A new and unusual late Cretaceous mammal from Patagonia

Gondwanatherium patagonicum is a new mammalian genus and species from the Upper Cretaceous Los Alamitos Formation of Patagonia. It is represented by several isolated, high-crowned, hypselodont molars that were found in association with hadrosaurs, titanosaurs, theropods, and a varied assemblage of small vertebrates. The presence of the hadrosaur Kritosaurus, titanosaurs, and data of regional geology indicate a Campanian age. The relationships of Gondwanatherium are uncertain. The closest phenetic resemblances are to a middle Paleocene xenarthran, Sudamerica, from Patagonia, although differences suggest that they belong to different families. The presence of Gondwanatherium in Patagonia is evidence for endemism of Gondwanan and Laurasian mammalian faunas during the pre-Maastrichtian Cretaceous.