You were probably taught that the stone age mega fauna in North America such as the Mammoth had gone extinct because as ice retreated at the end of the an ice age man entered N. America and ate them all. Seems kind of silly now. I mean considering there was tons of Buffalo and millions of more natives here when Europeans showed up. Why didn’t they eat all the animals? Well,probably because they didn’t have gun powder.
Anyway, there is a growing body of evidence that the earth was stuck by and asteroid or comet 12,000 year ago causing mass extinctions, flooding and general chaos resulting in death of the mega fauna,and the Clovis culture. This article is about the recent discovery of a giant crater in Greenland that may have landed about that time.
Personally, I think it would take more than one impact to cause that much damage. But there is a good chance that instead of just one impact there was a comet break up leading to the type of impact the shoemaker -levy9 recorded on Jupiter.
This guy does a great job explaining that theory…