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Bears of the Pleistocene
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Was there much size difference between an Arctodus simus boar and a sow? All the information I find reads as if there was only one sex.
 (06-02-2016, 01:09 AM)tigerluver Wrote: Was the Giant Short-Faced Bear a Hyper-Scavenger? A New Approach to the Dietary Study of Ursids Using Dental Microwear Textures Yet, the study as shown in the above short documentary ( post #254 ) shows that, from a chemical testing of the giant's bone, Arctodus simus was a pure-carnivore. Not having the build of a predator, he was perfectly designed to be an apex-scavenger. Someone is wrong. I was thinking that, perhaps, the giant was a scavenger who only fed on the soft tissues. But then, why the powerful jaws? Arctodus simus is an enigma.
www.researchgate.net/publication/233639688_The_type_specimen_of_Ursus_priscus_GOLDFUSS_1818_and_the_uncertain_status_of_Late_Pleistocene_brown_bears
carnivoraforum.com/topic/30156737/1/ Steppe brown bear Ursus arctos priscus Goldfuss, 1818 – huge scavenger of Late Pleistocene grasslands paleocommunities Adrian Marciszak1 – Charles Schouwenbourg2 – Grzegorz Lipecki3 – Wiktoria Gornig1 – Vlastislav Káňa4 – Martina Roblíčková4 1 Department of Paleozoology, Institute of Environmental Biology, Faculty of Biological Sciences, University of Wrocław, Sienkiewicza 21, 50-335 Wrocław, Poland; [email protected], [email protected] 2 Dorpsstraat 53, 3238BB Zwartewaal, Netherlands; [email protected] 3 Institute of Systematics and Evolution of Animals, Polish Academy of Sciences, Sławkowska 17, 31-016 Kraków, Poland; [email protected] 4 Moravian Museum, Anthropos Institute, Zelný trh 6, 659 37 Brno, Czech Republic; [email protected], [email protected] With opportunistic behaviour, extremely broad diet, ability to adapt to various habitats ranging from semi-deserts to Arctic tundra, including arid and mountain areas, Ursus arctos could adapt to the changes of environmental conditions. The brown bear remains from many European sites document the occurrence of a very particular kind of bear. This giant bear, called steppe brown bear Ursus arctos priscus, was a rare but permanent member of open grasslands mammal palaeocommunities. It is very characteristic that this form is always strangely difficult to find not only in open sites but also in caves. Compared to other carnivores, the steppe brown bear was never common in one locality and tended to be a solitary hunter and scavenger, which required large expanses of open grassland. This bear was a scavenger and kleptopa - rasit, whose huge size gave it advantage over other predators (also ancient hunters) (Fig. 1). It also followed herds of herbivores and took animals which died naturally or in another way. Occasionally it also hunted. In its behaviour, it resembled the modern Ursus maritimus or Arctodus simus from North America in the past. It can be conjectured that, except pregnant females, the steppe brown bear was active year-round following herbivores and other carnivores in search of food. Isotopic analysis shows that brown bears were highly carnivorous till the late glacial and became more omnivorous with the change of climate and environmental conditions. The last postglacial warming brought about a shrinkage of open grasslands, disappearance of ungulate herds and expansion of forests. The largest species like mammoths, rhinoceros, and some bovids became entirely extinct, other forms lived in smaller herds or small groups, and carcasses were much harder to obtain than previously. The density was much lower, and the amount of available food much smaller. There was not enough food and space for such a huge bear. During the postglacial times, the brown bear slowly dwarfed, and also smaller bears similar to the nominate subspecies entered from the south and southeast. The dwarfing process, however, was not the same in entire Europe, since in some regions large, robust bears of priscus-type survived longer. The form is only a smaller descendant of the Late Pleistocene form, which occurred till the early Holocene over the coast of the North and Baltic Seas as well as in some parts of Germany and Poland. Some populations slowly retreated to the northeast, while others were genetically swamped by the modern European bear. Finally, in the early Holocene, the modern brown bear appeared and became the sole bear species in Europe. What in fact was the steppe brown bear Ursus arctos priscus Goldfuss, 1818? Adrian Marciszak1 – Charles Schouwenbourg2 – Wiktoria Gornig1 1 Department of Paleozoology, Institute of Environmental Biology, Faculty of Biological Sciences, University of Wrocław, Sienkiewicza 21, 50-335 Wrocław, Poland; [email protected], [email protected] 2 Dorpsstraat 