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The dominant theory, taught in schools, confirms the disappearance of dinosaurs about 66 million years ago, with the fall of the meteorite on Earth.
But some scientists believe that this story is too simplistic and that massive volcanic eruptions of several hundred thousand years could have contributed to the extinction of dinosaurs at the end of the Cretaceous..
Science magazine has published two studies highlighting a long-standing scientific debate about the true causes of the extinction of these huge reptiles.
Before the 1980s, the most widespread theory about the disappearance of dinosaurs was that successive large volcanic eruptions had caused a rapid and deadly change in the Earth's atmosphere after vast clouds of ash, gas and dust had been released into the atmosphere. Ancient off the Caribbean in Mexico and assumed that this led to the dispersion of large amounts of debris and dust into the atmosphere, which hindered the process of photosynthesis of the plant and occurred three quarters of life on Earth.
Since then, there has been an ongoing debate about the relative contribution of both disasters to the extinction process..
The authors of the two new papers were able to determine with very great precision the date and time of a massive flow of volcanic ash, thus reducing the period from about a million years ago to tens of thousands of years..
"We were able to reorganize the events of the late Cretaceous with great precision," said geological science professor Loik Vanderleuksen of the University of Drexel in Philadelphia. Vanderleuksen was part of the team that described the history of volcanic eruptions known as Deccan Traps in India with the help of radioactive energy. The other team used a different date method.
The lava discharge over more than a million years, the thickness of the Deccan plateau sometimes exceeds 1200 meters in some places, enough to cover an area of France up to a depth several hundred meters,.
In any case, the new story reached by each of the two research teams is identical and one of the groups found that the "vibration" of the volcanic eruptions occurred before the massive extinction of these reptiles..
The second group was less specific but suggested the idea that most lava flows occurred after the asteroid struck the ground, pointing out that this impact had resulted in a very large earthquake, recorded at 11 degrees on the earth. the current Richter scale, never seen by man. The earthquake triggered a wave of volcanic eruptions that lasted for about 300,000 years.
This discovery confirms the theory that the impact of the asteroid was the main reason, Vanderlukluisnakan said, comparing a bottle of soft drink to a rapid acceleration of volcanic activity..
The researchers do not think that the close relationship between the two events, volcanic eruptions and extinction, is a coincidence, says geological sciences professor Blair Schoen of Princeton University and the other participant at the University of Princeton. study, that other periods of intensive volcanic activity coincide with other mass extinction events, explaining that the fundamental question Is an extinction without impact, or at on the contrary, would an extinction have taken place without volcanic eruptions? "I do not think we have an answer"He said.
"The most striking conclusion we draw is that it is not so simple: nature is complex, and by studying the phenomenon in great detail, we can try to understand what the whole story is."He said.
The long-term extinction schedule is very important to understand the consequences of the "sixth extinction" that humans are currently causing.
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