https://phys.org/news/2019-02-volcanoes-asteroid-blame-dinosaur-extinction.html

But it leaves unclear to what degree the two catastrophes contributed to the near-simultaneous mass extinction that killed off the dinosaurs and many other forms of life.

The research sheds light on huge lava flows that have erupted periodically over Earth's history, and how they have affected the atmosphere and altered the course of life on the planet.