NEW CONTRIBUTIONS TO THE KNOWLEDGE OF ABELISAURIDAE (DINOSAURIA, THEROPODA) FROM THE UPPER CRETACEOUS IBERO-ARMORICAN LANDMASS

Abstract

Abelisaurids were medium- to large-bodied theropods that inhabited Gondwana and Europe, even becoming the apex predators in
the latest Cretaceous ecosystems of many of these areas. European abelisaurids remain elusive, but their remains are becoming increasingly abundant in the Upper Cretaceous Ibero-Armorica. In this work, systematic, morphometric, and cladistic analyses of tooth samples from the Campanian–Maastrichian deposits of three localities (Chera 2, Montrebei and Viso) from the Iberian Peninsula have allowed these elements to be reassigned to abelisaurids. The specimen from Chera 2 is assigned to Arcovenator sp. whereas teeth from Montrebei and Viso are classified as Abelisauridae indet. The latter represents the first confirmed abelisaurid remain from the Cretaceous of Portugal. The axial remains identified as belonging to Rhabdodon from Laño are here attributed to cf. Arcovenator. These findings indicate that abelisaurids were the only apex terrestrial predators and among the most abundant theropods in the Upper Cretaceous of the Ibero-Armorican landmass. The reclassification of mid- to large-sized isolated teeth from Ibero-Armorica as abelisaurids, rather than carcharodontosaurids or closely related forms, suggests that Abelisauridae had already become the dominant apex theropod lineage by the Cenomanian. The abelisauroid fossil record in Ibero-Armorica spans from the Albian to the latest Maastrichtian, indicating a complex and temporally extensive presence. Despite most of the specimens being fragmentary, the available evidence supports the persistence and diversification of abelisaurids across Ibero-Armorica, with multiple lineages arising either from a possible Albian stock or resulting from successive dispersals, followed by insular diversification throughout the Late Cretaceous.