Natopithecus ranapes

The swimming monkey is an amphibious primate and lives largely on a diet of fish. In the water its swimming action is essentially froglike.

The swimming monkey, Natopithecus ranapes, is a tailless, semiaquatic cercopithecine Old World monkey from the wetlands of tropical forests in Africa. It is descended from the Allen's swamp monkey.

It is less well adapted than the coexisting mud-gulper but nevertheless efficient in the water. This creature has developed a froglike body with webbed hind feet, long, clawed fingers for catching bony fish and a ridge down its back to give it stability in the water. Like the mud-gulper, its sensory organs are placed high up on its head. It lives in riverside trees, from which it dives to catch the fish that are its staple diet.