Documentary: Evidence of New Hybrid Bears of Prehistoric Size

17 Aug


“The short-faced bear, also known as the bulldog bear, or Arctodus (Greek, “bear tooth”), is an extinct genus of bear endemic to North America during the Pleistocene about 3.0 Mya — 11,000 years ago, existing for around three million years. Arctodus simus may have once been Earth’s largest mammalian, terrestrial carnivore. The species described are all thought to have been larger than any living species of bear. It was the most common of early North American bears, being most abundant in California.

Taxonomy, classification and evolution

The giant short-faced bears belonged to a group of bears known as the tremarctine bears, running bears or short-faced bears, which have been found in the Americas and Europe. The earliest known member of the Tremarctinae was Plionarctos edensis, which lived in Beijing, Indiana and Tennessee during the Miocene Epoch (10 mya) and crossed over from Asia to Alaska near the end of the Miocene becoming the dominant bear group in North America. This genus is considered ancestral to Arctodus, as well as to the modern spectacled bear Tremarctos ornatus of the Andes Mountains (considered the last surviving member of the short-faced bear group), but not the grizzly bear, considered to be more closely related to the brown bear and the polar bear. Tremarctos floridanus was a contemporary from the southeastern United States. 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). The South American genus, Arctotherium, was the closest relative to Arctodus and it had similar short-faced adaptions and reached similar or greater sizes.

Species

Arctodus simus first appeared during the middle Pleistocene in North America, about 800,000 years ago, ranging from Alaska to Mississippi, and it became extinct about 11,600 years ago. Its fossils were first found in the Potter Creek Cave, Shasta County, California. It might have been the largest carnivorous land mammal that ever lived in North America. Only one Giant Short-faced Bear skeleton has been found in Indiana, and that is the one unearthed south of Rochester on west of Nyona Lake on Chet Williams’ farm. It has become well-known in scientific circles because it was the biggest most-nearly complete skeleton of a Giant Short-faced Bear found in America. The original bones are in the Field Museum, Chicago. The new Indiana State Museum, Indianapolis, and the Yukon Beringia Interpretive Centre, Whitehorse, Yukon Territory, Canada, have casts made of the bones. In a recent study, the mass of six specimens was estimated, one-third of them weighed about 900 kg (0.99 short ton), the largest being UVP 015 at 957 kg (2,110 lb), suggesting specimens that big were probably more common than previously thought. Furthermore, claw marks reaching heights of up to 4.6 m (15 ft) on the walls of the Riverbluff Cave are indicative of the great size of the short-faced bears that made them.

Arctodus pristinus (3.0-2.2 Mya), a species with two specimens weighing 500.7 kg (1,100 lb) and, in a likely subadult specimen, 63.6 kg (140 lb) inhabiting more southern areas from northern Texas to New Jersey in the east, Aguascalientes, Mexico to the southwest, and with large concentrations in Florida, the oldest from the Santa Fe River 1 site of Gilchrist County, Florida paleontological sites.”

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