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Post by brobear on May 22, 2020 2:57:18 GMT -5
Cave Bear - wildfact.com/forum/attachment.php?aid=203Bite force of the extinct Pleistocene Cave bear Ursus spelaeus Rosenmüller from Europe by Aurora Grandal-d’Anglade Key points: Male specimens have stronger bite force than females as expected, but relatively, the two are equal. U. spelaeus carnassial bite force is similar to the giant panda, greater than the polar bear, and less than the lion and the tiger. The polar bear probably has a weaker bite force due to its relatively recent evolution. Key tables:
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Post by brobear on May 22, 2020 4:26:27 GMT -5
www.ncbi.nlm.nih.gov/pmc/articles/PMC1564077/ We provide the first predictions of bite force (BS) in a wide sample of living and fossil mammalian predators. To compare between taxa, we calculated an estimated bite force quotient (BFQ) as the residual of BS regressed on body mass. Estimated BS adjusted for body mass was higher for marsupials than placentals and the Tasmanian devil (Sarcophilus harrisii) had the highest relative BS among extant taxa. The highest overall BS was in two extinct marsupial lions. BFQ in hyaenas were similar to those of related, non-osteophagous taxa challenging the common assumption that osteophagy necessitates extreme jaw muscle forces. High BFQ in living carnivores was associated with greater maximal prey size and hypercarnivory. For fossil taxa anatomically similar to living relatives, BFQ can be directly compared, and high values in the dire wolf (Canis dirus) and thylacine (Thylacinus cynocephalus) suggest that they took relatively large prey. Direct inference may not be appropriate where morphologies depart widely from biomechanical models evident in living predators and must be considered together with evidence from other morphological indicators. Relatively low BFQ values in two extinct carnivores with morphologies not represented among extant species, the sabrecat, Smilodon fatalis, and marsupial sabretooth, Thylacosmilus atrox, support arguments that their killing techniques also differed from extant species and are consistent with ‘canine-shear bite’ and ‘stabbing’ models, respectively. Extremely high BFQ in the marsupial lion, Thylacoleo carnifex, indicates that it filled a large-prey hunting niche. Bite force (BS) is an important aspect of carnivore ecology, with the potential to shed light on the evolution of community structure and prey size in fossil taxa (Meers 2002; Vizcaíno & de Iuliis 2003; Rayfield 2004). However, empirical data are not easily obtained; BS has been measured in only three mammalian carnivore species (Thomason 1991; Dessem & Druzinsky 1992; Binder & Van Valkenburgh 2000) and the comparative biology of BS in mammals has remained largely unexplored. Important unanswered questions are: is bite force (i) allometrically related to body mass, (ii) phylogenetically constrained, (iii) more strongly influenced by skull length or skull width, (iv) relatively higher in bone-cracking specialists and (v) related to prey size in extant taxa? Answers will define the limits of using BS estimate as a predictor of behaviour and prey size in fossil species. We calculated theoretical maximum bite forces using the ‘dry skull’ method (Thomason 1991; Electronic Appendices, sections A and B). Our sample comprised 49 specimens representing 39 taxa (31 extant and eight extinct). The dry skull method, derived from relationships between skull dimensions and jaw muscle cross-sectional areas, models the jaw as a simple lever. It is most applicable to the anterior-most portion of the jaw, where the caniniform teeth are located (Electronic Appendix, section A). Consequently, and because morphology of the canines has long been considered a significant predictor of predatory behaviour in mammalian carnivores (Wroe et al. 1998; Farlow & Pianka 2002), we have largely restricted our discussion to estimates of force for static bites at the canines (CBS). However, analyses of BS at the carnassial showed the same qualitative trends as for CBS (Electronic Appendix, section C). A further advantage of the ‘dry skull’ method is that because results are derived solely from skull morphology, comparisons can be made between fossil and extant taxa. The relationship between CBS and body mass between species is allometric (figure 1; Meers 2002; r2=0.85). To compare bite forces in taxa of greatly differing body masses an estimated bite force quotient (BFQ) was calculated using the residuals of regression (table 1; Electronic Appendix, section A). ‘Average’ BFQ was set at 100. Variance in allometry adjusted bite force is small relative to that for absolute BS (Thomason 1991; Electronic Appendix, section D) and a second advantage of using BFQ is that it allows more meaningful comparisons based on small datasets. This quality is particularly valuable in analyses incorporating fossil taxa where sample sizes are limited.
