Pleistocene Grizzly of N. America

[brobear]

Book: The Grizzly Almanac ( 2000 ) ...
The grizzlies took over the ecological niche formerly occupied by the giant short-faced bear ( Arctodus simus ), which had arrived in North America about 1.3 million years ago. This huge beast was the largest carnivorous land animal ever, standing upright at a height of up to 11 feet ( 3 m ). It's snout was short, leading to it's nickname of bulldog bear. It had a low forehead, long legs, and weighed almost a ton, making the bulldog bear a powerful predator. The giant short-faced bear and it's cousins finally became extinct in the mid-Pleistocene Period. The most likely reason for their demise is increasing competition from the brown bears, which spread rapidly across the continent.

Estimated size of Pleistocene grizzly bear ( average mature male )
shoulder height - 4.5 feet.
length - 8 feet 9 inches.
weight - 800 pounds.

Estimated size of Arctodus simus:
shoulder height - 5.5 feet.
length - 9 feet 10 inches.
weight - 1,500 pounds

[brobear]

The grizzly who lived among saber-toothed cats, dire wolves, and giant bears.

[King Kodiak]

A LATE PLEISTOCENE BROWN BEAR (URSUS ARCTOS) FROM NORTHWEST WASHINGTON.







www.researchgate.net/publication/294746156_A_Late_Pleistocene_brown_bear_Ursus_arctos_from_northwest_Washington

[brobear]

This discovery has previously been mentioned; but I wish to elaborate:

www.sciencedaily.com/releases/2004/11/041115002514.htm

Ancient Fossil Offers New Clues To Brown Bears Past
Date:
November 15, 2004
Source:
University Of Alaska Fairbanks
Summary:
While nosing around the Quaternary mammal collection at the Provincial Museum of Alberta two years ago, Paul Matheus, a paleontologist with the Alaska Quaternary Center, came across a brown bear fossil that seemed out of place. The fossil had been collected by Jim Burns, curator of Quaternary mammals at the PMA a few years earlier near Edmonton, Alberta, in gravels that date to before the last ice age (older than 24,000 years). If this was true, Matheus thought, it could be a very important find.

While nosing around the Quaternary mammal collection at the Provincial Museum of Alberta two years ago, Paul Matheus, a paleontologist with the Alaska Quaternary Center, came across a brown bear fossil that seemed out of place. The fossil had been collected by Jim Burns, curator of Quaternary mammals at the PMA a few years earlier near Edmonton, Alberta, in gravels that date to before the last ice age (older than 24,000 years). If this was true, Matheus thought, it could be a very important find. Burns loaned the specimen to Matheus so he could take it back to the University of Alaska Fairbanks to confirm its age using radiocarbon dating methods. Results showed the bear was indeed about 26,000 years old, and the two researchers realized the fossil's signficance-the history of brown bears in North America would have to be rewritten.

The ancestors of modern brown bears in North America are believed to have migrated from Asia to Alaska and Yukon (then a part of Beringia) between 50,000 and 100,000 years ago, and old brown bear fossils are not particularly uncommon in Beringia. Between roughly 13,000-23,000 years ago, the route from Beringia to areas of the continent further south was blocked by continental glaciers, so brown bears were more or less bottled up in Beringia. The oldest brown bear fossils south of Beringia, in areas like southern Canada and the northern U.S., are about 12,000-13,000 years old, so paleontologists concluded that's when they first arrived.

[brobear]

This discovery has previously been mentioned; but I wish to elaborate: continued....

"It's always been a mystery, though, why brown bears didn't migrate farther south if they were in Beringia as early as 100,000 years ago and the passage south wasn't blocked by glaciers until about 23,000 years ago," said Matheus. "The discovery of the Edmonton specimen indicates that brown bears migrated south much earlier than previously thought."

The recent findings and their implications, are the subject of an article in the Nov. 12 issue of the journal Science titled Pleistocene Brown Bears in the Mid-Continent of North America.

