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Post by brobear on Jan 11, 2018 6:12:31 GMT -5
All bears of the genus Ursus originated during the Pleistocene - the Ice Age. After a brief summary of what and when the Pleistocene occurred, then this topic is to post pictures ( art work ) showing the landscape and the animals which our favorite bears had to contend with, and to discuss them. www.ucmp.berkeley.edu/quaternary/pleistocene.php The Pleistocene Epoch This mammoth, found in deposits in Russia, was one of the largest land mammals of the Pleistocene, the time period that spanned from 2.6 million to 11,700 years ago.* Pleistocene biotas were extremely close to modern ones — many genera and even species of Pleistocene conifers, mosses, flowering plants, insects, mollusks, birds, mammals, and others survive to this day. Yet the Pleistocene was also characterized by the presence of distinctive large land mammals and birds. Mammoths and their cousins the mastodons, longhorned bison, saber-toothed cats, giant ground sloths, and many other large mammals characterized Pleistocene habitats in North America, Asia, and Europe. Native horses and camels galloped across the plains of North America. Great teratorn birds with 25-foot wingspans stalked prey. Around the end of the Pleistocene, all these creatures went extinct (the horses living in North America today are all descendants of animals brought from Europe in historic times). It was during the Pleistocene that the most recent episodes of global cooling, or ice ages, took place. Much of the world's temperate zones were alternately covered by glaciers during cool periods and uncovered during the warmer interglacial periods when the glaciers retreated. Did this cause the Pleistocene extinctions? It doesn't seem likely; the large mammals of the Pleistocene weathered several climate shifts. The Pleistocene also saw the evolution and expansion of our own species, Homo sapiens, and by the close of the Pleistocene, humans had spread through most of the world. According to a controversial theory first proposed in the 1960s, human hunting around the close of the Pleistocene caused or contributed to the extinction of many of the Pleistocene large mammals. It is true that the extinction of large animals on different continents appears to correlate with the arrival of humans, but questions remain as to whether early human hunters were sufficiently numerous and technologically advanced to wipe out whole species. It has also been hypothesized that some disease wiped out species after species in the Pleistocene. The issue remains unsolved; perhaps the real cause of the Pleistocene extinction was a combination of these factors. Many paleontologists study Pleistocene fossils in order to understand the climates of the past. The Pleistocene was not only a time during which climates and temperatures shifted dramatically; Pleistocene fossils are often abundant, well-preserved, and can be dated very precisely. Some, such as diatoms, foraminifera, and plant pollen, are both abundant and highly informative about paleoclimates. Today, there is concern about future climate change (e.g., global warming) and how it will affect us. Paleontologists who work on Pleistocene fossils are providing a growing amount of data on the effect of climate change on the Earth's biota, making it possible to understand the effects of future climate change.
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Post by Deleted on Jan 11, 2018 9:19:12 GMT -5
Pleistocene Beringia
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Post by Deleted on Jan 11, 2018 9:22:33 GMT -5
Pleistocene in North America. Line up, and also a visual comparison, of the animals that lived there in that time.
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Post by Deleted on Jan 11, 2018 9:23:57 GMT -5
One more lineup with Russian animals from the Ice Age.
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Post by brobear on Jan 11, 2018 11:55:36 GMT -5
Second picture, we see a grizzly watching a group of lions, but keeping his distance. The giant is walking straight towards them. Those lions are about to lose their kill. Third picture has a grizzly up-front and looking small among so many huge animals, especially the giant short-faced bear. This grizzly roughly 3 feet and 2 or 3 inches high. Fourth picture ( Siberia ) I see an Asiatic black bear, a grizzly, and a much bigger cave bear. The grizzly is portrayed here as slightly larger than the black bear and smaller than the big cats. Error! However, these pictures can give us some idea of the world as it was during the Pleistocene. -Special thank you to Gurahl.
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Post by brobear on Jan 19, 2018 20:08:58 GMT -5
After giving the matter some thought; in N. America, most grizzlies were living in more remote locations ( away from the crowd ) where a she-bear would be less at risk, especially one with cubs. And of course a boar will generally be where there are she-bears living. Less crowded also means less prey animals which produces bears generally ( IMO ) from 300 to 500 pounds with the occasional exception-to-the-rule ( as there always will be ). Those grizzlies that do ( in much smaller numbers ) live out among the mega-beasts were likely ranging in size ( IMO ) from perhaps 500 to 1,000 pounds - half the size of the giant.
