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Post by brobear on Mar 24, 2017 2:38:14 GMT -5
Evolutionary History
The evolution of bears begins in the early Miocene era, approximately 20 mya (million years ago), when the first bear type animal named Ursavus elmensis evolved from a dog-like ancestor (Hitchcock, 2004). Fossil records from U. elmensis show carnassial teeth with larger molars for more chewing area, a trait common to present day bears. Another early bear in the lineage leading to grizzlies is Ursus minimus of the cave line bears, which lived in the Pliocene era, about 10 mya. The cave line bears persisted until the most recent ice age 10,000 years ago but then became extinct. However, roughly 1.5 mya a new lineage of bears diverged from the cave bear line. These bears, which were most similar to Ursus etruscus of the cave bear line, were the common ancestors of the brown bears, Ursus arctos, and the black bears, Ursus americanus. The closest relative of the brown bear is the polar bear, which diverged from U. arctos about 300,000 years ago. Brown bears have diverged into a large number of subspecies, one of which being the grizzly bear common to North America.
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Post by brobear on Nov 11, 2018 16:35:44 GMT -5
Post by brobear on Mar 18, 2017 at 11:36am iceage.museum.state.il.us/mammals/grizzly-bear-0
Grizzly bears, or brown bears, are a relatively recent addition to North American fauna, having migrated to this continent in the late Pleistocene. These large, omnivorous bears were once widely distributed across North America; however, during the 20th century they were extirpated from most of the U.S. and central Canada.
North American Ice Age Distribution: Grizzly bears are fairly late arrivals to North America, having migrated from Eurasia towards the end of the late Pleistocene (ca. 50,000-25,000 years ago). During this time they were concentrated in Alaska and the northwest portion of Canada, although they rapidly expanded south and east as the continental ice sheets retreated at the end of the Pleistocene (Kurtén and Anderson 1980; Schwartz et al. 2003) Status at the end of the Pleistocene: Not only did the grizzly bear survive the mass extinctions of the terminal Pleistocene, but they were able to expand into most of North America as the continental ice sheets retreated to the north. By the early Holocene, they ranged as far east as Ontario, Ohio and Kentucky and as far south as Mexico. This distribution retreated north and west, somewhat, as environmental conditions continued to fluctuate through the Holocene, and by historic times, they ranged through most of western North America and into the central Plains of the U.S. (Schwartz et al. 2003). Midwestern Paleontological Finds: Despite their relatively recent arrival, remains of grizzly bears have been recovered from late Pleistocene sites in the central Midwest. Most notably, remains have been recorded at Polecat Creek in eastern central Illinois, the Overpeck Ursus find south of Dayton, Ohio, and in Welsh Cave, southwest of Lexington, Kentucky. Pictured: Art by: Ken Doud - California grizzly meets giant short-faced bear, Arctodus simus.
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Post by brobear on Nov 11, 2018 16:45:06 GMT -5
Post by brobear on Mar 19, 2017 at 5:18pm The Bear Almanac by Gary Brown.
The brown bears derived from Etruscus and along the same line that produced cave bears. It evolved in open spaces, lived mostly in nonforest or woodland areas and, not being a forest animal, had to stand and fight for its territory, food, and cubs. Spread widely across the Pleistocene landscape, with the earliest bears living in China, the brown bear succeeded Arctodus simus over much of its range.
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Post by brobear on Nov 11, 2018 16:45:46 GMT -5
Grizzly Years by Doug Peacock.
Black bears are forest creatures, evolved from Etruscan bears in the Old World. They crossed over into North America some 500,000 years ago. The grizzly bear is a much more recent product of evolution. The grizzly wandered over the Bering land bridge as recently as 40,000 to 12,000 years ago and encountered great open expanses of tundra, the rich periglacial of the Pleistocene. One of the consequences was that away from their ancestral forests in Asia and Europe, grizzlies became more aggressive in response to the treeless tundra, where mothers had to learn to protect their young from other bears, wolves, and several now-extinct Pleistocene carnivores. Defense became a good offense; this increased aggressiveness no doubt accounting for the bear's subspecies name, 'horribilis'.
