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Bears of the Pleistocene
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Spalea, I agree wholeheartedly. I know that it has been accepted now pretty much as fact that Smilodon lived and hunted as a pride. I have read it both ways considering atrox. If the American lion hunted in groups, then they too would have posed a huge threat to the grizzly. If they hunted as individuals like a leopard or a tiger, then probably they would stalk the occasional sub-adult and sometimes a mature she-bear. But, loners or group hunters, the bear would no doubt do his best to avoid them.
I also agree with your ideas concerning the La Brea tar pits. Bear fossils are scarce in comparison with Smilodon and the wolves. Perhaps like the bears, atrox would sometimes observe and recognize the danger. There is no doubt that the stench of death from the pits would draw bears from many miles around. The grizzlies and black bears were late arrivals, but even the short-faced bears are low in numbers by comparison. It had to be tough for both atrox and the bears to see and smell so much meat and walk away, even when sensing the danger.  
Post 301 is converting the shoulder height to American showing that this massive cave bear had a shoulder height of 4 feet and nearly 5 inches. He likely weighed 1500+ pounds.
Unrelated to cave bear data: The panda bear has been proven to be closely related to the Andean bear, or to be more specific, the short-faced bear lineage. This brings such monsters as Indarctos and Agriotheruim into the lineage. Also, in comparing the panda bear with the Andean bear for similarities, we might see attributes basic to this lineage. Both the panda bear and the Andean bear have extremely strong jaws. This is proven to be true in extinct short-faced bears. Panda bears and Andean bears prove to be more vocal the Ursus bears. Perhaps this too was a short-faced bear trait. Neither the panda bear nor the Andean bear hibernates. It is widely accepted that the extinct short-faced bears never hibernated.
From brown bear to cave bear. Amazing evolution.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC45432/ Tracking the origins of the cave bear (Ursus spelaeus) by mitochondrial DNA sequencing. C Hänni, V Laudet, D Stehelin, and P Taberlet The different European populations of Ursus arctos, the brown bear, were recently studied for mitochondrial DNA polymorphism. Two clearly distinct lineages (eastern and western) were found, which may have diverged approximately 850,000 years ago. In this context, it was interesting to study the cave bear, Ursus spelaeus, a species which became extinct 20,000 years ago. In this study, we have amplified and sequenced a fragment of 139-bp in the mitochondrial DNA control region of a 40,000-year-old specimen of U. spelaeus. Phylogenetic reconstructions using this sequence and the European brown bear sequences already published suggest that U. spelaeus diverged from an early offshoot of U. arctos--i.e., approximately at the same time as the divergence of the two main lineages of U. arctos. This divergence probably took place at the earliest glaciation, likely due to geographic separation during the earlier Quaternary cold periods. This result is in agreement with the paleontological data available and suggests a good correspondence between molecular and morphological data.  (04-09-2018, 11:47 PM)brotherbear Wrote: From brown bear to cave bear. Amazing evolution. It is probably due the admixture from the Cave bear within the population of the modern European Brown bear. 
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About #302: Andean Bear, Giant Panda and the Short Faced Bear belong to the same lineage ? They also have a extremely strong jaws ? Intereseting because they share this special feature above their diet: 100% vegetarian as concerns the giant panda, omnivorous for the Andean bear, 100% meat-based for the short-faced bear. Perhaps too as you say, the short-faced bear was a "vocal" bear ? But how would we be able to know, determine, that ? (04-10-2018, 02:32 AM)Spalea Wrote: @ Maybe the Giant Panda belongs to the tribe of Ailuropodini of the subfamily Tremactinae, whereas the Andean bear and Short-Faced bear belong to the tribe of Tremactini of the same subfamily. BTW, the lineage of Ailuropodini remained in the old world, whereas the lineage of Tremactini migrated to the new world.
Tremactinae - cat-like bears with shorter muzzle
Ursinae - dog-like bears with longer muzzle These two major branches of the bear might have split in a brief period after the formation of Ursidae.
Spalea, your idea of the atrox displacing Smilodon is interesting. Doug Peacock's book should be arriving tomorrow. I am in hopes that he gives some of his insight on the Pleistocene grizzly. Books about the Ice Age ( in general ) always talk about those animals which are now extinct as if those who survived were never there.
(09-08-2018, 04:13 PM)brotherbear Wrote: Spalea, your idea of the atrox displacing Smilodon is interesting. Doug Peacock's book should be arriving tomorrow. I am in hopes that he gives some of his insight on the Pleistocene grizzly. Books about the Ice Age ( in general ) always talk about those animals which are now extinct as if those who survived were never there. Bears are resilient animals as it can rely on many sources of food. Eating plants when there was not enough meat, meanwhile to steal the carcass from your opponent to acquire more protein. The SF bear was probably too big to be messed with, but not the much smaller American lion. As the Pleistocene grizzly might be 50% heavier than an adult male American lion, and I do believe that the success rates for the Pleistocene grizzlies to steal the carcass from those lone American lions might be quite high.
http://www.sci-news.com/paleontology/cav...05195.html
Research Sheds New Light on Biology of Extinct Cave Bear Sep 5, 2017 by Enrico de Lazaro |
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