In the Geologically short span of 2,000 years North America looked drastically different. As the Earth began to warm, plant communities once restricted to the tropics began their slow push northward. During this time period the megafauna in North America adapted and thrived as the land that was once covered by ice became usable by plant communities.

Between 11,000 radiocarbon years ago and 8,000 r.c.y.a the Earth continued to warm. What was once temperate open woodland in the Southwest became semi-desert, mid taiga became grassland in the Midwest. It was during this time that the majority of megafauna in North America became extinct. Why had they been able to live through the previous climate changes between 13,000 and 11,000 rcya but had suddenly died during this period?
A new predator was now living amongst these giant mammals, Man.