following the connection of the previously isolated North and South America via the Isthmus of Panama. Macrauchenia, Xenorhinotherium (Macraucheniidae) and Neolicaphrium (Proterotheriidae) were the last surviving genera of litopterns. All became extinct at the end of the Late Pleistocene around 12,000 years ago as part of the end-Pleistocene extinction event,