History of the domestic sheep exact line of descent between domestic sheep and their wild ancestors is unclear. The most common hypothesis states that "Ovis aries" is descended from the Asiatic ("O. orientalis") species of mouflon. A few breeds of sheep, such as the Castlemilk Moorit from Scotland, were formed through crossbreeding with wild European mouflon. The urial ("O. vignei") was once thought to have been a forebear of domestic sheep, as they occasionally interbreed with mouflon in the Iranian part of their range. However, the urial, argali ("O. ammon"), and snow sheep ("O. nivicola") have a different number of chromosomes than other Ovis species,
Wild horse Wild horse The wild horse ("Equus ferus") is a species of the genus "Equus", which includes as subspecies the modern domesticated horse ("Equus ferus caballus") as well as the undomesticated tarpan ("Equus ferus ferus", now extinct), and the endangered Przewalski's horse ("Equus ferus przewalskii"). Przewalski's horse had reached the brink of extinction but was reintroduced successfully back into the wild. The tarpan became extinct in the 19th century, though it is a possible ancestor of the domestic horse; it roamed the steppes of Eurasia at the time of domestication. However, other subspecies of "Equus ferus" may have existed and could