Bears of the Pleistocene

[brotherbear]

Ice Age Mammals of North America by Ian M. Lange.

Subfamily Tremarctinae.

The subfamily Tremarctinae included extinct species within the genera Tremarctos and Arctodus. One species of Tremarctos, the spectacled bear ( Tremarctos ornatus ), still resides in South America. Extinct species of bears that roamed North America during the Ice Age until its bitter end about 10,000 years ago included the Florida cave bear ( Tremarctos floridanus ) and the so-called 'bulldog bears,' the giant short-faced bear ( Arctodus simus ) and the lesser short-faced bear ( Arctodus pristinus ). Reply

[brotherbear]

Yellowstone Bears in the Wild by James C. Halfpenny.

Two other bears also roamed North America, the lesser short-faced bear ( Arctodus pristinus ) and the Florida cave bear ( Tremarctos floridanus ), but their fossils have been found only in eastern and southeastern North America, not near Yellowstone. All three species of Tremarctine bears evolved in the New World but none survive in North America today; their reign ended during the Ice Ages. Today, the spectacled bear of South America is the only Tremarctine bear in the world.
During the Ice Ages the development of the great ice sheets lowered the sea level and allowed the formation of the Bering Land Bridge between the Old World and the New World. Many species, including bears, crossed the exposed land from Asia to North America. Perhaps as long ago as 4.3 million years, the first Ursine bear arrived in North America, Ursus minimus, a small bear whose fossils have been found in Idaho not far from Yellowstone. U. mimimus is known as "First Bear" because it was the earliest bear of the genus Ursus, the genus of the true bears we know today.
First Bear probably gave rise to the ancestors of the American black bear, Ursus americanus, in the Old World about 1.5 million years ago. Those ancestors also migrated over the Bering Land Bridge and by 8,000 years ago Ursus americanus had replaced the Florida cave bear and the lessor short-faced bear. Scientists speculate their extinctions were ecolological replacements resulting from the American black bear being a better competitor. Reply

[brotherbear]

Bears of the World by Lance Craighead.

The grizzly or brown bear, Ursus arctos, began to evolve in the Old World from the ancestral Ursus etruscus during the middle Pleistocene about 1.6 million years ago. The oldest known fossils of today's brown bears were found in France and are about 900,000 years old. A more recent fossil was found in China, and is about 500,000 years old. This and other fossil data suggest that brown bears were well established in Europe by the mid Pleistocene about 800,000 years ago. They may have also been in central Asia at that time. They subsequently dispersed into eastern Asia and eventually into North America following the route taken by the black bears.

The brown bear also coexisted with the giant short-faced bear, Arctodus simus. The only known association of these two species south of Alaska is from Little Box Elder Cave near Douglas, Wyoming. The grizzly was probably in competition with the giant short-faced bear throughout its range and eventually replaced it.

Bear populations expanded slowly, one female home range at a time. As grizzlies expanded their range south of the ice sheets they competed with the black bear and in some cases restricted the black bear's range. By the time of the earliest historical records, the grizzlies had expanded as far south as central Mexico.

Half a million years ago, ancestral brown/grizzly bears ranged all across northern Eurasia. At about this time, the European cave bear was also present. Cave bears probably evolved earlier and they went extinct as brown bears increased. Reply

[brotherbear]

Ice Age Mammals of North America by Ian M. Lange.

BEARS - Family Ursidae.

Like most animals, these magnificent creatures had humble beginnings. Bears descended from a small, tree-climbing carnivore of the Miacidae family that lived in Europe in late Eocene to early Oligocene time, 40 million to 35 million years ago. About 27 million years ago, in middle to late Oligocene time, bear ancestors were evolving from bearlike dogs in North America. By 20 million years ago, Ursavus elemensis, the oldest true bear, was wandering around subtropical Europe. It was a small animal, about the size of a fox terrier.

