Dinosaur species were already in decline long before meteor strike, study finds – Technology News, Firstpost
France Media AgencyJune 30, 2021 2:04:21 PM IST
Dinosaurs may have been in decline millions of years before meteors impact, often attributed to their extinction, according to a study released Tuesday examining the role of climate change.
The Chicxulub meteor, which struck what is now Mexico’s Yucatan Peninsula around 66 million years ago, is believed to have led to the Cretaceous-Paleogene extinction that killed three-quarters of life on Earth, including dinosaurs.
Now, new research suggests that a number of species of terrible lizards may have declined up to 10 million years before the meteor’s impact.
Research published in the journal Nature examined data from 1,600 dinosaur remains found across the planet to model the frequency of certain carnivorous and herbivorous dinosaur species during the Late Cretaceous Period.
The team found that the decline of the species began around 76 million years ago.
Fabien Condamine, of the Institute of Evolutionary Sciences at the University of Montpellier and lead author of the study, said his team had tracked the decline of six dinosaur families, comprising nearly 250 distinct species.
“We had a peak in diversity about 76 million years ago,” he told AFP. “Then there is a decline that lasts 10 million years – that’s more than the entire duration of the genus Homo.”
The team found two possible explanations for the decline in dinosaur diversity identified in the fossil record and their own computer modeling.
On the one hand, the rate of decline of the species corresponded to a strong 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 mesothermal – mostly hot and humid – climate that had prevailed for tens of millions of years throughout their time on Earth.
“With strong cooling, like other large animals, they probably weren’t able to adapt,” he said.
The second possible explanation for the decline came as a shock to the team.
While herbivores and carnivores should have been affected around the same time, the team found a two-million-year lag between their respective declines.
“So the decline in herbivores, which were the prey, would therefore have cascaded down to a decline in carnivores,” Condamine said.
The study concluded that not only the cooling of the climate and the reduction in diversity among the herbivores led to the slow decline of the dinosaurs, but also left the various species unable to recover after the impact of the meteor.
“These factors hampered their recovery after the final catastrophic event,” he said.