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Dinosaurs Already in Decline Before Massive Meteor

FILE - Tyrannosaurus rex went extinct in a relatively short compared to the dinosaur line that led to birds. (Credit: Royal Ontario Museum)

A study claims dinosaurs were already on their way to becoming extinct millions of years before a meteor impact delivered what is regarded to be a final blow.

Previously, it had been thought the meteor, which hit the Earth 66 million years ago, was the main factor that drove the giant reptiles to extinction.

“We were not expecting this result. 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,” according to Manabu Sakamoto of the University of Reading and the paleontologist who led the research.

Through statistical analysis of the fossil record, the researchers said that 50 million years before the meteor, there was a decline of all types of dinosaurs, but the long-necked sauropod dinosaurs were declining more rapidly. Dinosaurs like the Tyrannosaurus rex were seeing a slower decline in numbers.

“Our work is groundbreaking in that, once again, it will change our understanding of the fate of these mighty creatures,” said Sakamoto. “While a sudden apocalypse may have been the final nail in the coffin, something else had already been preventing dinosaurs from evolving new species as fast as old species were dying out. This suggests that for tens of millions of years before their ultimate demise, dinosaurs were beginning to lose their edge as the dominant species on Earth.”

Dinosaurs dominated the world for approximately 150 million years, but according to the study’s co-author, Mike Benton of the University of Bristol, they lost their ability to “speciate” or evolve fast enough in response to factors such as the “breakup of continental land masses, sustained volcanic activity and other ecological factors.”

The study is published in the journal Proceedings of the National Academy of Sciences.