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''Pliohippus'' is an extinct genus of Equidae, the "horse family". ''Pliohippus'' arose in the middle Miocene, around 15 million years ago. It was similar in appearance to ''Equus'', but had two long extra toes on both sides of the hoof, externally barely visible as callused stubs. The long and slim limbs of ''Pliohippus'' reveal a quick-footed steppe animal. Until recently, because of its many anatomical similarities, ''Pliohippus'' was believed to be the ancestor of the present-day horse and its relatives in ''Equus''. Although ''Pliohippus'' clearly is an equid and thus related to ''Equus'', its skull had deep facial ''fossae'', a feature not found in any member of ''Equus''. Additionally, its teeth were strongly curved, unlike the very straight teeth of modern horses. Consequently, it is unlikely to be the ancestor of the modern horse; instead, it is likely to be the ancestor of ''Astrohippus''.〔MacFadden, B. J. (1984). "Astrohippus and Dinohippus". ''J. Vert. Paleon''. 4(2):273-283.〕 ''Pliohippus'' stood approximately 1.25 metres, similar to the modern horse. Also like the modern horse, ''Pliohippus'' was a grazer that fed of steppe grasses of the North American plains it inhabited. Fossils of ''Pliohippus'' have been found at many late Miocene localities in Colorado, the Great Plains (Nebraska and the Dakotas) and also Canada. ''Pliohippus'' has been found beside ''Neohipparion''. File:Pliohippus 01.jpg|Specimen at American Museum of Natural History File:Pliohippus.jpg|Restoration of a ''Pliohippus'' herd ==References== 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Pliohippus」の詳細全文を読む スポンサード リンク
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