Reproductive isolation from a cross between a horse and a donkey or between a mare and a donkey, respectively. These animals are nearly always sterile due to the difference in the number of chromosomes between the two parent species. Both horses and donkeys belong to the genus "Equus", but "Equus caballus" has 64 chromosomes, while "Equus asinus" only has 62. A cross will produce offspring (mule or hinny) with 63 chromosomes, that will not form pairs, which means that they do not divide in a balanced manner during meiosis. In the wild, the horses and donkeys ignore each other and do not
Australopithecus africanus of the Witwatersrand in Johannesburg, South Africa, became interested in fossils found at a limestone quarry at Taung near Kimberley, South Africa in 1924. The most promising of these was a skull of an odd ape-like creature presenting human traits at the eye orbits, teeth, and, most importantly, the hole at the base of the skull over the spinal column (the foramen magnum); its placement indicated a human-like upright posture and implied a high probability that this hominid-to-hominin primate had achieved bipedal, as opposed to quadrupedal locomotion. Dart assigned the specimen the name "Australopithecus africanus" ("southern ape of Africa"); it