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Post by brobear on Apr 1, 2017 17:08:25 GMT -5
jpaleontol.geoscienceworld.org/content/84/1/79 Fossils of the giant short-faced bear, Arctodus simus (Cope, 1879), have been recovered from over 100 localities in North America, extending from Mexico to Alaska and California to Virginia. Despite this large range, the species has never been recorded from the southeastern United States. The lesser short-faced bear, Arctodus pristinus Leidy, 1854 is well represented from this region, particularly Florida, but all known occurrences are late Pliocene – middle Pleistocene in age (about 2.5 to 0.3 Ma). Differentiating A. simus from A. pristinus can be difficult because large individuals of A. pristinus overlap in size with small individuals of A. simus, and there are few morphological differences. However, these two taxa can be clearly separated based on the relative proportions of their molars and premolars. Two Pleistocene records of A. simus representing a minimum of three individuals from the Withlacoochee River drainage of central Florida are reported here, substantially extending the distribution of this massive bear into southeastern North America. A late Pleistocene age for these occurrences is corroborated by an associated Rancholabrean fauna and rare earth elemental analyses. One of the reported individuals is quite large, supporting the hypothesis of extreme sexual dimorphism in A. simus and rejecting a hypothesis of two subspecies.
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Post by brobear on May 2, 2017 17:38:22 GMT -5
animaliaenthusiasts.proboards.com/thread/203/giant-short-faced-arctodus-simus Introduction: Arctodus (Greek, "bear tooth") — known as the short-faced bear or bulldog bear — is an extinct genus of bear endemic to North America during the Pleistocene ~3.0 Ma.—11,000 years ago, existing for approximately three million years. Arctodus simus may have once been Earth's largest mammalian, terrestrial carnivore. It was the most common of early North American bears, being most abundant in California. Taxonomy, classification and evolution: The short-faced bears belonged to a group of bears known as the tremarctine bears or running bears, which are endemic to North America and Europe. The earliest member of the Tremarctinae was Plionarctos edensis, which lived in Indiana and Tennessee during the Miocene Epoch, (10 mya). This genus is considered ancestral to Arctodus, as well as to the modern spectacled bear, Tremarctos ornatus. Tremarctos floridanus was a contemporary. Although the early history of Arctodus is poorly known, it evidently became widespread in North America by the Kansan age (about 800 kya). A parallel group of bears are the South American genus Arctotherium, which reached similar size and short faced adaptions.They were also 11 feet tall on hind legs. Size: Arctodus simus (2 to 1.9 Ma.), 110.2 kg (240 lb) and 800 kg (1,800 lb) as noted by Legendre and Roth, inhabiting a generally more northern and larger range. It was native to prehistoric North America from about 800,000 years ago, and became extinct about 12,500 years ago. It has been found from as far north as Ikpikpuk River, Alaska to Lowndes County, Mississippi. It is one of the largest bears in the fossil record and was among the largest mammalian land predators of all time. The type specimen came from Potter Creek Cave in Shasta County, California. Males from the Yukon region - the largest representatives of the species - would have stood about 1.80 m (5.9 ft) at the shoulder (on all fours), 4 m (13.1 ft) upright and may have weighed about 800 kg (1,864 lb). Arctodus simus was the largest carnivorous mammal that ever lived in North America. Dietary habits: Researchers disagree on the diet of Arctodus. Analysis of Arctodus bones showed high concentrations of nitrogen-15, a stable nitrogen isotope accumulated by meat-eaters, with no evidence of ingestion of vegetation. Based upon this evidence A. simus was highly carnivorous, and as an adult would have required 16 kilograms (35.3 lb) of flesh per day to survive. One theory of its predatory habits envisions Arctodus simus as a brutish predator that overwhelmed the large mammals of the Pleistocene with its great physical strength. However, despite being very large its limbs were too gracile for such an attack strategy. Alternatively, long legs and speed (50–70 kilometers per hour (30–40 mph)) may have allowed it to run down 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 skeletons do not articulate in a way that would have allowed for quick turns, an ability required of any predator that survives by killing agile