Asteroid impact ‘only plausible explanation’ for dinosaur extinction

Dinosaurs were wiped off the Earth by an asteroid, and not volcanic activity as some theories suggest, according to a new research.

The asteroid, which struck the Earth off the coast of Mexico at the end of the Cretaceous era 66 million years ago, has long been believed to be the cause of the extinction of all dinosaur species except those that became birds.

However, some researchers have suggested that tens of thousands of years of large volcanic eruptions may have been the actual cause of the extinction event.

But researchers from Imperial College London, the University of Bristol and University College London have now shown that only the asteroid impact could have created conditions that made the planet uninhabitable for dinosaurs.

They also suggest the massive volcanism could also have helped life recover from the asteroid strike in the long-term.

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Lead researcher Dr Alessandro Chiarenza, who conducted this work whilst studying for his PhD at Imperial, said: “We show that the asteroid caused an impact winter for decades, and that 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.

“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.”

Research suggests the asteroid strike would have released particles and gases high into the atmosphere, blocking out the Sun for years and causing permanent winters.

Volcanic eruptions also produce particles and gases with Sun-blocking effects, and around the time of the mass extinction there were tens of thousands of years of eruptions at the Deccan Traps, in present-day India.

To determine whether the asteroid or volcanism had more climate-changing power, researchers have traditionally used geological markers of climate and powerful mathematical models.

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In the new paper they combined these methods with information about what kinds of environmental factors, such as rainfall and temperature, each species of dinosaur needed to thrive.

They then mapped where these conditions would still exist in a world after either 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, the study published in Proceedings of the National Academy of Sciences suggests.

Co-author Dr Philip Mannion, from University College London, added: “In this study we add a modelling approach to key geological and climate data that shows the devastating effect of the asteroid impact on global habitats. Essentially, it produces a blue screen of death for dinosaurs.”