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Post by Gorilla king on Jul 3, 2021 12:18:39 GMT -5
South American giant short-faced bear (Arctotherium angustidens) diet: evidence from pathology, morphology, stable isotopes, and biomechanics.
Abstract
Arctotherium angustidens Gervais and Ameghino, 1880 (the South American giant short-faced bear) is known for being the earliest (Ensenadan Age, early to middle Pleistocene) and largest (body mass over 1 ton) of five described Arctotherium species endemic to South America. Here we assess the diet of this bear from multiple proxies: morphology, biomechanics, dental pathology, stable isotopes and a previous study using geometric morphometric methodology. Results favor the idea of animal matter consumption, probably from large vertebrates in addition to vegetable matter consumption. Most probably, active hunting was not the unique strategy of this bear for feeding, since its large size and great power may have allowed him to fight for the prey hunted by other Pleistocene carnivores. However, scavenging over mega mammal carcasses was probably another frequent way of feeding. South American short-faced bears adjusted their size and modified their diet through Pleistocene times, probably as a response to the diversification of the carnivore guild (from the few precursory taxa that crossed the Panamanian Isthmus during the Great American Biotic Interchange).
bioone.org/journals/journal-of-paleontology/volume-88/issue-6/13-143/South-American-giant-short-faced-bear-Arctotherium-angustidens-diet/10.1666/13-143.short
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Post by Gorilla king on Jul 3, 2021 12:23:17 GMT -5
Standing at 11 Feet: World's Largest Known Bear Unearthed
The largest land predator of its time, the South American giant short-faced bear (Arctotherium angustidens), in comparison to a person.
Credit: Soibelzon, Schubert, Journal of Paleontology.
The fossils of the largest known bear to have ever lived have been found, a giant that was the most powerful land carnivore of its time, scientists said.
The remains were unearthed during the construction of a hospital in La Plata City, Argentina. It was a South American giant short-faced bear (Arctotherium angustidens), the earliest and largest member of its genus (its group of species of bears). This titan lived between 2 million to 500,000 years ago, with its closest living relative being the spectacled bear (Tremarctos ornatus) of South America.
Based on measurements of the fossil's leg bones and equations used to estimate body mass, the researchers say the bear would have stood at least 11 feet tall (3.3 meters) on its hind legs and would have weighed between 3,500 and 3,855 pounds (1,588 and 1,749 kilograms). In comparison, "the largest record for a living bear is a male polar bear that obtained the weight of about 2,200 pounds (1,000 kg)," said researcher Leopoldo Soibelzon, a paleontologist at the La Plata Museum.
"During its time, this bear was the largest and most powerful land predator in the world," researcher Blaine Schubert, a paleontologist at East Tennessee State University in Johnson City, told LiveScience. "It's always extremely exciting to find something that's the largest of its class — and not just a little bit larger, but quite a bit larger."
Although this bear probably had an omnivorous diet, flesh likely dominated. Megafauna or large creatures likely played an important role in what it ate, and potentially included giant ground sloths, now-extinct relatives of elephants, camels, tapirs, and armadillo-like creatures known as glyptodonts.
"This does not imply that active hunting was its primary strategy for feeding, since its large size and great power may have permitted the bear to fight for prey hunted by other Pleistocene carnivores such as the saber-toothed cat," Schubert said. "Scavenging megaherbivore carcasses was probably another frequent way of feeding."
The research team's analysis of the bear's bones suggests it was an old male that survived a number of serious injuries during life. These might have come from battles with other males, while hunting megafauna, or during fights with other carnivores over a carcass.
The scientists also suggested the reason why this species might have grown so huge. When bears arrived in South America after the land bridge between the Americas appeared about 2.6 million years ago, there were relatively few other large predators there at the time, with the exception of the saber-toothed cat. The bears then grew, taking advantage of the large amount of prey, researchers suggested. The species eventually became extinct after more carnivores evolved in South America.
