Page "Clovis culture" Paragraph 9

The largely discredited Younger Dryas impact hypothesis suggests that one or more bolide impacts caused the mass extinction and triggered a period of climatic cooling.

The hypothesis proposed that an extraterrestrial object such as a comet exploded in Earth's atmosphere above North America's Great Lakes region about 12, 900 years ago, and significantly impacted the human Clovis culture.

Recent published research disputes the quality of the evidence of an extraterrestrial impact.

Additional possible evidence of comet impact is occurrence of microdiamonds and black mats in a layer of sedimentary rocks of that era, but those observations were not repeated in other analyses, the dates of the layer were disputed, and there was a lack of other supporting evidence, especially the dates and level of megafaunal extinction.