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Post by brobear on Sept 16, 2018 5:28:56 GMT -5
www.thevintagenews.com/2018/06/13/pleistocene-park/ Pleistocene Park: A Russian scientist is creating an Ice Age environment in Siberia. www.businessinsider.com/russia-pleistocene-park-mammoths-2016-3 Russia is trying to bring back the age of the mammoths. On the unforgiving plains of the Russian tundra, researchers are undertaking an ambitious experiment. They're trying to restore the entire ecosystem to the way it was when mammoths roamed the Earth 15,000 years ago. Here's why — and how — they're doing it. The project is called Pleistocene Park, which researcher Sergey Zimov founded in 1989. It's primarily funded by government grants and the Pleistocene Park Foundation, a non-profit organization. The Pleistocene epoch began 1.8 million years ago and ended when humans started dominating the Earth 11,500 years ago. Across the northern part of the globe during this period, the steppe ecosystem dominated. Its characteristic grasses high in nutrients were great for the planet. According to an analysis by Zimov and his collaborators, every 0.39 square miles of pasture on the Siberian steppe had about one mammoth, five bison, six horses, and 10 reindeer. Humans didn't have a large impact on the environment yet. The researchers want to bring back the mammoth steppe ecosystem because its permafrost stored carbon, and its grasses reflected sunlight — two great ways to guard against global warming. They're trying to change the ecosystem by planting the grasses native to the area during the Pleistocene. They're also constructing caves to bring back the permafrost. The first one took them three years to complete. And they're bringing in tons of animals — like these baby moose — to get the ecosystem back to the concentration it once had. Herds of reindeer can tamp down the existing vegetation, further helping grasses retake the land. Like the mammoths in their day, bison and musk ox are the largest animals on the steppe today. The animals are all built for the bitterly cold winters. These semi-wild horses have long hair to keep them warm. These Wapiti (also known as elk) are growing their antlers. For now, all the animals are fenced in so they stay in the park enclosure. The park covers almost 4,000 acres now, but the researchers hope to keep expanding it.
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Post by brobear on Sept 16, 2018 5:40:31 GMT -5
CONTINIED: "If enough area is covered by steppe," they say, "it would diminish the effects of global warming caused by increased anthropogenic greenhouse gas emissions." Maybe one day the big-dreaming researchers from Sooam Biotech in South Korea will succeed in cloning a real woolly mammoth. If and when that day comes, the mammoth might just be able to live in its native steppe habitat at Pleistocene Park, where a small corner of the world has traveled back in time. *I for one would love to see live mammoths.
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Post by Deleted on Apr 3, 2019 1:53:06 GMT -5
One more lineup with Russian animals from the Ice Age. So that is how the brown bear and siberian tiger used to live before many animals got extinct.
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Post by brobear on Apr 3, 2019 5:11:57 GMT -5
Europe:
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Post by Deleted on Apr 3, 2019 8:22:36 GMT -5
Well done brother bear. It seems brown bears of the past lived with lots of animals wherever they are in which is what develops their aggression.
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Post by OldGreenGrolar on Jun 28, 2019 3:18:49 GMT -5
Europe: I really like how that Pleistocene grizzly looks.
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Post by brobear on Nov 3, 2019 6:32:39 GMT -5
www.sciencedaily.com/releases/2019/10/191025110314.htm Did an extraterrestrial impact trigger the extinction of ice-age animals? Archaeologist finds evidence in South Carolina to support controversial theory Date: October 25, 2019 Source: University of South Carolina Summary: Based on research at White Pond near Elgin, South Carolina, archaeologists present new evidence of a controversial theory that suggests an extraterrestrial body crashing to Earth almost 13,000 years ago caused the extinction of many large animals and a probable population decline in early humans. A controversial theory that suggests an extraterrestrial body crashing to Earth almost 13,000 years ago caused the extinction of many large animals and a probable population decline in early humans is gaining traction from research sites around the world.
