What caused the Pleistocene Mass Extinction?

[brotherbear]

Yes, I understand that Arctodus simus was an omnivore. But, what I am implying is that he was also a scavenger and kleptoparasite. I know that he also feasted on plants and perhaps the occasional bee hive ( maybe ). But, it is also possible that he lacked the skills of catching fish and digging for roots or ground burrowing rodents. Did the short-faced bear hibernate? No evidence to support this, but then being from a totally different lineage of bears, there is no reason to assume that his habits were exactly like that of the bears of the genus Ursus. 
As for the size of the existing black bears and grizzlies, I have no reason to believe that their size was any different from that of their living descendants depending on their available food resources. Even a big grizzly can dig himself a comfortable den for a long winter's sleep. Reply