At least two bear subfamilies, containing six species, lived in North America during the Rancholabrean Land Mammal Age, from 200,000 to about 10,000 years ago. The sub-families included Ursinae, or the living bears of Old World origin, and Tremarctinae of New World derivation. The genus Ursus, which includes the three modern North America species, arose about 5 million years ago in Eurasia. By 2.5 million years ago, black, grizzly, and cave bears were evolving toward their present forms in Europe from their common ancestor Ursus etruscus, or 'modern bear.' Approximately 1.5 million years ago, Ursus etruscus arrived in North America from Asia via Beringia, and the present North American species are its descendants.

North America presently has black ( Ursus americanus ), grizzly ( Ursus arctos ), and polar bears ( Ursus maritimus ). Black bears can be traced back about 1 million years to the primitive black bear ( Ursus abstruscus ), a descendant of Ursus etruscus. Grizzlies date back to early Irvingtonian Land Mammal Age, 1.5 million years ago, and crossed into North America from Siberia between 200,000 and 130,000 years ago. We know little about the early history of polar bears because they live on ice and drop into the sea when dead. Over the millennia, bears have evolved toward larger size and, except for the polar bear, toward a more omnivorous diet. In general, modern male bears are usually much larger than females. Male blacks weigh up to 590 pounds, grizzly males up to 1,700 pounds, and male polar bears up to 1,100 pounds. Reply

[brotherbear]

Grizzly Years by Doug Peacock.

Black bears are forest creatures, evolved from Etruscan bears in the Old World. They crossed over into North America some 500,000 years ago. The grizzly bear is a much more recent product of evolution. The grizzly wandered over the Bering land bridge as recently as 40,000 to 12,000 years ago and encountered great open expanses of tundra, the rich periglacial of the Pleistocene. One of the consequences was that away from their ancestral forests in Asia and Europe, grizzlies became more aggressive in response to the treeless tundra, where mothers had to learn to protect their young from other bears, wolves, and several now-extinct Pleistocene carnivores. Defense became a good offense; this increased aggressiveness no doubt accounting for the bear's subspecies name, 'horribilis'. Reply

[brotherbear]

Yellowstone Bears in the Wild by James C. Halfpenny.

On the heels of the American black bear came another bear of the genus Ursus, the brown bear/grizzly bear ( see sidebar on page 13 ). At the height of the last ice advance perhaps 50,000 years ago, several populations of brown/grizzly bears occupied Beringia, the area of the Bering Land Bridge including the current state of Alaska. Near the end of the Ice Age, some grizzly bears moved south toward Yellowstone. Common dogma says brown bears reached the continents interior by traveling through a land corridor between the central continental and western mountain ice sheets about 13,000 years ago, give or take 1,000 years. However, a fossil leg bone found by Greg McDonald in an Oregon cave suggests brown bears may have reached the southern areas of the continent 30,000 years ago by a route along the coast.
No matter when or by what route, the arrival of grizzly bears evidently sealed the fate of the giant short-faced bear. Perhaps it was the new competition and perhaps it was climate change, but the net effect was the extinction of the giant bear by the end of the Ice Age. From then on, only grizzly and black bears roamed North America, including the Yellowstone area. Reply

[brotherbear]

From my book, 'Land of the Bear' by Denny Geurink: Brown bears are one of the most majestic and awe-inspiring creatures in the world ... and also one of the most dangerous. Scientists tell us that the brown bears found in North America are direct descendants of brown bears from Russia. They both belong to the same species, Ursus arctos. Somewhere way back in time, they crossed a land bridge over the Bering Sea and made their way into Alaska and then down into Canada and the lower 48 states.