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Post by brobear on Nov 11, 2018 16:46:29 GMT -5
Post by brobear on Mar 19, 2017 at 5:20pm www.allgrizzly.org/#!pleistocene-holocene-diet/c1xe9 I've spent a fair amount of time during my morning walks thinking about what the world of grizzly bears might have been like during the late Pleistocene and early Holocene in North America. Much of my curiosity has focused on their likely diet...as well as their likely predators and competitors. The foundation for all of these imaginings is necessarily a reconstruction of the environment and the foods, whether animal or vegetal. Here I focus on environments and diet between roughly 20,000 and 9,000 years before present, from the peak of the last glaciations (the Last Glacial Maximum or LGM) and the onset of serious heat and drought during the Altithermal. I start below with a synoptic overview of broad-scale environments, then briefly consider vegetal foods, and conclude with a consideration of animal foods, especially meat from large herbivores. For more detail on climates during this period see Early prehistory. For more detail of probable diets during the centuries immediately preceding the arrival of Europeans, see Pre-European diets. *Note: a huge amount of information found on this given site. Please take a look.
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Post by brobear on Nov 11, 2018 17:16:55 GMT -5
Post by brobear on Mar 19, 2017 at 7:43pm www.sciencedaily.com/releases/2004/11/041115002514.htmAncient 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.
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Post by brobear on Nov 11, 2018 17:17:38 GMT -5
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.
"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.
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Post by brobear on Nov 11, 2018 17:19:53 GMT -5
tolweb.org/treehouses/?treehouse_id=4728 The evolution of bears begins in the early Miocene era, approximately 20 mya (million years ago), when the first bear type animal named Ursavus elmensis evolved from a dog-like ancestor (Hitchcock, 2004). Fossil records from U. elmensis show carnassial teeth with larger molars for more chewing area, a trait common to present day bears. Another early bear in the lineage leading to grizzlies is Ursus minimus of the cave line bears, which lived in the Pliocene era, about 10 mya. The cave line bears persisted until the most recent ice age 10,000 years ago but then became extinct. However, roughly 1.5 mya a new lineage of bears diverged from the cave bear line. These bears, which were most similar to Ursus etruscus of the cave bear line, were the common ancestors of the brown bears, Ursus arctos, and the black bears, Ursus americanus. The closest relative of the brown bear is the polar bear, which diverged from U. arctos about 300,000 years ago. Brown bears have diverged into a large number of subspecies, one of which being the grizzly bear common to North America.
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Post by brobear on Nov 11, 2018 17:26:20 GMT -5
Post by brobear on Mar 23, 2017 at 5:18am www.pnas.org/content/97/4/1651.full.pdf Population genetics of Ice Age brown bears. The Pleistocene was a dynamic period for Holarctic mammal species, complicated by episodes of glaciation, local extinctions, and intercontinental migration. The genetic consequences of these events are difficult to resolve from the study of present-day populations. To provide a direct view of population genetics in the late Pleistocene, we measured mitochondrial DNA sequence variation in seven permafrost-preserved brown bear (Ursus arctos) specimens, dated from 14,000 to 42,000 years ago. Approximately 36,000 years ago, the Beringian brown bear population had a higher genetic diversity than any extant North American population, but by 15,000 years ago genetic diversity appears similar to the modern day. The older, genetically diverse, Beringian population contained sequences from three clades now restricted to local regions within North America, indicating that current phylogeographic patterns may provide misleading data for evolutionary studies and conservation management. The late Pleistocene phylogeographic data also indicate possible colonization routes to areas south of the Cordilleran ice sheet.
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Post by brobear on Nov 11, 2018 17:26:49 GMT -5
Post by brobear on Mar 23, 2017 at 10:30am iceage.museum.state.il.us/mammals/grizzly-bear-0
Grizzly bears, or brown bears, are a relatively recent addition to North American fauna, having migrated to this continent in the late Pleistocene. These large, omnivorous bears were once widely distributed across North America; however, during the 20th century they were extirpated from most of the U.S. and central Canada.
North American Ice Age Distribution: Grizzly bears are fairly late arrivals to North America, having migrated from Eurasia towards the end of the late Pleistocene (ca. 50,000-25,000 years ago). During this time they were concentrated in Alaska and the northwest portion of Canada, although they rapidly expanded south and east as the continental ice sheets retreated at the end of the Pleistocene (Kurtén and Anderson 1980; Schwartz et al. 2003) Status at the end of the Pleistocene: Not only did the grizzly bear survive the mass extinctions of the terminal Pleistocene, but they were able to expand into most of North America as the continental ice sheets retreated to the north. By the early Holocene, they ranged as far east as Ontario, Ohio and Kentucky and as far south as Mexico. This distribution retreated north and west, somewhat, as environmental conditions continued to fluctuate through the Holocene, and by historic times, they ranged through most of western North America and into the central Plains of the U.S. (Schwartz et al. 2003). Midwestern Paleontological Finds: Despite their relatively recent arrival, remains of grizzly bears have been recovered from late Pleistocene sites in the central Midwest. Most notably, remains have been recorded at Polecat Creek in eastern central Illinois, the Overpeck Ursus find south of Dayton, Ohio, and in Welsh Cave, southwest of Lexington, Kentucky.
