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Discovery of a new mass extinction

Discovery of a new mass extinction

A round-up of major extinction events over time, highlighting the new Carnian Pluvial episode 233 million years ago. Photo credit: D. Bonadonna / MUSE, Trento

A new mass extinction is not often seen; After all, such events were so devastating that they really stand out in the fossil record. In a new article published in today Advances in scienceAn international team identified a great extinction of life 233 million years ago that triggered the takeover of the world by dinosaurs. The crisis was known as the Carnian Pluvial Episode.

The team of 1

7 researchers, led by Jacopo Dal Corso from the China University of Geosciences in Wuhan and Mike Benton from the School of Earth Sciences at the University of Bristol reviewed all of the geological and paleontological evidence and determined what had happened.

The cause was most likely massive volcanic eruptions in Wrangellia province in western Canada, where huge amounts of volcanic basalt were poured out and form much of the west coast of North America.

“The eruptions have reached their peak in Carnic,” says Jacopo Dal Corso. “I studied the geochemical signature of the eruptions a few years ago and found some massive effects on the atmosphere around the world. The eruptions were so large they were pumping large amounts of greenhouse gases like carbon dioxide, and there were spikes in global warming.” The warming was associated with an increase in rainfall, and this was noted as early as the 1980s by geologists Mike Simms and Alastair Ruffell as a wet episode lasting about 1 million years in total. Climate change caused a great loss of biodiversity in the ocean and on land, but shortly after extinction, new groups took over and formed more modern ecosystems. The climatic changes promoted the growth of plants and the expansion of modern coniferous forests.

“The new floras likely provided a slim harvest for the surviving herbivorous reptiles,” said Professor Mike Benton. “I had noticed a flower change and an ecological catastrophe in herbivores as early as 1983 by the time I graduated with my PhD. We now know that dinosaurs formed about 20 million years before that event, but they remained fairly rare and unimportant until the Carnian Pluvial episode It was the sudden dry conditions after the wet episode that gave the dinosaurs their chance. “

Not only did dinosaurs emerge at this time, but also many modern groups of plants and animals, including some of the earliest turtles, crocodiles, lizards and the earliest mammals.

The Carnian Pluvial episode also had an impact on marine life. It marks the beginning of modern coral reefs as well as many modern groups of plankton, indicating profound changes in ocean chemistry and the carbonate cycle.

“So far, paleontologists have identified five” major “mass extinctions in the last 500 million years of life,” says Jacopo Dal Corso. “Each of these events had profound implications for the evolution of the earth and life. We have identified another major extinction, and it appears to have been instrumental in resetting life on land and in the oceans and marking the origins of modern ecosystems. ”

The mass extinction crisis sparked the expansion of dinosaurs

More information:
“Extinction and beginning of the modern world in the Carnic (Late Triassic)” Advances in science (2020). progressive.sciencemag.org/lookup… .1126 / sciadv.aba0099

Provided by the University of Bristol

Quote: Discovery of a New Mass Extinction (2020, September 16), accessed September 16, 2020 from https://phys.org/news/2020-09-discovery-mass-extinction.html

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