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Post by Gorilla king on Jul 2, 2021 15:54:21 GMT -5
Giant Short-faced Bears (Arctodus simus) in Pleistocene Florida USA, a Substantial Range Extension
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. sinus 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.
www.researchgate.net/publication/250071137_Giant_Short-faced_Bears_Arctodus_simus_in_Pleistocene_Florida_USA_a_Substantial_Range_Extension
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Post by Gorilla king on Jul 2, 2021 15:56:24 GMT -5
Demythologizing Arctodus simus, the ‘Short-Faced’ Long-Legged and Predaceous Bear that Never Was
Abstract
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.
bioone.org/journals/journal-of-vertebrate-paleontology/volume-30/issue-1/02724630903416027/Demythologizing-Arctodus-simus-the-Short-Faced-Long-Legged-and-Predaceous/10.1080/02724630903416027.short
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Post by Gorilla king on Jul 2, 2021 15:58:16 GMT -5
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Post by Gorilla king on Jul 3, 2021 8:12:24 GMT -5
Arctodus - predator or scavenger?
With such an immense size and obviously powerful jaws it’s tempting to paint a picture of Arctodus as an apex predator that could kill anything it wanted. However, real science is not based upon assumptions that are established upon superficial glances but on in depth study of the available fossil material. With this in mind the analysis of Arctodus remains has led to a surprising but very plausible theory about its nature and behaviour. Many Pleistocene mammal fossils have been subjected to a process termed oxygen isotope analysis. This is based upon the principal that different environments have different isotope levels which get absorbed by the plants growing on them. As these plants are eaten the isotopes are absorbed and stored in the herbivores tissues as a marker that allows palaeontologists to establish which types of animal were active in which environment and what they were eating. In turn as these herbivores were killed and eaten by carnivores the isotopes get re-absorbed into the carnivores’ bodies which reveal roughly which animals were being eaten by which carnivores (for example the sabre toothed cat Smilodon seems to have had a preference for bison). The analysis for Arctodus shows that it was what is termed a hypercarnivore, an animal that has a diet where seventy to a hundred per cent of the eaten food is the tissue from other animals. However it also revealed that Arctodus ate all kinds of animals, and did not specialise in just one type of prey, something that is highly unusual for a predator, but quite normal for a scavenger. The skeleton also reveals hints to both the travelling and predatory ability of Arctodus, with special reference to the long limbs. These could be seen as giving Arctodus a significant reach advantage that allowed it to swipe at prey animals, but the problem here is that first Arctodus would have to get close enough to its prey to do this. In terms of speed the long legs with their broad strides are thought to have given Arctodus a top speed approaching fifty kilometres an hour, something that would have seen it able to comfortably match most of the available prey species. However these same legs are proportionally much thinner than they are in other running animals, and are considered too fragile to be able to support a heavy animal like Arctodus if it made a sharp turn when running at speed. This could mean an injury such as a break or dislocation that probably would have been serious enough to cause the death of the injured bear as it could no longer move about. But it is actually these long legs that further support the scavenger theory as since they are lightweight they would not require a great amount of effort to move. Additionally the long sweeping arc of the feet meant that Arctodus could comfortably cover more ground with each step, making locomotion such as walking or even running extremely energy efficient. This means that Arctodus could cover territories that spanned several hundred square kilometres on a reduced amount of food than would be required by a dedicated predator. This is a vital survival adaptation when you consider that a scavenger does not know when or where its next meal is coming from. Another clue comes from the immense size of the body. Arctodus simus was the largest carnivorous mammal currently known from Pleistocene North America, and possibly the largest carnivorous animal since dinosaurs like Tyrannosaurus disappeared at the end of the Cretaceous period. As such it’s extremely unlikely that the other Pleistocene predators would have put up much of a fight and risked injury or even death from a more powerful animal. This behaviour has been well documented in modern times where grizzly bears will walk in and steal kills away from packs of grey wolves that let the more powerful predator take what it wants rather than risking injury.
The final support for Arctodus being a scavenger comes from the skull. Arctodus is known as the short faced bear because its snout is proportionately shorter than that of other bear genera. These means that when food is placed in the mouth it is nearer the fulcrum (point of articulation) of the skull and mandible (lower jaw). This focuses a greater amount of pressure from the jaw muscles onto whatever is between the jaws, and seems to have been an adaptation that allowed Arctodus to crack open bones to get at the marrow within them. This is another key survival adaptation as Arctodus would inevitably come across carcasses that had already been picked clean, but the bones still in place because the predators that killed the animal were unable to crunch the bones open. Even more critical to survival is the fact that bone marrow can remain nutritious for months and even years after an animal dies, something that would help Arctodus to survive even when there were no fresh kills to steal. Also fossil evidence of large bison bones exist that look like they have been bitten open by an animal like Arctodus, a feat that would be beyond the scope of smaller predators like wolves. Arctodus also had a proportionately large nasal opening in the front of its skull which indicates that it was capable of sampling a larger volume of air for scents. This coupled with the bears larger size meant that it could sniff out and sample scents that were being carried higher up, possibly to the point of detecting a carcass from several kilometres away by smell alone. All of these factors combined point to the short faced bear Arctodus being a much specialised scavenging animal.
