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 was saved from the brink of extinction and reintroduced successfully to the wild. The tarpan became extinct in the 19th century, though it was a possible ancestor of the domestic horse, and roamed the steppes of Eurasia at the time of domestication.〔〔〔 However, other subspecies of ''Equus ferus'' may have existed and could have been the stock from which domesticated horses are descended.〔 Since the extinction of the tarpan, attempts have been made to reconstruct its phenotype, resulting in horse breeds such as the Konik and Heck horse. However, the genetic makeup and foundation bloodstock of those breeds is substantially derived from domesticated horses, so these breeds possess domesticated traits.
The term "wild horse" is also used colloquially to refer to free-roaming herds of feral horses such as the mustang in the United States, the brumby in Australia, and many others. These feral horses are untamed members of the domestic horse subspecies (''Equus ferus caballus''), and should not be confused with the two truly "wild" horse subspecies extant into modern times.
==Subspecies and their history==
''E. ferus'' had several subspecies. Three survived into modern times:
* The domestic horse (''Equus ferus caballus'').
* The tarpan or Eurasian wild horse (''Equus ferus ferus''), once native to Europe and western Asia, became effectively extinct in the late 19th century, and the last specimen died in captivity in an estate in Poltava Governorate, Russian Empire, in 1909.
* Przewalski's horse (''Equus ferus przewalskii''), also known as the Mongolian wild horse or Takhi, is native to Central Asia and the Gobi Desert.
The latter two are the only never-domesticated "wild" groups that survived into historic times.〔Colin Groves, 1986, "The taxonomy, distribution, and adaptations of recent Equids," In Richard H. Meadow and Hans-Peter Uerpmann, eds., ''Equids in the Ancient World, volume I,'' pp. 11-65, Wiesbaden: Ludwig Reichert Verlag.〕 However, other subspecies of ''Equus ferus'' may have existed and could have been the stock from which domesticated horses are descended.〔
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