The brown bear we call a grizzly is a subspecies, scientifically known as Ursus arctos horribilis. Some scientists believe the grizzly evolved from the bigger coastal brown ( bears ) when it moved inland and started feeding on other things besides salmon. Others believe there may have been two separate brown bear migrations into North America from Russia.
They believe that the grizzlies stem from the narrow-skulled bears found in northern Siberia. These bears, they contend, migrated into central Alaska and into the interior of Canada and the lower 48 states. Meanwhile, the big coastal Alaskan brown bears, or Kodiak bears, are direct descendants of the broader-skulled bears found in Kamchatka. Brown bears were at one time quite widespread in Canada and the lower 48, with fossil remains found as far east as Ontario and Labrador in Canada and as far east as Kentucky and Ohio in the United States. Reply

[brotherbear]

Ice Age Mammals of North America by Ian M. Lange.

Short-faced bears - genus Arctodus.

The giant and lesser short-faced bears and the spectacled bear of South America probably descended from an earlier tremarctine, Plionarctos, that lived between 5 million and 10 million years ago in Texas. Both short-faced bears were widespread in North America by 800,000 years ago.

The giant ( Arctodus simus ) and lesser ( Arctodus pristinus ) short-faced bears resembled each other. Their snouts appear short relative to the size of their heads - thus, the name 'short-faced' bear. The width of the giant's skull was 80% that of the skull's length. With short faces and wide muzzles, the skulls of these two species resembles that of a big cat.

Both bears were less pigeon-toed than living bears and so walked a straight path rather than waddling from side to side. This toe-foot structure probably allowed the short-faced bears to run faster than brown or black bears. Most males were on average 15% larger than female bears. Studies of bones of both species show that some of these bears suffered from diseases similar to tuberculosis and syphilis.

The giant and lesser short-faced bears differ from each other in several important ways. The giant short-faced bear was not only at least several hundred pounds larger, but it also had longer legs, a shorter snout, and bigger, broader, and more crowded teeth well adapted to eating meat. The tooth structure of the lesser short-faced bear supported a more omnivorous diet than did that of its bigger cousin.

The lesser short-faced bear lived in the eastern United States and south into Mexico, preferring the wetter, forested regions. These magnificent animals lived until at least about 20,000 years ago.

The giant short-faced bear evidently preferred the more open, drier, grassy country west of the Mississippi River. Remains have been found from Alaska and Yukon south into Mexico, and from Pennsylvania west to California. Specimens of these animals found in the La Brea tar pits in southern California and elsewhere north into the Arctic show that the more northerly bears were larger than their cousins to the south. Cave remains are not uncommon, so both male and female bears may have inhabited caves for part of the year where they were available.

The giant short-faced bear, while long legged, was relatively short bodied for its leg length when compared with living bears. It also was not as heavily built as brown or grizzly bears. Even so, giant short-faced bears reached enormous size. At 5.5 feet tall and almost 10 feet long, the giant short-faced bear would dwarf the modern grizzly, which measures up to 4 feet tall and 9 feet long. When standing on their hind feet, the top of their headwas more than 11 feet high. Male giant short-faced bears probably weighed more than 2,000 pounds in the fall prior to hibernation. Compare this with a large grizzly bear, which before hibernation weighs about 1,700 pounds.

The giant short-faced bear has been traced back to Irvingtonian Land Mammal Age. It may have come north from South America and coexisted with brown and grizzly bears. The youngest remaims of these giant bears date at 12,650, plus or minus 350 years, before present. At least thirty specimens have been recovered from the La Brea tar pits in California and one from the Columbian mammal burial pit at Hot Springs, South Dakota. Other important fossil localities are in Texas, Montana, Utah, and Wyoming.

What did the giant short-faced bear - the largest and most powerful of the Pleistocene bruins - eat? Whatever it was, they needed a lot. Paul Matheus, director of the Alaska Quaternary Center in Fairbanks, is convinced that these steppe-loving animals - with their very powerful jaws and large teeth capable of ripping, crushing, and gnawing - ate only meat. His proof comes from their bones. The ratio of two isotopes of nitrogen 15 and nitrogen 14, in bones can help researchers distinguish between carnivores, herbivores, and omnivores. Herbivore bones contain a low ratio whereas carnivore bones have a high ratio. Matheus found that the bones of giant short-faced bears have a high ratio of nitrogen15 to nitrogen 14, supporting the contention that the animals were highly carnivorous.

