Abstract

South American continental tetrapod assemblages, particularly dinosaurs and crocodyliforms are well known during the latest Late Cretaceous of Argentina and Brazil. Yet, little is known about the presence of dinosaurs and allies in the foreland basins developed on the western margin of South America during this lapse. The Quebrada Municipalidad beds, exposed in the coast of Algarrobo, central Chile, preserves one of the few known early Maastrichtian continental faunas along the Weddellian Province. Previous discoveries show the presence of marine turtles, plesiosaurs and mosasaurs together with a diversity of bony and cartilaginous fishes, all undoubtedly indicators of marine conditions. Despite the above, remains of putative dinosaurs have been mentioned yet formally undescribed until now. In this work, the dinosaur material collected from these levels is reassessed, revealing evidence of large-bodied ornithopods. Additionally, fragmentary avian remains, which previously were attributed to Eocene rocks, prove to be from the older Upper Cretaceous beds. Therefore, the latest cited finding could be one of the oldest Neornithes in the Late Cretaceous of South America. The dinosaurs from Algarrobo are relevant to understanding the biogeography of tetrapods during the Late Cretaceous, constituting the northernmost continental evidence within the Weddellian Biogeografic Province, shortly before the K/Pg extinction event. (c) 2026 Elsevier Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.