Soibelzon and Schubert detailed their findings in the January issue of the Journal of Paleontology.
www.livescience.com/11701-standing-11-feet-world-largest-bear-unearthed.html
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Post by Gorilla king on Jul 3, 2021 12:24:24 GMT -5
The largest land predator of its time, the South American giant short-faced bear (Arctotherium angustidens), in comparison to a person. (Image credit: Soibelzon, Schubert, Journal of Paleontology.) |
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Post by Gorilla king on Jul 3, 2021 12:37:13 GMT -5
Fossil of 700,00-year-old giant bear found north of Buenos Aires
The La Matanza National University's Scientific Dissemination Agency reported on Tuesday that they had uncovered the fossil remains of a giant bear that roamed the earth just north of Buenos Aires 700 thousand years ago.
Thursday 14 March, 2019
Scientists have found fossilised remains of a giant bear that inhabited Argentina some 700,000 years ago, in an excavation located 170 kilometres north of the capital, the La Matanza National University's Scientific Dissemination Agency reported Tuesday.
"It is a large bear of the genus Arctotherium angustidens, who at their largest, standing up, could reach up to 4.5 metres in height," said paleontologist Leopoldo Soibelzon, researcher at the Museum of La Plata and the National Scientific and Technical Research Council (CONICET).
"It was possible to see the remains of this specimen that walked the Pampas region about 700,000 years ago, thanks to the actions of the excavator," explained José Luis Aguilar, director of the Museum of the town of San Pedro, the place of discovery.
He was identified as a young male who weighed about 800 kilos at the time of death and who would have measured approximately 2.5 meters standing upright.
Aguilar, who made this finding along with researchers Matías Swistun and Julio Simonini, said that the remains were located in an area where a sedimentary layer was detected along with the remains of an old swamp.
"Some of the big animals that hunted or that came to drink water were trapped in that mud, in that swamp," the scientist speculated.
He also highlighted "the impressive state of preservation of the skull along with its two mandibular branches, which have preserved all of the teeth" and in reference to the latter detailed that "it has fangs about six centimetres long, which are strong, compact, pointed and were prepared to tear the flesh of their prey.”
In addition to the skull, part of the pelvis, a fragment of the humerus, part of its radius and six articulated vertebrae were also found.
Several studies allowed them to identify certain fungi, algae and some vegetables in the sediment where the remains of the animal were found.
"This lets us know that this giant bear lived in a steppe environment made up of herbaceous plants, with a somewhat sandy soil and always with bodies of water nearby," Aguilar said.
For his part, Soibelzon said that "these bears lived in the Pampa region until about 500 thousand years agowww.batimes.com.ar/news/argentina/fossil-of-700-thousand-year-old-giant-bear-found-north-of-buenos-aires.phtml?fbclid=IwAR041jW2nUZIcMJml5gqNRbV4BQzOqY0qk63N2yvx6BOje0jreM30i6NHbA
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Post by Gorilla king on Jul 5, 2021 7:25:59 GMT -5
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Post by Gorilla king on Jul 5, 2021 7:30:37 GMT -5
Fossils of Giant Prehistoric Beasts Discovered in Underwater Ice Age Death Cave
More than 10,000 years ago, as the last Ice Age ended, vast sheets of ice receded, scarring and causing massive cracks to appear on the bridge between North and South America. At that time, the land bridge was known to have been inhabited by fearsome beasts; now new evidence shows these prehistoric beasts included giant ‘wolf-like carnivores’ and the ‘largest bear’ ever to have walked on planet Earth.
‘10,000 BC’ was a 2008 American epic adventure film set in prehistory. It told the adventures of a prehistoric tribe of mammoth hunters. After its world premiere on February 10, 2008 in Berlin, although it was an immediate box office hit, the film became regarded by professional critics as one of the worst films of the year. The Sunday Times review section noted that the film was “archaeologically inaccurate and contains many factual errors and anachronisms.” But now it would appear this movie was based firmly in reality!
