An asteroid 10 kilometers in diameter hit Mexico’s Yucatan Peninsula 66 million years ago and wiped out most of our planet’s species by releasing a large amount of molten material and gases into the atmosphere.

This event led to the acidification of the ocean’s surface waters and a sudden warming that lasted years and wiped out the dinosaurs. This is the best known theory about the extinction of the dinosaurs. However, scientists have not always agreed on the origin of this mass extinction. A part of the scientific community has acknowledged that the intense volcanic activity produced by the impact on the area known as Deccan Traps in India also contributed to the disappearance of fauna, as published by SINC .

Experts argue whether volcanism occurred in the late Cretaceous, coinciding with the extinction event  known as K-Pg, or during the initial Paleogene.

“The fact that there were two events of planetary importance that coincided at more or less the same time has created this debate about which of the two mechanisms caused the extinctions: whether volcanism could weaken ecosystems and the impact of a meteorite gave the last push or whether it was only the meteorite,” says Laia Alegret, co-author of the study published by the journal Science and paleontologist at the University of Zaragoza.

This new research closes the debate by demonstrating that volcanic activity did not play a direct role in the mass disappearance of dinosaurs. According to the team led by Yale University, the only cause was the asteroid.

“Volcanoes can drive mass extinctions because they release lots of gases, like SO2 and CO2, that can alter the climate and acidify the world,” explains Pincelli Hull, lead author of the paper and professor of geology and geophysics at the American university. However, volcanic activity and associated warming occurred before and after the impact and not during the extinctions.

New research shows that only the impact of the asteroid coincided with the disappearances. Subsequently, new volcanic phases slowed the recovery of ecosystems.

What happened to the volcanoes?

“Volcanic activity in the late Cretaceous caused a gradual global warming event of about two degrees Celsius, but not mass extinction,” says Michael Henehan of Yale University. “A number of species moved toward the North and South poles but moved back well before the asteroid impact,” the expert says.

“A lot of people have speculated that volcanoes mattered to K-Pg, and we’re saying, ‘No, they didn’t’,” Hull stresses.

To reach these findings, the researchers analyzed surveys and outcrops of all oceans and latitudes, combined climate, biotic, and carbon cycle records, which were obtained from sediments and marine fossils such as fish teeth and shells.

The result was the creation of the most detailed reconstruction of the global temperature of that period. “The models that best fit our temperature curve are those in which the main phase of volcanism occurred in the late Cretaceous and ended 200,000 years before extinctions and the impact of the asteroid,” Alegret adds.

Researchers demonstrate in this way that most of the release of gas occurred long before the asteroid’s impact and that this was the sole driver of the extinction.

“A lot of people have speculated that volcanoes mattered to K-Pg, and we’re saying, ‘No, they didn’t’,” Hull stresses. In addition, scientists reject the hypothesis of mass eruptions in India’s Deccan region after extinction because “there is no warming event to match.”

“The K-Pg extinction was a mass extinction, and this profoundly altered the global carbon cycle. These changes would allow the ocean to absorb an enormous amount of CO2 on long time scales, perhaps hiding the warming effects of volcanism in the aftermath of the event,” concludes Donald Penman, co-author of the paper and postdoctoral researcher at Yale.

Here’s where you can read the full research.

*With information from SINC Agency


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