The asteroid that ended the dinosaurs happened to strike a shallow seabed rich in sulphur and buried hydrocarbons, throwing soot and aerosols into the sky — and researchers argue the same rock hitting most other places might not have ended their reign.

The asteroid that struck near Chicxulub, in what is now the Yucatán Peninsula, about 66 million years ago did not hit a random patch of the planet. It hit a shallow tropical seabed layered with sulphur-bearing rock and buried hydrocarbons. A 2017 paper in the…