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Post by brobear on Nov 26, 2019 2:59:55 GMT -5
www.sciencedaily.com/releases/2019/09/190920124648.htm As part of an international research group based at the Smithsonian Museum of Natural History, anthropology assistant professor Amelia Villaseñor contributed to a large, multi-institutional study explaining how the human-influenced mass extinction of giant carnivores and herbivores of North America fundamentally changed the biodiversity and landscape of the continent. In their study published today in Science, researchers from Australia, the United States, Canada and Finland showed that humans shaped the processes underlying how species co-existed for the last several thousand years. Smaller, surviving animals such as deer changed their ecological interactions, the researchers found, causing ecological upheaval across the continent. The researchers' work has implications for conservation of today's remaining large animals, now threatened by another human-led mass extinction. The study's primary author is Anikó Tóth at Macquarie University in Sydney, Australia. Tóth collaborated with Villaseñor and several other researchers at the Smithsonian's Evolution of Terrestrial Ecosystems Program, as well as researchers at other institutions. Tóth and the co-authors focused on how large mammals were distributed across the continent in the Pleistocene and Holocene geological epochs. (The Pleistocene Epoch occurred from about 2.5 million to 11,700 years ago. Starting at the end of the Pleistocene, the Holocene is the current geological epoch.) To do this, the researchers analyzed how often pairs of species were found living in the same community or in different communities. To rule out community changes that were the result of reduced diversity or lost associations involving extinct species, the researchers analyzed only those pairs in which both species survived. Prior to the extinction, co-occurrence was more common. After extinction, segregations were more common. Villaseñor's research focuses on human fossil remains as a way to understand how human ancestors interacted with mammal communities for the last 3.5 million years. Her more recent research explores how modern humans have shaped today's ecosystems. "Rather than thinking of humans as separate from 'natural' environments, our research has illuminated the major impacts that humans have had on the ecosystem for many thousands of years," Villaseñor said. "The results of this paper and others from our group illuminate the outsized impacts that human-mediated extinction has had in North America." By the end of the Late Pleistocene in North America, roughly 11,000 years ago, humans contributed to the extinction of large mammals, including mammoths and sabre-toothed cats. Recent work, driven by today's crisis in biodiversity, has looked at understanding the ecological and evolutionary legacies of this event. There was ecological transformation across the continent -- the mammoth steppe disappeared, vegetation and fire regimes changed and large carnivores were lost. Story Source: Materials provided by University of Arkansas. Note: Content may be edited for style and length.
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Post by brobear on May 16, 2020 18:04:26 GMT -5
What was the Pleistocene world like for the early members of the Ursus bears? www.sci-news.com/paleontology/science-pleistocene-hyper-carnivores-03379.html Paleontologists: Pleistocene Hyper-Carnivores Kept Giant Plant-Eaters in Check For several decades, scientists have wondered how Pleistocene ecosystems (2.5 million to 11,700 years ago) survived despite the presence of huge herbivores, such as mammoths, mastodons and giant ground sloths. Now, a team of researchers – led by a scientist from the University of California, Los Angeles (UCLA) – argues that the ecosystems were effectively saved by enormous predators (hyper-carnivores) that helped keep the population of large plant-eaters in check. Using several different techniques and data sources, Prof. Blaire Van Valkenburgh of UCLA’s Department of Ecology and Evolutionary Biology and her colleagues from the United States, South Africa and the UK, have found that the hyper-carnivores (such as lions, saber-tooth cats and hyenas) were very capable of killing young mammoths, mastodons and other species.
Their findings are reported in a paper published online by the Proceedings of the National Academy of Sciences on October 26, 2015. “Based on observations of living giant herbivores, such as elephants, rhinos, giraffes and hippos, scientists have generally thought that these species were largely immune to predation, mainly because of their large size as adults and strong maternal protection of very young offspring,” Prof. Van Valkenburgh said.
“Data on modern lion kills of elephants indicates that larger prides are more successful and we argue that Pleistocene carnivore species probably formed larger prides and packs than are typically observed today — making it easier for them to attack and kill fairly large juveniles and young adult huge herbivores.”
