In death of dinosaurs, it was all about the asteroid - not volcanoes

Volcanic activity did not play a direct role in the mass extinction event that killed the dinosaurs, according to an international, Yale-led team of researchers. It was all about the asteroid. In a break from a number of other recent studies, Yale assistant professor of geology & geophysics Pincelli Hull and her colleagues argue in a new research paper in Science that environmental impacts from massive volcanic eruptions in India in the region known as the Deccan Traps happened well before the Cretaceous-Paleogene extinction event 66 million years ago and therefore did not contribute to the mass extinction. Most scientists acknowledge that the mass extinction event, also known as K-Pg, occurred after an asteroid slammed into Earth. Some researchers also have focused on the role of volcanoes in K-Pg due to indications that volcanic activity happened around the same time. " Volcanoes can drive mass extinctions because they release lots of gases, like SO₂ and CO₂, that can alter the climate and acidify the world," said Hull, lead author of the new study. "But recent work has focused on the timing of lava eruption rather than gas release." To pinpoint the timing of volcanic gas emission, Hull and her colleagues compared global temperature change and the carbon isotopes (an isotope is an atom with a higher or lower number of neutrons than normal) from marine fossils with models of the climatic effect of CO₂ release.