What killed the dinosaurs? An asteroid or volcanoes? Or both?

Maybe it wasn't just the asteroid that killed off most of the dinosaurs 66 million years ago: New research reveals how volcanoes half a world away may have played a role.

An asteroid slammed into the Earth near present-day Mexico, unleashing huge tsunamis and ash that blotted out the sun. That led to a "nuclear winter" that wiped out more than half the animal and plant species on the planet.

Volcanoes – in what's now India – may have contributed to the extinctions, and the new studies pinpoint when those eruptions occurred and how long they lasted. This should give further clues as to what caused the extinction.

“To understand volcanoes’ role in mass extinction, we need to understand when the eruptions were occurring, how long they occurred for and how much volume was erupted during what time,” study co-author Courtney Sprain, a geoscientist at the University of Liverpool, told Gizmodo.

Sprain and other researchers traveled to India to study those long-past volcanic eruptions, looking at immense mounds of hardened lava known as the "Deccan Traps."

Those lava flows, which began before the asteroid impact but erupted for several hundred thousand years afterward, probably spewed immense amounts of carbon dioxide and other noxious, climate-modifying gases into the atmosphere, according to the University of California–Berkeley.

Thursday, in the peer-reviewed journal Science, two separate research teams published studies about what they found in the Deccan Traps.

One study, led by Sprain, says it's likely that the asteroid impact caused the volcanic eruptions in India to intensify as most of the lava erupted about 600,000 years after impact.

The other research, headed by geoscientist Blair Schoene of Princeton University, said the eruptions happened before the asteroid hit. This implies that the climate changes caused by the eruptions "could have triggered mass extinction ahead of the collision," CNN reported.

Though they may differ on the details, what both studies found was that the volcanoes in India erupted for about 1 million years and that both events were probably a factor in the mass extinctions.

Both reports pave the way for ongoing research into the subject.

The studies also shed light on our era of man-made global warming: Studying past climate change "is as relevant today as for these catastrophic events in Earth history," Schoene's study concludes.

This article originally appeared on USA TODAY: What killed the dinosaurs? An asteroid or volcanoes? Or both?