Isolated petrosal of the extinct sloth Glossotherium tropicorum (Xenarthra, Folivora, Mylodontidae) from the island of Trinidad

Abstract

This report is the first to identify the presence of the extinct ground sloth Glossotherium tropicorum from Pleistocene-aged tar pit deposits in Trinidad. G. tropicorum is known primarily from extensive skeletal material recovered from the Pleistocene of western Ecuador and Peru. Our identification is based on an isolated left petrosal bone, which exhibits a variety of derived diagnostic features of mylodontid sloths in general, e.g., the presence of an epitympanic recess, and the genus Glossotherium in particular, including a reduced anteroventral process of the tegmen tympani. This represents only the second published record of the genus Glossotherium from outside continental South America, and is a substantial range extension for the species G. tropicorum. The present study also represents the first published description of a mylodontid sloth fossil from Trinidad. The specimen is part of a collection that was initially documented in an unpublished Master’s thesis, and that includes additional sloths and other Pleistocene mammals. This fauna confirms the presence of extensive savanna-type habitats on Trinidad during the Pleistocene, and is consistent with the presence of a land bridge connection between the island and mainland South America at that time.