Which small African mammal is the closest living relative of the hippopotamus?

The pygmy hippopotamus is a small African mammal and the closest living relative of the common hippopotamus.

Pygmy hippos live in and around streams, swamps, and dense forests of Liberia, with smaller populations in Sierra Leone, Guinea, and Côte d’Ivoire. They are far smaller than common hippos and are more solitary and terrestrial, although they still rely on water to keep their skin moist and regulate body temperature.

Genetic and fossil evidence shows that pygmy and common hippos share a relatively recent common ancestor. Their closest broader relatives are cetaceans, the group that includes whales and dolphins, rather than pigs or other hoofed forest mammals.

The species is threatened by habitat loss, hunting, and political instability across parts of its range. It is classified as Endangered, and much of the remaining population occurs in fragmented West African forest.