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Post by brobear on May 22, 2020 4:32:59 GMT -5
Table 1 Measurements of basal skull length (BSL) and maximum skull width at the zygoma (SWZ); and estimates of body mass (BoM), canine bite force (CBS), and bite force quotient (BFQ), for 39 taxa of recent and fossil mammals. (Measurements and calculations were taken from prepared skulls. Methods for body mass estimations given in Electronic Appendix, section A. Fossil taxa indicated with †.) www.ncbi.nlm.nih.gov/pmc/articles/PMC1564077/table/tbl1/?report=objectonly *Bite force quotient (BFQ) is the regression of the quotient of an animal's bite force in newtons divided by its body mass in kilograms.[1][2] It does not take into account sharpness of teeth or other differences in tooth form; an animal with sharp teeth will project its bite force over a small surface area, while an animal with flatter teeth will spread the force out over a larger area. Animal BFQ Tasmanian devil 181 Spotted-tailed quoll 179 Thylacine 166 Least weasel 164 Northern olingo 162 Sun bear 160 African wild dog 142 Jaguar 137 Clouded leopard 137 Grey wolf 136 Sand cat 136 Dhole 132 Tiger 127 Dingo 125 Cheetah 119 Domestic dog 117 Spotted hyena 117 Brown hyena 113 Lion 112 European badger 109 Cougar 108 Singing dog 100 Arctic fox 97 Leopard 94 Red fox 92 Coyote 88 Grey fox 80 Brown bear 78 Aardwolf 77 Jaguarundi 75 American black bear 64 Domestic cat 58 Cape genet 48 Asiatic black bear 44
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Post by brobear on May 22, 2020 4:49:29 GMT -5
*Note: according to this study, while the sun bear ranks pretty high ( just below the giant panda not included here ) the brown bear and both black bears rank very low.
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Post by theundertaker45 on May 22, 2020 4:55:52 GMT -5
brobear The study in your above comment is an outdated version of the one I have shared before; it was conducted by Wroe in 2005, however, he teamed up with Christiansen in 2007 and they published a more extensive study on bite forces having a much bigger sample size; they also explain that they missed some major components in the study that was published in 2005. The flaws in this study are easily visible when looking at the enormous BFQ of the thylacine who was later determined to have relatively feeble jaws which most likely led to his extinction as it was susceptible to small disturbances to the ecosystem. The original study conducted in 2005 is still widely used among various enthusiasts that want their favourite animal to have a relatively high bite force; I've noticed that over the last couple of months on other forums.
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Post by brobear on May 22, 2020 5:05:01 GMT -5
From Reply #92: Regarding the ursids involved in the study, we have the following BFQ-ranking (I am focusing on the BFQ at the canine tips as the canines play the major role in delivering a killing bite):
1. Sun Bear - 160.5 at the canine tips 2. Giant Panda - 151.4 at the canine tips 3. Spectacled Bear - 103.1 at the canine tips 4. Brown Bear - 99.3 at the canine tips 5. Asian Black Bear - 95.6 at the canine tips 6. Polar Bear - 92.3 at the canine tips 7. American Black Bear - 77.2 at the canine tips 8. Sloth Bear - 59.9 at the canine tips
Here are some other measurements:
Tiger - 130.4 at the canine tips Lion - 123.8 at the canine tips Jaguar - 118.6 at the canine tips Leopard - 119.8 at the canine tips Cougar - 118.8 at the canine tips Cheetah - 72.7 at the canine tips Grey Wolf - 127.3 at the canine tips African Wild Dog - 131.1 at the canine tips Spotted Hyena - 99.6 at the canine tips Wolverine - 104.6 at the canine tips
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Post by brobear on May 22, 2020 5:12:29 GMT -5
I hadn't noticed the first time I saw this; the sun bear actually beats the giant panda. However; both the giant panda and the Andean bear are above all other Ursinae bears. Add this with the fact that Agriotheium and the short-faced bears were all known to have had extremely powerful jaws. I'm happy to see that the brown bear does not rank low. Of course, the big cats have him beat in bite-force but not by any great degree. I also notice that the brown bear and the spotted hyena are pretty much at parity. *I believe also that the gorilla has a bite-force pretty much at parity with the brown bear.
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Post by brobear on May 25, 2020 6:23:36 GMT -5
Considering that bears have dog-like jaws, a long muzzle, and that cats have a short rounded face, this will give the cats an advantage in bite-force at the canines ( I would think ). Just wondering how these predator's bite-force might compare back at the molars, where one might use to crack a bone? Over the years, I have read completely contradicting reports on the bite-strength of the polar bear - two very different extremes.
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Post by OldGreenGrolar on Jun 1, 2020 20:36:50 GMT -5
Polar bear’s jaws are highly underrated. Being able to slice the hide or a beluga and walrus is an achievement in itself honestly.
