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Bears of the Pleistocene
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  *This image is copyright of its original author Weights are subject to change. Shoulder height were determined by measuring full skeleton photos or reading literature data. The largest A. simus is from a 723 mm femur. The largest A. angustidens is from a 620 mm humerus. The largest U. m. tyrannus is from a 485 mm ulna. The largest cave bear (U. ingressus) is from a 485 mm basal length skull. The largest A. africanus is from a fragmented femur estimated to be around 530 mm in length. The largest polar bear (U. maritimus) I took from Derocher and Wiig (2002) and rounded up 10 kg. Yes, I edited A. angustidens to look like a steroidal spectacled bear. 
Post #162: Incredible tigerluver; beautifully done. Really puts them in perspective.
The largest skull of Ursus ingressus should be around 55 cm based on the GSL, and it does look like being slightly longer than both Simus/Angustidens (52.1 cm for the longest Simus skull) on the screen.
However, the head of the Ursus maritimus tyrannus looks a bit disproportionally larger, and the modern Ursus maritimus tyrannus should weigh more than 1100 lbs, more like a 1500 lbs specimen.
I actually did not aim to scale specific body parts in this photo as I just took real life specimens or drawings and scaled them onto the chart. I did occasionally make a bear proportionately longer or shorter depending on the need.
I am unsure of the normal max for a polar bear. I've read around 500 kg and need help verifying the larger weights and sources. Perhaps using 500 kg would still be okay as due to sample size, I doubt the largest fossils found were the largest specimens in existence for each species. 
Larger Yukonian Short-Faced Bear having a longer femur (or leg region) than its closest relative Arctotherium can only mean one thing: this subpopulation of Arctodus is larger than Arctotherium, which makes the latter second largest on average now.
This is due to short-faced bears having forelimbs that are particularly much longer than the hindlimbs, assuming bone length ratios are the same in all skeletons. (01-06-2017, 12:56 AM)brotherbear Wrote: If a grizzly can breed successfully with a polar bear; meaning that they have fertile offspring, as we know happens on occasion, then it seems reasonable to assume that a grizzly could also breed successfully with a cave bear - should one ever be cloned. I have also given thought that the Kamchatka and Kodiak bears appear very cave bear-like. Any chance this lineage could have a touch of cave bear? Quoting this here. U. spelaeas diverged 1.2-1.7 mya according to most sources (ie. Baca et al. 2012; Loreille et al. 2001). So that's analogous to the cave lion and modern lion in terms of how much cave bear could be in modern bear. Functionally none in all likelihood, although I'm sure the two could interbreed with occasionally fertile offspring as 1.5 mya is not that far diverged.
This kind of genetic distance is like that between Homo sapiens and Homo neanderthalensis.
That's why most modern Homo sapiens still contain 1-4% of Neanderthal DNA but still being fertile. The two Black bear species are also closely related, so I assume they can also breed and produce the functional offspring.
We can getting a little off topic here but... http://messybeast.com/genetics/hybrid-bears.htm
 *This image is copyright of its original author
From the site found by tigerluver on post #170, I found this:
https://www.researchgate.net/publication/263414302_Isotopic_evidence_for_dietary_flexibility_among_European_Late_Pleistocene_cave_bears_Ursus_spelaeus The proposed dietary pattern of extinct Late Pleistocene cave bears (Ursus spelaeus Rosenmüller, 1794) has become controversial, as some authors have suggested that they were strictly vegetarian, whereas others maintain they were omnivores that at times ate large amounts of animal protein. We evaluated these alternatives by compiling stable isotope data of carbon (δ13C) and nitrogen (δ15N) from the bone collagen of adult European cave bears from the Late Pleistocene (Marine Isotopic Stage 3). The data include previously published analyses and additional data from the southeastern European (Carpathian) sites of Cioclovina, Muierii, Oase, and Urşilor. The cave bear isotopic values from bone collagen were compared with those from hair keratin occurring in grizzly bears (Ursus arctos horribilis Ord, 1815) collected from 1989 to 2009 in the western United States (Yellowstone National Park). The Yellowstone bears have access to a wide diversity of plants and animals, such that their diets can range from vegetarian to carnivorous. Thus, there was considerable δ13C and δ15N variation among the grizzly bear isotopic values, and the cave bear isotopic variation was encompassed within the overall grizzly bear isotopic distribution. More importantly, the δ15N distributions, reflecting principally trophic level, were not different between the cave bears and the grizzly bears; the cave bear values are, on average, slightly higher or lower than those of the grizzly bears, depending on the criteria for inclusion in the comparisons. It is therefore no longer appropriate to view Late Pleistocene cave bears as strictly or even predominantly vegetarian but as flexible omnivores within their diverse communities.
The classic Cave bear subspecies known as Ursus spelaeus spelaeus was mostly vegetarian, while the southeastern subspecies Ursus spelaeus ingressus was highly carnivorous.
Thank you GrizzlyClaws. That was my confusion. I did not know that ingressus was a subspecies of spelaeus. I thought that they were completely different species of cave bears; as American black bear is to a grizzly. Thanks for the clarification.
(01-08-2017, 11:54 PM)brotherbear Wrote: Thank you GrizzlyClaws. That was my confusion. I did not know that ingressus was a subspecies of spelaeus. I thought that they were completely different species of cave bears; as American black bear is to a grizzly. Thanks for the clarification. Although ingressus was sometimes labelled as an independent species of its own, but their difference with the classic Cave bear is probably only subspecific. Since all Cave bear population descended from the European Etruscan bear, while the Brown bear is more distinctly descended from the Asian Etruscan bear. If the Brown bear is so closely related to the Cave bear, then ingressus and the classic Cave bear are probably only subspecific at each other.
Makes perfect sense; like U. arctos arctos, U. arctos horribilis, and U. arctos middendorffi, we have U. spelaeus spelaeus, U. spelaeus ingressus, and a few others. I love it when the puzzle pieces start falling into place.
Here is the common ancestor of the Asiatic Black bear and Etruscan bear. The American Black bear is a quite young species and probably split from the Asiatic Black bear not long ago.
https://en.wikipedia.org/wiki/Ursus_minimus |
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