Buffalo

Buffalo were cow-like creatures that lived on Earth. Because Roz Forrester's family name translated as "buffalo", she wasn't allowed to eat a buffalo. (PROSE: The Also People)

The Seventh Doctor and Ace saw living in the Ngorogoro Crater in 1926. (DWM: Prelude: Birthright)

Cultural references to buffalo
The Ninth Doctor told Mickey Smith to use the password buffalo to access a variety of areas of the UNIT website. (TV: World War Three)

Behind the scenes
The DWU fails to use buffalo as a synonym for bison — which it is, in a limited sense. Certainly, North American buffalo are bison. However, the kind the Seventh Doctor and Ace saw in Africa would have been and not at all bison.