| Bison occidentalis Temporal range: Pleistocene – Holocene | |
|---|---|
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| A life restoration of Bison occidentalis | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Artiodactyla |
| Family: | Bovidae |
| Subfamily: | Bovinae |
| Tribe: | Bovini |
| Genus: | Bison |
| Species: | †B. occidentalis |
| Binomial name | |
| †Bison occidentalis Lucas, 1898 | |
Bison occidentalis is an extinct species of bison that lived in North America and Eurasia including Japanese archipelago from about 11,000 to 5,000 years ago, spanning the end of the Pleistocene to the mid-Holocene. Likely evolving from Bison antiquus, Bison occidentalis was smaller overall from its ancestor and other species such as the steppe bison. Bison 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, Bison occidentalis was replaced by today's smaller Bison bison.
Bison 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 Bison occidentalis and ancestral modern bisons, so Bison occidentalis was proposed to have been a localized offshoot of Bison antiquus and part of the transition from that chronospecies to modern bisons.
Evolution[]
Likely evolving from Bison antiquus, B. occidentalis was smaller overall from its most direct ancestor, 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's size depletion from Bison antiquus was likely caused by the influence of human pressures and may be related to the demise of the Folsom culture.[6] The smaller size likely helped B. occidentalis to flourish in number and shaping of modern American bisons after migrating into North America, as Bison antiquus faced population depletion by human hunting and was replaced by B. occidentalis in ecological niches and hybridization of the two bison species resulted in the appearance of today's smaller Bison bison.[6] The wood bison (Bison bison athabascae) preserves some of original traits of B. occidentalis which was more similar to the phenotype of the steppe bison, making it more primitive than the plains bison.
More recently ancient DNA studies have proven interbreeding between B. occidentalis and ancestral modern bison, so B. occidentalis was proposed to have been a localized offshoot of B. antiquus and part of the transition from that chronospecies to modern bison.