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Post by brobear on Nov 11, 2018 17:28:12 GMT -5
www.researchgate.net/publication/233346740_Correlation_of_carnassial_tooth_size_and_body_weight_in_Recent_carnivores_Mammalia The correlation between the lower carnassial crown area and the body weight is examined for modern carnivores. It is very high, but the ursids and felids show a relationship different from the other carnivore families. Some exceptions are discussed. The possibility of predicting body weight for fossils is given. Post by brobear on Mar 23, 2017 at 10:31am www.sciencedaily.com/releases/2004/11/041115002514.htmAncient 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.
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Post by brobear on Nov 11, 2018 17:29:16 GMT -5
When I asked about the size of the Pleistocene grizzly over at - wildfact.com/forum/ - Tigerluver answered thus: 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 parenthesis): Smilodon fatalis (100-280 kg), American lion (150-400 kg), Short faced bear (300-1000 kg), Dire wolf (50-80 kg, although a 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.
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Post by brobear on Nov 11, 2018 17:30:10 GMT -5
Post by brobear on Mar 23, 2017 at 12:57pm wildfact.com/forum/attachment.php?aid=90
THE FOSSIL BEARS OF SOUTHEAST ALASKA TIMOTHY H. HEATON1 , FREDERICK GRADY2 1 Department of Earth Sciences, University of South Dakota, Vermillion, SD, 57069, USA 2 Department of Paleobiology, Smithsonian Institution, Washington, DC, 20560, USA Southeast Alaska is home to brown bears (Ursus arctos) and black bears (U. americanus) with an unusual distribution. Both species inhabit the mainland, while only black bears inhabit the islands south of Frederick Sound and only brown bears inhabit the islands north of Frederick Sound. Brown bears of the northern islands belong to a distinct lineage and are genetically more similar to polar bears than their mainland counterparts. Bears are among the most common fossils found in caves in the region, and they indicate that both species made greater use of caves as dens when the climate was colder. But no bear fossils are known from the Last Glacial Maximum (LGM), even at On Your Knees Cave where foxes and marine mammals have been recovered across most of this interval. This begs the question of whether bears survived the LGM on coastal refugia or recolonized the islands after the ice retreated. No evidence has been found to settle the question for black bears. Black bears are far more common than brown bears in On Your Knees Cave for the period before the LGM, but they were slower than brown bears in expanding their range across the islands after the ice melted. The evidence for survival in a local refugium is much stronger for brown bears. While they are less common before the LGM, they had a greater distribution than black bears immediately following the LGM, including some of the outermost islands of the archipelago. The lack of brown bear fossils from mainland sites during early postglacial times may indicate that the mainland was not the source of this population. The distinct genetic character of modern island brown bears also suggests that they did not derive from the mainland. Two fossil brown bears from caves of Prince of Wales Island have had successful DNA extractions and match the distinct lineage that now lives only on the northern islands of Southeast Alaska. A refugium for brown bears may have been offshore on the continental shelf which was exposed during the LGM but was flooded by rising sea level in the early postglacial period.
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Post by brobear on Nov 11, 2018 17:30:56 GMT -5
wildfact.com/forum/attachment.php?aid=91
Brown bear (Ursus arctos) (9880 ± 35 BP) from late-glacial Champlain Sea deposits at Saint-Nicolas, Quebec, Canada, and the dispersal history of brown bears C. Richard Harington, Mario Cournoyer, Michel Chartier, Tara Lynn Fulton, and Beth Shapiro
Some comments on the appearance and habits of the brown bear, the species featured here, are warranted. Brown bears are mainly solitary, relatively large (males: 170–230 cm long, weighing 250–350 kg; females: 145–213 cm long, weighing 80–225 kg), having medium to dark brown fur, a dished head profile, distinctly high, muscle-filled humps powering the forelegs, long front claws, short round ears, and short tails. The largest, heaviest individuals in North America are from the Pacific Coast. They are a northern hemisphere species occurring in both Eurasia and North America. Their dispersal history is discussed later. They prefer open areas such as alpine meadows, river valleys, and scrublands, and hibernate in winter where dens are usually located in mountainous or heavily forested areas often under tree roots, where snow cover is deep. Male home ranges are much larger than those of females. They are omnivorous, their diet being composed mainly of vegetative matter, but they also feed on fishes, small mammals, birds, and carrion (Naughton 2012). Their keen sense of smell and need to feed heavily before hibernation can draw them to shorelines where fishes, nesting birds, and washed-up marine mammal carcasses can be relatively abundant. The purpose of this paper is to describe the bear fossil from the Saint-Nicolas site, Quebec, discuss its stratigraphic position, paleoenvironment, radiocarbon age, and identification through morphometric comparison with modern brown, polar, and black bear specimens, as well as analysis of its ancient DNA. The specimen is also considered in relation to the dispersal history of brown bears, and to the known Champlain Sea fauna from Saint-Nicolas.
