Megatheriinae were a group of elephant-sized ground sloths that lived from 2 million to 8,000 years ago. Their smaller ground sloth cousins were the Mylodon.
Unlike its living relative, the tree sloth, Megatherium was one of the largest mammals to walk the Earth. Weighing almost as much as an african bull elephant, it had huge claws on its feet. These claws meant that it could not put its feet flat on the ground and so, like a modern anteater, it had to walk on the sides of its feet. Its footprints show that it walked mainly on its hind legs. When it stood on its hind legs, it was about twice the height of an elephant, or about twenty feet tall. They were one of the abundant Pleistocene megafauna - a wide variety of very large mammals that lived during the Pleistocene epoch.