53, 3238BB Zwartewaal, Netherlands; [email protected] Steppe brown bear Ursus arctos priscus is a very particular kind of bear. This giant arctoid bear (Fig. 1), was a rare but permanent member of open grasslands mammal palaeocommunities. Described almost two centuries ago, till recent there are no sharply defined metrical and morphological features characterising this form. Many authors proposed in the past factors like great size, robust build, massive metapodials and a significant amount of speleoid features in morphology, especially dentition. But till new, partially because not a sufficient number of specimens, partially because of the enormous variability of the brown bear as a species. Obtained so far by us data showed that genetic analysis is no answer, what in fact is steppe brown bear. Our metrical and morphological analysis revealed that it is an example of the plasticity of Ursus arctos and answer of the species for the availability of the large amount of meat in open grasslands in steppetundra. It should be considered as a different chronoform/ecomorph, which features like immense posture and broad teeth are an expression of specialisation to scavenge. Moreover, the bear remains in somewhat older faunal assemblages, often coexisted with thermophile species such as Palaeoloxodon antiquus or Stephanorhinus kirchbergensis, might indicate the presence of another form, closely related to the steppe brown bear. The Taubach bear Ursus arctos taubachensis Rode, 1935, which appeared already in the late Middle Pleistocene, is a characteristic component of European interglacial faunas like Taubach, Weimar Ehringsdorf, Kent’s Cavern or Tornewton Cave (Kurtén, 1957). Sometimes synonymised with Ursus arctos priscus, it differs nevertheless in some metric and morphological features (Baryshnikov, 2007), which points to a distinct form (Marciszak et al., 2017). The problem needs further adna analysis, which may resolve the presence of other bear forms in Silesian open sites.
www.pnas.org/content/97/4/1651.full
www.counterpunch.org/2017/06/16/the-epic-shared-journey-of-bison-and-grizzly-bears/ June 16, 2017 The Epic Shared Journey of Bison and Grizzly Bears by David Mattson Yellowstone National Park is the only place on Earth where bison and grizzly bears coexist in significant numbers. Most people, inured to the on-going ecological holocaust of recent centuries, probably think this 2-million-acre area is huge. Yet the current joint distribution of bison and grizzlies comprises only around 2% of what we once had in this country; 1% of what we once had on this continent; and a truly miniscule fraction of what we once had in the Northern Hemisphere. Bison and brown or grizzly bears of some sort coexisted in close relationship for 10s of thousands of years in a 11,000-mile-long swath from Europe, across Siberia, through northwestern North America, to northeastern Mexico. What we have in Yellowstone Park is a truly infinitesimal remnant barely 60 miles across. But this remnant is not inconsequential. Yellowstone’s populations of bison and grizzly bears have sustained a relic relationship between these two species that was probably critical to grizzly bears in much of their former North American range. A Little About Yellowstone’s Grizzlies and Bison. I was fortunate enough to participate in and then oversee field investigations of grizzly bears for 15 years in the Yellowstone ecosystem. We documented exploitation of ungulates such as bison and elk by radio-collared grizzlies, and monitored transects along which we documented scavenging by bears during springtime. This work followed a similar decade-long pioneering effort by John and Frank Craighead. These studies, along with less intensive monitoring of spring scavenging between 1996 and the present, spanned a total of over 50 years and provided unparalleled insights into relations between bison and grizzly bears. From this we can glimpse the undoubtedly richer and more complex natural history of bears and bison in Europe, Asia, and North America, recognizing that our modern-day studies span only ¼ of 1% of the time and space shared by these two species. One thing we know for sure. Bison have been and still are an important source of food—meat—for Yellowstone’s grizzly bears, far exceeding anything one might expect simply from numbers of bison in the ecosystem—by a factor of 2-½-fold and more. Bears obtain almost all this meat by scavenging rather than by predation. Bison are too big, too well-armed, too collectively aggressive, and typically too far from ambush cover for a bear to kill outright. But bison do tip over dead for all sorts of reasons—from starvation and disease during winter and spring, from complications of birthing, from injuries sustained during the rut, and less often from being