''Bison occidentalis'' is an extinct species of bison that lived in North America, and in continental

Eurasia Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelago ...

C. G Van Zyll de Jong , 1986, A systematic study of recent bison, with particular consideration of the wood bison (Bison bison athabascae Rhoads 1898), p.53, National Museum of Natural Sciences and the

Japanese archipelago The Japanese archipelago (Japanese: 日本列島, ''Nihon rettō'') is a group of 6,852 islands that form the country of Japan, as well as the Russian island of Sakhalin. It extends over from the Sea of Okhotsk in the northeast to the East Chin ...

from about 11,700 to 5,000 years ago, spanning the end of the

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in ...

to the mid-

Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togeth ...

Characteristics

Likely evolving from ''

Bison antiquus ''Bison antiquus'', the antique bison or ancient bison, is an extinct species of bison that lived in Late Pleistocene North America until around 10,000 years ago. It was one of the most common large herbivores on the North American continent dur ...

'', ''B. occidentalis'' was smaller overall from its most direct ancestor, but was similar to the distant ancestor the steppe bison (''Bison priscus'') in size. ''B. occidentalis'' had a highly variable morphology, and their horns, which pointed rearward, were much thinner and pointed than other Pleistocene species of bison. ''B. occidentalis'', like other bison species, may have existed in small, scattered populations and been unable to increase in numbers until after the

Pleistocene epoch The Pleistocene ( , often referred to as the ''Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in ...

ended 10,000 years ago because of competition with other large grazers during the

Evolution

''B. occidentaliss decrease in size from ''

'' was likely caused by both human hunting and natural selection.Valerius Geist, 1996, Buffalo Nation, Voyageur Press The smaller size likely helped ''B. occidentalis'' increase in population after migrating into North America. As ''

'' was forced to lived on open grasslands and faced pressure from human hunting, it responded by downsizing into ''B. occidentalis''. Hybridization of these two bison species produced the modern

American bison The American bison (''Bison bison'') is a species of bison native to North America. Sometimes colloquially referred to as American buffalo or simply Bubalina, buffalo (a different clade of bovine), it is one of two extant species of bison, alongs ...

''Bison bison'', which further decreased body size and increased population. The

wood bison The wood bison (''Bison bison athabascae'') or mountain bison (often called the wood buffalo or mountain buffalo), is a distinct northern subspecies or ecotype of the American bison. Its original range included much of the boreal forest regions ...

(''Bison bison athabascae'') preserves some original traits of ''B. occidentalis'' which was more similar to the ancestral steppe bison, making the wood bison more primitive than the

plains bison The Plains bison (''Bison bison bison'') is one of two subspecies/ecotypes of the American bison, the other being the wood bison (''B. b. athabascae''). A natural population of Plains bison survives in Yellowstone National Park (the Yellowstone ...

(''Bison bison bison'').C. G Van Zyll de Jong , 1986, A systematic study of recent bison, with particular consideration of the wood bison (Bison bison athabascae Rhoads 1898), p.53, National Museum of Natural Sciences More recently

ancient DNA Ancient DNA (aDNA) is DNA isolated from ancient specimens. Due to degradation processes (including cross-linking, deamination and fragmentation) ancient DNA is more degraded in comparison with contemporary genetic material. Even under the bes ...

studies have proven interbreeding between ''B. occidentalis'' and ''Bison bison'', so ''B. occidentalis'' was proposed to have been a localized offshoot of ''B. antiquus'' and part of the transition from that

chronospecies A chronospecies is a species derived from a sequential development pattern that involves continual and uniform changes from an extinct ancestral form on an evolutionary scale. The sequence of alterations eventually produces a population that is p ...

to modern bison.

References

Bison Prehistoric bovids Pleistocene even-toed ungulates Prehistoric mammals of North America Holocene extinctions Fossil taxa described in 1898 {{paleo-eventoedungulate-stub

Characteristics

Evolution

See also

References