In order to really nail the significance of the find, Matheus and Burns needed one more piece of important information-they needed to know something about the fossil brown bear's genetic identity. So, they brought in colleagues from the University of Oxford and the Max Planck Institute in Germany to sequence mitochondrial DNA from the specimen and assign the bear to one of the known genetic populations of modern and ancient brown bears. This was possible because of a previous collaborative study by Matheus and the Oxford lab using ancient DNA to uncover the population structure of ancient brown bears in Beringia.

"One thing that earlier study could not explain was the ancestry of modern brown bears in the southern part of their range, in places like southern Alberta, British Columbia, Montana, and Idaho," said Matheus. "Those bears belong to a genetic population thought to be extinct in North America for as much as 35,000 years."

Consequently, paleontologists and geneticists have found it difficult to explain where the ancestors of southern brown bears came from when ice sheets retreated about 13,000 years ago-their genetic type did not exist in Beringia at that time. DNA results in the current study show that the new Edmonton specimen belongs to the same genetic group as modern southern brown bears.

The age and genetic identity of this bear mean that brown bears not only made it far south sooner than previously thought, but that those bears in the Edmonton area about 26,000 years ago were very close relatives of southern bears we see today.

"Its like finding a missing piece of a puzzle, or even a proverbial missing link," said Matheus. "Their ancestors must have been stuck south of the ice sheets at the peak of the last ice age, 13,000-23,000 years ago because Edmonton was covered with ice most of that time. That represents a real shift in ideas about brown bear evolution in North America."

Matheus is a research scientist at the Alaska Quaternary Center and a research associate at the Institute of Arctic Biology. Both are located on the University of Alaska Fairbanks campus.

Story Source:

Materials provided by University Of Alaska Fairbanks. Note: Content may be edited for style and length.

[brobear]

Key Notes concerning replies # 63 and 64:

1- Quote: Results showed the bear was indeed about 26,000 years old, and the two researchers realized the fossil's signficance-the history of brown bears in North America would have to be rewritten.

2- "One thing that earlier study could not explain was the ancestry of modern brown bears in the southern part of their range, in places like southern Alberta, British Columbia, Montana, and Idaho," said Matheus. "Those bears belong to a genetic population thought to be extinct in North America for as much as 35,000 years."

Consequently, paleontologists and geneticists have found it difficult to explain where the ancestors of southern brown bears came from when ice sheets retreated about 13,000 years ago-their genetic type did not exist in Beringia at that time. DNA results in the current study show that the new Edmonton specimen belongs to the same genetic group as modern southern brown bears. 
 
*So, what does this all mean to me? The ancestors of such grizzlies as those found in Yellowstone lived among the super-predators and mega-fauna of N. America's Ice Age for roughly 14,000 years. Obviously, the grizzly fit right in and thrived. About 12,000 years ago, when the giant lions, saber-toothed cats, and the short-faced bears failed to survive, the grizzly stepped-up to become America's "King of Beasts". 

[King Kodiak]

The ancestors of such grizzlies as those found in Yellowstone lived among the super-predators and mega-fauna of N. America's Ice Age for roughly 14,000 years

Yeah, maybe even longer. The grizzlies starting crossing over in the late Pleistocene, about 50.000 years ago, so they could have lived among those super predators for like 38.000 years. All these dates and times are just estimates. The grizzly is a great survivor.

[brobear]

Mar 4, 2020 7:06:44 GMT -5 King Kodiak said:

The ancestors of such grizzlies as those found in Yellowstone lived among the super-predators and mega-fauna of N. America's Ice Age for roughly 14,000 years

Yeah, maybe even longer. The grizzlies starting crossing over in the late Pleistocene, about 50.000 years ago, so they could have lived among those super predators for like 38.000 years. All these dates and times are just estimates. The grizzly is a great survivor.

