Arctodus simus
From Wikipedia, the free encyclopedia
| Arctodus simus Fossil range: Middle to Late Pleistocene |
||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
 A 1.6m tall Arctodus simus next to a 1.8m human.
|
||||||||||||||||
| Scientific classification | ||||||||||||||||
|
||||||||||||||||
| Binomial name | ||||||||||||||||
| A. simus (Cope, 1897) |
||||||||||||||||
 Range of Arctodus simus
|
Arctodus simus, also known as giant short-faced or bulldog bear is an extinct species of bear of the genus Arctodus. It is the largest bear that ever lived based on fossil finds. It lived in prehistoric North America from about 800,000 to 12,500 years ago.
Contents |
[edit] Sub-family
The short-faced bears belonged to a group of bears known as the Tremarctine bears or running bears, which are of New World origin. The earliest member of the Tremarctinae was Plionarctos, which lived in Texas during the Pliocene Epoch (5 million–2 million years ago). It thought that this genus is ancestral to Arctodus, as well as the modern Spectacled Bear (Tremarctos). Although the early history of Arctodus is poorly known, it evidently became widespread in North America by the Kansan age (about 800,000 years ago).
[edit] Physiology
Arctodus simus stood as high as 6 feet (1.8 m) at the shoulder on all four legs. When standing, the animal was over 11 feet (3.3 m). It is estimated to have weighed up to 600 kilograms (1,300 pounds), around the same weight of its contemporary, the grizzly bear.[1] The largest specimens were found in Alaska and Yukon.[2] Males were 20% bigger than females..[3] It was the largest land predator during the Ice Age in North America.[3] The skull was unusual due to its lack of a well-defined forehead and the presence of a short broad muzzle, resembling that of a Panthera rather than that of any modern bears. The muscles which passed between the broad cheek bones to power the lower jaws were extremely well-developed and are thought to be adapted for bone crushing in order to obtain the rich marrow. An A. simus lower jaw can be distinguished from those of the genus Ursus by the slanting ridge dividing muscle attachment areas.[3] Rather than having a waddling gait like modern bear species, A. simus had toes extending straight forward, presumably being able to move with greater ease. In addition, unlike Ursus, A. simus had a passage on the lower inside portion of the humerus for a slip of muscle (entepicondylar foramen).[3]
Arctodus had a very short, broad muzzle, the skull having an olfactory area twice as large as that of a grizzly bear, allowing it to identify a carcass from as far away as 6 miles (10 km)[citation needed]. The jaw bone was further back in the head than on other bears[clarify], allowing Arctodus to easily break and eat bones and marrow.[4]
There are currently two recognized subspecies; the large specimens of Alaska, Yukon, Nebraska, California (Irvington) and perhaps Utah are called A. s. yukonensis, while the smaller specimens of Rancho La Brea are A. s. simus.[3]
It was distinguished from its cousin and possible ancestor Arctodus pristinus by its bigger, broader, more crowded teeth, its shorter face and relatively longer legs.[3]
Analysis of Arctodus simus bones show it occasionally suffered from diseases such as osteomyelitis, as well as tuberculosis-like and possibly syphilis-like infections.[3]
[edit] Range
Arctodus simus, was native to North America, where it ranged in the north central plains, Alaska, from Canada to central Mexico, and California to Virginia. It was the most common of early North American bears, being mostly abundant in California. [2]
[edit] Dietary habits
Stable Isotope Analysis on Arctodus simus bones showed high concentrations of nitrogen-15, a nitrogen isotope accumulated by meat eaters, with no evidence of ingestion of vegetation. Arctodus simus was a complete carnivore and an adult would have had to consume 35 pounds (16 kg) of meat daily to survive.[4][5]
One theory on its predatory behaviour envisions Arctodus simus as a brutish predator that overwhelmed the large mammals of the Pleistocene with its great physical strength. This idea is considered problematic, as Arctodus simus, though very large, was very gracile in build. In order to bring down megafauna, Arctodus simus would have to have been a more robust creature with a denser skeletal structure. Other experts think the long-legged Arctodus was able to run down smaller Pleistocene herbivores such as steppe horses and saiga antelopes in a cheetah-like fashion. However, in this scenario, the bear’s sheer physical mass would be a handicap. Arctodus simus's skeletal structure did not articulate in a way that would have allowed it to make quick turns, an ability required of any predator that survives by killing agile prey.[5] Paul Matheus, Ph.D. of the University of Alaska Fairbanks determined that Arctodus simus' moved in a pacing motion like a camel, making it built more for endurance than speed.[5] Arctodus simus was ill-equipped to be an active predator, leading certain scientists to conclude that it was a kleptoparasite[5], using its enormous size to intimidate smaller predators such as the dire wolf, Smilodon and American lion from their kills.
Though Arctodus simus is considered by some as primarily a scavenger, it could have attacked a slow-moving animal such as Megatherium, according to Greg McDonald, a paleontologist with the National Park Service. The battle between the two could have gone in favor of either animal depending on which animal wielded the element of surprise. Despite being a herbivore, megatherium may have also scavenged on carcasses, leading certain experts[who?] to think that it was a competitor of Arctodus.
[edit] Extinction
The short-faced bear became extinct some 12,000 years ago, perhaps partly because some of its large prey died out earlier, and partly because of competition with the smaller, more herbivorous brown bears that entered North America from Eurasia. Since its demise coincides with the development of the Clovis technology and improved hunting techniques by humans in North America, hunting may also have contributed to its extinction both directly and due to the depletion of other large mammals on which it depended for food.
[edit] In media
The short-faced bear appears in Zoo Tycoon 2: Extinct Animals as an adoptable animal available at 3 1/2 stars. It also appears in BBC documentaries Monsters We Met (Also known as Land of Lost Monsters) and Wild New World.
[edit] References
- ^ Macdonald, David (1992). The Velvet Claw, 256. 0563208449.
- ^ a b Brown, Gary (1996). Great Bear Almanac, pp.340. ISBN 1558214747.
- ^ a b c d e f g North American Short-Faced Bear. Harrington, C.R. Yukon Beringia interpretive centre. Retrieved on 2008-01-14.
- ^ a b National Geographic Channel, Sept 16, 2007 Prehistoric Predators: Short faced bear, interview of Dr. Paul Matheus
- ^ a b c d "The Biggest Bear ... Ever". Nancy Sisinyak. Alaska Fish and Wildlife News. Retrieved on 2008-01-12.
[edit] See also
[edit] External links
- U. of Alaska-Fairbanks: Matheus, Ancient fossil offers new clues to brown bears past
- An artist's impression of an Arctodus
- The Biggest Bear ... Ever
- beringia.com