killed by wolves. And when bison do die, they constitute a big package of meat that not only provides a large reward for any bear lucky enough to find it, but also increases odds that stinky carrion will persist long-enough for discovery by animals, such as bears, endowed with an acute sense of smell. These fundamentals suggest that bison were always a comparatively important food for brown/grizzly bears wherever both species overlapped in time and space. In fact, availability of meat from bison probably dictated the terms of existence for grizzly bears for over 10 millennia in the mid-section of North America. Ice Age Bison The murky scientific waters of ever-evolving methods applied to ever-more data have, over time, clarified the evolutionary biogeography of bison and bears, along with the formative context of dynamic climates, ephemeral corridors, and shifting barriers of ice and vegetation. Disagreements and uncertainties remain, especially given the indirect measures necessary to reconstruct a long-gone past, but the broad outlines of a shared journey have emerged. Steppe bison, Bison priscus—the progenitor of all subsequent bison—probably first arrived in North America around 150,000 years ago during the penultimate Illinoian Ice Age. Like all bison, steppe bison were predominantly grazers that followed a broad swath of grass-dominated steppe tundra from eastern Siberia across the Bering Land Bridge into what is now Alaska. This bridge between Eurasia and North America was exposed then, as it was during all Ice Ages, by lower sea levels resulting from the capture of ocean water in continent-spanning ice-sheets. Bison of North America, including the giant Ice Age Bison latifrons farthest left, our comparatively small modern-day bison farthest right, and the ancestral steppe bison, Bison priscus, in the middle. Illustrations by Roman Uchytel. Roughly 25,000 years later North America’s continental ice sheets were rapidly melting, creating an ephemeral grass and forb-dominated corridor from eastern Beringia south to mid-latitudes. It was during this early part of our penultimate interglacial period—the Sangamonian—that bison moved south into the grasslands that they have occupied ever since, and where they were then isolated by consolidating boreal forests from steppe bison in the north. By 120,000 year ago these southern bison had rapidly evolved into an enormous long-horned variant called Bison latifrons, presumably in response to the predatory pressures of a host of now-extinct large carnivores that included lions, saber-toothed tigers, scimitar-toothed cats, and giant short-faced bears. These giant Ice Age bison weighed 2-3-times more than modern-day bison. Enter Ice Age Grizzlies Grizzly bears didn’t arrive in North America until much later, also from Eurasia, and only with reemergence of the Bering Land Bridge early during the last, Wisconsinan, Ice Age. We don’t know exactly when grizzlies arrived, but probably around 70,000 years ago during a mini-maximum of glacial ice. Subsequent short-lived retreats of the ice sheets produced perhaps more than one ephemeral ice-free corridor from Beringia south to mid-latitudes that closed by between 55,000 and 30,000 years ago. But grizzlies slipped through, as evidenced by 32,000-year-old remains found near Edmonton, Alberta. As a result, we had grizzly bears living among bison, along with a slew of other large predators, throughout the Last Glacial Maximum south of the continental ice sheets. Curiously, grizzlies in Beringia mixed it up with steppe bison for perhaps 35 millennia, up until around 35,000 years ago, and then disappeared or declined to very low densities for a 15,000-year period that coincided with a burgeoning of giant 700 to 2200-pound short-faced bears. Some paleontologists have implicated competition from or even predation by the formidable short-faced bears in the demise of Beringian grizzlies. The Pleistocene bestiary of North America large carnivores, including grizzly bears top middle, and giant short-faced bears top left. All illustrations of extinct species by Sergio De la Rosa. But by 20,000 year ago short-faced bears were largely gone from eastern Beringia, only to be replaced by another wave of migrant grizzly bears from Siberia, arriving hard on the heels of a second major wave of migrant bison. Both bison and grizzly bears remained bottled up in Beringia for another 9,000 years, with grizzlies probably scavenging bison whenever and wherever they could, up until yet another ice-free corridor opened between the rapidly-melting Laurentide and Cordilleran Ice-sheets around 13,000 years ago. Not long after, the Bering Land Bridge disappeared for the last time, isolating both bears and bison from conspecifics on the supercontinent of Eurasia, where brown bears