Ursus Rossicus
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''Ursus rossicus'' is an extinct species of bear that lived in the steppe regions of northern
Eurasia Eurasia ( , ) is a continental area on Earth, comprising all of Europe and Asia. According to some geographers, Physical geography, physiographically, Eurasia is a single supercontinent. The concept of Europe and Asia as distinct continents d ...
and
Siberia Siberia ( ; , ) is an extensive geographical region comprising all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has formed a part of the sovereign territory of Russia and its predecessor states ...
during the
Pleistocene The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...
. It is part of the
cave bear 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 '' ...
species complex.


Discovery

Vereshchagin discovered the first ''U. rossicus'' remains in the
Altai Mountains The Altai Mountains (), also spelled Altay Mountains, are a mountain range in Central Asia, Central and East Asia, where Russia, China, Mongolia, and Kazakhstan converge, and where the rivers Irtysh and Ob River, Ob have their headwaters. The ...
in 1973. Mandibles of the bear were found in Bachatsk Quarry, Krasni Yar (in
Tomsk Tomsk (, ) is a types of inhabited localities in Russia, city and the administrative center of Tomsk Oblast in Russia, on the Tom (river), Tom River. Population: Founded in 1604, Tomsk is one of the oldest cities in Siberia. It has six univers ...
Province) and Mokhovo Quarry; skull fragments were found in Krasni Yar. More fossil remains of ''U. rossicus'' were discovered in the famous
Denisova Cave Denisova Cave () is a cave in the Altai Mountains, Bashelaksky Range of the Altai Mountains in Siberia, Russia. It is widely known for having provided items of great archaeology, paleoarchaeological and paleontology, paleontological interest. ...
.


Description

The small 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 the largest modern-day bears.


Diet

''U. rossicus'' dental specimens when separated into groups of different ontogenetic stages do not show significant variations in microwear, suggesting the diets of these bears stayed fairly constant over the course of their lifetimes. Cave bear teeth show greater wear than most modern bear species, suggesting a diet of tough materials. However,
tubers Tubers are a type of enlarged structure that plants use as storage organs for nutrients, derived from stems or roots. Tubers help plants perennate (survive winter or dry months), provide energy and nutrients, and are a means of asexual reprod ...
and other gritty food, which cause distinctive tooth wear in modern brown bears, do not appear to have constituted a major part of cave bears' diets on the basis of
dental microwear Dental microwear analysis is a method to infer diet and behavior in extinct animals, especially in fossil specimens. It has been used on a variety of taxa, including hominids, victoriapithecids, amphicyonids, canids, ursids, hyaenids, hyaenodont ...
analysis. The morphological features of the cave bear chewing apparatus, including loss of premolars, have long been suggested to indicate their diets displayed a higher degree of
herbivory A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat n ...
than the Eurasian brown bear. Indeed, a solely vegetarian diet has been inferred on the basis of tooth morphology. Results obtained on the stable isotopes of cave bear bones also point to a largely vegetarian diet in having low levels of
nitrogen-15 Natural nitrogen (7N) consists of two stable isotopes: the vast majority (99.6%) of naturally occurring nitrogen is nitrogen-14, with the remainder being nitrogen-15. Thirteen radioisotopes are also known, with atomic masses ranging from 9 to 23, ...
and
carbon-13 Carbon-13 (13C) is a natural, stable isotope of carbon with a nucleus containing six protons and seven neutrons. As one of the environmental isotopes, it makes up about 1.1% of all natural carbon on Earth. Detection by mass spectrometry A m ...
, which are accumulated at a faster rate by carnivores as opposed to herbivores. 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.Gli orsi spelèi delle Conturines/ Ursus Spelaeus
Altabadia.it. Retrieved on 2011-09-26.


References

Pleistocene bears Pleistocene mammals of Europe Pleistocene carnivorans Fossil taxa described in 1930 Ursus (mammal) {{paleo-carnivora-stub