Black wildebeest the hybrid as compared to either of its parents. In some animals, the auditory bullae are highly deformed, and in others, the radius and ulna are fused. Black wildebeest are sexually dimorphic, with females being smaller in size and more slender than males. The head-and-body length is typically between . Males reach about at the shoulder, while females reach . Males typically weigh and females . A distinguishing feature in both sexes is the tail, which is long and similar to that of a horse. Its bright-white colour gives this animal the vernacular name of "white-tailed gnu", and also distinguishes
Black wildebeest found in their fossil ancestors. The earliest known fossil remains are in sedimentary rock in Cornelia in the Orange Free State and date back about 800,000 years. Fossils have also been reported from the Vaal River deposits, though whether or not they are as ancient as those found in Cornelia is unclear. Horns of the black wildebeest have been found in sand dunes near Hermanus in South Africa. This is far beyond the recorded range of the species and it has been suggested that these animals may have migrated to that region from the Karoo. The black wildebeest is known