persisted, but steppe bison went extinct. The Cusp of the Holocene. As an upshot, North America is the only place on Earth where an undiluted bison lineage survived, notwithstanding a distant relative called wisent that occurred across much of Europe until being nearly driven to extinction by hunters during the 1800s and 1900s. Despite sometimes being called bison, wisent descended from an aurochs x bison hybrid, leaving yaks as the closest surviving relative of our North American bison. The rapidly melting ice at the end of the last glacial epoch and beginning of our current Holocene era was associated with a wildly fluctuating climate, rapidly shifting vegetation, expansion of human populations armed with lethal stone-tipped weapons, and extinctions of virtually all the large carnivores and herbivores that had dominated Ice Age landscapes—including mammoths, mastodons, camels, horses, giant stag-deer and muskox, and lumbering ground sloths. Around 10,000 years ago the last and largest of the megafauna literally and figuratively left standing were bison, moose, and grizzly and polar bears. Although grizzlies remained much the same, albeit of different genetic lineages north and south of the melting ice sheets, between 22,000 and 15,000 years ago bison had yet again rapidly evolved into different forms, including a southern morph called Bison antiquus. Lots of ink has been spilled disputing the taxonomic status of bison, but there is widespread agreement that bison looked different 14,000-10,000 years ago compared to before or after, and were still larger than our present-day bison. There is also widespread agreement that essentially all bison and grizzly bears in mid-latitudes of North America descended from genetically distinct animals that were part of the earliest waves of migrants south from Beringia. Grizzly bears of the last wave of migrants from Siberia never made it south of central Alberta, and northern bison of the direct Bison priscus lineage eventually went extinct, in some places as recently as 200-400 years ago. The Rocky Altithermal Bison of the mid-latitudes have been denizens primarily of the great North American grasslands ever since the end of the Ice Age. When you plot known locations of bison dating between roughly 500 and 10,000 years ago, virtually all occur in areas with abundant grass, which is not surprising given that modern bison are grazers. But all was not static during those 9,500 years. For one, North America entered a sustained period of severe drought even as the continental ice sheets were still melting. This epic period of hot dry conditions that lasted between 9,000 and 4,500 years ago is known by various names, most commonly the Altithermal. Bison numbers were held at a nadir during this bleak period not only by drought-diminished forage, but also by the spread of less nutritious grasses north across the Great Plains. These grasses, which include species such as blue grama and buffalo grass, are adapted to warm dry conditions, but support significantly lower densities of bovids such as bison, in the past, and cattle now-a-days. By contrast, grass species typical of northern latitudes, such as wheat- and bluegrasses, support much higher densities of both wild and domesticated grazers. Several researchers have suggested that conditions were so tough on the southern Great Plains during the height of the Altithermal that bison disappeared there for several millennia. Grizzlies were profoundly affected by these environmental changes. In fact, grizzly bears seem to have disappeared from most of the Great Plains for most of the Altithermal as well as for several millennia after. I have no doubt that this dearth of bears was a direct consequence of a dearth of bison, aggravated by competition with humans and black bears for shared foods concentrated along the west-east-trending river corridors of the Plains. People were also probably killing their share of grizzlies. But, despite the epic droughts, grizzly bears probably hung on and even flourished in the Northern Plains, and may have even benefited from the activities of humans. Bison densities were almost certainly always highest in the north, simply because of more bounteous forage. Not by coincidence, most of the known pre-equestrian sites where humans engaged in mass kills of bison were also located in this region, including most buffalo jumps and corrals. Kills at these sites could be so large that some bison carcasses were left untouched by the involved people, while others were butchered only for the choicest cuts—“gourmet butchering.” As a result, ample meat was available for scavengers such as grizzlies who undoubtedly took full advantage of the opportunity. In fact, it is easy enough to imagine repeated vignettes where grizzlies lurked around kill