A Death Pit of Giant Prehistoric Creatures
At the bottom of an underwater cave in Mexico archaeologists have discovered an ancient graveyard including the skeletons of ancient sloths, sabretooth cats, cougars, elephant-like gomphotheres, bears, and dog-like animals. According to the researchers’ new paper, published in Biology Letters , they have recovered the skull of an enormous short-faced bear ( Arctotherium wingei ) and remains of a wolf-like dog known as Protocyon troglodytes.
Furthermore, in 2007, researchers even found “two human skeletons dating to more than 12,000-years-old.” These are now thought to be two of the “oldest human skeletons ever found in the Western hemisphere” and they inform experts that our ancestors once lived alongside giant ground sloths, towering bears, and fierce wolf-like carnivores.
The remarkable discoveries were made in the Hoyo Negro pit (Spanish: blackhole) in the Sac Actun cave system on the eastern coast of the Yucatán Peninsula . Researchers have described it as “an underworld of exquisitely preserved fossils” naturally formed from limestone in the Late Pleistocene. It is thought that animals fell nearly 60 meters (200 feet) into the death pit and when the melting glaciers filled the pit the remains became a permanent installation.
This large-scale archaeological project is being financially support by a consortium including INAH (National Institute of Anthropology and History), National Geographic Society, the ETSU Center of Excellence in Paleontology, the Archaeological Institute of America, and DirectAMS and Strauss Family Fund. Among the bones recovered by scientists over the past 12 years, the team of US and Mexican researchers were most impressed by the remains of a giant bear and a wolf-like creature .
While having been collected several years ago, both giant species were misidentified until now. But it’s not only the awe inspiring size of these two skeletons that is fascinating scientists, it’s the fact that they are causing anthropologists to redress their theories about ancient animal populations in South America .
How so? Up until their correct identification, scientists were convinced that the short-faced bear and wolf only populated the southern aspects of the South American continent, “more than 2,000 kilometers away.”
When Did these Prehistoric Beasts Travel Such Vast Distances?
Lead author and paleontologist from the East Tennessee State University, Blaine Schubert, told reporters at Live Science , “The whole previous record of this particular type of bear is just known from a few localities in South America, and those are fragmentary remains.” And having come from almost no knowledge of this bear, the scientists now have what is being called “the best record of this type of bear from the Yucatán of Mexico.”
Trying to account for how the bear and wolf got as far north as Mexico, scientists refer to “many cross-over events between North and South America.” Another possibility being proposed by the authors is that having walked all the way south, during or after the last full glacial event between 35,000 and 12,000 years ago, they returned northwards to the region of the cave. The scientists wrote, “We suggest that landscape and ecological changes caused by latest Pleistocene glaciation supported an interchange pulse that included Homo sapiens.”
When 10,000 BC was released in 2008 critics at Variety wrote: “10,000 BC reps a missed opportunity to present an imaginative vision of a prehistoric moment.” However, in April 29, 2008 the movie had grossed approximately $268.6 million worldwide, which was said to be “dead money.” Now, it appears the movie was a really, really expensive archaeological lesson.
Top Image: A diver holds the skull of an ancient bear known as an Arctotherium. It is one of the species of “prehistoric monsters” found in an underwater Yucatan cave. Source: Copyright Roberto Chavez-Arce
 www.ancient-origins.net/news-history-archaeology/prehistoric-beasts-0011853
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Post by Gorilla king on Jul 5, 2021 7:32:43 GMT -5
SOUTH AMERICAN SHORT FACED BEAR (ARCTOTHERIUM ANGUSTIDENS) DISPLACING A SOUTH AMERICAN PLEISTOCENE JAGUAR (PANTHERA ONCA MESEMBRINA)
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Post by Gorilla king on Jul 5, 2021 7:49:02 GMT -5
Biggest Bear Ever Found—"It Blew My Mind," Expert Says
"There's nothing else that even comes close."
Paleontologist Leopoldo Soibelzon holds an upper arm bone of the giant bear next to an elephant's.
PHOTOGRAPH COURTESY LEOPOLDO SOIBELZON
There's a new titleholder for the biggest, baddest bear ever found.
A prehistoric South American giant short-faced bear tipped the scales at up to 3,500 pounds (1,600 kilograms) and towered at least 11 feet (3.4 meters) standing up, according to a new study.
