Sloth Group Representatives (image) American Museum of Natural History Share Print E-Mail Caption In the tree, going clockwise from left: extinct West Indian sloth (Acratocnus), extant three-toed sloth or ai (Bradypus), and extant two-toed sloth or unau (Choloepus). From left to right on the ground are representative giant ground sloths: Mylodon (South America), Megalonyx (North America), and Megatherium (South America). According to new molecular studies, Bradypus is most closely related to a group that includes Megalonyx and Megatherium. Choloepus is related to Mylodon, but Acratocnus and its West Indian kin represent a separate branch that is distinct from that of all other sloths. Human for scale: 1.8.5 m (6 ft 1 in). Credit Jorge Blanco Usage Restrictions Can be used with appropriate credit Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.