sites negotiating access with the wary but heavily-laboring people. European Bio-ethnic Cleansing. But all this changed with arrival of Europeans and their diseases in the late 1400s. Native peoples were decimated. Some scholars reckon that between 40 and 80% died from fast-spreading disease alone, well before any contact with Europeans themselves. This reduction in Native populations, along with related increases in grassy woodlands, seems to have opened the way for the spread of substantial numbers of bison into eastern North America for the first time in the last 9,000 years. European adventurers thus encountered bison—but not any grizzly bears—as far east as coastal Florida and South Carolina during the early 1600s. But by 1800, a short 200-years later, the tide had irreversibly turned for bison and bears. Europeans embarked upon a systematic slaughter of both. By 1810 only a few enclaves of bison survived in the East. A decade later, they were completely gone from the East and pushed back west of the Mississippi River. By around 1800, Europeans, most notably Meriwether Lewis and William Clark, were recording their first encounters with grizzlies, including their first accounts of killing them. The accounts thereafter become tediously terrible. Bison were served up on the altar of an ever-widening trade in hides and meat spawned by European demand, but with Native Americans fully complicit. Most bison in most places where they had existed in 1600 had probably been slaughtered by the time the Transcontinental Railroad split surviving bison into the “great” northern and southern herds around 1870. Within 25 years the 40-80 million bison that had once roamed the Great Plains had been reduced to a few hundred wild survivors in the remote enclave of what had become our first National Park. Grizzly bears didn’t fare much better. They were gone from the central and southern Plains by around 1850, out-pacing even the slaughter of bison. Sixty years later grizzlies could only be found in scattered haunts restricted to the most rugged and remote parts of the mountain West. By 1950 they were extirpated from roughly 97% of the areas they had once occupied in 1800 and relegated to two main populations each of a few-hundred individuals. One of these populations hung on in Yellowstone along with our remnant wild bison. The Aftermath Where does this leave the epic relationship between bison and grizzlies—and humans? For the last 2,500 years, up until roughly 1800 A.D., bison and grizzly bears coexisted in an area roughly 950,000 square miles in size, spanning most of the western part of what is now the United States, and encompassing roughly 60% of former grizzly bear range within this same area. The only place on Earth where this relationship persists is in the Yellowstone ecosystem, in an area comprising <2% of what we once had. And how are we treating this rare and highly vulnerable relic? Last year we killed roughly 1,400 wild bison as part of a plan to deliberately confine them to within the boundaries of Yellowstone National Park. This slaughter was justified by the presumed need to protect a handful of regional livestock producers from the near non-existent threat of disease transmitted from bison to cattle—a disease called brucellosis that was originally introduced by cattle. Simultaneously, we are poised to remove Endangered Species Act protections for Yellowstone’s grizzly bears, with the intent of turning them over to the tender mercies of State wildlife managers fully intent on instituting a trophy hunt. And nowhere in the mountain of tedious planning documents spawned by the numerous involved management agencies will you find any recognition of, much less prioritization for, the precious remnant we have in Yellowstone of a relationship between bears and bison that once spanned continents and millennia. In short, a travesty. There is much more that can be said—that needs to be said—about our current management of bison and the unique surviving relationship between bison and grizzly bears in the Yellowstone ecosystem. Stay tuned for more on this front in the next part of this two-part series… For more information on the Evolutionary Biogeography of North American Grizzly Bears and Bison, see here and these papers: ( See much more on site posted ).
I now know that a typical grizzly of Pleistocene N. America was basically in the size-range of a grizzly from modern-day Montana or Wyoming. But, over in Pleistocene Europe, there was the much-larger Steppe brown bear, Ursus arctos priscus. Now my question is - how big? How did this big grizzly compare with Ursus speleaus ingressus or Ursus maritimus tyrannus?
I do believe that upon the arrival of the Grizzlies, they had witnessed the downfall of the megafaunas like the SF bears and American lions.
