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.
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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 peaked 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 big they pumped huge amounts of greenhouse gases like carbon dioxide, and there were spikes in global warming. “The warming was associated with an increase in precipitation, and this was noted as a wet episode lasting about 1 million years by geologists Mike Simms and Alastair Ruffell as early as the 1980s. 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. “In 1983, when I was completing my doctoral thesis, I noticed a change of flowers and an ecological catastrophe among herbivores. We now know that dinosaurs formed about 20 million years before this event, but they remained fairly rare and unimportant until the Carnian Pluvial episode hit. 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 had a profound influence on the development of the earth and life. We have identified another major extinction that appears to have been instrumental in resetting life on land and in the oceans and marking the origins of modern ecosystems. “
Reference: “Extinction and beginning of the modern world in the Carnic (late Triad) ”By J. Dal Corso and 16 others in Advances in science 6, eaba0099.