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Pleistocene Polar Bear v Daeodon
Topic Started: Jan 31 2012, 02:50 PM (19,499 Views)
Taipan
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Pleistocene Polar Bear - Ursus maritimus tyrannus
Ursus maritimus tyrannus was a very large fossil subspecies of the polar bear that descended from an Arctic population of brown bears. Its name in Latin means Tyrant Sea Bear. Initially the isolated brown bears were no different than the variations of brown bears of that time period. Because litters of cubs can show significant species variations in hair color and hair thickness, this gave certain individuals a survival advantage passed on each generation. Eventually skull changes and even changes in dentition occurred leading to the smooth and rather quick evolution of U. maritimus tyrannus. U. maritimus tyrannus was considerably larger then its modern relative. If everything is scaled out correctly from its remains, it would had been 183 cm (6 ft) at the shoulders, 3,6 m (12 ft) long and would have weighted an average of 1.2 tons, making it the largest bear "and one of the largest mammalian carnivores to ever walk on land". Its tremendous size makes it even bigger than the other "largest" mammalian carnivores that ever lived, including Andrewsarchus, Agriotherium, and Arctodus simus. It's speculated that this gigantic bear would, due to its formidable size and strength, have preyed on mammoths which also lived during the time.

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Daeodon shoshonensis
Daeodon, one of the largest, if not the largest, entelodont artiodactyls, lived 25-18 million years ago in North America. The 3.6 m (12 ft) long, about 1.8 m at the shoulder, 90 cm long skulled, 600 - 1000 kg mass animal strongly resembled a giant, monstrous pig or warthog, possessing huge jaws with prominent tusks and flaring cheekbones. It possibly was a huge, bone-crushing scavenger and predator, found at Agate Springs Quarry. It had long skull bones under its eyes and bony protrusions on the lower jaw, not dissimilar to the 'warts' of the warthog, which may have supported jaw muscles. The well-known genus Dinohyus ("terrible pig") has now been synonymized with Daeodon, as the latter is the earlier name, having priority.

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Wolf Eagle
Jan 31 2012, 11:41 AM
Pleistocene Polar Bear vs. Daeodon
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Sci Fyena
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Here's a size comparison I found that compares Daeodon to an Arctotherium. I am not saying the two bears are the same, (they're not!) or should be treated as such, but, if this comparison is accurate (please let me know if it isn't) I think that the entelodont's wider gape and larger jaws would be a significant advantage, especially compared to that of the bear.

Posted Image

Again, I'm only including the non-polar bear to illustrate the difference in jaw proportions between the two types of animal.
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blaze
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It's accurate when in comes to proportions.

If size between the pleistocene polar bear and Daeodon is what you want to see.

I made this one for that.
Posted Image

I'm not totally convinced on the size of the bear though, the head might be smaller and it might be shorter in stature, the ulna in question, while 13% longer than that of the subadult polar bear it was compared to in the original description, was only 4% thicker, normally, when you are comparing an individual noticeably bigger than another, you'll expect it's bones to be thicker by a greater percentage than by what it is longer, IMO, U. m. tyrannus just had proportionally longer arms but of course, that's just my opinion.
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Bob5
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There was a South American giant short faced bear vs daeodon comparison, and the bear was just as big as daeodon, so does this mean that the South American short faced bear was much bigger than this one? And based on the comparison, I would give it to the bear, it would probably be able to wrestle the pig down and kill it.
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Bob5
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The bear also still had a very strong bite force, nowhere near daeodons, but still very big.
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Ausar
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blaze
Dec 9 2013, 02:13 PM
It's accurate when in comes to proportions.

If size between the pleistocene polar bear and Daeodon is what you want to see.

