In the shadow of dinosaurs: late Cretaceous frogs are distinct components of a widespread tetrapod assemblage across Argentinean and Chilean Patagonia

Abstract

Frogs (Anura) are nowadays common and abundant constituents of terrestrial and freshwater ecosystems near globally and their fossil record shows that they were already important during Cretaceous times. However, their fossils are often very incomplete, challenging their identification, which, coupled to historical reasons, has led to their marginalization in studies of Cretaceous tetrapod assemblages. We here report on the identities of frogs from three upper Campanian–lower Maastrichtian assemblages from Chilean (Dorotea Formation) and Argentinean (Allen and Los Alamitos formations) Patagonia, with focus on humeral morphology. Records from the Dorotea Formation represent the first described Mesozoic frogs from Chile and include the southernmost record of pipids worldwide. In the three assemblages we have identified humeri of the pipid Kuruleufenia and of calyptocephalellid frogs, proving humeral morphology valuable in diagnosing and identifying Cretaceous frogs from Patagonia. These frogs are diagnostic components of the South American Allenian tetrapod assemblage that was widespread across Patagonia near the end of the Cretaceous.