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Mar 24, 2012 10:49:14 GMT -9
Post by warsaw on Mar 24, 2012 10:49:14 GMT -9
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Mar 26, 2012 11:44:54 GMT -9
Post by warsaw on Mar 26, 2012 11:44:54 GMT -9
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Jul 19, 2012 12:01:52 GMT -9
Post by grrraaahhh on Jul 19, 2012 12:01:52 GMT -9
Description English: Cave bear (Ursus spelaeus Blum.) Skull Stage: 370 000 - 10 000 Years Pleistocene Locality: Gargas cave, France. Excavations F.Regnault, 1888. On display at National Museum of Natural History, Gallery of Paleontology and Compared Anatomy. Français : Ours des cavernes (Ursus spelaeus Blum.) Crâne. Etage: 370 000 - 10 000 ans (Pléistocène moyen et supérieur) Localité: Grotte de Gargas, France. Fouilles F.Regnault, 1888 Muséum National d'Histoire Naturelle de Paris, Galerie de Paléontologie et d'Anatomie Comparée. commons.wikimedia.org/wiki/File:Ursus_spelaeus_MNHN.jpg
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Nov 23, 2012 9:42:37 GMT -9
Post by grrraaahhh on Nov 23, 2012 9:42:37 GMT -9
Source: F. Prat & CI. Thibault (1976).
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Mar 21, 2013 5:39:51 GMT -9
Post by grrraaahhh on Mar 21, 2013 5:39:51 GMT -9
How closely related were the cave bears to brown bears? I moved your question to one of two topic appropriate areas, here being the first; the second option would be the 'PREHISTORIC & EARLY BEARS (GENERAL)/PREHISTORIC & EARLY BEARS' section. The brown bear originates in Asia then moves to Europe sometime during the late Pleistocene replacing the Etruscan bears and gave rise as a side branch, to the cave bear line. There are other brown bear migrations to Asia, North Africa, and eventually North America. The brown bear is robust and adaptable. The brown bear historical range overlaps with other animals including the European cave lion, Asiatic, European & North African lions; tigers stretching from central to east Asia, polar bears of the arctic circle, black bears, cave bears, and there is some evidence that a small number of brown bears successfully penetrated North America (IIRC, settling along the southern Canada/northern US border) during the time of the Giant Short Faced Bear. Some of the overlapping were brief time while other continue through today. The point being (I did digress from the original question) is that the brown bear is quite durable.
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Mar 21, 2013 6:59:12 GMT -9
Post by brotherbear on Mar 21, 2013 6:59:12 GMT -9
Thank you Grrraaahhh. Answered perfectly.
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Mar 21, 2013 12:47:00 GMT -9
Post by Ursus arctos on Mar 21, 2013 12:47:00 GMT -9
and there is some evidence that a small number of brown bears successfully penetrated North America (IIRC, settling along the southern Canada/northern US border) during the time of the Giant Short Faced Bear. Here is the article. To summarize: Clades 2c, 3c, and 4 were present in Beringia 35+ ka. After this brown bears disappeared until 21 ka, when new clades appeared in their place. Today western and central Alaskan brown bears belong to clade 3a, and extreme eastern and Northwestern Canada bears belong to clade 3b-too new clades that appeared when Beringia was opened up again. Yet-brown bears of Southern Canada and the continental US belong to clade 4. As does the ~25 ka old brown bear cranial fragment ("collected in fluvial gravels near Edmonton, Alberta"). Modern grizzlies living in the continental US descend from bears that crossed through Beringia more than 35,000 years ago; from bears that lived alongside Arctodus simus and other North American megafauna since at least ~25,000 years ago.
