Scientific name: Arctodus simus Scientific classification:
Phylum: Chordata Class: Mammalia Order: Carnivora Family: Ursidae
When did it become extinct? This bear is thought to have died out around 12,500 years ago.
Where did it live? This bear and its close relatives were only found in North America. Their remains have been found from Alaska and the Yukon to Mexico and from the Pacific to the Atlantic coasts.
Thousands of years ago, northern North America was not the land of forest that it is today. Expansive grasslands stretched out toward the horizon, which were populated by great herds of herbivorous mammals, including mammoth, bison, deer, and caribou. Predators like the saber tooth cat, scimitar cat, and dire wolf stalked these herds, and dependent on them were the scavengers. One of these scavengers was the largest bear that has ever lived—a bear so big that even when it was standing on all fours, it could still look a grown man in the face. This was the giant short-faced bear, and in these prehistoric northern climes, it was the dominant carnivorous animal, although it is now widely believed that it was a scavenging animal, rather than an active predator.
This giant bears closest living relative is the spectacled bear (Tremarctos ornatus) of South America, but in appearance, it was unique, with long limbs and a short, wide head. Fully grown, they were enormous—an adult male could have easily tipped the scales at 900 kg (by comparison, a really big male polar bear is around 600 kg). The way the bones of the giant short-faced bear articulate suggest that this huge carnivore was easily able to rear up onto its back legs. A big, standing male was around 3.4 m tall, with a vertical reach extending to around 4.3 m—this is more than 1 m above a basketball hoop. Like modern bears, this extinct brute probably reared up to sniff the air for the telltale odor of meat and to intimidate animals that dared to get between it and its food. We know that the short-faced bear had a big space in its skull for nasal tissue, and its sense of smell was probably very keen—even better than that of modern bears, with their very sensitive noses.
Once this huge bear caught a whiff of some food, it would head for the source. For a long time, it was thought that the favored locomotion of this long-limbed bear was running, but recent research suggests that it moved in the same way as a camel, with what is best described as a pace whereby the two left limbs move together, followed by the right limbs. This is a very efficient gait, and like a speed walker, the bear was able to cover long distances without tiring.
How do we know that this extinct bear was a scavenger? The levels of two types of nitrogen in the bones of an animal (even long-dead ones) can tell us if they were an omnivore or a dedicated carnivore. The nitrogen signature of the short-faced bear's bones suggests that it fed solely on meat, but although it was big, it was not really equipped to be a predator. Its bones seem too slender to have enabled it to tackle the large animals that its big appetite required, and although it was an endurance athlete, it was not fleet of foot enough to catch fast-running prey. In some ways, scavenging is an easy option: you let another animal do the dirty work of killing, the smell of death gets carried on the air, and then you turn up to chase the predators away from their kill with your formidable size. Easy! This is not to say that the short-faced bear didn't actively kill when the opportunity arose, but scavenging seems much more likely. It is easy to imagine the scene of a pack of wolves feasting on the carcass of a young mammoth, only to be scared off by the sight of a giant bear looming over them. With the carcass to itself, the bear could have proceeded to gorge itself on meat. Its teeth and jaws appear to have been sufficiently strong to break the bones of a carcass to get at the nutritious marrow within—the same technique used by the modern-day spotted hyena.
So what became of the giant short-faced bear? How come it can no longer be found lumbering around the northern wilderness, sniffing out carcasses? The long-standing belief was that this giant was outcompeted by the brown bear as the latter species migrated into North America via the Bering land bridge. As it is now assumed that the giant short-faced bear was a scavenger, the two species only came into direct competition in certain circumstances, for example, in the event of dwindling resources. The brown bear is an omnivore that gets its calories from a wide variety of sources, of which carrion makes up only a fraction. Competition may have played a part in the demise of this giant; climate change was probably the most important factor. Toward the end of the last glaciation, the increase in global temperatures was responsible for the disappearance of northern grasslands, as the warmer, wetter conditions favored the growth of forests. These boreal forests cover vast swathes of the Northern Hemisphere today, and thousands of years ago, they probably deprived the giant bears of prime scavenging territory. The dwindling populations under pressure due to habitat loss, competition, and even disease transmitted by the spreading brown bears may have been sufficient to drive the giant short-faced bear to extinction.
♦ The giant short-faced bear is known to have existed for at least 800,000 years, and possibly far longer. In that time, the species experienced many global warming and cooling events, lending support to the theory that it was not one single factor that led to the extinction of this species.
♦ The remains of this bear have been found in caves. The bones discovered in Potter Creek Cave, California, are all from females, indicating that this species may have made dens in such places to give birth and to raise their young, until they were big enough to face the rigors of the outside world.
♦ The bones of this bear even provide a window into some of the diseases from which they suffered. There is evidence of osteomyelitis, tuberculosis-like diseases, and syphilislike infections.
♦ Humans definitely hunted the large animals on which the giant short-faced bear was dependent, and this may have been another factor contributing to the bear's extinction.
Further Reading: Matheus, P. E. "Diet and Co-ecology of Pleistocene Short-Faced and Brown Bears in Eastern Beringia." Quaternary Research 44 (1995): 447-53; Voorhies, M. R., and R. G. Corner. "Ice Age Superpredators." University of Nebraska State Museum, Museum Notes 70 (1982): 1-4.
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