What did it really cause the dinosaurs to exterminate? For a long time, it was believed that only the asteroid that collided with the earth would have responsibility for the end of the prehistoric creatures. However, several studies published in recent decades have pointed out that the population of dinosaurs could already be declining before the collision, citing reasons such as intense volcanic activity.
Gondwanax artistic concept Paraisensis in a triásic landscape in today’s southern Brazil. He lived almost 10 million years before any other known dinosaur – Photo: Matheus Fernandes Gadelha
Now, however, a new work rekindles the debate by providing evidence that, in fact, the extinction of Jurassic animals may have been caused only by the asteroid – were it not for him, possibly dinosaurs would still be alive. This is what researchers from the University College of London states in the United Kingdom, who published the study in the scientific journal Current Biology.
According to the authors, the idea that dinosaurs were already declining before an asteroid exterminated most of them, 66 million years ago, can be explained by an increasingly scarce fossil record of that period rather than a real real reduction in their populations.
Scientists have analyzed more than 8,000 North America fossils in the 18 million years that preceded the impact of the asteroid at the end of the Cretaceous period (between 66 and 84 million years ago). They explain that at first glance, the data actually suggest that dinosaurs would have reached the peak of their population around 75 million years ago, and declined 9 million years before the asteroid.
It was evidence like this that led to the belief on the part of the scientists that the collision was not solely responsible for the extermination. However, the new study states that this observed trend was the fact that the latest fossils were more scarce, partly because there are fewer places with exposed and accessible rocks from the end of the Cretaceous, and not by a real decline of populations.
“This has been a theme debated for over 30 years-the dinosaurs were condemned and already declining before the asteroid reached them? We analyzed the fossil registration and found that the quality of registration of four dinosaur groups (Clados) worsens in the six million years before the asteroid,” summarizes the main author of the UCL Earth Sciences Department, Chris Dean, in communication.
The expert also explains that while the likelihood of finding dinosaurs of this time diminishing, the chances of dinosaurs continued alive and living in these areas remained stable, at least in North America.
“Therefore, our findings suggest that at least in this region, dinosaurs may have been in a better situation than previously thought of the times before the impact, possibly with a diversity of species greater than we see in the gross fossil record,” the scientist continues.
“The dinosaurs were probably not inevitably condemned to extinction at the end of Mesozoic. If it were not for the asteroid, they might still share this planet with mammals, lizards and their surviving descendants: birds,” adds Alessandro Chiarenza, also author of the study department of UCL.
The clades of dinosaurs analyzed were: ankylosauridae (shielded herbivores such as the ankylosaur), keratopsidae (large herbivores of three horns, such as the tricing), Hadrosauridae (herbivores of duckboss such as Edmontassaur) and Tyrannosauuridae (carnivores like the carnivores Tyrannosaurus Rex).