Matheus's research also leads him to believe that the bone structure of this animal was not strong enough for it to bring down really large animals without getting hurt. Smaller animals such as horses, however, could evade the fast but less maneuverable bears. Matheus, therefore, thinks these animals were scavengers and that this lifestyle probably contributed strongly to their extinction. Once the other predators, such as American lions and scimitar cats, and their large prey were gone, there was not enough carrion left for the giant short-faced bear. Reply

[brotherbear]

Yellowstone Bears in the Wild by James C. Halfpenny.

During the Pleistocene Ice Age, the giant short-faced bear ( Arctodus simus ), perhaps the largest land mammalian carnivore ever to roam North America, imposed its might on giant bison, horses, and even mammoths. This bear was estimated to have weighed on average more than 1,300 pounds and may have reached a maximum weight of more than 2,000 pounds. Fossils of the giant short-faced bear have been found near the Yellowstone area.
The giant short-faced bear had long legs and its toes pointed forward. Both adaptations allowed the bear to gallop at great speeds. Some scientist have argued that this was the fastest, greatest predator of all, while others, citing the bear's teeth, believe the huge bruin was a vegetarian. My late colleague Dr. Elaine Anderson, bear paleontologist and co-author of Pleistocene Mammals of North America, summed it up by saying, "When you are that big, you eat anything you please, anytime you want. The giant was probably little different than recent bears in that it ate vegetation but dined on meat obtained through predation whenever possible." Reply

[brotherbear]

Ice Age Mammals of North America by Ian M. Lange.

Florida Cave Bear - Tremarctos floridanus.

The Florida cave bear arrived in North America about 1.3 million years ago and went extinct about 8,000 years ago or later. This large but relatively small-toothed animal ranged widely in the southern United States. Its dentition suggests that it was probably vegetarian. The Florida cave bear was a large and muscular creature similar in shape, diet, and habits to the also-extinct European cave bear ( Ursus spelaeus ), and larger than its North American cousin the lesser short-faced bear ( Arctodus pristinus ).

Both Florida cave bears and European cave bears had skulls larger than those of most living bears except big grizzly bears. Their skulls, however, had a domed or vaulted forehead that is not seen in other species. Their large did not contain proportionally larger brains than those of their other large cousins. The bears had large nasal cavities but small eye sockets, leading paleontologists to theorize that these cave bears probably had poor eyesight but a good sense of smell. The cave bears had the large grinding teeth of herbivores rather than the small grinding teeth of omnivorous grizzly bears, so they were most likely strict vegetarians.

Both sexes of cave bears had barrel-shaped bodies and big heads on long necks. They had short but very heavy and powerful limbs and feet, and wide paws. These massive beasts probably lumbered slowly along, swaying from side to side in their quest for tasty vegetation. Male cave bears were considerably larger than females. An average-sized male probably weighed 900 to 1,000 pounds and considerably more in the fall before hibernation.

During the Rancholabrean Land Mammal Age, the Florida cave bear inhabited swamps, lowlands, and valleys across the southern states from Florida to New Mexico and as far north as Georgia and Tennessee. Remains have been found in caves and sinkholes, commonly with those of black bears. Remains of European cave bear are plentiful in caves across central and southern Europe from southern England and the Pyrenees Mountains of northern Spain to the Caucasus Mountains in the east.