The Grizzlies would likely avoid the direct confrontation with the larger SF bears, but the Grizzlies managed to outcompete the SF bears with its versatility in term of food acquisition. The Grizzlies can rely on a larger amount of vegetable diet, whilst the SF bears had to depend on larger quantity of meat. In comparison, to tackle against the smaller American lions, I think the Grizzlies would frequently try to steal their carcasses. For its sake of survival, a weakened American lion would have no choice but to defend relentless against the food robber. A wounded Grizzly had higher chance to survive than a wounded lion, because the lion would be crippled and unable to hunt anymore, while the bear can rely on other food sources. That's why the Grizzlies can manage to extrude these two megafaunas permanently out of the food chain in the North America. (01-23-2018, 12:13 AM)brotherbear Wrote: I now know that a typical grizzly of Pleistocene N. America was basically in the size-range of a grizzly from modern-day Montana or Wyoming. But, over in Pleistocene Europe, there was the much-larger Steppe brown bear, Ursus arctos priscus. Now my question is - how big? How did this big grizzly compare with Ursus speleaus ingressus or Ursus maritimus tyrannus? Could be larger than today's Kodiak bear, but slightly smaller than the Southeast Cave bear and Tyrant Polar bear. BTW, I also believe that Jurassic Fight Club had highly sensationalized/dramatized the fight script between the SF bear and American lion. In contrast, the conflict occurred between the newly arrived Grizzlies and the weakened American lions could have a much higher rate, since their size discrepancy was also much smaller, that could embolden the Grizzlies to steal the carcasses more often from the lions, while the lions wouldn't be so easily to get intimidated by the smaller Grizzlies in comparison of the larger SF bears. 
@
Your accounts are fascinating for a quite layman like me: such a profusion of big predators ! I don't want to be out of sequence but, if I may so, I would like just to believe a little bit more about the prospects of the American lion's way of living: in groups or in small prides. Being faced to a very violent environment, probably very closes ties governed the members of the pride, and just imagine 5 or 6 American lions defending a kill. 5 or 6 predators weighing each 250 - 300 kilos amount to a 1500-1800 kilos meat eater, do they ? In this case, perhaps it should have been enough to keep victoriously the kill perhaps not against a big short faced bear, but otherwise, against any other opponent ? With this hypothesis, I make an analogy with the current model in Africa: the spotted hyenas standing against a lioness around a kill. We indeed admit that from 4 the numbers of hyenas prevails. American lions were the biggest brained felids of all time, perhaps they were able to sustain the intense competition between these North American large predators (not enough for finally surviving to the end of the Ice Age though, being entirely predator like the short faced bear they disappeared, as you told only the grizzly survived). (01-23-2018, 11:45 AM)Spalea Wrote: @ Imagine in the twilight of the Pleistocene era or the dawn of the Holocene era, the old ecosystems of the North America had just collapsed as most herbivorous megafaunas of the Pleistocene era were just gone. The SF bears and American lions were just few residual survivors that kept struggling for survival. But even worse, they now have to face the competition from the two newly arrived species, human and grizzly bear. As the food source was becoming scarce in the early Holocene era, the conflict over the food would become pervasive in the daily life. I would say that the human could play an even bigger role for the extinction of the residual megafaunas than the grizzly bear. Since there weren't enough room for everyone, so some species needed to be wiped out in order to vacate more living space for other more competitive species.
Post by brobear on Jan 21, 2018 at 5:20pm
hamzatriestoblog.quora.com/Interesting-new-findings-on-Ice-age-carnivores Interesting new findings on Ice age carnivores Hamza Ahmad Shaikh This is actually a paper from June 2015, and I only hatched the thought to share now, so I should have told you earlier, but alas, here it is. Unfortunately, only the abstract is available free of charge, but it's still an interesting read (I haven't read the actual paper). It's really challenged some of the preconceptions we've had about ice age carnivores in the Mammoth steppe. Here's the Highlights + Abstract (ctrl+c'd and ctrl+v'd): Highlights •Cave bears were virtually all herbivores. •Giant short-faced bears were consuming meat but not necessarily purely carnivores. •Scimitar tooth cats were not specialized mammoth predators. •Most cave lions were focussing on reindeer, especially when competing with other large carnivores. •Wolves outcompeted cave lions in Europe during Lateglacial. Abstract Isotopic tracking of carnivore palaeoecology is a relatively new approach that yielded important results for the study of the non-analogue