prey. Dr. Paul Matheus, paleontologist at the University of Alaska Fairbanks, determined that Arctodus' moved in a pacing motion like a camel, horse, and modern bears, making it built more for endurance than for great speed. Arctodus simus, according to these arguments, was ill-equipped to be an active predator, leading some to conclude that it was a kleptoparasite, using its enormous size to intimidate smaller predators such as dire wolves, Smilodon and American lions from their kills. Recently, closer dietary research on the giant short-faced bear as well as the Cave Bear suggests that both bears were omnivores like most modern bears, and that the former did eat plants depending on availability. Extinction: The giant short-faced bear became extinct about 12,000 years ago, perhaps partly because some of its large prey died out earlier, and partly also because of competition with the smaller, more omnivorous 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 pressure may also have contributed to its extinction, both directly (human hunting) or indirectly (due to the depletion of other large mammals which it may have followed to scavenge kills or depended upon as prey). Popular culture references: Arctodus simus, the giant short-faced bear, was featured in the ninth episode of Jurassic Fight Club, where it fought with an American Lion over a Steppe Bison kill made by the lion. The battle was based on a fossil find from the Natural Trap Cave, in the U.S. state of Wyoming. The program used the available fossil evidence to predict who would win in the aforementioned fight. In the end, the Arctodus won by throwing the 750-pound Mega-Lion into the enormous cave, where it died of the fall. Read more: animaliaenthusiasts.proboards.com/thread/203/giant-short-faced-arctodus-simus#ixzz4fxogU6iz
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Post by brobear on May 3, 2017 0:48:53 GMT -5
www.bioone.org/doi/abs/10.1080/02724630903416027 In this study, we review the previous evidence on the paleobiology of the giant, ‘short-faced’ bear Arctodus simus (Mammalia: Carnivora: Ursidae) and contribute new ecomorphological inferences on the paleobiology of this enigmatic species. Craniodental variables are used in a comparative morphometric study across the families Felidae, Hyaenidae, Canidae, and Ursidae. Principal components analyses (PCAs) do not show an ecomorphological adaptation towards bonecracking or hypercarnivory in the ‘short-faced’ bear. In contrast, PCAs and discriminant analyses restricted to the craniodental data set of ursids suggest close morphological resemblance between A. simus and the extant omnivorous bears. In addition, the scaling of snout length on neurocranial length in bears indicates that the face of A. simus was not particularly short. Body mass estimates obtained from major limb bone measurements reveal that A. simus specimens of around 1000 kilograms were more common than previously suspected. Scaling relationships in extant bears of limb lengths on the least width of the femoral shaft (the variable best correlated with body mass) indicate that A. simus was not as relatively long-legged as previously thought. For these reasons, although the isotopic signature of A. simus has been interpreted as evidencing that it consumed large amounts of flesh relative to some contemporary populations of Ursus arctos, our results do not support the previous views of A. simus as a fast-running super-predator or as a specialized scavenger. In contrast, the picture that emerges from this study is one of a colossal omnivorous bear whose diet probably varied according to resource availability. 1000 kg = 2,200 pounds.
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Post by Deleted on Jan 2, 2018 9:02:23 GMT -5
Comparison: Short Faced Bear vs American Lion.
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Post by brobear on Jan 2, 2018 17:52:32 GMT -5
The atrox really looks too big here. He was just under 4 feet high at the shoulders - the bear just under 6 feet. In this picture the atrox is considerably longer than the bear. Can't say for sure but it appears that "this" giant bear is about a foot too short ( height and length ). What do you think?
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Post by Deleted on Jan 2, 2018 18:14:17 GMT -5
Thanks for the feedback.
And yes, I think I made the cats a little bit too big in all of these last comparisons. I was more concerned with getting the height right, and may have overlooked the lenght but yes, you're on point on that.
I think that, even with the mistakes that surely are there, the idea of the size difference gets through, even with the cat looking bigger.
