Aepyceros datoadeni
Aepyceros datoadeni is an extinct impala which lived in what is now Ethiopia during the Pliocene epoch around 3 million years ago. It was described by Denis Geraads, René Bobe and Kaye Reed in 2012. In most respects, including the shape of the horns and teeth, it very closely resembled the living impala, although it was significantly smaller. References

Bovidae
Pliocene even-toed ungulates
Prehistoric bovids
Fossil taxa described in 2012
Pliocene mammals of Africa