The disappearance of the dinosaurs is a story that has fascinated paleontologists and the general public alike for decades. The most widely accepted theory today is that the impact of a giant meteorite delivered the final blow. But there are other very solid ways too. And above all, it is quite unlikely that a single isolated factor ended the era of large reptiles. The reality is certainly like that much more nuanced, and a recent study supports this hypothesis; according to the authors, The dinosaurs were probably already doomed before the fatal impact.
This work comes from the team of Don Baker, professor of planetary science at Canada’s University of McGill. To retrace the history of dinosaurs, they ventured into the heart of one of the world’s most spectacular geological structures: the Deccan Trapps.
The majestic Trapps of the Deccan. © Nichalp – Wikimedia Commons
It is an igneous province in eastern India that was formed after a gigantic volcanic eruption Hundreds of thousands of cubic kilometers of lava. It is the subject of particular interest among geologists for many reasons, but one thing in particular has caught the attention of paleontologists: its age.
In fact, the rocks of the Deccan Trapp have been dated between the end of the Mesozoic and the beginning of the Cenozoic 60 to 68 million years B.C. BC. A point in time that is anything but trivial when you know that the dinosaurs have disappeared… sort of 65 million yearsor in the middle of that big volcanic episode.
The volcano trail
For this reason, many researchers assume that these are massive eruptions directly involved in the Cretaceous-Tertiary crisis, which spelled the death knell for large reptiles. Because these events, especially those of this magnitude, not only release large amounts of lava. They also release large amounts of gas and ash.
In particular, models suggest that an eruption the size of the one that formed the Deccan Trapps would have released large amounts of sulfur into the atmosphere – enough to significantly alter the climate of the entire planet.
It is this path that the McGill researchers have explored. They analyzed several lava deposits in the Deccan, but also in Sweden and England, to estimate what amounts of sulfur and fluorite were released into the atmosphere in the 200,000 years before the dinosaurs went extinct.
To achieve this, they developed a new technique that helped them decipher this volcanic history. To explain it, the team used an amazing culinary analogy.
“Imagine cooking pasta at home. You boil the water, add the salt and finally the pasta. Some of the salt in the water goes into the pasta – but only a small amount,” says Don Baker.
“Following the same logic, certain elements become trapped in minerals as they cool after an eruption. Just as one can calculate the salinity of water by analyzing the salt content of pasta cooked in it, this new technique made it possible to infer the amount of gas released in these eruptions from the levels of sulfur and fluorite in rock samples. »
Meteorite or not, the dinosaurs were doomed
At the end of these analyses, they were able to confirm that the amounts of sulfur released by these eruptions were enough to trigger a huge drop in global temperatures. However, dinosaurs and the other animal and plant species they depended on for food were simply unable to withstand this volcanic winter for very long.
“Our research shows that climatic conditions were certainly unstable, with recurring volcanic winters that could have lasted for decades. This instability would have made life very difficult for plants and animals and led to the extinction of the dinosaurs,” Baker concludes.
Note that this work did not study the influence of the famous meteorite at all. They therefore do not allow a precise determination as to how their existence finally ended. On the other hand, this study confirms this Meteorite or not, the dinosaurs were undoubtedly doomed to disappear, whatever happened, as many theories already suggest. Fate has definitely dealt these majestic reptiles a hard time.
Supervolcanoes, an existential threat
Incidentally, this work can also be interpreted as a Booster shot regarding the threat of supervolcanoes. In fact, it would be very presumptuous to believe that humanity would be better off than the dinosaurs if an eruption comparable to the Deccan struck Earth today.
In autumn 2022, researchers sounded the alarm: this risk had been largely underestimated. In particular, they flaunted a statistic that sends shivers down your spine. According to their estimates, humanity has approx 1 in 6 chance by the end of the century will suffer an eruption of magnitude 7 out of 8 – or 10 to 100 times stronger than that of Hunga Tonga in January 2022. So it is a a much more likely outcome than, say, an asteroid impact.
These researchers also insisted on the fact that humanity does not do this absolutely not prepared for such an event. SThe consequences would therefore be catastrophic. It is therefore imperative to increase research efforts around supervolcanoes in order to best predict these eruptions and potentially limit the damage. Otherwise, it is quite possible that humanity will be among the victims of the vagaries of our planet, like the dinosaurs.
The text of the study can be found here.