Fossils were dated - quote: Results showed the bear was indeed about 26,000 years old.
*But of course, there could have been grizzlies around before these bears died leaving these fossil remains. So yes, possibly even loner ago. 

[brobear]

www.nydailynews.com/news/national/ny-bear-skull-hundred-thousand-years-old-kansas-flooding-20191021-7sblg7b5xfe4do7jyynwtnot7u-story.html

Bear skull believed to be hundreds or thousands of years old found after Kansas flooding.

By DAVID MATTHEWS - NEW YORK DAILY NEWS - OCT 20, 2019 | 10:43 PM

Two sisters on a kayaking trip on the Arkansas River made quite the find when they came across a bear skull that could be thousands of years old.

Ashley and Erin Watt were paddling down the river in south-central Kansas in August and saw the skull sticking out of the sandbar, the Kansas Department of Wildlife, Parks and Tourism said.

Experts believe the skull was uncovered after major flooding in the region.

The sisters posted the skull photos on Facebook and the post made its way to paleontologists from the Sternberg Museum of Natural History in Hays, Kansas.

“The bear skull was washed out of the same river sediments that routinely produce the skulls and bones of the American bison, some of which could date back as far as the last Ice Age,” Mike Everhart, one of the Sternberg paleontologists who examined the skull, said.

“Whether it is hundreds or thousands of years old, the skull gives us a better insight into the richness of life on the plains before Western man,” Everhart said.

The wildlife department said the fossil was most likely newer since only a few of its teeth are missing.

According to the University of Kansas, historical records show grizzlies were wiped out in the plains state in the mid-1850s as westward expansion ramped up, but the new skull would be the first physical evidence grizzlies ever called Kansas home. 
   
 

[brobear]

TheUndertaker45 ... What information do you have on the mysterious Pleistocene grizzly? What size-range would you suspect? Anything at all greatly appreciated.

[brobear]

From the first post of Earliest Bear Ancestors - Basic Bear Evolution:

Quote: U. arctos apparently entered Alaska about 100,000
YBP but did not move south until the late Wisconsin,
about 13,000 YBP. Kurten and Anderson (1980)
suggest the possibility of 2 independent migrations;
narrow-skulled bears from northern Siberia through
central Alaska to the rest of the continent becoming
U. a. horribilis, and a southern migration of broadskulled
bears from Kamchatka to the Alaskan peninsula
becoming U. a. middendorffi. Fossils of brown bears
in Ontario, Ohio, Kentucky (Guilday 1968), and
Labrador (Spiess and Cox 1976) indicate they were
once found much farther east than historical records
show. Guilday (1968) suggested that immediately after
the glacial retreat, a relatively boreal, parkland
coniferous forest spread across the central and southern
portions of the continent and with it, several western
species, including brown bears.

[brobear]

wildfact.com/forum/topic-bears-of-the-pleistocene?page=2 ( 06-10-2015 )...( 5 years ago )...

For a long time now, I have been searching for evidence concerning the size range of Pleistocene brown bears; especially those of Ice Age North America. My theory is that with the abundance of mega-fauna ( so much available meat ) that those grizzlies might well have been in a size catagory with coastal brown bears. But so far I have come up empy-handed. What do the fossil records show?


GrizzlyClaws says: Me too, i am also interested about the brown bear fossil record, but not much info came out of water.

But i also heard they were a bit larger than the modern brown bear which should be deemed as normal as the Pleistocene animals generally faced less human pressure than their modern counterparts.

[brobear]

Continued ... by tigerluver ( biologist )...

What's exactly the size of the coastal brown bears? I've read conflicting measurements. Let's say 400-750 kg for males, so 225-750 kg including both genders.
Have you read the attached documents? They don't look to be of bears any larger than modern specimens.

