Agence France-PresseJune 30, 2021 2:04:21 PM IST
Dinosaurs may have been in decline millions of years before the meteorite impact that is often attributed to their extinction, according to research published Tuesday examining the role climate change plays.
The Chicxulub meteor, which slammed into what is now Mexico’s Yucatán Peninsula about 66 million years ago, is believed to have triggered the Cretaceous-Paleogene extinction event that wiped out three-quarters of life in the Earth, including dinosaurs.
Now, new research suggests that various species of dire lizards may have been declining for up to 10 million years before the meteor’s impact.
Research published in the journal Nature examined data from 1,600 dinosaur remains found around the planet to model how common certain species of carnivorous and herbivorous dinosaurs were in the late Cretaceous.
The team found that the decline of the species began around 76 million years ago.
Fabien Condamine, from the Institute of Evolutionary Sciences at the University of Montpellier and lead author of the study, said his team had followed the decline of six families of dinosaurs, comprising nearly 250 different species.
“We have a diversity peak around 76 million years ago,” he told AFP. “Then there is a decline that lasts 10 million years, that’s more than the total duration of the genus Homo.”
The team found two possible explanations for the diversity of falling dinosaurs identified in the fossil record and their own computer model.
On the one hand, the rate of decline in species corresponded to a sharp cooling of the global climate around 75 million years ago, when temperatures fell to eight degrees Celsius.
Condamine said the dinosaurs were adapted to a predominantly hot and humid mesothermic climate that had prevailed for tens of millions of years throughout their time on Earth.
“With strong cooling, like other large animals, they probably couldn’t adapt,” he said.
The second possible explanation for the decline was something that surprised the team.
While both herbivores and carnivores were expected to be affected around the same time, the team found a two million year lag between their respective declines.
“Therefore, the decline of herbivores, which were the prey, would have led to a decline of carnivores,” Condamine said.
The study concluded that not only did a cold climate and reduced diversity among herbivores lead to the slow decline of the dinosaurs, it also left the various species unable to recover after the meteorite impact.
“These factors prevented its recovery from the final catastrophic event,” he said.