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Mar 21, 2013 18:33:35 GMT -9
Post by grrraaahhh on Mar 21, 2013 18:33:35 GMT -9
and there is some evidence that a small number of brown bears successfully penetrated North America (IIRC, settling along the southern Canada/northern US border) during the time of the Giant Short Faced Bear. Here is the article. To summarize: Clades 2c, 3c, and 4 were present in Beringia 35+ ka. After this brown bears disappeared until 21 ka, when new clades appeared in their place. Today western and central Alaskan brown bears belong to clade 3a, and extreme eastern and Northwestern Canada bears belong to clade 3b-too new clades that appeared when Beringia was opened up again. Yet-brown bears of Southern Canada and the continental US belong to clade 4. As does the ~25 ka old brown bear cranial fragment ("collected in fluvial gravels near Edmonton, Alberta"). Modern grizzlies living in the continental US descend from bears that crossed through Beringia more than 35,000 years ago; from bears that lived alongside Arctodus simus and other North American megafauna since at least ~25,000 years ago. My understanding is different. There are two major migration pushes of brown bear into North America. The first push happens between 100 – 50 ka (unglaciated Alaska and Yukon) but their migration ends in eastern Beringia. They are brown bears Clades 2a, 2b, 2c, 3a, 3b, 3c. Until recently, conventional thinking included Clade 4. The collective fossil history for these brown bear disappears around 35-21 ka. Along with other notable megafauna extinction, Arctodus simus (GSFB) vanishes sometime around 13 ka, which happens to coincide around the time of the opening of the mid-continental ice-free corridor (IFC) 13-12 ka. Shortly thereafter, the surviving descendant sub-clades from the earlier first migration of brown bear of eastern Beringia radiate south and east into North America establishing the modern phylogeographic structure of North American brown bears by 10 ka. The Edmonton fossil descends from the earlier Clade 4 bears and not to the other surviving sub clades from the original eastern Beringia brown bear populations. This is what makes the Edmonton fossil (dating 27,000-25,000 years old) find important. Not only its age, but also its location. Clade 4 brown bears were the only ones successful enough to penetrate this far south and east (the other bears were blocked in eastern Beringia). Popular thinking took the position that brown bear migration from Asia into North America went as far as eastern Beringia and that not until the extinction of GSFB did we see successful deeper brown bear migration into North America. The Edmonton fossil find is the first solid evidence to challenge the GSFB North America Gatekeeper model. shaggygod.proboards.com/index.cgi?board=prehistoricearlybears&action=display&thread=962
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Mar 23, 2013 16:19:16 GMT -9
Post by Ursus arctos on Mar 23, 2013 16:19:16 GMT -9
My understanding is different. There are two major migration pushes of brown bear into North America. The first push happens between 100 – 50 ka (unglaciated Alaska and Yukon) but their migration ends in eastern Beringia. They are brown bears Clades 2a, 2b, 2c, 3a, 3b, 3c. Until recently, conventional thinking included Clade 4. The collective fossil history for these brown bear disappears around 35-21 ka. Along with other notable megafauna extinction, Arctodus simus (GSFB) vanishes sometime around 13 ka, which happens to coincide around the time of the opening of the mid-continental ice-free corridor (IFC) 13-12 ka. Shortly thereafter, the surviving descendant sub-clades from the earlier first migration of brown bear of eastern Beringia radiate south and east into North America establishing the modern phylogeographic structure of North American brown bears by 10 ka. The Edmonton fossil descends from the earlier Clade 4 bears and not to the other surviving sub clades from the original eastern Beringia brown bear populations. This is what makes the Edmonton fossil (dating 27,000-25,000 years old) find important. Not only its age, but also its location. Clade 4 brown bears were the only ones successful enough to penetrate this far south and east (the other bears were blocked in eastern Beringia). Popular thinking took the position that brown bear migration from Asia into North America went as far as eastern Beringia and that not until the extinction of GSFB did we see successful deeper brown bear migration into North America. The Edmonton fossil find is the first solid evidence to challenge the GSFB North America Gatekeeper model. shaggygod.proboards.com/index.cgi?board=prehistoricearlybears&action=display&thread=962I admit I'm not that familiar with literature on the genetic history of brown bears (but I definitely intend to read: Cahill JA, Green RE, Fulton TL, Stiller M, Jay F, et al. Genomic Evidence for Island Population Conversion Resolves Conflicting Theories of Polar Bear Evolution. PLoS Genet, 9(3): e1003345; 2013 DOI: 10.1371/journal.pgen.1003345 press release here-although you've likely already seen it). You say views have changed. Which is possible, as I was basing my comments on the 9 year old article: P98.5.374 was found to belong to clade 4 (same as modern bears in same regions of NA): " Until recently, conventional thinking included Clade 4" So clade 4 was not found in Eastern Beringia (contradicting the article)? " The Edmonton fossil descends from the earlier Clade 4 bears and not to the other surviving sub clades from the original eastern Beringia brown bear populations." Where do the earlier Clade 4 bears come from? " Shortly [after A. simus extinction and ice-free corridor], the surviving descendant sub-clades from the earlier first migration of brown bear of eastern Beringia radiate south and east into North America establishing the modern phylogeographic structure of North American brown bears by 10 ka." So, contradicting the article, modern Edmonton, southwestern Canada, and northwestern US grizzlies are not clade 4 bears (descendent's of bears like P98.5.374, surviving alongside NA megafauna)? But instead of eastern Beringia bears? -I would have thought that clade assignments to given specimens would have been something less likely to change. Thanks, I'd be interested in reading up to date summaries (with references) on brown bear cladistics, if any are available.