www.prehistoric-wildlife.com/species/a/arctodus.html
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Post by Gorilla king on Jul 3, 2021 8:15:27 GMT -5
Cursorial Adaptations in the Forelimb of the Giant Short-Faced Bear, Arctodus simus, Revealed by Traditional and 3D Landmark Morphometrics
Abstract
The paleobiology of the Pleistocene North American giant short-faced bear, Arctodus simus, has eluded paleontologists for decades. Its more gracile form has led past researchers to myriad intepretations of the locomotion and feeding ecology of this species. While earlier studies have focused on craniodental morphology and simple postcranial indices, it is forelimb morphology that represents a direct compromise between locomotor and foraging behavior. The study here uses traditional and 3D landmark morphometrics to more completely compare the 3-dimensional shape of the major forelimb elements and their muscle attachment sites between A. simus, extant ursids, and other carnivorans. Results herein agree well with previous studies and provide additional evidence for reduced abductor/adductor and supinator/pronator musculature, more restricted parasagittal motion, increased stride length, and lighter and more packed distal elements. Forelimb skeletal morphology therefore supports the hypothesis that A. simmus represents a bear in the early stages of cursorial evolution. dc.etsu.edu/etd/1477/
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Post by Gorilla king on Jul 3, 2021 8:18:19 GMT -5
Short-faced bears, largest carnivores in the Ice Age, became omnivores to survive
Summary: Based on the analysis of fossil teeth, a study shows that short-faced bears (Arctodus simus), the largest carnivores in the Ice Age, became omnivores to survive. Share:
FULL STORY Based on the analysis of fossil teeth conducted by researcher Alejandro Romero, from the University of Alicante's Departament of Biotechnology, a study shows that short-faced bears (Arctodus simus), the largest carnivores in the Ice Age, became omnivores to survive. The study, led by the University of Málaga (UMA) researcher Borja Figueirido, was recently published in the journal Scientific Reports.
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The scientific community previously thought that this extinct animal from North America was exclusively carnivorous, but, as pointed out by Mr Figueirido, "we dethroned the largest hypercarnivorous mammal ever to roam the Earth." He adds: "Our results also suggest that the Arctodus simus population in southern North America was more omnivorous than the highly carnivorous populations in the north-east."
Specifically, after the analysis involving microscopic techniques and virtual models developed by the UA researcher, carious lesions caused by carbohydrates, present in plants, were found in the dental remains discovered at the La Brea Tar Pits site in Los Angeles, California, described by Alejandro Romero as "one of the most paradigmatic sites to study fossil mammals from the Pleistocene in North America."
The UA researcher also highlights that "this is an interesting study, as caries were found for the first time in the dental remains of Arctodus simus, which proves that they could adapt to plants present in their diet as a result of climate change or competition with other predators."
Other participants in the study included vertebrate ecology and palaentology experts like Alejandro Pérez-Ramos, from the UMA, and researchers from the Natural History Museum and the La Brea Tar Pits Museum of Los Angeles, USA.
www.sciencedaily.com/releases/2018/03/180322112509.htm
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Post by Gorilla king on Jul 3, 2021 8:20:24 GMT -5
Mammoth Site finds prehistoric giant bear bone
Bear The Mammoth Site confirmed it has found the humerus bone of a giant short-faced bear. Isaac Zarecki▲ Bones ▲ Isaac Zarecki Hot Springs Star Aug 6, 2018 HOT SPRINGS | The Mammoth Site confirmed the discovery of remains from a second giant short-faced bear in its dig site last week.
Scientists uncovered the humerus of an adult, male giant short-faced bear this April.
Giant short-faced bears are estimated to have been as tall as five and a half feet at the shoulder while on all fours and it is thought they could've weighed around 1,500 pounds.
They existed from 800,000 years ago until going extinct around 11,000 years ago. Remains have been found from central Mexico to Alaska.
The gender of the bear was determined by the size of the bone. Males were significantly larger than females.
Evidence from bone growth on the first bear points to it being an adult but not necessarily finished growing.
The first bear skull was found at the site in 1983. From then until the mid-1990s, the site unearthed ribs, a partial bear pelvis, a jawbone and isolated teeth. In 2003, Sharon Holte helped discover the humerus of the smaller bear. She was in high school and working at the dig site as a volunteer excavator for the summer.
Following the discovery of the smaller humerus, it was not immediately clear if it belonged to a giant short-faced bear. Holte wound up confirming that it belonged to a bear in her undergraduate thesis at the South Dakota School of Mines. She is now the science educator at the Mammoth Site.
Both bears were found in similar parts of the site. Mammoth Site researchers are now tasked with determining what bones go with what bear. Scientists reserve the idea that more than two bears could be in the pit, further complicating the investigation.
Determining why the bears died in the pit is a tall order, and though scientists may not know exactly why each individual is there, they can infer to the best of their ability.
Dr. Blaine Schubert, an expert in giant short-faced bear research, believes it is possible the bears were scavenging mammoths.
