information:extraction, linguistic:paraphrasing
Early Miocene and before

In the early Miocene, bovids began diverging from the cervids (deer) and giraffids. The earliest bovids, whose presence in Africa and Eurasia in the latter part of early Miocene (20 Mya) has been ascertained, were small animals, somewhat similar to modern gazelles, and probably lived in woodland environments. Eotragus, the earliest known bovid, weighed 18 kg (40 lb) and was nearly the same in size as the Thomson's gazelle. Early in their evolutionary history, the bovids split into two main clades: Boodontia (of Eurasian origin) and Aegodontia (of African origin). This early split between Boodontia and Aegodontia has been attributed to the continental divide between these land masses. When these continents were later rejoined, this barrier was removed, and both groups expanded into the territory of the other. The tribes Bovini and Tragelaphini diverged in the early Miocene. Bovids are known to have reached the Americas in the Pleistocene by crossing the Bering land bridge.

The present genera of Alcelaphinae appeared in the Pliocene. The extinct Alcelaphine genus Paramularius, which was the same in size as the hartebeest, is believed to have come into being in the Pliocene, but became extinct in the middle Pleistocene. Several genera of Hippotraginae are known since the Pliocene and Pleistocene. This subfamily appears to have diverged from the Alcelaphinae in the latter part of early Miocene. The Bovinae are believed to have diverged from the rest of the Bovidae in the early Miocene. The Boselaphini became extinct in Africa in the early Pliocene; their latest fossils were excavated in Langebaanweg (South Africa) and Lothagam (Kenya).