What caused the Pleistocene Mass Extinction?

[tigerluver]

I feel different aspects of the mass extinction hypotheses affected different areas of the world. Africa and Asia still kept relatively large animals. The Americas and Europe (bar the bears) lost all the large megafauna, so some differences must've been present. 

At least for Asia and Africa, I believe they were a bit warmer than the other areas, as for example, Java was a tropical grassland. Maybe the temperature increase didn't affect the fauna of the areas as much for this reason. Northern Asia/Eurasia and North America seemingly had cooler temperature adapted vegetation. These areas faced the worse of  the extinction. With this thought, Kitchener and Dugmore and Luo et al. maybe right in the theory that tigers colonized Manchuria in the last 10,000 years. Tigers may have lived in warmer areas then. Temperature increased, the cave lion was not adapted for the warm temperature, and thus the tiger was the next most suitable successor. 

The issue with this hypothesis is that South America was likely warmer, so what happened there? Reply