Short-faced bear

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Temporal range: Middle Pleistocene to Early Holocene, 1.8–0.011 Ma
A. simus from the La Brea tar pits
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Family: Ursidae
Subfamily: Tremarctinae
Genus: Arctodus
Leidy, 1854
Type species
Arctodus pristinus
Leidy, 1854
  • A. pristinus (Leidy, 1854)
  • A. simus (Cope, 1879)

The short-faced bear (Arctodus sp.) is an extinct bear genus that inhabited North America during the Pleistocene epoch from about 1.8 Mya until 11,000 years ago. It was the most common early North American bear and was most abundant in California.[1] There are two recognized species: Arctodus pristinus and Arctodus simus, with the latter considered to be one of the largest known terrestrial mammalian carnivores that has ever existed. It has been hypothesized that their extinction coincides with the Younger Dryas period of global cooling commencing around 10,900 BC.


This species appears to have a disproportionately short snout compared to other bears, giving the species its name, "short-faced." This characteristic is also shared by its extant relative the spectacled bear. However, this apparent shortness is an illusion caused by their deep snouts and short nasal regions.[2] The scientific name of the genus, Arctodus, derives from Greek, and means "bear tooth".


Restoration of Arctodus simus

The short-faced bear belongs to a group of bears known as the Tremarctinae, which appeared in North America

during the earliest parts of the late Miocene epoch in the form of Plionarctos, a genus considered ancestral to Arctodus. During the Great American Interchange that followed the joining of North and South America, tremarctines invaded South America, leading to the evolution of Arctotherium and the modern spectacled bear (Tremarctos ornatus). 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.

Arctodus simus first appeared during the middle Pleistocene in North America, about 800,000 years ago, ranging from Alaska to Mississippi,[3][4] and it became extinct about 11,600 years ago. Its fossils were first found in the Potter Creek Cave, Shasta County, California.[5] It might have been the largest carnivorous land mammal that ever lived in North America. A giant short-faced bear skeleton has been found in Indiana, unearthed south of Rochester.[6] It has become well known in scientific circles because it was the most nearly complete skeleton of a giant short-faced bear found in America. The original bones are in the Field Museum, Chicago.[6]

Arctodus pristinus inhabited more southerly areas, ranging from northern Texas to New Jersey in the east, Aguascalientes, Mexico[7] to the southwest, and with large concentrations in Florida, the oldest from the Santa Fe River 1 site of Gilchrist County, Florida paleontological sites.


A. simus compared to a human

In a recent study, the mass of six A. simus specimens was estimated, one-third of them weighed about 900 kg (1 short ton), the largest 957 kg (2,110 lb), suggesting specimens that big were probably more common than previously thought.[2] However some studies suggest that it was much lighter than previously thought reaching 540 kg (1,190 lb).[8] It stood 8–10 feet (2.4–3.0 m) tall on hind legs,[9] with a large specimen standing up to 11–12 feet (3.4–3.7 m) tall with a 14-foot (4.3 m) vertical arm reach. When walking on all fours, it stood 5–6 feet (1.5–1.8 m) high at the shoulder and would be tall enough to look a human in the eye.[10][11][12] At Riverbluff Cave, Missouri, a series of claw marks up to 15 feet (4.57 m) high have been found along the cave wall indicating short-faced bears up to 12 feet (3.66 m) tall.[13][14]


American mastodon arm bone with A. simus tooth marks at the Denver Museum of Nature & Science in Denver, Colorado

Researchers disagree on the diet of Arctodus. Analysis of bones from Alaska showed high concentrations of nitrogen-15, a stable nitrogen isotope accumulated by meat-eaters, with no evidence of ingestion of vegetation. Based on this evidence, A. simus was suggested to have been highly carnivorous and as an adult would have required 16 kg (35.3 lb) of flesh per day to survive.[9][15][16] Others point out that the species would have had a varied diet across its range,[17] and that the short-faced bear's skull shares many features with herbivorous bears and likely did include some plant matter in its diet.[2]

One proposal for its predatory habits envisages A. simus as a brutish predator that overwhelmed the large mammals of the Pleistocene with its great physical strength. However, some suggest that despite being very large, its limbs were too gracile for such an attack strategy.

