Megatheriids appeared during the Late Oligocene (Deseadan in the SALMA classification), some 23 million years ago, in South America. The group includes the heavily built Megatherium (given its name 'great beast' by Georges Cuvier[2]) and Eremotherium. An early megatheriid, the more slightly built Hapalops, reached a length of about 1.2 metres (3.9 ft).