I will give it another try and upload it again, and see how I do.
EDIT: I uploaded it again, tell me what you think of it.
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Post by brobear on Jan 2, 2018 20:16:19 GMT -5
Oh yes; that looks right. I just noticed that the lion's legs in walking are kind of sprawled out causing him to appear shorter. Nice job Gurahl.
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Post by Deleted on Jan 2, 2018 20:21:52 GMT -5
Thank you. I'm still learning how to do these things, so it's going to look a bit messy like this until I learn to do them better, but I'm glad you like it.
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Post by Polar on Jan 3, 2018 11:03:47 GMT -5
How tall was Arctodus and Arctotherium, by the way?
And thank you very much, Gurahl. Even with me being an engineering student and kind-of decent with photo editing, I still wouldn't do good comparisons lol!
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Post by brobear on Jan 3, 2018 12:25:45 GMT -5
Both of the two biggest bears ever stood ( on all fours ) roughly 6 feet high at the shoulders - max. Probably more often about 5.5 feet.
Roughly 11 feet tall standing bipedal.
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Post by Polar on Jan 3, 2018 13:22:11 GMT -5
Most sources do say around 6 feet on all four legs. But I do think Arctotherium meets this criteria since it was a little larger than Arctodus, Arctodus was more about 5'5" to 5'8" from GrizzlyClaws on WildFact.
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Post by brobear on Jan 17, 2018 6:19:57 GMT -5
I have been searching for information on "dimorphism" - the size difference between male and female. Came up empty but I did learn from many resources online that the bipedal height of Arctodus simus was 12 feet tall ( 3.66 m ).
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Post by brobear on Jan 20, 2018 7:32:19 GMT -5
extinct-animals-facts.com/Extinct-Animals-List/Giant-Short-Faced-Bear-Facts.html Giant Short-Faced Bear Facts Roaming the North American countryside up until about 11,000 years ago was a huge deadly animal that must have given our early ancestors nightmares. This beast was the Giant Short-Faced Bear; it could look a 6 foot man in the eyes while standing on all fours and tower 7 feet above him when standing on its hind legs. One swipe of its huge paw would bring instant death. Here we list interesting facts about this amazing extinct animal including what it looked like and theories about why it became extinct. Interesting Giant Short-Faced Bear Facts The giant short-faced bear (also referred to as the bulldog bear) lived in North America from approximately 1.8 million years ago until about 11,000 years ago. There were two species of Short-Faced Bears; Arctodus pristinus and Arctodus simus. Arctodus simus is the largest and is called the Giant Short-Faced Bear. It is one of the biggest mammalian predators ever to roam the earth. This now extinct massive predator lived in North America across a wide range stretching from Alaska to as far south as Mississippi. They get their name, short-faced bear, due to the shape of their skulls. It appears from the skull that they had a short snout; but this was not the case. From fossil evidence it seems that this predator was most abundant in California. These bear's genus name, Arctodus, is derived from Greek and means "bear tooth". Around 800,000 years ago, during the Kansan glaciation, the Giant Short-Faced Bears became abundant in North America; in fact it became the most abundant bear in North America for thousands of years. The first fossils of this species were discovered in Northern California at a site named Potter Creek Cave. In this limestone cave numerous fossils of various extinct animals were unearthed. These huge bears were definitely carnivores and would have to have eaten 35 pounds (16 kilograms) of meat daily to survive. There is also evidence that they would eat plants from time to time as do modern day bears. These animals were big but were also built for speed. In fact it is the fastest bear that ever existed. It is believed they could run up to 40 miles per hour (64.4 Kilometers per Hour). There are several theories on how the Giant Short-Faced Bear hunted. These bears could run very fast which might have enabled them to run down even fast prey such as horses. However some experts believe its large size and inability to make sharp turns would have meant it would not be able to chase down most prey. These experts suggest it may have waited for other predators like the Dire Wolf and American Lion to make a kill and then moved in scaring the other predators away and stealing their kills. Why did the Giant Short-Faced Bear become extinct? The answer is not known for certain but two main reasons are believed to have contributed to its extinction. The first is that their extinction correlated with the mass extinction of many species which they depended on as a food source. At the end of the last ice age there was what has been called a mega fauna extinction brought about by climate changes. The second reason that may have contributed to this animals demise was the fact that humans were increasingly populating their habitats and as the humans hunting skills increased they were able to dominate the bears in the competition for limited food supplies. Giant Short-Faced Bear Description Standing on all four legs its height would be 8 - 10 feet (2.44 - 3.05 meters). The Short-Faced Bear could stand up to 12 feet high when standing on its hind legs although 8 to 10 feet is believed to be more common. It is estimated that these extinct bears could weigh an amazing 1,984 pounds (900 kilograms). With at least one specimen estimated to weigh 2109 pounds (957 kilograms). The Giant Short-Faced Bear had feet that pointed forward, most bears have feet that point inward. This enabled it to run fast. This extinct predator had long sharp canine teeth along with several big sharp molars; perfect for ripping through the meat of its prey.
