Steppe bison

The steppe bison (Bison priscus), also less commonly known as the steppe wisent and the primeval bison) is an extinct species of bison which lived from the Middle Pleistocene to the Holocene. During the Late Pleistocene, it was widely distributed across the mammoth steppe, ranging from Western Europe to eastern Beringia in North America. It is ancestral to all North American bison, including ultimately modern American bison.^[2][3] Three chronological subspecies, Bison priscus priscus, Bison priscus mediator, and Bison priscus gigas, have been suggested.^[4]

Steppe bison Temporal range: Middle Pleistocene to Holocene 0.65–0.003 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
"Blue Babe", a mummified specimen from Alaska
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Artiodactyla
Family:	Bovidae
Subfamily:	Bovinae
Genus:	Bison
Species:	†B. priscus
Binomial name
†Bison priscus Bojanus, 1825[1]

Evolution

Steppe bison are divided into three chronologically successive subspecies, Bison priscus gigas from the early Middle Pleistocene of Siberia and Eastern Europe, Bison priscus priscus from the late Middle Pleistocene spanning from Western Europe to Siberia, and the Late Pleistocene Bison priscus mediator.^[5]

The steppe bison first appeared during the mid Middle Pleistocene in eastern Eurasia,^[2] subsequently dispersing westwards as far as Western Europe.^[6] During the late Middle Pleistocene, around 195,000-135,000 years ago, the steppe bison migrated across the Bering land bridge into North America,^[7] becoming ancestral to endemic North American bison species, including the largest known bison, the long-horned Bison latifrons, and the smaller Bison antiquus, the latter of which is thought to be ancestral to modern American bison.^[3]

Description

Skeleton of a steppe bison

Resembling the modern bison species, especially the American wood bison (Bison bison athabascae), adult bull steppe bison could likely reach over 2 m (6 ft 7 in) tall at the withers, and over 1,000 kg (2,200 lb) in weight.^[8] The steppe bison is also anatomically similar to the European bison (Bison bonasus), to the point of difficulty distinguishing between the two when complete skeletons are unavailable.^[9] Like living bison species, the steppe bison had a hump on its back immediately above its front legs.^[8]

Skulls of steppe bison are distinguished from those living bison and other extinct Bison species by the shape of their horn cores (the bony inner part of the horn).^[5] The horn cores of adult steppe bison generally project laterally outwards to the sides and curve upwards towards their tips.^[8] The size of steppe bison horn cores varied between subspecies, with the earliest subspecies Bison priscus gigas having horn cores that could spread to 2 m (6 ft 7 in) tip to tip, with this breadth progressively declining in later subspecies, down to 0.9–1.36 m (2 ft 11 in – 4 ft 6 in) in Bison priscus priscus, and to less than 0.9 m (2 ft 11 in) in the final subspecies Bison priscus mediator, corresponding with a body size decease between B. priscus gigas and B. priscus mediator,^[5] though the average breadth of the tips of the horn cores is still on average larger than those of living bison even in Late Pleistocene steppe bison.^[8]

The hair of the mummified "Yukagir bison" specimen is similar to living bison, but generally denser with the hair on the head varying from light brown to black depending on position, with the mane being almost black. The body hair of the "Yukagir bison" is generally shorter than the living American bison, consisting of light brown under hairs and black guard hairs.^[8]

Palaeoecology

Life restoration

Dental microwear analysis suggests the steppe bison was a mixed feeder, with its diet including a substantial amount of browse, rather than a strict grazer like the living American bison.^[10] Like other bison species, steppe bison are thought to have lived in herds.^[11] Likely predators of steppe bison include cave hyenas, whose dens have been found to contain steppe bison remains,^[12] cave lions, whose bite marks have been found on the frozen mummified "Blue Babe" specimen from Alaska,^[13] scimitar toothed cats (Homotherium) and possibly wolves.^[14]

Relationship with humans

Cave art of bison at Lascaux cave, France

"Bison licking insect bite", a well known French Paleolithic carving of a bison made of reindeer antler

Steppe bison are known to have been hunted by Neanderthals during the Middle Paleolithic in Europe.^[15] Modern humans are known to have fed on steppe bison during the Last Glacial Period, with their processed remains having been found in Upper Palaeolithic archaeological sites.^[16] Steppe bison were depicted by Paleolithic Europeans in cave art, with artists apparently distinguishing between steppe bison (depicted at sites like Lascaux cave, Chauvet Cave and Trois-Frères cave in France), and European bison, which co-occurred in Europe with steppe bison, with suggested depictions of steppe bison more common in early Upper Paleolithic cave art, prior to the Magdalenian, when suggested depictions of European bison became more common.^[17] Paleolithic Europeans also depicted bison in a variety of other mediums, such as carvings, though it is difficult to distinguish whether they are depicting European or steppe bison.^[18]

Extinction

The steppe bison distribution contracted to the north after the end of the Last Glacial period, surviving into the mid Holocene before becoming extinct as part of the Late Quaternary extinction event.^[8][19] A steppe bison skeleton was dated to 5,578-5327 calibrated years Before Present (c. 3450 BCE) in Alaska.^[20] B. priscus remains in the northern Angara River in Asia were dated to 2550-2450 BCE,^[9] and in the Oyat River in Leningrad Oblast, Russia to 1130-1060 BCE.^[21] The causes for the extinction of the steppe bison and many other primarily megafaunal species remain hotly debated, but the selectivity for large animals suggests that the spread of modern humans played a substantial role.^[22][23]

Discoveries

Bison priscus skeleton at the Mammoth Museum in the Canton of Zürich, Switzerland

Blue Babe is the 36,000-year-old mummy of a male steppe bison which was discovered north of Fairbanks, Alaska, in July 1979.^[24] The mummy was noticed by a gold miner who named the mummy Blue Babe – "Babe" for Paul Bunyan's mythical giant ox, permanently turned blue when he was buried to the horns in a blizzard (Blue Babe's own bluish cast was caused by a coating of vivianite, a blue iron phosphate covering much of the specimen).^[25] Claw marks on the rear of the mummy and tooth punctures in the skin indicate that Blue Babe was killed by a cave lion. Blue Babe appears to have died during the fall or winter, when it was relatively cold. The carcass probably cooled rapidly and soon froze, which made it difficult for scavengers to eat.^[26] Blue Babe is also frequently referenced when talking about scientists eating their own specimens: the research team that was preparing it for permanent display in the University of Alaska Museum removed a portion of the mummy's neck, stewed it, and dined on it to celebrate the accomplishment.^[27]

In early September 2007, near Tsiigehtchic, local resident Shane Van Loon discovered a carcass of a steppe bison which was radiocarbon dated to c. 13,650 cal BP.^[28] This carcass appears to represent the first Pleistocene mummified soft tissue remains from the glaciated regions of northern Canada.^[28]

In 2011, a 9,300-year-old mummy was found at Yukagir in Siberia.^[29]

In 2016, a frozen tail was discovered in the north of the Republic of Sakha in Russia. The exact age was not clear, but tests showed it was not younger than 8,000 years old.^[30][31] A team of Russian and South Korean scientists proposed extracting DNA from the specimen and cloning it in the future.^[30][31]

The steppe wisent is known from Denisova Cave, famous for being the site where the first Denisovan remains were discovered.^[32]