Scientists discover missing mass extinction event before the end of dinosaurs

BRISTOL, United Kingdom — Imagine a global catastrophe so massive it changes the face of the Earth and ushers in an age ruled by dinosaurs. It sounds like a science-fiction movie, but a new study finds it’s actually a missing piece of history. Researchers say this newly discovered mass extinction not only allowed the dinosaurs to thrive, but also paved the way for plants and animals we still see today.

The international team of researchers says the mass extinction struck the Earth around 233 million years ago. Study leader Jacopo Dal Corso from the China University of Geosciences at Wuhan says this catastrophe most likely centered around massive volcanic eruptions in the Wrangellia Province of present day Canada. The geological evidence points to huge amounts of volcanic rock from these eruptions forming what we now call the west coast of North America. Scientists call this event the Carnian Pluvial Episode.

“The eruptions peaked in the Carnian,” says Dal Corso in a university release. “The eruptions were so huge, they pumped vast amounts of greenhouse gases like carbon dioxide, and there were spikes of global warming.”

What did the Carnian Pluvial Episode do to the Earth?

The major extinction events throughout time, highlighting the new Carnian Pluvial Episode 233 million years ago. (Credit: D. Bonadonna/ MUSE, Trento.)

The study finds the spike in global warming also brought about much more rainfall in prehistoric times. Geologists in the 1980’s found this humid period lasted for about one million years and changed the biodiversity of the planet.

Study co-author Mike Benton says this dramatic shift in the climate killed off much of the diverse populations in the oceans and on land. The University of Bristol professor adds this extinction event is what gave dinosaurs, who were still a minor species at the time, their opportunity to take over the planet. It also helped to form the plant life and modern ecosystems that have been seen on Earth since then.

“The new floras probably provided slim pickings for the surviving herbivorous reptiles,” Prof. Benton adds. “We now know that dinosaurs originated some 20 million 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.”

The importance of this missing mass extinction

Study authors say dinosaurs and plants weren’t the only things to benefits from these devastating eruptions. The paleontological records show that the first turtles, crocodiles, lizards, and even some mammals appear during this global shift. The Carnian Pluvial Episode also played a role in forming modern coral reefs and several varieties of plankton, showing the event drastically changed Earth’s oceans as well.

“So far, paleontologists had identified five ‘big’ mass extinctions in the past 500 million years of the history of life,” Dal Corso reports. “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.”

The study appears in the journal Science Advances.

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