mammoth steppe biome. After describing the prerequisite to apply this approach and the possible complications, the main achievements will be described for extinct carnivore species such as scimitar-tooth cat Homotherium serum, cave lion Panthera spelaea, giant short-faced bear Arctodus simus, cave bear Ursus spelaeus s.l., as well as for ancient representatives of extant species such as brown bear Ursus arctos and wolf Canis lupus. Isotopic tracking showed that scimitar-tooth cats in Alaska were not specialist proboscidean predators but rather generalist consumers of other large herbivores. The majority of cave lions analysed so far were focused on reindeer, some individuals were specialized on cave bears, especially in contexts of competition with cave hyenas. Giant short-faced bears in Alaska were not pure herbivores and consumed meat from reindeer, muskoxen and possibly other predators, but may have still incorporated plant resources in their menu. In contrast, all cave bear populations studied so far for which a clear dietary reconstruction could be done were virtually pure herbivores, only a few cases are still unclear. Interestingly, brown bears used the opposite extreme of the dietary spectrum when competing with other large bears such as cave bears and giant short-faced bears, i.e. were more carnivorous in Europe and more herbivorous in Alaska. Finally wolves seem to have been outcompeted by hyenas but became dominant predators during the Lateglacial in Europe to the expense of the last cave lions. The results obtained through this approach are also relevant for improving conservation strategies of endangered extant large carnivores. Paper: Isotopic tracking of large carnivore palaeoecology in the mammoth steppe I found these findings very interesting, mostly due to my fascination for ice age animals, but also because of how they challenged our previous notions of some of these carnivores. From the beginning, it was clear to me that the Cave bear wasn't very carnivorous, but I had always figured they had a sizeable amount of meat in their diet, like most modern bears do. It seems that they were actually far more herbivorous than that - to the point where, when their ranges overlapped, the cave bear's close cousin, Ursus arctos, had to exploit a more carnivorous diet in order to avoid competition for plant materials with its larger relative. Known also for its conflict and relationship with Neanderthals (whose validity was brought to my attention by Rolf Kohl, see Cave bear hunting in Hohle Fels Cave in the Ach Valley of the Swabian Jura and Withering Away—25,000 Years of Genetic Decline Preceded Cave Bear Extinction), its reputation as a giant savage ice age bear has been somewhat softened. In fact, this isn't really a carnivore, unlike the others discussed in the paper with their meaty diets. While it was larger and by no means cuddly, I would wager you'd be more likely to be hunted by a brown bear than a cave bear, should you travel to Europe during the ice age. I don't have much familiarity with the Short-faced bear, but from what I had heard, they were supposedly highly-carnivorous, and were either viscous juggernaut hunters and/or kleptoparasites, scavenging and chasing other predators such as the contemporaneous (but smaller) Smilodon and American lion (see here) off their kills. Indeed, it does appear that their Brown bear neighbours were exhibiting the opposite extreme to those in Europe, but being a bear, one would expect that this beast, however exaggerated by popular multimedia, would have been at least capable of mixed feeding. This also attests to the adaptability of Brown bears to varying conditions, and may help explain why they survived, while other large bears became extinct. This one struck me the most. Whenever one read of Homotherium, there would be at least some mention of its Mammoth-eating tendencies. Hell, I was even lead to write about this ostensible pachyderm eater's tendencies in Hamza Ahmad Shaikh's answer to What are some fascinating facts about the woolly mammoth?. Indeed, findings from Friesenhahn Cave in North America bore evidence that H. serum, the North American species of scimitar cat, hunted and killed young proboscideans, but given the cat's build, it did appear that these lithe sabretooths weren't ideally equipped mammoth killers. Mauricio Antón touched on this in one of his blog posts,Homotherium, slayer of giants? on the hunting of mammoths by these cats. He concluded that these cats were either hunting in packs very frequently, or that the Friesenhahn mammoth/ mastodon killings were a local phenomenon, not typical of the entire genus. In the mammoths steppe ecosystem, mammoths were to be found, but in far larger quantities there was other large game that you would expect a lion-sized cat to be hunting. According to Sergey Zimov, "On each square kilometer of pastures lived 1 mammoth, 5 bison, 8 horses, 15 reindeer. Additionally, more rare musk ox, elks, wooly rhinoceros, saiga, snow sheep, and moose were present. Wolves, cave lions and wolverines occupied the landscape as predators. In total, over 10 tons of animals