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Bears of the Pleistocene
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The Cave Bear Story... The brown bear then acted as a substitute ( or, to use the technical term, vicar ) of the cave bear in Britain. This is unexpected. Students of the living Ursus arctos stress that this species avoids caves as winter quarters. Dr. Peter Krott, who lived for several years in the Alps with the bears he had brought up ( "they are not really dangerous, as long as you behave in a bearish way yourself," he commented ), noted that they dug their own dens, although natural caves were available in the area. The Craighead brothers, speaking on the basis of unparallelled experience, emphasize the same for the grizzlies of Yellowstone Park. And yet we find the British bears violating the code of brown bear behavior and denning in caves!
The Cave Bear Story... Behavior is plastic and evolves in adaptation to environment and mode of life. After all, the brown bears and cave bears were closely related, and the absence of the other species may have made it possible for the brown bears to step into the "niche" of the cave bear on British soil.
How close the parallel was is a matter of speculation. It may be that in this area, a less exclusive vegetarian form was better equipped to make a living. whatever the reason, it is a fact that the British Isles came to be a stronghold of Ursus arctos throughout the later Pleistocene, and it survived well into historical times. In 1871, W. Pennant noted that bears survived in the mountains of Scotland to as late as the year 1057. Ireland also had a Pleistocene and postglacial population of bears.
The Cave Bear Story... At the Peking man site in Choukoutien in China, some skulls and bones were found. These represent a very large type of brown bear, and some of them are so immense that Dr. Pei Wen-chung thought the bear might be a true cave bear. But the anatomical details agree better with the brown bear, so I think this must be Ursus arctos too.
The Cave Bear Story... But, although the grizzly appears at various open-air sites in North America, including the famous tar pits of Rancho La Brea in Los Angeles, California, it is not present in caves.
The black bears, to judge from their fossil record, are somewhat more prone to cave-denning than the brown and grizzly bears. In my own words... there is simply too much to copy word-by-word about both Asiatic and American black bear remains found in caves, sometimes in great quantities.
The Cave Bear Story... The Andean bear of South America, Tremarctos ornatus, is the last survivor of a great tribe of bears that ranged widely through the Americas in Pleistocene times. A closely related species was the Florida cave bear, Tremarctos floridanus, whose remains have been found in Mexico and the southern United States - California, New Mexico, Texas, Tennessee, Georgia, and especially Florida. Although many of the finds come from caves, there are no mass occurrences like those of the European cave bear, or even the Cumberland black bears, and so the name might seem ill chosen. But there is a point to it. The bodily resemblance of this American species to the European cave bear is almost uncanny.
Of course there are differences. Anatomical details make it clear that the Florida cave bear was closely related to the living Andean bear, and their connection with the Ursus bears is certainly rather distant. Yet evolution, working with such different raw materials, brought forth a creature mirroring the European form in some of its most conspicuous features. The Florida cave bear was a big animal. The weight of a large male has been estimated at some 650 pounds ( upwards of 300 kg ), while the much smaller female weighed about half as much. It was very heavily built, with a barrel-like rib cage, short, broad paws, and elongated upper arm and thigh bones. The anterior premolars were reduced, and back teeth enlarged, and the jaw articulation shifted well above the plane of the teeth. The profile of the forehead shows a distinct step. The neck was lengthened, the back sloping, and the hindquarters were relatively weak. All this could just as well read as a list of the special features in which the cave bear, Ursus spelaeus, differed from its close relative the brown bear. It seems clear that, within limits, the Florida cave bear was trying to do just the same as its European counterpart.
BEARS of the last frontier by Chris Morgan... The grandeur of the landscape in the Denali region seems matched by the impressive array of mammals. During the peak of the last glacial period, so much of the earth's seawater was locked up in ice that the Bering Land Bridge was exposed, providing a grassland corridor to North America. A curious exchange of species occured between the two continents over thousands of years and led to a 'Who's Who' of fascinating mammals from the past and present. From North America traveled horses and camels, which were to become the donkeys, zebras, and dromedaries of the Asia we know today. And from Asia came caribou, foxes, ground squirrels, wolves, Dall sheep, beaver, and of course, grizzly bears.
At this time, around 12,000 years ago, these species utilized the Alaskan ice age refugium, an ice-free region of interior Alaska that provided lush vegetation for grazers and, as a result, plenty of prey for carnivores. Other species found here included the ground sloth, saber-toothed cat, woolly mammoth, giant short-faced bear, and the large-horned bison.
On this episode of "Prehistoric Beasts", the short-faced bear is proven, from a study of their bones, to be pure-carnivore. Also, from a study which includes their leg structure, their sense of smell, and powerful bone-crushing jaws, the short-faced bear was a full-time scavenger. The only thing on this documentary that I disagree with is them telling that this bear would rear up and stand bipedal to frighten other predators from a kill. The grizzly does not do this. It is possible that this bear had different habits, but no way for the paleontologists to know this.
https://www.youtube.com/watch?v=k5z2TmJB2SU 
I take this study's word at the moment:
"In contrast, the picture that emerges from this study is one of a colossal omnivorous bear whose diet probably varied according to resource availability." From "DEMYTHOLOGIZING ARCTODUS SIMUS, THE ‘SHORT-FACED’ LONG-LEGGED AND PREDACEOUS BEAR THAT NEVER WAS" Link File's too big to attach.