"These big bears would have been amazing super scavengers. Being the biggest means you are going to be good at scavenging," Schubert said. "Having two individuals here could mean they both went down to scavenge something and got stuck themselves."
Schubert is the Director of the Center of Excellence in Paleontology and its Natural History Museum at East Tennessee State University. He is a visiting researcher at the Mammoth Site.
Based on the behavior of modern bears, researchers also think the ancient bears were most likely solitary animals. However, modern bears have been known to congregate around large food sources like whale carcasses so it is possible that multiple bears could have been scavenging a dead mammoth at the same time.
Giant short-faced bears are now officially the second most common large animal found at the site. As the Mammoth Site continues to excavate, the mystery of how these animals died in the pit may become clearerrapidcityjournal.com/news/local/mammoth-site-finds-prehistoric-giant-bear-bone/article_c8da2fc8-8541-5040-b998-05c2ff91ea3a.amp.html
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Post by Gorilla king on Jul 3, 2021 8:22:07 GMT -5
ARCTODUS VS SMILODON RECREATION. LOOKS LIKE THE BEAR WENT FOR THE CARCASS.
A TERRITORIAL DISPUTE BETWEEN 2 ARCTODUS SIMUS.
SHORT FACED BEAR VS PLEISTOCENE JAGUAR:
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Post by Gorilla king on Jul 3, 2021 8:29:09 GMT -5
SHORT FACED BEAR VS GROUND SLOTH RECREATION:
ARCTODUS SIMUS CHASING A YOUNG BISON:
ARCTODUS SIMUS DISPLACING DIRE WOLVES:
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Post by oldindigosilverback on Jul 5, 2021 17:24:15 GMT -5
Arctodus simus VD small coalition of smilodon fatalis.
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Post by oldindigosilverback on Jul 5, 2021 17:28:08 GMT -5
A video game fight prediction. Not everything might be accurate.
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Post by oldindigosilverback on Jul 5, 2021 17:29:08 GMT -5
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Post by Gorilla king on Jul 5, 2021 17:29:32 GMT -5
oldindigosilverback Reply #9, 1 Simus vs 3 Fatalis, in a fight to the death, what do you think would happen?
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Post by oldindigosilverback on Jul 5, 2021 17:30:48 GMT -5
American lion vs Arctodus Simus.
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Post by oldindigosilverback on Jul 5, 2021 17:32:52 GMT -5
oldindigosilverback Reply #9, 1 Simus vs 3 Fatalis, in a fight to the death, what do you think would happen? In a real fight to death, I think the fatalis can win but at least one member of the Sabre tooth cat family will win. Sabre tooth cats would probably rather retreat than risk one member gone, no wild animal has the fighting mentality of gladiator dogs or game roosters.
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Post by Gorilla king on Jul 5, 2021 17:38:21 GMT -5
oldindigosilverback Reply #9, 1 Simus vs 3 Fatalis, in a fight to the death, what do you think would happen? In a real fight to death, I think the fatalis can win but at least one member of the Sabre tooth cat family will win. Sabre tooth cats would probably rather retreat than risk one member gone, no wild animal has the fighting mentality of gladiator dogs or game roosters. I agree. I think 3 all attacking at once is just too much even for Simus, but i believe at least 1 Fatalis would die. I also agree that in an interaction, the 3 cats would retreat from a kill site.
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Post by Gorilla king on Jul 5, 2021 17:43:47 GMT -5
A video game fight prediction. Not everything might be accurate. You know what? I actually agree with the outcome of this video. 2 vs 1, i think it would be 50%. But when the cats win, 1 will still die.
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Post by tyrannosaurs on Jul 6, 2021 15:12:38 GMT -5
Ecomorphology of the giant short-faced bears Agriotherium and Arctodus: The hypothesis that giant short-faced bears of the genera Agriotherium and Arctodus were primarily carnivorous and preyed on large terrestrial mammals is examined. It is argued that the shape and wear pattern of the cheek teeth and the presence of the premasseteric fossa on the mandible in these two ursids suggest a large amount of plant material in their diet. Likewise, the absence of adaptations for either ambush or pursuit predation in their skull and postcranial skeleton suggest that they did not prey on large terrestrial mammals. Further support for this conclusion is provided by a comparison of the dental and skeletal morphology of Agriotherium and Arctodus to that of Hemicyon ursinus, an extinct ursid widely accepted to have been a predaceous carnivore. However, it is also argued that the giant short-faced bears included a large amount of animal material in their diets, which was obtained by scavenging. www.researchgate.net/publication/247494638_Ecomorphology_of_the_giant_short-faced_bears_Agriotherium_and_Arctodus
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Post by tyrannosaurs on Jul 6, 2021 15:21:42 GMT -5
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Post by Gorilla king on Jul 6, 2021 15:29:48 GMT -5
tyrannosaurs Welcome to the forum bro. Great sources you posted. According with most sources i have read, Simus was mostly a kleptoparasite/scavenger. Of course he was able to hunt some also, but because of his long, slender hind limbs, he wasn't able to run down prey as other species of bears.
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