Paleontologists have been wondering for decades what caused the extinction of dinosaurs. Like 75% of living things on the planet, these animals disappeared about 65 million years ago , shortly after the impact of an asteroid of at least 10 kilometers in diameter that fell in what is now the Gulf of Mexico. . In fact, most experts believe that, among all the hypotheses that have been put forward, this shock was the one that precipitated the so-called Cretaceous-Tertiary mass extinction.
Now, a team of researchers from the universities of Reading and Bristol, in the United Kingdom, assures that dinosaurs were already in decline 50 million before that event took place ; that is, the rate of disappearance of species was greater than that of the appearance of new ones.
In an article published in the journal Proceedings of the National Academy of Sciences , these experts point out that although this phenomenon affected all dinosaurs, it did not occur in the same way in all genera. To determine this, they built a statistical model from the information obtained from the fossil record . Thus, they found, for example, that the large sauropods, characterized by their long necks, were the ones that experienced this decline most rapidly. Among the theropods, the suborder that tyrannosaurs are found in, for example, this one was more gradual.
The paleontologist Manabu Sakamoto of the University of Reading, who has coordinated the trial, indicates that, in any case, the results are surprising . “The impact of the asteroid may explain the final disappearance of the dinosaurs, but from an evolutionary point of view, it is clear that these animals were already out of their early youth, so to speak,” he says.
The extinction of the dinosaurs, which dominated terrestrial ecosystems for 150 million years , had important implications for many other living things. Mammals, for example, would eventually settle in the niches they left and would become the dominant animals on land.
Image: Allie Caulfield via MathKnight / CC