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Post by brobear on Jan 20, 2018 7:35:32 GMT -5
Quote: Standing on all four legs its height would be 8 - 10 feet (2.44 - 3.05 meters). Obviously a typo. Standing on all four legs its height - from 5 feet 6 inches to 6 feet high.
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Post by Deleted on Jan 27, 2018 15:59:11 GMT -5
Sculpture of a short faced bear.
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Post by brobear on Jan 27, 2018 16:09:46 GMT -5
Arctodus simus as seen in above picture, tall, lean and mean! 12 feet tall ( 3.66 meters ) and weighing from 1200 to 2000 pounds ( 900 kg ). Mush leaner than a grizzly. A grizzly standing 12 feet tall would be much heavier; but no grizzly of such immense proportions has ever lived. Arctodus was very much a giant. Look at the size of those paws!
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Post by tom on Jan 29, 2018 17:41:08 GMT -5
Very impressive sculpture !!
Being leaner but larger than that of even the Kodiak bears of today, would you also attribute leaner to mean more agile? Thus would Short-faced Bear have a much better chance, or maybe easier would be the correct word of taking down large Bovines such as Bison or Cape buffalo?
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Post by brobear on Jan 30, 2018 11:45:23 GMT -5
It has been determined that the giant could not run-down prey animals. He was too big and heavy for his long comparatively slender leg-bones. He could not dart and dodge like a grizzly does when he chases down such prey as an elk calf. Therefore, the giant was more likely ( almost ) a full-time scavenger. I say almost because he still retains the teeth of an omnivore. I would say that if a Kodiak-sized grizzly standing ten feet high went up against a giant standing ten feet tall, the grizzly would have a substantial weight advantage. The giant was probably a long-distance walker and, in a relatively straight line, could probably cover miles quickly running camel-fashion. His physique was one ( IMO ) of a bear who could fight and fight with a capital F.
