Fossil Cave Bear Tooth
Age: 30,000 - 25,000 Years Old
Late Pleistocene Epoch
Species: Ursus Spelaeus
Specimen: Tooth
Discovered: Carparth Mountains, Romania
 
The cave bear (Ursus spelaeus) is a prehistoric species of bear that lived in Europe and Asia during the Pleistocene and became extinct about 24,000 years ago during the Last Glacial Maximum.
Both the word "cave" and the scientific name spelaeus are used because fossils of this species were mostly found in caves. This reflects the views of experts that cave bears may have spent more time in caves than the brown bear, which uses caves only for hibernation.
 
Cave bear skeletons were first described in 1774 by Johann Friedrich Esper, in his book Newly Discovered Zoolites of Unknown Four Footed Animals. While scientists at the time considered that the skeletons could belong to apes, canids, felids, or even dragons or unicorns, Esper postulated that they actually belonged to polar bears. Twenty years later, Johann Christian Rosenmüller, an anatomist at Leipzig University, gave the species its binomial name. The bones were so numerous that most researchers had little regard for them. During World War I, with the scarcity of phosphate dung, earth from the caves where cave bear bones occurred was used as a source of phosphates. When the "dragon caves" in Austria’s Styria region were exploited for this purpose, only the skulls and leg bones were kept.
 
Many caves in Central Europe have skeletons of cave bears inside, such as the Heinrichshöhle in Hemer and the Dechenhöhle in Iserlohn, Germany. A complete skeleton, five complete skulls, and 18 other bones were found inside Kletno Bear Cave, in 1966 in Poland. In Romania, in a cave called Bears' Cave, 140 cave bear skeletons were discovered in 1983.
 
Cave bear bones are found in several caves in the country of Georgia. In 2021, Akaki Tsereteli State University's students and a lecturer discovered two complete cave bear skulls, with molars, canines, humerus, three vertebrae and other bones, in a previously-unexplored cave.
 
The cave bear had a very broad, domed skull with a steep forehead; its stout body had long thighs, massive shins and in-turning feet, making it similar in skeletal structure to the brown bear. Cave bears were comparable in size to, or larger than, the largest modern-day bears, measuring up to 2 m (6.6 ft) in length. The average weight for males was 350 to 600 kg (770 to 1,320 lb), though some specimens weighed as much as 1,000 kg (2,200 lb), while females weighed 225 to 250 kg (495 to 550 lb). Of cave bear skeletons in museums, 90% are classified as male due to a misconception that the female skeletons were merely "dwarfs". Cave bears grew larger during glaciations and smaller during interglacials, probably to adjust heat loss rate.
 
Cave bears of the last Ice Age lacked the usual two or three premolars present in other bears; to compensate, the last molar is very elongated, with supplementary cusps. The humerus of the cave bear was similar in size to that of the polar bear, as were the femora of females. The femora of male cave bears, however, bore more similarities in size to those of Kodiak bears.
 
Overhunting by humans has been largely dismissed because human populations at the time were too small to pose a serious threat to the cave bear's survival, though the two species may have competed for living space in caves. Unlike brown bears, cave bears are seldom represented in cave paintings, leading some experts to believe the cave bear may have been avoided by human hunters or their habitat preferences may not have overlapped. The late paleontologist Björn Kurtén hypothesized cave bear populations were fragmented and under stress even before the advent of the glaciers. Populations living south of the Alps possibly survived significantly longer.
 
Some evidence indicates that the cave bear used only caves for hibernation and was not inclined to use other locations, such as thickets, for this purpose, in contrast to the more versatile brown bear. This specialized hibernation behavior would have caused a high winter mortality rate for cave bears that failed to find available caves. Therefore, as human populations slowly increased, the cave bear faced a shrinking pool of suitable caves, and slowly faded away to extinction, as both Neanderthals and anatomically modern humans sought out caves as living quarters, depriving the cave bear of vital habitat. This hypothesis is being researched at this time. According to the research study, published in the journal Molecular Biology and Evolution, radiocarbon dating of the fossil remains shows that the cave bear ceased to be abundant in Central Europe around 35,000 years ago.[45]
In 2019 the results of a large scale study of 81 bone specimens (resulting in 59 new sequences), and 64 previously published complete mitochondrial genomes of cave bear mitochondrial DNA remains found in Switzerland, Poland, France, Spain, Germany, Italy and Serbia, indicated that the cave bear population drastically declined starting around 40,000 years ago at the onset of the Aurignacian, coinciding with the arrival of anatomically modern humans. It was concluded that human hunting and/or competition played a major role in their decline and ultimate disappearance, and that climate change was not likely to have been the dominant factor. In a study of Spanish cave bear mtDNA, each cave used by cave bears was found to contain almost exclusively a unique lineage of closely related haplotypes, indicating a homing behaviour for birthing and hibernation. The conclusion of this study is cave bears could not easily colonize new sites when in competition with humans for these resources.
 
In 2020 a well preserved ice age cave bear was found on the Bolshoy Lyakhovsky Island. Nearby, on the Siberian mainland of Yakutia, a small, well preserved cave bear cub recently emerged from another patch of melting permafrost.