African wild ass 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
Equus conversidens Equus conversidens Equus conversidens (Owen 1869), or the Mexican horse, is a dubious Pleistocene species of horse, now extinct, that inhabited North America. The holotype of "Equus conversidens", a partial palate, was unearthed in Pleistocene deposits northeast of Mexico City, Mexico. In January 1963, a partial skeleton was found in the city of Canyon, Texas in a white clay bed during the excavation of a basement, and was referred to "E. conversidens" by Dalquest and Hughes (1965), who interpreted the species as medium to small-sized, and added additional records of the species from Texas (including a skeleton from Slaton), Arizona,