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''Bison occidentalis'' is an extinct species of bison that lived in North America from about 11,000 to 5,000 years ago, spanning the end of the Pleistocene to the mid-Holocene. Likely evolving from ''Bison antiquus'', ''B. occidentalis'' was smaller overall from its ancestor and other species such as the steppe bison. ''B. occidentalis'' had a highly variable morphology, and their horns, which pointed rearward, were much thinner and pointed than Pleistocene species of bison.〔 Around 5,000 years ago, ''B. occidentalis'' was replaced by today's smaller ''Bison bison''. ''B. occidentalis'' may have declined in numbers because of competition with other grass eaters of the megafauna epoch. More recently ancient DNA studies have proven interbreeding between ''B. occidentalis'' and ancestral modern bisons, so ''B. occidentalis'' was proposed to have been a localized offshoot of ''B. antiquus'' and part of the transition from that chronospecies to modern bisons. ==See also== * Great bison belt * Bison antiquus * Bison bison ==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「Bison occidentalis」の詳細全文を読む スポンサード リンク
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