The previous heavyweight was a North American giant short-faced bear—a related extinct species—that weighed up to 2,500 pounds (1,134 kilograms). The largest bear on record in modern times was a 2,200-pound (998-kilogram) polar bear shot in Alaska in the 19th century.
The South American giant short-faced bear roamed its namesake continent about 500,000 to 2 million years ago and would have been the largest and most powerful meat-eater on land at the time, scientists say.
(Related: "Ancient Bear DNA Mapped—A First for Extinct Species.")
As meat-eaters go, "there's nothing else that even comes close" during the time period, said study co-author Blaine Schubert, a paleontologist at East Tennessee State University in Johnson City, Tennessee.
"It just blew my mind how big it was."
The bear skeleton, found in Buenos Aires Province, Argentina, in 1935, was recently reexamined by Schubert and study co-author Leopoldo Soibelzon, a paleontologist from Argentina who specializes in South American fossil bears.
By measuring its almost elephant-size humerus, or upper arm bone, the team was able to calculate the size of the rest of the bear's body, Schubert said.
Their analysis also revealed that the animal was an old male that had endured several serious injuries throughout his life.
For Bear, Size Matters
Less certain, however, is what and how these bears ate—and why they were so different from their North American cousins, Schubert noted.
For instance, the South American giant short-faced bear species started huge and became smaller over time, while the North American species grew bigger.
In South America, Schubert suspects, a glut in prey and a lack of competition combined to make the bear king of the continent. But as more meat-eaters evolved, short-faced bears adapted, becoming smaller and more omnivorous, like the modern-day black bear.
(See "Comet 'Shower' Killed Ice Age Mammals?")
In North America, the short-faced bear's increasing size may have offered an advantage—its sheer heft may have scared off saber-toothed cats and other predators from their kills, the researchers speculate.
And the short-faced bear's reign in North America would have also coincided with an explosion in Ice Age megafauna, such as giant ground sloths, camels, and mammoths—all potential new food sources.
"We had an Africa here," Schubert said, and "it's gone now."
The biggest-bear study appeared in the January issue of the Journal of Paleontology.
www.nationalgeographic.com/animals/article/110203-biggest-bear-largest-giant-short-faced-animals-science
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Post by arctozilla on Jul 30, 2021 11:16:40 GMT -5
Just one question: what's the largest bear that ever lived in your opinion, Arctotherium, Arctodus, tyrant polar bear or cave bear? And what was Arctotherium average weight and is it really larger than its North American cousin on average?
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Post by Gorilla king on Jul 30, 2021 11:35:32 GMT -5
Just one question: what's the largest bear that ever lived in your opinion, Arctotherium, Arctodus, tyrant polar bear or cave bear? And what was Arctotherium average weight and is it really larger than its North American cousin on average? |
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Post by Gorilla king on Jul 30, 2021 12:13:16 GMT -5
Here is a post from a very knowledgeable poster called "Verdugo", here he explained to me perfectly why Arctotherium is not larger than Simus:
I'm well aware of those 1500+ kg estimates for Arctotherium. All of those estimates originated from the Soibelzon 2011 paper (that i linked above). It's needed to keep in mind that the mass figures for extinct animals are not actual mass of the animals but are just estimates (since all you got are fragments of their bones). The 1500 kg estimate for Arctotherium was obtained by using a slightly different methodology than the 1000 kg estimates for Arctodus simus. If you use the methodology from Soibelzon 2011 and apply that to the measurements of Arctodus simus, it's very likely that you could also obtain a figure of 1500+ kg for Arctodus. On the other hand, if you use the methodology in Figueirido 2010 (which was used to obtain the 1000 kg mass for Arctodus) and apply that to the measurements of Arctotherium, you would probably only get a figure of ~1000 kg. My point here is that, if you look at the bone measurements, there aren't any indications to suggest that Arctotherium was a much bigger bear considering that, as i said in my previous post, the largest Arctotherium's humerus is slightly shorter than the largest Arctodus's humerus. The humerus of the Arctotherium is more robust (has greater transverse/mediolateral diameter), however, humerus robustness is a bad predictor for body mass in Ursids (Figueirido 2010, Table 2).
www.tandfonline.com/doi/full/10.1080/02724630903416027
You are free to take that 1500 kg figure for Arctotherium as it is because it's still the 'official' estimate for Arctotherium. However, if you look at the bone measurements of these animals and put them next to one another, there aren't any reasons to believe Arctotherium was any bigger than Arctodus. The great difference in mass estimates here is merely from the use of different methodologies.
