What happened to the dinosaurs when an asteroid about six miles wide struck Earth some 66 million years ago in what is today Mexico is well known: It wiped them out. But the exact fate of our planet’s diverse ocean dwellers at the time — shelly ammonites, giant mosasaurs and other sea creatures — has not been as well understood.

New research now makes the case that the same incident that helped bring an end to the reign of the dinosaurs also acidified the planet’s oceans, disrupted the food chain that sustained life underwater and resulted in a mass extinction. The study, published Monday in Proceedings of the National Academy of Sciences, aims to shore up the hypothesis that the Chicxulub event’s destruction of marine life — the result of sulfur-rich rocks depositing acid rain into the oceans — was just as severe as the fire and fury it brought to land.

“It’s flash acidification, and it transformed ecosystems for millions of years,” said Noah Planavsky, a biogeochemist at Yale and one of the study’s authors. “We were shocked that we actually found this.”

The impact of the Chicxulub asteroid — so named for the crater it carved out around the Gulf of Mexico — sent columns of rock into Earth’s atmosphere, incinerated the planet’s forests and drove tsunamis far across the oceans. But the connection between the crash and the marine extinction has been less solid.