Megatherium americanum is a giant ground sloth that belongs to the order Xenarthra, which also includes armadillos, glyptodonts, anteaters, tree-sloths, and ground-sloths. Megatherium americanum had a heavy build, long front limbs, and large claws. Fossilized footprints in Argentina show that Megatherium americanum not only walked on all fours but could have walked on its hind legs for short distances. Megatherium americanum was one of the largest land mammals of the time. It could be up to 6m long and weighed about 3.8 tons. Megatherium americanum lived during the Pleistocene (about 1.8 million to ~10,000 years ago), when the most recent ice ages took place. They lived in woodlands and grasslands in southern South America. It was a browser that fed on leaves and twigs of trees and could sit upright to feed high in trees. This giant ground sloth went extinct about 10,000 years ago at the end of the Pleistocene epoch.

Megatherium americanum was one of the largest species of ground sloth, a group of closely related animals once common in the Americas, particularly South America. Its scientific name translates as ‘a big animal from America’.There were once many different kinds of ground sloth but all are now extinct. They were a widespread and successful group of mammals - their fossils have been found from Patagonia to Alaska. The last ground sloths seem to have died out about 10,000 years ago when humans colonised the Americas.

Megatherium americanum belongs to the Megatheriidae family and early members of the Megatheriidae family first appeared approximately 33 million years ago in South America.

Megatherium americanum appeared during the early Pleistocene (about 1.8 million years ago) and was found in southern South America. Other species of Megatherium have been found at high elevations on the Altiplano (a high plateau) in the Andes. A close relative, Eremotherium, lived in the tropics in South America but has been found as far north as the southeastern United States. This giant ground sloth went extinct about 10,000 years ago at the end of the Pleistocene epoch.



Megatherium americanum is a giant ground sloth that belongs to the order Xenarthra, which also includes armadillos, glyptodonts, anteaters, tree-sloths and ground-sloths. Species in the Xenarthra order are known for low body temperature and short and massive limb bones with well-developed claws. Megatherium americanum was a huge sloth, close to modern elephants in size, with a heavy build, long front limbs and large claws. They had five teeth above and four below in each side of the skull. These teeth lacked roots and were always growing. The chewing surfaces of the teeth were formed by two horizontal ridges, which cut vegetation like scissors. One unusual feature of Megatherium is that the back feet were turned inwards so the animal walked on the sides of its feet. This was seen in fossilized footprints found in Argentina. These footprints also show that Megatherium americanum usually walked on all fours, and could possibly walk on its hind legs for short distances.

Megatherium americanum was first described by the famous French comparative anatomist Baron Georges Cuvier in 1796 on the basis of drawings of a mounted skeleton sent to him from Madrid. The Madrid skeleton had been brought over from the Spanish colonies in South America in 1785. After that, the remains of this gigantic sloth were avidly sought after by museums all over the world.The Natural History Museum (then part of the British Museum) purchased Megatherium material from a Señor de Angelis in 1845. It had been collected from Lujan, near Buenos Aires in Argentina in 1837.Meanwhile, the Royal College of Surgeons in England had Megatherium bones in their collection from the bed of the Rio Salada, just south of Buenos Aires, Argentina.

Making a complete skeleton to exhibit
In 1849, plaster casts of bones from both collections were put together to form a composite skeleton. A small number of missing bones were modelled to fit - mainly ribs and vertebrae. The skeleton was mounted in the manner suggested by William Buckland, Dean of Westminster, and Richard Owen, Conservator of the Hunterian Collection at the Royal College of Surgeons (and later Superintendent of the Natural History Museum). The original Madrid specimen had been mounted on all fours like an elephant. Buckland and Owen realised that it was probably a bipedal animal, supporting most of its weight on its back legs.This skeletal reconstruction can still be seen at the Natural History Museum in London, where it has been on continuous public display since 1850.

Megatherium americanum was one of the largest land mammals of the time. It could be up to 6m long and weighed about 3.8 tons, which is about the same weight as a modern elephant. 

Megatherium americanum lived during the Pleistocene (about 1.8 million to ~10,000 years ago), when the most recent ice ages took place. It was most likely a browser (ate twigs, leaves and high-growing vegetation) and fed off leaves and branches of trees in woodlands and savanna grasslands in Argentina.

Megatherium americanum ate plants. It was a browser that fed on leaves and twigs of trees and could sit upright to feed high in trees. Fossil dung of this animal has been found in caves in Argentina.

Distribution
Ground sloths are only known from North and South America and all had become extinct by the end of the last Ice Age, 10,000 to 12,000 years ago. This corresponds to the period when modern humans colonised the Americas.The final demise of the ground sloths and the appearance of humans are very likely to be linked, though this is still a controversial issue among palaeontologists and archaeologists.Megatherium americanum, the giant ground sloth, is known from Late Pleistocene deposits in the Pampas region of Argentina and neighbouring countries. It appears to have been one of the last species of ground sloth to die out.

Ecology
In ecological terms ground sloths fulfilled many of the same functions as elephants, rhinoceroses and horses. They specialised in feeding on very coarse, low-grade plant matter, deriving what they needed to survive by consuming huge quantities of food rather than eating anything particularly nutritious.We are able to discover a lot about their food from large deposits of dung left by cave-dwelling species of ground sloth in both North and South America.