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Bears of the Pleistocene
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 (01-01-2018, 11:14 AM)tigerluver Wrote: What exactly would we like in the comparison? Bone to bone comparisons? I hadn't thought of that but it's a great idea. Skulls and other bones compared; sounds interesting. But later on, a picture over at 'Terrestrial Animals' at 'Size Comparisons'. It would be great to have a bear of the Genus Ursus comparable to the giant short-faced bears. 
How would you suppose Ursus ingressus would stack up against Ursus maritimus tyrannus in size? Which bear is the largest of the Genus Ursus?
(01-01-2018, 09:53 PM)brotherbear Wrote: How would you suppose Ursus ingressus would stack up against Ursus maritimus tyrannus in size? Which bear is the largest of the Genus Ursus? Skull wise, I think Ursus ingressus probably did score the longest skull of the entire Ursidae family with a mind boggling 57.14 cm skull. Body wise, I think Actotherium angustidens would still come out on top, and the comparison between Ursus ingressus and Ursus maritimus tyrannus would be quite uneasy as the body fossils are too fragmented for these two species before making a conclusive point. Maybe @tigerluver could do us a favor again?  (01-01-2018, 09:04 PM)GrizzlyClaws Wrote:(01-01-2018, 11:14 AM)tigerluver Wrote: What exactly would we like in the comparison? Bone to bone comparisons? Ok, I'll need a few weekends as I don't have access to that specific computer on the weekdays. If you find any good skull photos, please post them here so I can use them in the comparison.
Some time ago, with what he had to work with, Tigerluver came up with this comparison: Size Comparisons page #8 - post #107.
Ursus ingressus - Sh. Height: 170 cm ( 5 feet 7 inches ). Weight: 740 kg ( 1,631 pounds ). Ursus maritimus tyrannus - Sh. Height: 170 cm ( 5 feet 7 inches ). Weight: 700 kg ( 1,543 pounds ). I have the strong feeling that, just as with Arctodus simus and Arctotherium angustodens, these two will be close enough in size so that which is the largest will be debatable.
Two newly found skulls: https://www.livescience.com/17936-short-...skull.html
https://www.allgrizzly.org/pleistocene-holocene-diet
I suspect that the amount of meat in local diets of Pleistocene grizzlies varied widely, primarily as a function of the competition they faced from other carnivores. However, I also suspect that the meat in grizzly bear diets increased substantially during the late Pleistocene-Holocene transitions as most of their competitors (and predators) went extinct, and despite the demise of most species of large herbivores as well. Why do I think this? As I describe in the page devoted to Early Prehistory, there were a lot of large carnivores around during the Pleistocene, including lions, short-faced bears, dire wolves, and saber-tooth and scimitar-tooth cats. Grizzlies would not have fared well trying to either protect a kill or contest a found carcass when confronting such competitors. In fact, they probably sometimes ended up as prey of the largest of these predators, as seems to have been the case for cave bears in Pleistocene Europe and as continues to be the case for brown bears in areas occupied by Siberian tigers. On the other hand, in the absence of such competitors brown and grizzly bears can be quite carnivorous, as is the case for contemporary populations in meat-rich environments. But getting back to the Pleistocene. I suspect that competition with and predation by other large carnivores could have been intense enough to limit most grizzlies to marginal areas such as the swath of tundra along the continental icesheet margins (see above). But given such limits, grizzlies were probably locally adaptive in response to variations in competition and the meat resource. Herve Bocherens describes precisely such a situation in Pleistocene Eurasia, where brown bears coexisting with the largely herbivorous cave bears in Europe seem to have been quite carnivorous, while grizzlies hanging around meat-eating giant short-faced bears in Beringia were much more herbivorous. What might this mean for Pleistocene grizzlies? First, there was probably a lot of meat around in the form of carrion in most areas of the West. Even though the competition for this resource was probably intense, a fast-moving lucky grizzly might have still been able to scavenge of lot. Second, smaller-bodied camels and horses might have been an especially important resource given that competing for meat from a fallen giant such as an elephant was probably particularly hazardous for a grizzly. And, third, the concentration of elephant remains along recently-melted margins of the ice sheet would have likely increasingly contributed to the sustenance of grizzlies in these dynamic rapidly revegetating environments of the East. This would fit my speculations about the distribution of early Holocene grizzly remains in this region, the extent to which grizzlies seemed to track recently melted environments, and the apparent absence of eastern grizzlies after about 9k years ago.
https://fineart.ha.com/itm/fossils/mamma...96-81039.s
Fossil Bear Claw Ursus uralensis Pleistocene Russia While often misrepresented as Cave Bear specimens, remnants of "spelaeoid" or Cave-Bear-Like animals were not true "Cave" Bears as they were not actually cave-dwelling mammals. Fossils of specimens from Russia are of an extinct variety similar to modern-day Grizzly Bears. This haunting specimen from Russia is from an Ursus uralensis which was smaller than the actual Cave Bear Ursus spelaeus. The hand has an almost "human-like" quality with the exception of the claw tips on the digits. The specimen measures an impressive 11 inches (28 cm) and is considerably larger than even a big human hand. This one is spooky! Overall Measurements: 11.31 x 8.11 x 2.19 inches (28.72 x 20.60 x 5.56 cm) (01-03-2018, 12:06 PM)brotherbear Wrote: https://fineart.ha.com/itm/fossils/mamma...96-81039.s I think that measurement belongs to the entire paw. The longest Grizzly claw I known was 7 inches over curve and 5 inches in straight line.
Yes, they are showing the picture of a "hand skeleton" and referring to it as a claw.
I found post #229 interesting. That is why I was looking up Pleistocene grizzly skulls last night. The shape of the skull should answer whether the Ice Age grizzly of N. America was more herbivorous or carnivorous. I thought that I was looking at a Pleistocene grizzly skull; but it was simply a grizzly. I (01-03-2018, 09:40 PM)brotherbear Wrote: Yes, they are showing the picture of a "hand skeleton" and referring to it as a claw. The Grizzly bear is a flexible survivor, and his diet would change accordingly to the available food sources. More available preys, then more carnivorous, and being more herbivorous with less available preys.
http://www.sciencemag.org/news/2010/03/e...tic-tundra
The DNA evidence and the location of the find suggest that polar bears were just beginning to spread out across their Arctic habitat between the last two ice ages, when Earth's climate was warmer than it is today. In just 1000 generations or so, U. maritimus morphed from a stocky brown bear to a long-necked bear with thick fatty layers and that signature white coat. Lindqvist says the Svalbard area, north of the Arctic Circle and far from the competitors inhabiting the continental land masses, offered just the right refuge where the bears could persist through the warming period before the last ice age and then begin to adapt to a life amid the frozen sea.
https://www.americaherald.com/primitive-...oth/29904/
According to the researcher, this discovery marks the first and earliest documented occurrence of high-calorie diets in basal bears. He believes the diet is related to fat storage which helped the primitive bear survive the harsh Arctic winters. (01-05-2018, 06:25 PM)brotherbear Wrote: http://www.sciencemag.org/news/2010/03/e...tic-tundra The possible admixture from the Cave bear could also possibly accelerate the mutation and divergence of the Polar bear from other Brown bears. However, we still regard this as an alternate theory, and we also need to extract the possible genome of the Cave bear within the modern Polar bears. |
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