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Post by brobear on Nov 11, 2018 17:32:06 GMT -5
Post by brobear on Mar 28, 2017 at 6:19am www.discovery.com/tv-shows/great-bear-stakeout/about-grizzlies/first-grizzlies/ The First Grizzlies The story of the grizzly bear begins in the treetops of Asia some 34 million years ago. There, a dog-sized predator known as Cephalogale first appeared. This earliest ancestor of bears gave way to the "dawn bear," a small, arboreal hunter with teeth designed for grinding vegetation. A more grizzly-like bear made its appearance in Europe some 5 million years ago in the form of the Etruscan bear, the earliest known member of the genus Ursus, which includes the grizzly. The Etruscan bear was carnivorous, but its large and flat teeth indicate a diet that relied heavily on vegetation. Around 1.3 million years ago, the brown bear, Ursus arctos, appeared in China. A successful opportunist, it spread quickly across the continent into Europe and northern Africa. It reached the Americas during one of the early ice ages, traveling across the Bering Land Bridge at least 200,000 years ago. Back then, the short-faced bear - the largest bear that ever lived - roamed the continent. But it and many other bear species went extinct shortly after the brown bear arrived. Over time, America's brown bear developed distinctive characteristics and became what we know today as the grizzly bear, or Ursus arctos horribilis. Tens of thousands of years later, grizzlies were joined in North America by the earliest human migrants to the Pacific Northwest. The special relationship between these Native American tribes and the grizzly bear would give rise to a number of origin myths and legends, far more imaginative than scientific explanation...
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Post by brobear on Nov 11, 2018 17:35:54 GMT -5
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. "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.
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Post by brobear on Nov 11, 2018 17:36:38 GMT -5
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.
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Post by brobear on Nov 11, 2018 17:38:05 GMT -5
By Polar: Post by Polar on Jan 3, 2018 at 10:59am Regarding the holocene diet post, maybe that is the same reason why cave bears in different regions of Europe are more-or-less carnivorous when compared with each other. As one moves into east Europe, the cave bears become more carnivorous (with the exception of southern Spain and Portugal). The more west, the more herbivorous.
Humans lived and migrated mostly into western Europe (Neanderthals), and they could proven to have been much greater competition than the other active carnivores around the area. Prey was also less abundant than in the much free eastern Europe. Bears (as a result) could have decided to move to more vegetarian diets to avoid death-causing competition.
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Post by brobear on Nov 11, 2018 17:39:03 GMT -5
I have - in the past - had posters argue that the grizzly was not present below Canada until the extinction of the giant bears. Well then, how did their fossils get here? en.wikipedia.org/wiki/List_of_fossil_species_in_the_La_Brea_Tar_Pits
Carnivora: †Arctodus simus (giant short-faced bear) Bassariscus astutus (ring-tailed cat) †Canis dirus (dire wolf) Canis lupus familiaris (dog) †Canis latrans orcutti (Pleistocene coyote) Canis lupus (gray wolf) †Homotherium serum (scimitar-toothed cat) Lynx rufus (bobcat) Mephitis mephitis (striped skunk) †Miracinonyx inexpectatus (American cheetah) Mustela frenata (long-tailed weasel) †Panthera leo atrox (American lion) †Panthera onca augusta (Pleistocene North American jaguar) Procyon lotor (raccoon) Puma concolor (cougar) Urocyon cinereoargenteus (gray fox) Ursus americanus (American black bear) Ursus arctos horribilis (grizzly bear) †Smilodon fatalis (saber-toothed cat) Spilogale gracilis (western spotted skunk) Taxidea taxus (American badger)
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Post by brobear on Nov 11, 2018 17:40:04 GMT -5
www.sciencedaily.com/releases/2004/11/041115002514.htm 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. "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.
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