Megatherium ( meg-ə-THEER-ee-əm; from Greek méga (μέγα) 'great' + theríon (θηρίον) 'beast') is an extinct genus of large ground sloths endemic to South America that lived from the Early Pliocene through the end of the Late Pleistocene. It is best known for the elephant-sized, 3.5–4 tonnes (7,700–8,800 lb) type species Megatherium americanum, primarily known from the Pampas, but ranging southwards to northernmost Patagonia and northwards to southern Bolivia during the late Middle Pleistocene and Late Pleistocene. Various other species have been described, including those belonging to the Andean subgenus Pseudomegatherium, which range in size from comparable to M. americanum down to approximately 1 tonne (2,200 lb). The first (holotype) specimen of Megatherium americanum was discovered in 1787 on the bank of the Luján River in what is now northern Argentina. The specimen was then shipped to Spain the following year wherein it caught the attention of the pioneering French paleontologist Georges Cuvier, who named the animal in 1796, making it one of the first prehistoric animals to be scientifically named, and was the first to determine, by means of comparative anatomy, that Megatherium was a giant sloth. Megatherium is part of the sloth family Megatheriidae, which also includes the closely related and similarly giant Eremotherium, comparable in size to M. americanum, which was native to tropical South America, Central America and North America as far north as the southern United States. Megatherium americanum is thought to have been a browser that fed on the foliage and twigs of trees and shrubs using a black rhinoceros–like prehensile upper lip (rather than a prehensile tongue as often historically depicted). Despite its large body size, Megatherium americanum is widely thought to have been able to rear up on its hind legs at least while standing and braced, which allowed it to grasp and feed on high-growing leaves, as well as possibly to use its claws for defense. Megatherium became extinct around 12,000 years ago as part of the end-Pleistocene extinction event, simultaneously with the majority of other large mammals in the Americas. The extinctions followed the first arrival of humans in the Americas, and at least one and potentially several sites where M. americanum was slaughtered and butchered by humans are known, suggesting that hunting could have been a factor in its extinction.