When it comes to dinosaur extinction, two long-standing theories have been floating around for years. The first is that an asteroid, which struck the Earth off the coast of Mexico at the end of the Cretaceous era 66 million years ago causes the demise.
The other is that large volcanic eruptions may have killed off almost 75% of life on Earth. Now, a research team from Imperial College London, the University of Bristol and University College London is claiming that only the asteroid impact could have created the dinosaur extinction and that the massive volcanism could have actually helped life recover.
“We show that the asteroid caused an impact winter for decades, these environmental effects decimated suitable environments for dinosaurs. In contrast, the effects of the intense volcanic eruptions were not strong enough to substantially disrupt global ecosystems," said Lead researcher Dr. Alessandro Chiarenza, who conducted this work whilst studying for his Ph.D. in the Department of Earth Science and Engineering at Imperial.
“Our study confirms, for the first time quantitatively, that the only plausible explanation for the extinction is the impact winter that eradicated dinosaur habitats worldwide.”
To find out which factor, the asteroid or the volcanism, had more of an impact on the dinosaurs, researchers have conventionally used geological climate markers and mathematical models. In the new study, the team used these same methods but combined them with data about what kinds of environmental factors the dinosaurs required to survive.
They then mapped where these conditions would still exist in a world hit by either an asteroid strike or massive volcanism. They came to the conclusion that only the asteroid strike wiped out all potential dinosaur habitats, while volcanism left some viable regions.
Volcanoes might have helped actually
But that's not all. The team found that since volcanos also release carbon dioxide that stays around and builds up, warming the planet, the volcanism could have actually helped rebuild life after the asteroid strike by restoring many habitats.
"We provide new evidence to suggest that the volcanic eruptions happening around the same time might have reduced the effects on the environment caused by the impact, particularly in quickening the rise of temperatures after the impact winter. This volcanic-induced warming helped boost the survival and recovery of the animals and plants that made through the extinction, with many groups expanding in its immediate aftermath, including birds and mammals," said Chiarenza.