The disappearance of dinosaurs due to an asteroid turned out to be worse than we thought

DINOSAURS – Deadly acid rain, sulfur clouds that make the sun disappear… This apocalyptic vision was experienced by our predecessors on Earth 66 million years ago. Thus, dinosaurs, animals and plants of that time survived the hell, the impact of which led to the extinction of the vast majority of the species of that time.

However, a study published on Monday, March 21 by the US National Academy of Sciences (PNAS) shows that this scenario turned out to be even worse than the researchers thought. Indeed, if an asteroid collided with our planet, a huge amount of sulfur would rise. If this phenomenon was already known, James Witts, co-author of the study, explains that the researchers “underestimated the amount of sulfur produced by this asteroid impact.”

The sun is no longer visible for decades

As a result, “the associated climate change could be much greater than we previously thought,” said James Witts, co-author of the study and Senior Lecturer at Live Science at the University of Bristol, UK.

Even today, traces of the meteorite impact that caused the extinction of the dinosaurs remain. On the Yucatan Peninsula in Mexico, you can observe the Chicxulub crater, where an asteroid with a diameter of 10 kilometers fell. Proof, if necessary, of the importance of the past catastrophe.

After the impact, a cloud of sulfur dioxide entered the atmosphere and settled in the stratosphere. This resulted in blocking the passage of the sun’s rays, plunging our planet into a dark night. Thus, the Sun disappeared for decades, perhaps even centuries.

A misfortune that never comes on its own, a huge cloud of sulfur also caused acid rain on our planet, changing the chemistry of the oceans for tens of thousands of years, much longer than we think.

accidental discovery

This study is the result of a happy accident. Indeed, the researchers were to study the geochemistry of ancient shells in a river in Falls County, Texas. Being close to the meteorite impact site, they decided at the last moment to take sediment samples in addition to their research.

They were then taken to the University of St Andrews in Scotland, where study co-author Aubrey Mirrorl, a geochemist and geobiologist, analyzed what they found. Looking at sulfur isotopes (kinds of atoms that differ in their mass), they noticed “unusual signals” indicating the presence of sulfur in the atmosphere 66 million years ago.

Although this discovery, again, is not new and has already been observed at the North and South Poles, the fact that this atomic signal is present in Cretaceous marine rocks (from where they took their samples) shows that there must have been a huge amount of sulfur in the atmosphere after fall of an asteroid.

Causing an estimated extinction of almost 76% of species, this cataclysm is also possibly an accident. Indeed, most of the sulfur lifted by the asteroid impact came from the sulfur-rich limestone of the volcanic Yucatán Peninsula. “If the asteroid had fallen somewhere else, perhaps so much sulfur would not have been released into the atmosphere, and the subsequent climate change might not have been so serious,” the researcher believes. Therefore, the extinction of the dinosaurs “might not have been as severe,” concludes James Witts.

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