A. simus skull, photographed at the Cleveland Museum of Natural History in Cleveland, Ohio

Because its long legs enabled it to run at speeds of 50–70 km/h (30–40 mph), an alternative hypothesis is that it may have hunted by running down Pleistocene herbivores, such as wild horses and saiga antelopes, in a cheetah-like fashion, at one time earning it the name "running bear".[18] However, during pursuit of speedy game animals, the bear's sheer physical mass would be a handicap. Arctodus skeletons do not articulate in a way that would have allowed for quick turns – an ability required of any predator that survives by chasing down agile prey.[9] A 2010 study found the "long-legged" features of the bear are an illusion created by the animal's relatively short back.[2]

Arctodus moved in a pacing motion like a camel, horse, and modern bears, making it built more for endurance than for great speed.[9] A. simus, according to these arguments, was ill-equipped to be an active predator, leading some to conclude that it was a kleptoparasite,[9] using its enormous size to intimidate smaller predators, such as dire wolves, saber-tooth cats, and American lions, or chase them from their kills and steal their food. This idea was challenged in a 2013 study of the micro-wear of the teeth of various extant and extinct bears. The researchers concluded that the short-faced bear was not a pure scavenger and in fact was even less of a scavenger than the modern polar bear.[17] A 2010 study concluded that the species was neither a super-predator nor pure scavenger but an opportunistic omnivore like modern brown bears.[2]

Some authors also suggest that the giant short-faced bear and the cave bear were omnivores, like most modern bears, and the former may have eaten plants depending on availability.[19]

See also[edit]


  1. ^ Brown, Gary (1996). Great Bear Almanac. p. 340. ISBN 978-1558214743.
  2. ^ a b c d e Figueirido; et al. (2010). "Demythologizing Arctodus simus, the 'short-faced' long-legged and predaceous bear that never was". Journal of Vertebrate Paleontology. 30 (1): 262–275. doi:10.1080/02724630903416027.
  3. ^ C. S. Churcher, A. V. Morgan, and L. D. Carter. 1993. Arctodus simus from the Alaskan Arctic Slope. Canadian Journal of Earth Sciences 30(5):1007-1013, collected by A. V. Morgan
  4. ^ Cassiliano M. L. (1999). "Biostratigraphy of Blancan and Irvingtonian mammals in the Fish Creek-Vallecito Creek section, southern California, and a review of the Blancan-Irvingtonian boundary". Journal of Vertebrate Paleontology. 19 (1): 169–186. doi:10.1080/02724634.1999.10011131.
  5. ^ Cope E. D. (1879). "The cave bear of California". American Naturalist. 13: 791.
  6. ^ a b Willard, S. "Rochester's Giant Bear Gets Famous". Retrieved 2017-07-17.
  7. ^ I. Ferrusquia-Villafranca. 1978. Bol Univ Nac Aut Mex Inst Geol 101:193-321
  8. ^
  9. ^ a b c d e Nancy Sisinyak. "The Biggest Bear ... Ever". Alaska Fish and Wildlife News. Retrieved 2008-01-12.
  10. ^ "Yukon Beringia Interpretive Centre". Archived from the original on 31 March 2014. Retrieved 17 April 2014.
  11. ^ "North American Bear Center". Extinct Short-faced Bear. Retrieved 17 April 2014.
  12. ^ Brown, Gary (December 3, 2013). The Bear Almanac, 2nd: A Comprehensive Guide to the Bears of the World. Lyons Press. p. 8. ISBN 978-0762788064.
  13. ^ "Bear Claw Marks". Riverbluff Cave - The Official Website. Retrieved 17 April 2014.
  14. ^ "Cave Animals". Riverbluff Cave - The Official Website. Retrieved 17 April 2014.
  15. ^ Bocherens, H.; Emslie, S. D.; Billiou, D.; Mariotti A. (1995). "Stable isotopes (13C, 15N) and paleodiet of the giant short-faced bear (Arctodus simus)". C R Acad Sci. 320: 779–784.
  16. ^ National Geographic Channel, 16 September 2007, Prehistoric Predators: Short-faced bear, interview with Dr. Paul Matheus
  17. ^ a b Donohue, Shelly L.; DeSantis, Larisa R. G.; Schubert, Blaine W.; Ungar, Peter S. (2013). "Was the giant short-faced bear a hyper-scavenger? A new approach to the dietary study of ursids using dental microwear textures". PLOS ONE. 8 (10): e77531. doi:10.1371/journal.pone.0077531. PMC 3813673. PMID 24204860.
  18. ^ US National Park Service paleontologist Greg McDonald.
  19. ^ ScienceDaily, 13 April 2009."Prehistoric bears ate everything and anything, just like modern cousins". ScienceDaily. Retrieved 2009-04-13.