Copperplate illustration of Giant Ground Sloth by Laurilliard, engraving by Couet, (from Bru), Plate 1 in Cuvier's account in 'Annales du Museum National d'Histoire Naturelle' 1804, Vol. 4, No 29. Cuvier's reputation with fossils began with this animal to which he gave the latin name Megatherium americanum (Big American Mammal). The creature had been found in Argentina near Buenos Aires in 1787 (Darwin would make similar discoveries on the Beagle) and was sent to Madrid. It was mounted by Juan Bautista Bru and put on display. Cuvier wrote his description secondhand from drawings and a description sent by Bru. Cuvier realised it bore a resemblance to the much smaller tree sloth. He proposed Megatherium was a giant ground sloth. As such a big animal would have been seen if it were alive, Cuvier suggested must be extinct. Until that time most fossils were assumed to be of creatures still alive somewhere on the globe.