Volcanos wiped out species to pave way for the dinosaurs

THE T-rex and other Jurassic and Cretaceous dinosaurs thrived because volcanic eruptions that wiped out other species warmed up the Earth, allowing them to take over, a study has found.

Scientists from the University of Bristol have discovered a new major extinction event that occurred because of massive volcanic eruptions in the Wrangellia area of western Canada, where huge volumes of volcanic basalt were poured out, forming much of the west coast of North America.

In a research paper, published today in Science Advances, the scientists lay out the evidence for a major extinction of life 233million years ago that triggered the dinosaur take over. The crisis has been called the Carnian Pluvial Episode.

The volcanic eruptions pumped out huge quantities of carbon dioxide, warming the Earth and causing much life to die out, changing the landscape.

Dinosaurs originated some time before the event but were “rare and unimportant” until the arid conditions caused by the eruptions took hold.

“The new floras probably provided slim pickings for the surviving herbivorous reptiles,” said Prof Mike Benton, from the University of Bristol.

“I had noted a floral switch and ecological catastrophe among the herbivores back in 1983 when I completed my PHD,” Prf Benton said.

“We now know that dinosaurs originated some 20million years before this event, but they remained quite rare and unimportant until the Carnian Pluvial Episode hit. It was the sudden arid conditions after the humid episode that gave dinosaurs their chance.”

Many modern groups of plants and animals also appeared after the extinction event, including some of the first turtles, crocodiles, lizards, and the first mammals.

Coral reefs also have the volcanoes to thank for their current form, as the ocean chemistry and carbonate cycle were changed by the release of carbon dioxide. It is likely ocean life is only what it is today because these changes impacted types of plankton in the sea.

“So far, palaeontologists have identified five ‘big’ mass extinctions in the past 500million years of the history of life,” said research co-author Jacopo Dal Corso, from the China University of Geosciences at Wuhan.

“Each of these had a profound effect on the evolution of the Earth and of life. We have identified another great extinction event, and it evidently had a major role in helping to reset life on land and in the oceans, marking the origins of modern ecosystems.”