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Volcanic eruptions helped dinosaurs rule Earth

The relationship between dinosaurs and volcanoes has not always seemed so lovable.

For decades, scientists have wondered whether volcanoes or an asteroid caused the dinosaurs’ brutal extinction 65 million years ago. It wasn’t until 2010 that an international panel of experts officially declared that it was space rock, and not giant eruptions, that was the main cause of the dinosaurs’ disappearance.

And now, a team of researchers are presenting the most compelling evidence to date that massive volcanic events likely helped dinosaurs conquer the planet, at least in another era. Their results were published Monday in the Proceedings of the National Academy of Sciences.

The Triassic Period, which began around 250 million years ago, was a time of massive ecological change after the largest mass extinction event on record. While dinosaurs had appeared around this time, they were different: leaner, more reptilian, less box office success that we flock to theaters to see. But it was during this period that dinosaurs diversified into marvelous beasts such as the Tyrannosaurus rex or the Triceratops that dominated ecosystems all over the Earth until the end of the Cretaceous.

In an undated image provided by Jing Lu and the Beijing University of Mining and Technology of China, rocks preserving evidence of the Carnian rain event identified in a drill core, recovered 1,200 feet, in the basin from Jiyuan, China. (Jing Lu, Beijing University of Mining and Technology via The New York Times)

To understand what led to this transformation of the dinosaurs, scientists looked at a phase spanning 2 million years during the Triassic Period known as the Carnian Rainfall, or CPE. During this episode, 234 million to 232 million years ago, the planet experienced an increase in global temperature, humidity and precipitation – a climate often referred to as “mega-monsoon.”

Researchers analyzed evidence from sediment and plant fossils from a lake in northern China and were able to match four intense phases of volcanic activity with changes in the Carnian rainfall event.

Previously, the researchers speculated that the changes in the global carbon cycle during the episode were the result of major volcanic eruptions from what is now a mass of igneous rock found throughout western L ‘North America. The new study links the timing of the episode with four distinct peaks of mercury – a well-established indicator of volcanic activity – to changes in the carbon cycle as well as precipitation, which resulted in local changes in vegetation on earth and in the lake.

“We are often able to link volcanism to global warming, but our study is unusual in that we have also linked it to periods of intense rainfall,” said Jason Hilton, paleobotanist at the University of Birmingham in England and co-author. of the study. “With each pulse of volcanism, we see an increase in plants adapted to humid and aquatic environments.”

Jing Lu, a researcher at the Chinese University of Mining and Technology and also a co-author of the study, added that these eruptions “were powerful enough to trigger evolutionary processes during the Triassic.”

During the episode, plant species that could not adapt to the wetter environment became extinct, as did a number of animal species, from the large reptilian herbivores on earth to small gastropods in the ‘water. “These changes have freed up ecological space for other groups of organisms, like dinosaurs, to thrive,” said Hilton.

In addition to the diversification of dinosaurs, researchers believe that the CEP laid the foundation for today’s ecosystems.

“During the CPE, we start to see this perfect mix of prehistoric monsters as well as modern mammals and reptiles,” said Emma Dunne, a researcher at the University of Birmingham who was not involved in the study but whose the work is focused on the drivers of diversification of ancient tetrapods such as dinosaurs. “You had turtles, but also pterosaurs. “

This new evidence is leading researchers to think more about our rapidly changing climate.

“The magnitude of these eruptions eclipses all volcanic eruptions in human history,” says Sarah Greene, study co-author and paleoclimatologist at the University of Birmingham. “But the rate at which these eruptions emit carbon dioxide is tiny compared to human carbon dioxide emissions today.”

Dunne echoed that thought. “Those 2 million years were a blink of an eye in geological time, so to think that we are changing the planet at an even faster rate than humans is kinda scary,” she said. “Who knows what we’re going to talk about.”

This article originally appeared in The New York Times.


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