Based on a series of mathematical models for the sizes of predators and prey in the late Pleistocene age, the scientists conclude that the largest cave hyena might have been able to take down a 5-year-old juvenile mastodon weighing more than a ton.
“Hunting in packs, those hyenas could possibly bring down a 9-year-old mastodon weighing two tons,” Prof. Van Valkenburgh and co-authors said.
Their analysis estimated size ranges for Pleistocene predators based on the fossil record, including teeth. Well-established formulas allow scientists to make a reasonable estimate of an animal’s size based on just the first molar.
“And in the fossil record, the one thing we’ve got a lot of is teeth,” Prof. Van Valkenburgh said. The team developed formulas for the relationship of shoulder height to body mass from data published for modern captive elephants to estimate how large some of the herbivores found in fossil evidence would have been.
“It’s hard to weigh an elephant; you need a truck scale. And truck scales aren’t the easiest thing to lug around the African savannah, so field researchers monitor shoulder heights in tracing a growing elephant’s size,” said co-author Dr V. Louise Roth of Duke University.
“The difficulty is that, even with the best measurements, modern adult elephants with the same shoulder height may vary by as much as two times in body mass.”
Nonetheless, the team developed a range for what some of these shaggy plant-eaters would weigh. From this, they calculated whether hyper-carnivores might be able to capture an herbivore.
Because there is no way to infer from the scant fossil evidence whether the carnivores hunted in packs, the scientists relied on estimated prey sizes and modeled the capacity of single predators and predators in groups to take them down. They conclude that juvenile mastodons and mammoths would indeed have been susceptible, especially if the carnivores were socially organized.
Hunting in packs – as modern lions, hyenas and wolves still do – would have made even larger juveniles susceptible. “Larger pack sizes, which may have been more common in the Pleistocene, further enhance hunting success,” Prof. Van Valkenburgh said. Many scientists had thought that the populations of mammoths, mastodons and giant ground sloths were limited through evolution by changes in reproductive timing in response to shortages in resources like food and water.
Today’s large predators benefit their ecosystems in part by providing carcasses that feed an array of smaller species. “The same was true during the Pleistocene, when keeping mega-herbivore populations in check meant that there was more vegetation for smaller mammals and birds,” the scientists said.
“The predators might even have had indirect effects on river ecosystems, because the banks of the rivers were not being denuded by mega-herbivores and less likely to erode.”
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Blaire Van Valkenburgh et al. The impact of large terrestrial carnivores on Pleistocene ecosystems. PNAS, published online October 26, 2015; doi: 10.1073/pnas.1502554112
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Post by brobear on May 16, 2020 18:08:58 GMT -5
paleontologyworld.com/exploring-prehistoric-life-prehistoric-flora-fauna-curiosities/pleistocene-epoch Pleistocene Epoch The Pleistocene Epoch is typically defined as the time period that began about 1.8 million years ago and lasted until about 11,700 years ago. The most recent Ice Age occurred then, as glaciers covered huge parts of the planet Earth. There have been at least five documented major ice ages during the 4.6 billion years since the Earth was formed — and most likely many more before humans came on the scene about 2.3 million years ago. The Pleistocene Epoch is the first in which Homo sapiens evolved, and by the end of the epoch humans could be found in nearly every part of the planet. The Pleistocene Epoch was the first epoch in the Quaternary Period and the sixth in the Cenozoic Era. It was followed by the current stage, called the Holocene Epoch. Worldwide ice sheets At the time of the Pleistocene, the continents had moved to their current positions. At one point during the Ice Age, sheets of ice covered all of Antarctica, large parts of Europe, North America, and South America, and small areas in Asia. In North America they stretched over Greenland and Canada and parts of the northern United States. The remains of glaciers of the Ice Age can still be seen in parts of the world, including Greenland and Antarctica. But the glaciers did not just sit there. There was a lot of movement over time, and there were about 20 cycles when the glaciers would advance and retreat as they thawed and refroze. Scientists identified the Pleistocene Epoch’s four key stages, or ages — Gelasian, Calabrian, Ionian and Tarantian. The name Pleistocene is the combination of two Greek words: pleistos (meaning “most”) and kainos (meaning “new” or “recent”). It was first used in 1839 by Sir Charles Lyell, a British geologist and lawyer. As a result of Lyell’s work, the glacial theory gained acceptance between 1839 