lived on each square kilometer of pasture- hundreds of times higher than modern animal densities in the mossy northern landscape." (see: Sergey Zimov’s Manifesto), leaving plentiful prey for scimitar cats to be exploiting. According to one blog post by someone who did buy and read the paper, the Yak was the preferred prey of scimitar cats: Then we come to Eurasian cave lions - for some reason or other, my favorite ice age creature. It was already clear to me that they hunted large quantities of Reindeer meat, with cave bears constituting for most of their diet's remainder. My suspicions for the reason this was the case has been reaffirmed, as it appeared that the Cave hyena had a diet comprising of larger quantities of horse and woolly rhino, amongst others (Prey deposits and den sites of the Upper Pleistocene hyena Crocuta crocuta spelaea (Goldfuss, 1823) in horizontal and vertical caves of the Bohemian Karst (Czech Republic)), and that other carnivores had differing diets to avoid competition. What surprised me about the cave lions is the conclusion that wolves out competed them. I had read beforehand that the cave lion experience a decline in range after the extinction of the cave hyena, but I was unsure why this would be the case, seeing as it was a competitor. It's clear to me now, that the hyena's suppression of the wolf in Europe prevented it from becoming to widespread (though they were huge, see Megafaunal wolf). In the dying days of the late glacial, the cave lion probably struggled to find enough reindeer, and the more generalistic wolf may have been one of the last nails in the coffin for this cat. (01-23-2018, 12:04 PM)GrizzlyClaws Wrote:(01-23-2018, 11:45 AM)Spalea Wrote: @ Quite agree ! You invoked the human factor as concerns the short faced bear and the American lion disappearance... All is said.
nhm.org/site/sites/default/files/pdf/contrib_science/CS39.pdf
www.earthfacts.com/evolution-and-life/rancholabreatarpits/ Many of the carnivores are old friends of the modern forest and plain: foxes, badgers, skunks, weasels, mountain lions, lynx, black bears and grizzly bears. These have changed little, and if we had their entire carcasses to study we might find they differed from their modern counterparts only at the subspecies level. Exceeding the Great Cat in size was the Short-Faced Bear. On all four feet it stood a foot higher than the modern Grizzly Bear, and was more massively built than the Kodiak Bear. Its teeth suggest a more carnivorous way of life than any living bears. nhm.org/site/research-collections/rancho-la-brea/about-rlb-mammals Ursidae Three species of bear are known from Rancho La Brea. The extinct giant short-faced bear (Arctodus simus), represented by 30 plus individuals, is both the largest and most common species recovered. Thus far, at least 700 elements have been identified. The short-faced bear had an extensive North American distribution ranging from the Yukon to Texas. Its closest living relative is the spectacled bear that lives in the Andes. Possibly the largest predator of the Ice Age, the male short-faced bear may have weighed up to 1,800 pounds and stood five feet at the shoulder. Sexual dimorphism is very evident with females being at least 25 percent smaller than the males. The black bear (Ursus americanus) and the grizzly bear (U. arctos) are restricted to the younger deposits and are rare. www.tarpits.org/sites/default/files/pdfs/return%20to%20the%20ice%20age.pdf blogs.dailybreeze.com/history/2015/06/27/when-saber-toothed-cats-mammoths-and-dire-wolves-roamed-the-south-bay/ The short-faced bear was once the most plentiful bear in California, but the pug-nosed species did not survive into the modern era. On the other hand, the California grizzly bear was one of the few large mammals to survive the end of the Pleistocene Era. It is the very symbol of California, and is depicted on the state flag. However, this fierce predator feared no animal, nor did it fear settlers, who first observed the California grizzly in the mid-18th century. The bear’s fondness for large grazing animals such as sheep and cattle made it ursina non grata to farmers and ranchers, and, as civilization encroached upon the grizzly’s territory, they were gradually hunted out of existence. The last California grizzly bear reported hunted down in the state was killed in Tulare County in 1922, and no California grizzlies have been seen since one was spotted in Sequoia National Park in 1925. The extinction of these various species (other than the California grizzly and pronghorn antelope) has been attributed to the arrival of humans, perhaps on a land bridge across the Bering Strait, but it also may have been caused by climate and landform changes that made the area drier and less hospitable to them.
Arctodus simus ... Sexual dimorphism is very evident with females being at least 25 percent smaller than the males.
I had been seeking this info. If ( as some suggest ) the average mature Arctodus boar weighed 1200 pounds, then the average she-bear would have weighed about 900 pounds. Still a huge bear! |
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