Dinosaurs On Its Way to Extinction Before Asteroid Collision, New Theory States

Dinosaurs may have already been on decline mode for tens of millions of years before an asteroid hit the Earth 66 million years ago, according to a study published in the Proceedings of the National Academy of Sciences (PNAS). Until now, researchers believed that the asteroid collision was the foremost reason that brought about the extinction of the prehistoric reptiles.

According to experts from the University of Bristol and the University of Reading, the extinction process of dinosaurs was spread over 50 million years, with the massive collision or eruption being thought of as the final nail on the coffin. Lead researcher Manabu Sakamoto and his colleagues studied statistical analysis of the fossil record to observe not only the pace at which the prehistoric reptiles were evolving into new species but also the rate at which those dinosaurs were going extinct.

The findings of the study suggested that though the new species evolved at a stunning speed, they were already losing steam 50 million years prior to the asteroid strike. It was speculated that the species were becoming extinct faster than the emergence of new ones. In short, the evolutionary boom time for dinosaurs was already over. "While the asteroid impact is still the prime candidate for the dinosaurs' final disappearance, it is clear that they were already past their prime in an evolutionary sense," Manabu Sakamoto said.

According to the PNAS report, the scientists conducted a new type of statistical analysis by looking into the large family trees of dinosaurs. The study, which allowed the researchers to look into the rise and fall of dinosaurs during the course of time, examined three major species: long-necked plant-eating sauropods like the Diplodocus, carnivorous theropods like the Tyrannosaurus rex and beaked herbivorous ornithischians like the Stegosaurus.

On the basis of the study, the researchers observed that though dinosaurs flourished from about 220 million years ago, it was around 140 million years ago when the numbers started to dwindle. Consequently, around 90 million years ago, approximately 24 million years before the asteroid collision, the prehistoric reptiles had already entered a long time decline phase, with the species getting annihilated faster than the emergence rate of new ones. The phenomenon could have made dinosaurs more vulnerable to extinction after the asteroid hit.