Mouflon vignei" (or "orientalis") "arkal" and "O. v./o. bochariensis", grouped with two different clades of argali ("Ovis ammon"). The ancestral sheep is presumed to have had 60 chromosomes, as in goats ("Capra"). Mouflon and domestic sheep have 54 chromosomes, with three pairs (1+3, 2+8, 5+11) of ancestral acrocentric chromosomes joined to form bi-armed chromosomes. This is in contrast to the argali and urial, which have 56 and 58 chromosomes respectively. If the urial is as closely related to the mouflons as mitochondrial DNA indicates, then two chromosomes would need to have split during its evolution away from the mouflon (sub)species. In
Wild horse cranial and metacarpal differences, indicates the presence of only two subspecies in postglacial times, the tarpan and Przewalski's horse. At present, the domesticated and wild horses are considered a single species, with the valid scientific name for the horse species being "Equus ferus." The wild tarpan subspecies is "E. f. ferus", Przewalski's horse is "E. f. przewalskii", and the domesticated horse is "E. f. caballus". The rules for the scientific naming of animal species are determined in the International Code of Zoological Nomenclature, which stipulates that the oldest available valid scientific name is used to name the species. Previously, when