and 1846, and scientists came to recognize the existence of ice ages. During this period, British geologist Edward Forbes aligned the period with other known ice ages. In 2009, the International Union of Geological Sciences established the start of the Pleistocene Epoch at 1.806 million years before the present. Defining an epoch While scientists haven’t been able to determine the exact causes of an epoch, changes in ocean current, composition of the atmosphere, changes in the position of the Earth in relation to the sun are believed to be key contributors. Overall, the climate was much colder and drier than it is today. Since most of the water on Earth’s surface was ice, there was little precipitation and rainfall was about half of what it is today. During peak periods with most of the water frozen, global average temperatures were 5 to 10 degrees C (9 to 18 degrees F) below today’s temperature norms. There were winters and summers during that period. The variation in temperatures produced glacial advances, because the cooler summers didn’t completely melt the snow. Life during the Ice Age While Homo sapiens evolved, many vertebrates, especially large mammals, succumbed to the harsh climate conditions of this period. One of the richest sources of information about life in the Pleistocene Epoch can be found in the La Brea Tar Pits in Los Angeles, where remains of everything from insects to plant life to animals were preserved, including a partial skeleton of a female human and a nearly complete woolly mammoth. In addition to the woolly mammoth, mammals such as saber-toothed cats (Smilodon), giant ground sloths (Megatherium) and mastodons roamed the Earth during this period. Other mammals that thrived during this period include moonrats, tenrecs (hedgehog-like creatures) and macrauchenia (similar to a llamas and camels). Although many vertebrates became extinct during this period, mammals that are familiar to us today — including apes, cattle, deer, rabbits, kangaroos, wallabies, bears, and members of the canine and feline families — could be found during this time. Other than a few birds that were classified as dinosaurs, most notably the Titanis, there were no dinosaurs during the Pleistocene Epoch. They had become extinct at the end of the Cretaceous Period, more than 60 million years before the Pleistocene Epoch began. Birds flourished during this period, including members of the duck, geese, hawk and eagle families. There were also some flightless birds such as ostriches, rheas and moas. The flightless birds did not fare as well, as they had to compete with mammals and other creatures for limited supplies of food and water, as a good portion of the water was frozen. Crocodiles, lizards, turtles, pythons and other reptiles also thrived during this period. As for vegetation, it was fairly limited in many areas. There were some scattered conifers, including pines, cypress and yews, along with some broadleaf trees such as beeches and oaks. On the ground, there were prairie grasses as well as members of the lilly, orchid and rose families. Mass extinction About 13,000 years ago, more than three-fourths of the large Ice Age animals, including woolly mammoths, mastodons, saber-toothed tigers and giant bears, died out. Scientists have debated for years over the cause of the extinction, with both of the major hypotheses — human overhunting and climate change — insufficient to account for the mega die-off. Recent research suggests that an extraterrestrial object, possibly a comet, about 3 miles wide, may have exploded over southern Canada, nearly wiping out an ancient Stone Age culture as well as megafauna like mastodons and mammoths.
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Post by brobear on May 16, 2020 18:09:21 GMT -5
Pleistocene Epoch
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Post by King Kodiak on May 19, 2020 10:41:53 GMT -5
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Post by OldGreenGrolar on May 22, 2020 23:59:56 GMT -5
These mastodons are scary.
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Post by brobear on Jun 30, 2020 16:24:13 GMT -5
What caused the Pleistocene Mass Extinction? I have spent some time pondering why the black bear and the grizzly survived in North America when the larger short-faced bears perished. i'm thinking that the surviving species might have had a wider range of food options. Were the short-faced bears diggers and fishers? Also, and perhaps the surviving bears' greatest advantage is the ability to sleep during long months of hard times. I also believe that the grizzly's size adaptability is a great survival trait. Those living in harsh terrain are small in size, thus in need of less food. Few large mammals of a singular species can range in size from -300 pounds to 1500+ pounds. The puma ( cougar ) was perhaps able to sustain on rabbits and rodents while the big cats had a much more difficult time. I believe that the culprit of the extinction was weather related; affecting the vegetation which in turn affects the animal kingdom.
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