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Post by brobear on Jun 4, 2020 5:46:57 GMT -5
Polar bear’s jaws are highly underrated. Being able to slice the hide or a beluga and walrus is an achievement in itself honestly. Well; like I mentioned, I have read two very different findings; two opposite extremes. Just how tough the flesh of a beluga or a walrus is; I don't know. But the majority of a polar bear's diet is blubber. A bear doesn't need the bite-strength of an alligator to eat blubber. But this in no way confirms that the polar bear has a weak bite. From Reply #92: has the polar bear as number #6 in the 8-bear line-up. But I agree with 'Taker when he said ( in another topic ) that bite-force in not a game-changer in a face-off confrontation. The polar bear; due to size and awesome strength, is the king of the bears.
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Post by King Kodiak on Jun 4, 2020 9:49:40 GMT -5
Remember that to get to the blubber, first you need to cut thru the skin. Walruses have 15 cm thick skin:
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Post by OldGreenGrolar on Jun 6, 2020 4:27:13 GMT -5
The thick skin of the walrus shows the polar bear has an efficient slicing bite.
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Post by brobear on Jun 6, 2020 4:37:12 GMT -5
The thick skin of the walrus shows the polar bear has an efficient slicing bite. Well, the bite force study places the polar bear between the Asiatic and the American black bears. Number #6 in the line-up of the eight bear species. He outranks the American black bear, the sloth bear, and the cheetah.
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Post by King Kodiak on Jun 6, 2020 9:10:12 GMT -5
The thick skin of the walrus shows the polar bear has an efficient slicing bite. Well, the bite force study places the polar bear between the Asiatic and the American black bears. Number #6 in the line-up of the eight bear species. He outranks the American black bear, the sloth bear, and the cheetah. Yes, but remember that list is relative to its size.
"Due to his enormous size the polar bear tops the list as the animal with the highest absolute bite force (a 780lbs polar bear would bite down with a force of ~1650N)"
"As brown bears/polar bears may attain weights of more than 1000lbs they should generally be considered as the carnivores having the highest absolute bite force with the polar bear sitting on top and the brown bear coming close second; third and fourth place would go to the tiger followed by the lion."
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Post by brobear on Jun 6, 2020 9:16:18 GMT -5
Well, the bite force study places the polar bear between the Asiatic and the American black bears. Number #6 in the line-up of the eight bear species. He outranks the American black bear, the sloth bear, and the cheetah. Yes, but remember that list is relative to its size.
"Due to his enormous size the polar bear tops the list as the animal with the highest absolute bite force (a 780lbs polar bear would bite down with a force of ~1650N)"
"As brown bears/polar bears may attain weights of more than 1000lbs they should generally be considered as the carnivores having the highest absolute bite force with the polar bear sitting on top and the brown bear coming close second; third and fourth place would go to the tiger followed by the lion."
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Post by brobear on Jun 6, 2020 9:18:24 GMT -5
The author of this wrote "Asian bear" as if only one species of bear lives in all of Asia. With the weak bite-force shown; my guess would be sloth bear. No clue what SAM-2M 35814 or AM M42656 means. ?
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Post by King Kodiak on Jun 6, 2020 9:25:13 GMT -5
Reply #114, look at the weight of those two polar bears used in that chart, they are very very small, 226 kg and 187 kg, not adult males, and they still had among the largest bite force compared to the rest.
Anything bite force related, you have to look the most reliable bite force study that we have, the one posted by Undertaker:
domainofthebears.proboards.com/post/26903/thread
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Post by King Kodiak on Jun 6, 2020 9:27:11 GMT -5
Those are the particular polar bears used, their identifications. which were very small, not adult males.
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Post by brobear on Jun 6, 2020 9:36:59 GMT -5
Those are the particular polar bears used, their identifications. which were very small, not adult males. 226 kilograms is equal to 498.24 pounds for the biggest polar bear cub used in this study. ( or a she-bear maybe ). 213 kilograms is equal to 469.58 pounds is a typical Yellowstone grizzly. Why would they screw-up a study by using juvenile bears?
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Post by King Kodiak on Jun 6, 2020 9:43:39 GMT -5
Those are the particular polar bears used, their identifications. which were very small, not adult males. 226 kilograms is equal to 498.24 pounds for the biggest polar bear cub used in this study. ( or a she-bear maybe ). 213 kilograms is equal to 469.58 pounds is a typical Yellowstone grizzly. Why would they screw-up a study by using juvenile bears? I have no idea brobear. But this is the most reliable bite force study that we have:
domainofthebears.proboards.com/post/26903/thread
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