Bears of the Pleistocene

[tigerluver]

What's exactly the size of the coastal brown bears? I've read conflicting measurements. Let's say 400-750 kg for males, so 225-750 kg including both genders.

Have you read the attached documents? They don't look to be of bears any larger than modern specimens.

The situation is more complex than just prey diversity and availability. Keep in mind that, even with more prey species, there were also more predator species, so tighter niches. Looking at North America, we have at the least (weight class in paranthesis): Smildon fatalis (100-280 kg), American lion (150-400 kg), Short faced bear (300-1000 kg), Dire wolf (50-80 kg, althought possible pack hunter, increasing prey size), and Homotherium (100-250 kg). Now where does that leave the brown bear? 

The brown bear could likely be omnivorous to better cope with such crowded predatory conditions. The 225-750 kg range essentially overlaps with all these aforementioned species. The high end of the range is overlaps greatly with the short faced bear. This is ecological unfavorable, thus fossil records showing not so large brown bears make sense.
 

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