Scientists believe dinosaurs were wiped from the earth by an asteroid, not by volcanic activity.
It has long been believed that the asteroid that struck Earth off the coast of Mexico 66 million years ago killed all types of dinosaurs except those that became birds.
However, some researchers have suggested that tens of thousands of years of large volcanic eruptions may have been the root cause of the extinction.
Now researchers from Imperial College London, the University of Bristol and University College London have shown that only asteroid impact could have created conditions that made the planet uninhabitable for dinosaurs.
They also suggest that massive volcanism may have helped life recover from the asteroid strike in the long run.
The lead researcher Dr. Alessandro Chiarenza, who was doing this while completing his PhD at Imperial, said: “We show that the asteroid has caused a felling winter for decades and that these environmental conditions decimated suitable environments for dinosaurs.
“In contrast, the effects of the intense volcanic eruptions were not strong enough to significantly disrupt global ecosystems.
“For the first time, our study confirms quantitatively that the only plausible explanation for the extinction is winter that has wiped out the habitats of dinosaurs worldwide.”
Research suggests that the asteroid impact would have released particles and gases high into the atmosphere, blocked the sun for years, and caused permanent winters.
Volcanic eruptions also produce particles and gases with sun-blocking effects, and around the time of the mass extinction, the Deccan traps in India today had tens of thousands of years of eruptions.
To determine whether the asteroid or volcanism has a stronger climate-changing power, researchers have traditionally used geological climate markers and powerful mathematical models.
In the new work, they combined these methods with information about the types of environmental factors such as precipitation and temperature that each dinosaur species needed to thrive.
They then mapped where these conditions would still exist in a world after an asteroid strike or massive volcanism, and found that only the asteroid strike wiped out all potential dinosaur habitats.
Volcanism left some viable regions around the equator, as suggested by the study published in Proceedings of the National Academy of Sciences.
The co-author Dr. Philip Mannion of University College London added, “In this study, we add a modeling approach to key geological and climate data that shows the devastating effects of asteroids on global habitats, and death for dinosaurs.”