Here is a picture of Arctodus's humerus
www.nps.gov/kova/blogs/ice-age-mammal-bones-of-northwest-alaska-5.htm
Like i said, isn't any smaller than that of Arctotherium
Reply #161:
domainofthebears.proboards.com/post/19256/thread
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Post by arctozilla on Dec 27, 2021 4:53:17 GMT -5
Found this study. According to DNA analysis done by Mitchell et al. there's a convergent evolution between Arctotherium and Arctodus within Arctotherium being more closely related to Andean bears than Arctodus. The Tremarctinae are a subfamily of bears endemic to the New World, including two of the largest terrestrial mammalian carnivores that have ever lived: the giant, short-faced bears Arctodus simus from North America and Arctotherium angustidens from South America (greater than or equal to 1000 kg). Arctotherium angustidens became extinct during the Early Pleistocene, whereas Arctodus simus went extinct at the very end of the Pleistocene. The only living tremarctine is the spectacled bear (Tremarctos ornatus), a largely herbivorous bear that is today only found in South America. The relationships among the spectacled bears (Tremarctos), South American short-faced bears (Arctotherium) and North American short-faced bears (Arctodus) remain uncertain. In this study, we sequenced a mitochondrial genome from an Arctotherium femur preserved in a Chilean cave. Our molecular phylogenetic analyses revealed that the South American short-faced bears were more closely related to the extant South American spectacled bear than to the North American short-faced bears. This result suggests striking convergent evolution of giant forms in the two groups of short-faced bears (Arctodus and Arctotherium), potentially as an adaptation to dominate competition for megafaunal carcasses. royalsocietypublishing.org/doi/10.1098/rsbl.2016.0062So what is this whole "Arctotherium and Arctodus are the same thing" bs? |
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Post by arctozilla on Dec 27, 2021 5:41:13 GMT -5
Note: most people say "Arctotherium and Arctodus are the same thing, Arctodus is just the Arctotherium of the North, thry are the same species in different locations, etc." but this is completely false. Arctotherium and Arctodus are just closely related to each other but above anything else they're still two different species belonging to two different genus although the Arctotherium being more closely related to Andean bears than Arctodus.
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Post by Gorilla king on Dec 27, 2021 8:05:58 GMT -5
Reply #11, that study was posted at reply #4, you can see the differences in the evolution chart, and also, this is clear:
4.DISCUSSION
Our results suggest that the North and South American short-faced bears (Arctodus and Arctotherium, respectively) ,do not form a monophyletic clade (figure 1) contrary to the suggestions of previous palaeontological studies [19]. In addition, our molecular dating analyses indicate that Arctotherium, Arctodus and Tremarctos all diverged from one another during the Late Miocene or Pliocene. This inferred timeframe suggests that the Miocene/Pliocene genus Plionarctos is ancestral to the Quaternary tremarctine genera. Our observations are consistent with the idea that giant representatives of Arctodus and Arctotherium evolved independently in both North and South America during the Pleistocene [4],
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Post by Gorilla king on Jan 23, 2022 12:14:28 GMT -5
ARCTOTHERIUM ANGUSTIDENS SKELETON:
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Post by oldindigosilverback on Jan 29, 2023 21:30:30 GMT -5
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Post by brobear on Jan 29, 2023 22:57:14 GMT -5
You scavenged up some really good information here on Arctotherium, King Kodiak. I especially found the information you obtained from Verdugo interesting.
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Post by Gorilla king on May 23, 2023 16:23:17 GMT -5
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