The common
hippopotamus (
Hippopotamus amphibius), or
hippo, is a large, mostly
herbivorous mammal in
sub-Saharan Africa, and one of only two
extant species in the
family Hippopotamidae, the other being the
pygmy hippopotamus (
Choeropsis liberiensis or
Hexaprotodon liberiensis). The name comes from the
ancient Greek for "river horse" . After the
elephant and
rhinoceros, the common hippopotamus is the third-largest type of land mammal and the heaviest extant
artiodactyl. Despite their physical resemblance to
pigs and other terrestrial even-toed
ungulates, the closest living relatives of the Hippopotamidae are
cetaceans (
whales,
porpoises, etc.) from which they diverged about . The common ancestor of whales and hippos split from other even-toed ungulates around . The earliest known hippopotamus fossils, belonging to the
genus Kenyapotamus in Africa, date to around .
