The asteroid-related KT extinction is so famous, it’s kind of made us all associate “major extinction” with “major collision.” But space debris didn’t really play a role in most of the five major extinctions, at least not as far as science has been able to tell.
Some scientists, though, are toying with the idea that the end-Triassic extinction may have been at least partially influenced by an impactor (science’s sort of generic name for an asteroid or comet that strikes the Earth).
The Manicouagan crater is a 60-mile wide crater located in Quebec, Canada (via NASA). Scientists think the impact happened around 215.5 million years ago, which is technically 15 million years or so too soon to have been a major factor in the end-Triassic extinction event. According to a 2016 study published in Nature, though, the impact may have caused a large local extinction event driven by the decline of single-celled species at the bottom of the marine food chain. Though this wouldn’t have been enough to cause the extinction event that began about 15 million years later, it may have at least contributed. Marine species like ammonites, for example, were already in decline as the end-Triassic extinction began, which may have been related to the major changes in the food chain that happened after the Manicouagan impact.