The huge rodent, reminding by proportions the American ground sloths Megatherium and Megalonyx became extinct in late Pleistocene. It descends from one of modern rodent agouti (Dasyprocta) species. The animal had adapted to inhabiting in moderately warm climate, lives on southern plains of continent and in foothills. The animal is sizable: height of the adult male standing on hind paws is up to 4 meters, the female - up to 3,5 meters. Hind legs are stronger, but shorter than forepaws, toe claws are thick and blunt. Forepaws are long and thin. On fingers II and III there are long hooked claws (length up to 25 cm by middle line). They are used for bending branches down, snow and the ground digging, and also for defense against predators. The thumb partly opposes to fingers, that feature allows animal to take even thin branches and stalks from the ground. The animal is fed, sitting on the ground in a vertical pose. It moves in a "semi-bipedal" pose similar to the gorilla, basing on long forward extremities. At such movement fingers with long claws are bent inside and load falls to the external side of a hand, where the skin is thick and cornificated. A tail is not present. Wool is long, to winter a rich underfur grows. The adult male has a wool of dark-grey color, on a chest there is a white spot which form is various at different individuals: from big single up to a narrow strip or several small spots. Female and cubs have a wool of gray-brown color with more dark head. The end of a muzzle is white at adult animal of both sexes, cubs have dark muzzles. Animals keep by family groups of one male, some (2 - 4) females and cubs in the age of till one year. Once a year in middle of spring the female gives rise to 2 (less often - 1 or 3) cubs covered with wool with opened eyes. About 2 months they are feeding mainly by mother’s milk. The female feeds cubs, sitting on hinder legs. At the age of half-year young animals completely pass to food of adult animals. They eat leaves of trees and bushes, fruits; frequently feed near reservoirs by rhizomes and tubers of marsh plants. To winter animals accumulate the big layer of fat. In winter time they dig grass and evergreen plants out under snow, gnaw young branches of trees.