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Przewalski's horse (pshəvälˈskēz), wild horse of Asia, Equus przewalski, E. ferus przewalski, or E. caballus przewalski, the only extant wild horse that, in the purebred state, is not descended from the domestic horse. Smaller than most domestic horses, it has a large head and bulging forehead. It is dun-colored, with an upright crest of dark hair on its head and neck, a dark stripe along the backbone, and a dark, plumed tail. The animal's former range probably extended from W Mongolia to N Xinjiang, China.
Przewalski's horse can interbreed with the domestic horse, and some authorities regard it as a subspecies of the domestic horse (E. caballus), although it has a different number of chromosomes. Because interbreeding with Mongol horses may have begun centuries ago, it is possible that even the original specimens of Przewalski's horse to be described were actually of mixed descent.
The horse was first recognized as a separate species by Nikolai Mikhailovich Przhevalsky, a Russian explorer and geographer, in the 1870s. In the 1960s the horse became extinct in the wild, largely due to competition with domestic livestock for grazing land and water and to hunting for horsemeat, but many specimens survived in zoos, where they breed well. Since 1992 the horse has been reintroduced with some success to several locations in Mongolia and China, using animals originally bred in European zoos.
Tarpan is the name for members of another race of the same species, E. ferus gmelini or E. caballus gmelini, which formerly ranged over the steppes of E Europe and W Asia, but has been extinct since the last century. Attempts have been made to breed back a tarpanlike horse from domestic horses believed to have been interbred with tarpans.
Wild horses are classified in the phylum Chordata, subphylum Vertebrata, class Mammalia, order Perissodactyla, family Equidae.