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Mar 24, 2013 19:17:41 GMT -9
Post by grrraaahhh on Mar 24, 2013 19:17:41 GMT -9
I admit I'm not that familiar with literature on the genetic history of brown bears (but I definitely intend to readI also need to review the earlier genetic literature. Cahill JA, Green RE, Fulton TL, Stiller M, Jay F, et al. Genomic Evidence for Island Population Conversion Resolves Conflicting Theories of Polar Bear Evolution. PLoS Genet, 9(3): e1003345; 2013 DOI: 10.1371/journal.pgen.1003345:Thanks for the link. I have not read the 2013 article. I will have to update the relating early polar bear thread, here.You say views have changed. Which is possible, as I was basing my comments on the 9 year old article:To clarify, the 2004 Matheus, Burns, and Weinstock article is the last update to the debate. Prior to 2004, it was theorized in some circles the GSFB served as gatekeeper to North America not only blunting the successful migration of brown bears but it was also argued human migration. Also, I read the Figure 1 clade map key incorrectly. I confused the clade map key on the left with the calendar dates. I think/hope the following revisions will help to settle any confusion. Clade Revision:~ 100 - 50 ka B.P.: Earliest brown bear migration to Beringia starts. > 35 ka B.P.: 2c, 3c, & 4 – First migration push ends in east Beringia. ~ 35-21 ka B.P.: – Brown bear fossil absence in eastern Beringia. ~ 27 – 25 ka B.P.: 4 – Discovery of the clade 4 Edmonton fossil P98.5.374. < 21ka B.P.: 2b, 3a, & 3b – Second brown bear migration recolonizes in east Beringia. ~ 21 - 10 ka B.P.: Brown bear recolonization is precisely coincident with the last record of short-faced bears in Beringia. < 10 ka B.P.: 3a – Had radiated to western/central Alaska & northwest Canada. < 10 ka B.P.: 3b – Had radiated to eastern Alaska, northwestern Canada. Despite the map key/clade/Fig. 1 mix up; the premise remains the same meaning that the big news over the Edmonton fossil is not only its clade identity but also its age and location. From the first brown bear migration (clades 2c, 3c, & 4) into eastern Beringia, their fossil record was thought to have vanished ~ 35-21 ka B.P. (almost true). The second brown bear migration to recolonize eastern Beringia belonged to different sub clades (2a, 3a, & 2b) not present prior to 35 ka B.P. By 10 ka B.P., they had radiated south and east to establish the modern phylogeographic structure of North American brown bears. Apparently, clade 2b bears disappear. From the first migration of brown bears into North America (clades 2c, 3c, & 4), clade 4 bears are the only surviving clade to penetrate this far south before the postglacial period and before the coalescence of the Laurentide and Cordilleran glaciers (clade 4 bears never reappear in eastern Beringia). Up until this point, the ancestry of brown bears from the mid-continental area was difficult to answer (the earlier clades 2 & 3 hypothesis proved problematic). At the same time, the age of the Edmonton fossil (a clade 4 brown bear) undermines the GSFB gatekeeper position. Relating LiteratureBarnes I, Matheus P, Shapiro B, Jensen D, Cooper A. Dynamics of Pleistocene population extinctions in Beringian brown bears. Science. 2002; 295: 2267–2270. Matheus, P.F., 1995. Diet and co-ecology of Pleistocene short-faced bears and brown bears in eastern Beringia. Quaternary Research 44, 447–453. Matheus, P.F., 2001. Pleistocene predators and people in eastern Beringia: did shortfaced bears really keep humans out of North America? In: Gerlach, S.C., Murray, M. (Eds.), Zooarchaeology in the North: People and Animals in Alaska, the Arctic, and Northwest North America. British Archaeological Reports 944, pp.79–101. Matheus, P., J. Burns, J. Weinstock, and M. Hofreiter. 2004. Pleis tocene brown bears in the mid continent of North America. Science 306:1150. Talbot SL, Shields GF (1996) Phylogeography of brown bears (Ursus arctos) of Alaska and paraphyly within the Ursidae. Molecular phylogenetics and evolution 5: 477–494. (this is the milestone paper on genetics that got the whole thing rolling so to speak).
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Mar 31, 2014 4:33:09 GMT -9
Post by warsaw on Mar 31, 2014 4:33:09 GMT -9
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Post by warsaw on Apr 6, 2014 9:38:06 GMT -9
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