The Florida cave bear was also similar to, but much larger than, the present-day South American spectacled bear, a 440-pound fellow that is barely surviving in mountainous regions of Panama south to Peru and Bolivia. Reply

[brotherbear]

The Bear Almanac - The European cave bear is one of the best-known ice age mammals. It inhabited mountainous and hill regions in the area of present day Germany, France, and Russia and lasted in Europe and Russia for two ice ages. It's head was very large, with a broad, domed skull and steep forehead; it had small eyes, upward-opening nostrils, and a grinding jaw. The body was stout, with long thighs; short, massive shins; large in-turned feet; the large bones close in structure to those of the grizzly bear. Males weighed up to 880 pounds. The cave bear was a specialist, a distinct herbivore, considerably more a browser than a predator. Ursus spelaeus was hunted and worshipped by Neanderthal man and has been found in burial positions. Reply

[brotherbear]

The Grizzly Almanac by Robert H. Busch - Somewhere around 5 million years ago, the first member of the Ursus genus appeared, probably in southern Europe. This was Ursus etruscus, the Etruscan bear. Fossil evidence suggests that this animal was the direct ancestor of brown bears, with large molar teeth that were useful for chewing up vegetation.

Most biologists believe that Ursus etruscus separated into two distinct lineages - the Asian brown bear and Ursus speleaus, the famed and formidable cave bear.

Cave bears were large animals that weighed up to 880 pounds. These bears were opportunistic omnivores, eating primarily vegetation. The European brown bear now occupies the same ecological niche. Cave bears were found in the mountainous areas of Germany, France, and Russia. They had a large head, small eyes, and large bones. The cave bear survived through two Ice Ages and did not die out until about 11,000 years ago. The first known relationships between humans and bears are thought to have been between cave bears and Neanderthal humans, in what is now southern Europe.

By around 1.3 million years ago, Ursus etruscus had disappeared and Ursus arctos, the brown bear, had evolved, perhaps in the area we now know as China. Grizzlies are a form of brown bear. Reply

[brotherbear]

Cave art in France depicts the cave bears in red which suggests that cave bears were typically red ( reddish brown ) in color. 
 
                                                                                     

*This image is copyright of its original author

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[brotherbear]

Ice Age Cave Bear by Barbara Hehner.

Even though the last cave bear died out about 10,000 years ago, they left behind many clues to what they looked like and how they lived. Above all, they left us their bones, hundreds of thousands of bones, in caves from France to Belgium, Holland, Germany, and Switzerland, eastward to Poland and south into Spain and Italy.

From these bones, scientists know that cave bears were as big as Kodiak bears, the largest brown bears found in Alaska today. Standing on their hind legs, male cave bears were as much as eight feet ( 2.4 m ) tall. On all fours, they might have been five feet ( 1.5 m ) tall at the shoulder. They weighed up to 1,500 pounds ( 680 kg ). Females were much smaller than the males, perhaps a third to half the size. All cave bears had heavy, barrel-shaped bodies and their hind legs were short, but thick and powerful.

Cave bears had even larger heads than Kodiak bears, and there was a distinct "step" from their muzzles to their broad, domed foreheads. ( This is what makes them easy to recognize when portrayed in cave art. ) Their eye-sockets were smaller than those of brown bears, but their nasal cavities were very large, suggesting an animal that relied more on a keen sense of smell than on eyesight to locate food.

Because of their enormous size, like large bears today, cave bears would have had few natural enemies. And yet the experts have concluded that for all their massive bodies, long claws, and pointed canine teeth, cave bears were mostly plant-eaters. The evidence is at the back of their mouths; large grinding molars - much larger than those of today's brown bears - for mashing plants. Raw plant fibers are very hard on teeth. Scientists have found that the molars of old cave bears, those that had lived for 20 years or so, were worn down to stubs.

At different times and places, bears have eaten a wide range of food. The cave bear menu probably consisted of grasses and other plants and berries. The bears may also have enjoyed fish, insects, small animals, and leftovers from lion or hyena kills. Their excellent sense of smell may have helped them locate decaying carcasses just as bears do today. Reply

[brotherbear]

There were three known species of European cave bear: Ursus ingressus, Ursus kudarensis, and the famous Ursus spelaeus ladinicus. Reply