Comet : Evidence found in North America linking comet to climate change , extinction . Prehistoric humans also suffered decline in population due to cosmic event . Diamonds found in North American soil suggest a comet led to the extinction of dozens of mammal species . Heat from comet 's impact likely melted ice that once covered Great Lakes region .
Comet : Evidence found in North America linking comet to climate change , extinction . Prehistoric humans also suffered decline in population due to cosmic event . Heat from comet 's impact likely melted ice that once covered Great Lakes region .