African wild ass

The African wild ass (Equus africanus) or African wild donkey, is a wild member of the horse family, Equidae. This species is thought to be the ancestor of the domestic donkey (Equus asinus), which is sometimes placed within the same species. They live in the deserts and other arid areas of the Horn of Africa, in Eritrea, Ethiopia and Somalia. It formerly had a wider range north and west into Sudan, Egypt, and Libya. It is Critically Endangered, with about 570 existing in the wild.

The African wild ass is about 1.2 metres (4 ft) tall and weighs approximately 250 kilograms (600 lb). The short, smooth coat is a light grey to fawn colour, fading quickly to white on the undersides and legs. There is a slender, dark dorsal stripe in all subspecies, while in the Nubian wild ass (E. a. africanus), as well as the domestic donkey, there is a stripe across the shoulder. The legs of the Somali wild ass (E. a. somaliensis) are horizontally striped with black, resembling those of a zebra. On the nape of the neck, there is a stiff, upright mane, the hairs of which are tipped with black.^{[citation needed]} The ears are large with black margins. The tail terminates with a black brush. The hooves are slender and approximately of the diameter as the legs.

The genus Equus, which includes all extant equines, is believed to have evolved from Dinohippus, via the intermediate form Plesippus. One of the oldest species is Equus simplicidens, described as zebra-like with a donkey-shaped head. The oldest fossil to date is ~3.5 million years old from Idaho in the United States. The genus appears to have spread quickly into the Old World, with the similarly aged Equus livenzovensis documented from western Europe and Russia.

Molecular phylogenies indicate the most recent common ancestor of all modern equids (members of the genus Equus) lived ~5.6 (3.9–7.8) mya. Direct paleogenomic sequencing of a 700,000-year-old middle Pleistocene horse metapodial bone from Canada implies a more recent 4.07 Myr before present date for the most recent common ancestor (MRCA) within the range of 4.0 to 4.5 Myr BP. The oldest divergencies are the Asian hemiones (subgenus E. (Asinus), including the kulan, onager, and kiang), followed by the African zebras (subgenera E. (Dolichohippus), and E. (Hippotigris)). All other modern forms including the domesticated horse (and many fossil Pliocene and Pleistocene forms) belong to the subgenus E. (Equus) which diverged ~4.8 (3.2–6.5) million years ago.

Different authors consider the African wild ass and the domesticated donkey one or two species; either view is technically legitimate, though the former is phylogenetically more accurate.^{[citation needed]} However, the American Society of Mammalogists classifies the donkey as a distinct species, as it does with almost all domestic mammals.

The species name for the African wild ass is sometimes given as asinus, from the domestic donkey, whose specific name is older and usually would have priority. But this usage is erroneous since the International Commission on Zoological Nomenclature has conserved the name Equus africanus in Opinion 2027. This was done to prevent the confusing situation of the phylogenetic ancestor being taxonomically included in its descendant.

Thus, if one species is recognized, the correct scientific name of the donkey is E. africanus asinus.

The first published name for the African wild ass, Asinus africanus, Fitzinger, 1858, is a nomen nudum. The name Equus taeniopus von Heuglin, 1861 is rejected as indeterminable, as it is based on an animal that cannot be identified and may have been a hybrid between a domestic donkey and a Somali wild ass; the type has not been preserved. The first available name thus becomes Asinus africanus von Heuglin & Fitzinger, 1866. A lectotype is designated: a skull of an adult female collected by von Heuglin near Atbarah River, Sudan, and present in the State Museum of Natural History Stuttgart, MNS 32026. The subspecies recognized: