It has been suggested that a large meteorite was responsible for an odd climatic twitch from about 12,800 to 11,500 years ago (the Younger Dryas , a temporary return to glacial conditions in the Northern Hemisphere) and for the extinction of the large mammals of North America. They hypothesize air bursts or impact of a swarm of meteors , centered around the Great Lakes. Probably this is all nonsense.
The topic of the Holocene extinction of megafauna seems to bring out the crazy in people. In my opinion, the people supporting this Younger Dryas impact hypothesis are nuts, and half of their opponents are nuts as well.
Let’s just think about this hypothesis as an explanation of megafaunal extinction. There certainly was such an extinction: North America had mammoths, mastodons, giant ground sloths, giant turtles, glyptodonts, giant armadillos, short-faced bears, sabertooths, something similar to the African lion (Felis Atrox), etc. No longer, which is just as well.
The problem for that meteorite explanation of North Ammerican megafaunal extinction is that South America had an even more varied set of megafauna (gomphotheriums, toxodonts, macrauchenia, glyptodonts, giant sloths, etc) and they went extinct around the same time (probably a few hundred years later). There’s no way for a hit around the Great Lakes to wipe out stuff in Patagonia, barring a huge, dinosaur-killer type hit that throws tremendous amount of debris into suborbital trajectories. But that would have hit the entire world… Didn’t happen.