Climate change likely drove the extinction of North America’s largest animals — 

A new study suggests that the extinction of North America’s largest mammals was not driven by over-hunting by rapidly expanding human populations following their entrance into the Americas. Instead, the findings, based on a new statistical modelling approach, suggest that populations of large mammals fluctuated in response to climate change, with drastic decreases of temperatures around 13,000 years ago initiating the decline and extinction of these massive creatures.

Source: Climate change likely drove the extinction of North America’s largest animals — ScienceDaily