Why did the giant cave bear become extinct while the brown bear survived the last Ice Age?
http://www.livescience.com/7622-huge-cav...eared.html Enormous cave bears that once inhabited Europe were the first of the mega-mammals to die out, going extinct around 13 millennia earlier than was previously thought, according to a new estimate. Why'd they go? In part because they were vegetarians. The new extinction date, 27,800 years ago, coincides with a period of significant climate change, known as the Last Glacial Maximum, when a marked cooling in temperature resulted in a reduction or total loss of the vegetation that the cave bears ate (today’s brown bears are omnivores). The loss of this food supply led to the extinction of the cave bear, Ursus spelaeus, one of a group of "megafauna" — including the woolly mammoth, woolly rhinoceros, giant deer and cave lion — to disappear during the last Ice Age, the researchers wrote in a research paper published online Nov. 26 in the journal Boreas. Mysterious disappearance Over the years, numerous cave bear remains have been discovered in caves where the animals probably died during winter hibernation. Cave bears were huge, with males growing up to around 2,200 pounds (1,000 kg). The maximum recorded weight of both Kodiak bears and polar bears — the largest bears living today — is 1,760 pounds (800 kg), with averages of around 1,100 pounds (500 kg). During the Middle Ages, the bones of cave bears, thought to be the remains of dragons, were collected and used for medicine, the researchers say. The question of what caused cave bears, woolly mammoths and the other large mammals to go extinct has been a mystery. Some researchers think humans hunted the mega-mammals to extinction, but researcher Martina Pacher of the University of Vienna and her colleague Anthony J. Stuart of the Natural History Museum, London, found no convincing evidence for this idea regarding cave bears. Another theory is that some virus or bacteria could have sickened populations of mega-mammals, but Pacher and Stuart think such a "hyperdisease" is unlikely to explain the timing of the extinctions or the fact that body sizes of the dying-out animals varied so much. 'One of the earliest to disappear' Pacher used new data and existing records of radiocarbon dating on cave bear remains to construct the new chronology for cave bear extinction that supports the climate change scenario. "Our work shows that the cave bear, among the megafauna that became extinct during the Last Glacial period in Europe, was one of the earliest to disappear," Pacher said. "Other, later extinctions happened at different times within the last 15,000 years." Many scientists previously claimed that cave bears survived until at least 15,000 years ago, but the methodology of these earlier studies included errors in dating as well as confusion between cave bear and brown bear remains, Pacher and Stuart say, so they excluded those data from the analysis. Pacher and Stuart also concluded, from evidence on skull anatomy, bone collagen and teeth, that these extinct mammals were predominantly vegetarian, eating a specialized diet of high-quality plants. Compared with other megafaunal species that would also become extinct, the cave bear had a relatively restricted geographical range, being confined to Europe (ranging from Spain to the Ural Mountains in Russia), which may offer an explanation as to why it died out so much earlier than the rest. "Its highly specialized mode of life, especially a diet of high-quality plants, and its restricted distribution left it vulnerable to extinction as the climate cooled and its food source diminished," Pacher said. Why did the brown bear survive? The brown bear, with which Ursus spelaeus shares a common ancestor, was spread throughout Europe and much of northern Asia and has survived to the present day. "A fundamental question to be answered by future research is: why did the brown bear survive to the present day, while the cave bear did not?" Stuart said. Answers to this question may involve different dietary preferences, hibernation strategies, geographical ranges, habitat preferences and perhaps predation by humans. Despite more than 200 years of scientific study — beginning in 1794 when anatomist Johann Rosenmüller first described bones from the Zoolithenhöhle in Bavaria as belonging to a new extinct species, which he called cave bear — the timing and cause of its extinction remain controversial. The research was funded by Natural Environment Research Council UK, the Cultural Grant of Lower Austria and the EU project: AlpiNet Culture 2000.
Was the Giant Short-Faced Bear a Hyper-Scavenger? A New Approach to the Dietary Study of Ursids Using Dental Microwear Textures
Short answer is no. The results show dental wear similar to that of the spectacled bear. The North American short-faced bear may have still scavenged, but it does not show the bone crushing-caused dental wear you usually find in scavengers. Softer materials seem to compose its diet and plants likely comprised a very significant chunk of the bear's diet.  *This image is copyright of its original author The two forms of giant short faced bear share a common ancestor and are not linearly related. The South American form is also more closely related to the spectacled bear than the North American form. 
@tigerluver,
That makes more sense since Arctotherium lived right S. America right where Tremarctos lived and lives. But one question I have is, where have all the short-faced bears decended from? What ancestral bear family or geographical location?  (06-02-2016, 10:13 PM)Polar Wrote: @tigerluver, The ancestor of the modern Spectacled bears also lived in the North America, more preciously Florida. https://en.wikipedia.org/wiki/Tremarctos_floridanus Maybe Arctotherium and Tremarctos used to diverge somewhere in the southern part of the North America during the Pliocene period?
http://www.nhm.org/site/sites/default/fi...e/CS39.pdf
I was looking at the skull of bear #133 pictured. It is the skull of a young female grizzly from Rancho La Brea. As I understand it, a grizzly population that leans more towards a vegetarian diet has a broader skull with a shorter muzzle while those who lean more towards a carnivore diet tend to have a more elongated narrow skull with longer canines. This skull appears to be long and narrow. http://www.jstor.org/stable/30059415?seq...b_contents
Some interesting material here referring to the Pleistocene grizzly: http://www.allgrizzly.org/#!pleistocene-...diet/c1xe9
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