I made this one for that.
Posted Image

I'm not totally convinced on the size of the bear though, the head might be smaller and it might be shorter in stature, the ulna in question, while 13% longer than that of the subadult polar bear it was compared to in the original description, was only 4% thicker, normally, when you are comparing an individual noticeably bigger than another, you'll expect it's bones to be thicker by a greater percentage than by what it is longer, IMO, U. m. tyrannus just had proportionally longer arms but of course, that's just my opinion.
Just like in the previous comparison, it looks like Daeodon could just bite the bear's head off.
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blaze
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@Bob5
The biggest Arctotherium is bigger than this one without a doubt but is not as big as commonly portrayed, no taller than 155cm at the shoulder by my estimation.
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Bob5
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blaze
Feb 13 2014, 07:00 AM
@Bob5
The biggest Arctotherium is bigger than this one without a doubt but is not as big as commonly portrayed, no taller than 155cm at the shoulder by my estimation.
Why do you think that? Also, how did you find out that the polar bear was only 400 kg?
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Bob5
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Can you send a link or something
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Vivyx
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Dynasty Warrior
Dec 8 2013, 07:48 AM
Catboy
Dec 8 2013, 06:25 AM
Big mismatch in favour of Daeodon, the PPB was only 400 kg.
Isn't it like 1.2 tonnes?
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BoomerSooner
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Sci Fyena
Dec 9 2013, 10:54 AM
Here's a size comparison I found that compares Daeodon to an Arctotherium. I am not saying the two bears are the same, (they're not!) or should be treated as such, but, if this comparison is accurate (please let me know if it isn't) I think that the entelodont's wider gape and larger jaws would be a significant advantage, especially compared to that of the bear.

Posted Image

Again, I'm only including the non-polar bear to illustrate the difference in jaw proportions between the two types of animal.
Judging on the picture, I'd give it to the bear, be it pleistocene polar bear or arctotherium. The daeodon's jaws are the only advantage it has. It has no other weapons and poor grappling ability. In retrospect, I don't think it's much different from a very large horse.

The bear looks thicker and stronger, and has the perfect body for wrestling/grappling. Not to mention it has formidable claws and jaws.

Then again, I'm still confused about whether or not the polar bear was actually that big.
Edited by BoomerSooner, Feb 24 2014, 12:04 PM.
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blaze
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@Bob5

The ulna of U. m. tyrannus, the only fossil there is, is estimated to be 485mm long (Kurten 1964) the ulna of the biggest Arctotherium angustidens is 570mm long, (Soibelzon & Schubert 2011) almost 18% larger so there we clear up that U. m. tyrannus is the smaller of the two, now, how tall is the largest Arctotherium?

Based on the total length measurements and the photos of the humerus and radius in Soibelzon & Schubert (2011) we can get the functional length of the bones, the functional length is the length between the surfaces of the bone that articulate with other bones. Functional length of the humerus is ~596mm and that of the radius is ~450mm, this measurements are 3% longer than those of FMNH PM24880 (a big and very complete specimen of Arctodus simus) so we can estimate that the largest Arctotherium was only about 3% taller, the question now is how tall was FMNH PR24880? 150cm is what I got in this this reconstruction I made, 150cm increased by 3% gets you 155cm.

The 400kg is a guesstime, it wasn't rigorous so I kind of don't like that is being quoted as it was definitely certain it was that weight, is based on the shoulder height, I made comparisons like the one with Daeodon and this one
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Blanchard (1987) has measurements and weights from a survey of brown bears in Yellowstone, the tallest bear there was 117cm tall and 325kg, and since U. m. tyrannus turns up at anything between 110cm to 130cm, it could have weighted anything between 300 to 450kg. I tend to favor the lower weights because the ulna is gracile.

Measurements of the Ulna (in mm) from Kurten (1964)
TaxonSpecimenLengthPDSDMDSLength/MDS
U. m tyrannusBM 24361
485954427.617.6
U. maritimusUZI 3
4288340.726.716
U. maritimusNRM uncatalogued
4108438.62814.6


PD is the diameter of the head of the ulna
SD, is the diameter of the "gap" in the ulna that articulates with the humerus
MDS is the minimum diameter of the shaft of the ulna.

As you can see while the ulna of U. m. tyrannus is around 15% longer than the other two polar bears is also proportionally 15% more gracile.
Edited by blaze, Feb 22 2014, 09:24 AM.
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