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Post by King Kodiak on Jan 6, 2021 15:40:34 GMT -5
Never said it was wrong. In fact, its very good data. That is 100% correct.
Both values should be valid, the 9+, and the 10+.
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Post by brobear on Jan 6, 2021 16:07:46 GMT -5
As is average fully-grown male Ussuri brown bear ( 10 years+) - 657 pounds. This too is actual data, not wrong. In one biological study, the numbers averaged out to 657 pounds. Next time it might be 648 pounds, or 672 pounds. The number will continue to change with each study. This is why I say, its ok to say average adult male Yellowstone grizzly, roughly 470 pounds and average adult male Ussuri brown bear, roughly 650 pounds. Even though animals are weighed, the averages are still estimates, considering the weights of each and every bear within any given location remains unknown.
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Post by King Kodiak on Jan 6, 2021 18:00:30 GMT -5
In conclusion:
9+ year old Ussuri averages 631 lbs. 10+ year old Ussuri averages 657 lbs.
Both are correct and can be used.
The median of that is 644 lbs, so rounding the overall average to 650 lbs is correct.
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Post by King Kodiak on Jan 10, 2021 9:56:11 GMT -5
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Post by brobear on Jan 10, 2021 10:18:47 GMT -5
Check it out on Reply #3. Much of this incomplete.
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Post by King Kodiak on Jan 10, 2021 10:21:19 GMT -5
brobearThanks buddy, it easier to find the weights now.
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Post by theundertaker45 on Jan 10, 2021 12:51:39 GMT -5
Prehistoric Bears: Edging out the reliable from the unreliable
I've taken a closer look at Christiansen's and Harris' study on the body weight of Arctodus Simus and Ursus Spelaeus; their equations resulted in a total averages ranging from extremely low figures to absurdely high numbers. Why is that the case?
Well, it depends on the methods being used. Every animal has its own characteristics; cave bears had extremely shortened femur bones whereas short-faced bears had extremely long limb bones in general with the largest individuals approaching the humerus length of an elephant.
Now, would it make sense to estimate them based on the length of their limb bones taking extant bears into account? I don't think so as the proportions of their limbs in relation to their overall body/torso are completely different. Would it make sense to estimate the weight of Ursus Spelaeus based on its extremely shortened femur bones taking extant bears into account? I also don't think so as no extant bear shares the same characteristics as we see today.
A much safer approach (and one that has also been compared to real life weight figures) would include looking at the width of the "bone heart" if you will (the least diameter) as that actually determines how much weight an animals should be able to carry. Then we won't have the problem with 2000kg Arctodus estimates or 300kg Ursus Spelaeus estimates anymore as the bone width generally proves to be a much more reliable and very accurate approach.
It is mentioned in Figueirido et al's study on the size of Arctodus for example:
"Based on the coefficient of correlation and the values obtained for%PE and%SEE, the minimum mediolateral width of the femoral shaft is the best mass predictor (Table 2)."
Another problem that often occurs and that regularly produces insanely low weight figures is that more gracile families are included into the equations. In Christiansen's and Harris' sample they also included mustelids, small cats and wolves which aren't in any way related to ursids regarding overall skeletal robusticity; I therefore dismissed those groups and solely focused on the equations that were based on extant bears only.
Now, having clarified this, let's go to the numbers themselves.
Arctodus Simus (gender unspecified, by Christiansen and Harris, 1999)
Average body mass according to humeral least circumference: 612kg (range: 468-956kg) Average body mass according to femoral least circumference: 1074kg (range: 811-1236kg) Total average body mass based on the two measurements: 843kg (range: 640-1096kg)
Ursus Spelaeus (females, by Christiansen and Harris, 1999)
Average body mass according to humeral least circumference: 304kg (range: 278-330kg) Average body mass according to femoral least circumference: 263kg (range: 224-291kg) Total average body mass based on the two measurements: 284kg (range: 251-311kg)
Ursus Spelaeus (males, by Christiansen and Harris, 1999)
Average body mass according to humeral least circumference: 486kg (range: 395-577kg) Average body mass according to femoral least circumference: 634kg (range: 543-734kg) Total average body mass based on the two measurements: 560kg (range: 469-656kg)
This would be my personal take on the mass of these two specimens based on Christiansen's and Harris' sample; a noteworthy thing is the decent femur stoutness in both specimens exceeding that of most other extant ursids.