The situation is more complex than just prey diversity and availability. Keep in mind that, even with more prey species, there were also more predator species, so tighter niches. Looking at North America, we have at the least (weight class in paranthesis): Smildon fatalis (100-280 kg), American lion (150-400 kg), Short faced bear (300-1000 kg), Dire wolf (50-80 kg, althought possible pack hunter, increasing prey size), and Homotherium (100-250 kg). Now where does that leave the brown bear?

The brown bear could likely be omnivorous to better cope with such crowded predatory conditions. The 225-750 kg range essentially overlaps with all these aforementioned species. The high end of the range is overlaps greatly with the short faced bear. This is ecological unfavorable, thus fossil records showing not so large brown bears make sense.

[brobear]

Quote: Have you read the attached documents?

wildfact.com/forum/attachment.php?aid=86

wildfact.com/forum/attachment.php?aid=87

[brobear]

Continued: Tigerluver, this fossil evidence would suggest that the grizzly bears of the Pleistocene were no larger than inland brown bears of today. However, it takes more than this small amount of evidence to draw any real conclusions. There must certainly be more than this handfull of grizzly fossils.
It will take more than this to completely convence me that a grizzly, with a nose estimated to be seven times more acute than that of a bloodhound, would ignore the smell of a mammoth carcass and be satisfied with eating acorns and digging for ground squirrels.
 
GrizzlyClaws says: The Pleistocene brown bear came out from such tightly competitive environment, so i can't imagine that they were no stronger than today when facing against so many fearsome rivals.

[brobear]

Tigerluver: In most paleontoligical cases, the sample size from which conclusions are drawn from are normally very small. I'd stray away from calling such conclusions are invalid when there are no better options.

Sure, bears may could get bigger, a few fossils doesn't tell enough, I agree.
Although, I would like you to understand that I am thinking under Hutchinson, Grinnel, Elton, etc. niche principle.

You're mammoth carcass idea. Ignoring the fact of resource depletion, that carcass will potentially attract all the aforementioned competitor predators. The American lion, a pack of dire wolves, Smilodon, and certainly Arctodus are massive hurdles blocking access to the carcass (this is interference competition). There's not as much available as one would like to think.

Moreover, often one predator is capping the size of the other. There are a lot of Pleistocene predators that can size cap the brown bears of that age.

The reality of the situation is still much more complex than this. Maybe some other factor not discussed here allowed the bears to grow the modern coastal sizes. Maybe time will change the status quo.

[brobear]

*More to see and read at: wildfact.com/forum/ - Extinct Animals - Prehistoric animals - Bears of the Pleistocene. 

[King Kodiak]

Replies #71-75, very good info from Tigerluver, good read.

Tigerluver, this fossil evidence would suggest that the grizzly bears of the Pleistocene were no larger than inland brown bears of today

At least we have an idea of the size of the Pleistocene grizzly.

[brobear]

Jun 4, 2020 17:25:43 GMT -5 King Kodiak said:

Replies #71-75, very good info from Tigerluver, good read.

Tigerluver, this fossil evidence would suggest that the grizzly bears of the Pleistocene were no larger than inland brown bears of today

At least we have an idea of the size of the Pleistocene grizzly.

( IMO ) There is only one reason why the grizzly was not at the top of the food chain as the dominant predator in Pleistocene, North America. The name of that one reason was Arctodus simus. If not for the giant short-faced bear, then that niche would have been filled by the brown bear. The grizzly would then have been within the same size-range as the brown bears of Pleistocene Europe. 

[King Kodiak]

IMO ) There is only one reason why the grizzly was not at the top of the food chain as the dominant predator in Pleistocene, North America. The name of that one reason was Arctodus simus. If not for the giant short-faced bear, then that niche would have been filled by the brown bear. The grizzly would then have been within the same size-range as the brown bears of Pleistocene Europe. 

I agree. So you think that if the Pleistocene North Amererican grizzly would had been same size as the Pleistocene European grizzly, aside from Simus, it would had been the top predator even over the Saber toothed cats and the American lions?