Isolated Abelisaurid Teeth from Gondwana and Dental Evolution in Abelisauridae

Several unpublished remains of indeterminate Late Cretaceous dinosaurscollected by Rodolfo Casamiquela during the late 1950s are housed in the paleontological collections of the Museo Histrico Jorge Gerhold (Ingeniero Jacobacci, Rio Negro, Argentina) under the acronym MHJG 189 Pa.Among them, one basicranium and two fragments of the ornamented skull roof of a mid-to-large abelisaurid stand out, representing the first record of Theropoda for the Angostura Colorada Formation.A recent prospection of the same locality produced an isolated abelisaurid tooth, representing the first undoubtedly theropod record for the Coli Toro Formation, a unit overlying the Angostura Colorada Fm.Despite their fragmentary nature, these abelisaurid remains represent the first evidence of theropod dinosaurs not only for the Ingeniero Jacobacci area, but for both Angostura Colorada and Coli Toro formations.