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Post by King Kodiak on Jan 10, 2021 14:30:38 GMT -5
theundertaker45 : Would that change the estimates on the 3 largest bears ever? I cant find the post now, but remember that you estimated them? They were over 2000 lbs.
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Post by theundertaker45 on Jan 10, 2021 14:32:12 GMT -5
King Kodiak Yes, I would have to redo it. There were some slight errors occurring but the difference will probably not be very significant.
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Post by King Kodiak on Jan 10, 2021 14:42:16 GMT -5
theundertaker45 : Ok here is the original post, when you have time, try to do the new estimations, and include Ingressus based on that 500 mm humerus of course:
Arctodus Simus (590mm Humerus): 957kg Arctotherium Angustidens (620mm Humerus): 1111kg Arctodus Simus (646mm Humerus): 1256kg
domainofthebears.proboards.com/post/46601/thread
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Post by theundertaker45 on Jan 10, 2021 17:08:38 GMT -5
King KodiakI confused the specimens regarding Arctodus Simus; the largest estimate described in scientific literature is "UVP 015"; it had an immensely long femur (723mm) and tibia (524mm). The average weight of this specimen (based on 4 equations) was estimated to be ~957kg but we have the same issue I adressed before: 2 of those equations just take the bone length into account without taking a look at the actual width of the bone. If we exclude these two equations, the average will go up to 1064kg as that bear's bones were very long and stout at the same time. So based on the width of two limb bones, the largest estimate would be 1064kg for that specimen, however, Christiansen and Harris had one specimen in their sample where the average turned out to be 1096kg (also based on the width of two limb bones exclusively).
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Post by King Kodiak on Jan 10, 2021 18:00:09 GMT -5
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Post by theundertaker45 on Jan 10, 2021 18:08:46 GMT -5
So as a short summary we may conclude that the largest Arctodus specimen described in scientific literature most likely weighed ~1100kg; there are a few single bones that may produce larger estimates but none of this has been officially investigated so far. The largest Arctotherium specimen may also fall in this max. weight figure but I figured out it may have been stockier which means a little bit shorter at the shoulders.
We know that there is an Arctodus specimen of larger dimensions than UVP 015 whose remains have been found near Kansas River. Fortunately for us, we have one measurement we can definitely compare between the two: the least transverse width of the femur shaft.
Least Transverse Width of Femur Shaft
KUVP 131586 (Kansas River specimen): 65.7mm UVP 015 (largest specimen whose mass has been estimated): 64mm; mass estimate for this measurement: 1109kg
Based on this measurement the smaller specimen was estimated at 1109kg; applying isometric scaling to the larger bear we would end up at ~1200kg. So the title of the largest bear that has ever lived may actually belong to the "Behemoth of Kansas River"...
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Post by brobear on Jan 10, 2021 18:13:10 GMT -5
Result of your conversion:1200 kilograms is equal to 2,645.55 pounds (avoirdupois) !
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Post by King Kodiak on Jan 10, 2021 18:15:19 GMT -5
theundertaker45 : So this specimen is the same that has the 646 mm Humerus and you had first estimated at 1256 kg correct?
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Post by theundertaker45 on Jan 10, 2021 18:30:27 GMT -5
King Kodiak Yes but instead of the humerus it was more reasonable to compare it based on the femur as we don't have any comparative humerus figures for UVP 015. I also exaggerated the shoulder height of that bear due to a miscalculation, it probably was ~193cm tall instead of 206cm; still an enormous individual. So here we have him; "The Behemoth of Kansas River":
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Post by brobear on Jan 10, 2021 18:35:24 GMT -5
193 cm = 6 feet 4 inches at shoulder height.
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Post by King Kodiak on Jan 10, 2021 18:37:06 GMT -5
theundertaker45 : I see mate. Well, 1200 kg, that is still a monster specimen, no big deal in the change. About the shoulder height, dont ask me how but somehow i knew that 206 cm was just too much.
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Post by theundertaker45 on Jan 10, 2021 18:39:29 GMT -5
King KodiakYes, I am sorry about that; I don't know how I messed that up, probably a mistyping in the formula or something like that. I think it's no surprise that the largest Arctodus specimen was found in one of the most fertile areas of the United States: The Mississippi River Delta.
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Post by theundertaker45 on Jan 10, 2021 18:42:34 GMT -5
tom I don't want to disturb you again but I will probably make a new "The Biggest Bears in the World" comparison cleaning up with some miscalculations; so be prepared to use your hightech skills again and pinning the new comparison onto the homepage.
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