Brazil, the carcharodontosaurid fossil record is limited to shed teeth and isolated postcranial elements from the Aptian-Cenomanian deposits of the eastern part of the country. Here we describe and identify a shed tooth from a little-known outcrop of the Early Cretaceous (Aptian-Albian) Itapecuru Formation of the Maranhão State, northeastern Brazil. Although some teeth have already been reported from the Aptian-Albian deposits of this unit, this specimen represents the first isolated dental material from the Parnaíba Basin that can be confidently assigned to a carcharodontosaurid through cladistic and morphometric techniques, but also based on a systematic study. The results of the herein conducted study suggest that the specimen belongs to a carcharodontosaurine closely related to the Patagonian taxa Giganotosaurus and Mapusaurus, which are younger in age. Although the specimen is closely related to the abovementioned Patagonian taxa, the faunal composition of the Parnaíba Basin seems to be more similar to that of North Africa. Nevertheless, further collecting efforts are needed in these localities to find skeletal carcharodontosaurid remains and to broaden the comparative base for the identification of theropod dentition.