Hippopotamus Saves Wildebeest From Crocodile

Taxonomy and evolution
The wildebeest, or the genus Connochaetes, is placed under family Bovidae and subfamily Alcelaphinae. The name Connochaetes was given by German zoologist Martin Hinrich Carl Lichtenstein in 1814. Wildebeest were first discovered about 1700 by Dutch settlers on their way to the interior of South Africa. Due to their resemblance to wild cattle, these people called them "wild ox" or "wildebeest". The black wildebeest was first known to westerners in the northern part of South Africa a century later, in the 1800s.
In the early twentieth century, one species of the wildebeest, Connochaetes albojubatus, was identified in eastern Africa. In 1914, two separate races of the wildebeest were introduced, namely Gorgon a. albojubatus (Athi white-beared wildebeest) and G. a. mearnsi (Loita white-bearded wildebeest). However, in 1939, the two were once again merged into a single race, Connochaetes taurinus albojubatus. In the mid-twentieth century, two separate forms were recognised, Gorgon taurinus hecki and G. t. albojubatus. Finally two distinct types of wildebeest - the blue and black wildebeest - were identified. The blue wildebeest placed under a separate genus of its own, Gorgon, while black wildebeest belonged to the genus Connochaetes. Today the genus Connochaetes consists of two species: the black wildebeest (C. gnou) and the blue wildebeest (C. taurinus).
According to an mtDNA analysis, the black wildebeest seem to have diverged from the main lineage during the Middle Pleistocene and became a distinct species around a million years ago. A divergence rate of approximately 2% has been calculated. The split does not seem to have been driven by competition for resources but instead by the fact that each species adopted a different feeding niche and occupied a different trophic level.