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Post by brobear on Jan 31, 2018 0:10:28 GMT -5
twilightbeasts.wordpress.com/2015/01/08/paddingtons-dangerous-cousin/ North and South America were the last continents to be conquered by humans. We have been in Africa since we first evolved, Europe and Asia for over a million years, in Australia for about 60,000 years, but in the Americas for only about 15,000. Considering that reaching Australia required a treacherous ocean voyage but you could walk to Alaska without getting your feet wet via the flat, treeless, mammoth steppe of Beringia (with plenty of game to hunt en-route), why did it take people so long to reach the promised land? Some researchers have suggested that perhaps people did reach Beringia much earlier, but what they met there prevented them from penetrating any further. Along with the mammoths, cave lions, bison, and horses, Beringia had something else. Something that would have been completely unfamiliar to the humans who encountered it. Something seemingly crafted from our deepest, darkest nightmares. Arctodus simus: the giant short-faced bear may have been the most terrifying land carnivore our species ever encountered. Today, the polar bear (Ursus maritimus) is the largest land carnivore but 12,000 years ago that title went to a member of the subfamily of bears known as the Tremarctinae. We still have one member of this unique subfamily left; the spectacled bear (Tremarctos ornatus). The only bear found in South America (including deepest, darkest Peru), this predominantly vegetarian teddy is technically the largest carnivore left on that continent, despite being a relatively puny 100-200kg. A sister species, the Florida cave bear (Tremarctos floridanus), also roamed Pleistocene North America. However, their close relative, the giant short-faced bears (genera Arctodus and Arctotherium/ Pararctotherium) were absolutely colossal beasts. Arctotherium/Pararctotherium (opinion is divided on how valid these generic distinctions are) has been found all over South America, even down into southern Patagonia. Arctodus simus has been found at sites all over North America, from Alaska and the Yukon Territory down to Florida and Texas. Whilst we have a mitochondrial genome from Arctodus and know it diverged from the spectacled bear during the late Miocene/early Pliocene, it is not known exactly how closely related Arctodus and Arctotherium/Pararctotherium are to each other. Ancient DNA work is happening right now that should give a handle on the complicated phylogenetics of these bears. Arctodus simus was an 800kg monster. To give some impression of its size: while on all fours this bear could gaze directly into my eyes (I’m 6’2”). Standing on its hind legs an average bear could reach 12-feet (in fact, the site of Riverbluff cave in Missouri has claw marks 15 feet up on some side walls that were probably produced by a large Arctodus). Another site with Arctodus is Big Bear cave in the Ozark mountains. The articulated skeleton found there is impressive for the amount of information it left about short-faced bear biology. The animal, like many other cave finds, was a small female, which cumulatively suggest that Arctodus females denned (perhaps surprisingly, only one fossil Arctodus baculum has ever been recovered). The Ozark skeleton is also unique in the preservation of fossilised hair at the site. What natural forces could possibly have conspired to produce a carnivore of such enormous dimensions? Most researchers think that the specialisations present in Arctodus (i.e. long legs, large size, short jaws), are adaptations to a life of extreme hypercarnivory. Long legs allow for efficient movement over a wide home range, necessary to locate carcasses, large size can act as an effective deterrent to other carnivores to scare them off a kill site (kleptoparasitism), and short jaws give extra bone crushing power. It seems that this hypothesis is backed up by good data. Stable isotope analysis of Arctodus remains show elevated ∂15 Nitrogen values- this indicates that Arctodus was consuming a very meaty diet, perhaps with a large component of caribou (Rangifer tarandus). However, as with most things in science, different researchers think that the opposite is true and have concluded that the morphology of short-faced bears indicate a life of herbivory with some omnivory. My money is still on Arctodus simus being one of the biggest and baddest animals ever to have lived. How badass was it? Well, a very interesting pattern cropped up when palaeontologists were looking at late Pleistocene radiocarbon dates from eastern Beringia. They found that during time periods when Arctodus simus was present (i.e. 20,000-45,000 14C years BP) there is a noticeable lack of other predators (lions, scimitar cats, brown bears). Either the environment was selectively excluding everything but short-faced bears during this time period, or perhaps more likely, Arctodus simus was such an efficient predator/scavenger that there was simply not enough prey biomass left for other carnivores to get a look in. If this was the case, it is perhaps no surprise that human presence in eastern Beringia is only known from after Arctodus’ extinction. Maybe one day we will find an Arctodus coprolite with some evidence of the pre-pre-Clovis pioneers! Written by Ross Barnett (@deepfrieddna)
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Post by brobear on Jan 31, 2018 0:33:37 GMT -5
KLEPTOPARASITE is a word we should remember. It is a better description of the giant short-faced bear's mode of life. Rather than simply find and devour a carcass, with such a huge variety of predators and scavengers in Pleistocene North America, Arctodus simus probably had to bluff or chase other carnivores from most found carcasses. Rather than refer to the giant as a scavenger; kleptoparasite much better describes this monster.
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