Dinosaurs Were Declining Long Before the Asteroid Perished Them: Study

66 million years ago, an asteroid fell from the sky and crashed into Yucatan Peninsula, causing devastating climate change that led to the end of Cretaceous period, killing with it three-quarters of animal species. Even though a small proportion of hardy birds managed to live, dinosaurs suffered mass extinction. However, the recent study shows that they were already declining.

University of Reading researcher, Manabu Sakamoto, reveals that the dinosaur species were waning faster than the new ones could regenerate. This was 40 million years before the end of the species.

In fact, many other researchers who looked into the fate of dinosaurs before the notorious extinction suggested that their numbers were already diminishing. However, this approach is not accurate as some rocks may have been capable of preserving the fossils better or may even have been analyzed more rigorously by some fossil-hunters.

Stephen Brusatte from University of Edinburgh adjusted these discrepancies and used latest information together with better statistical techniques to come up with study conclusions. According to his findings, there was "no evidence for a progressive decline in total dinosaur species richness." They used dinosaur "family trees" so that they could study the rise and fall of the species over a period of time.

Through their research, the authors believe, could resolve a longstanding controversy among paleontologists.

"One of the things that has been long debated about dinosaur evolution is whether they were reigning strong right up until the time of the meteorite impact, or whether there was a slow, gradual decrease in [the emergence of new species] or an increase in extinction before that time," said Chris Venditti, an evolutionary biologist at the University of Reading and an author of the paper.