Did dinosaurs go out with a bang or with a whimper? Scientists have debated the question for decades, but a team of scientists from the U.K. has a surprising new theory on where the giant reptiles may have gone.
A new study, published Monday in the Proceedings of the National Academy of Sciences, draws the conclusion that dinosaurs were most likely in a gradual, 50-million-year decline before a meteorite hit the area known as the Chicxulub crater 66 million years ago, causing an extinction event for many species, including dinosaurs. About three-quarters of all life on Earth became extinct after one significant event, but it is possible that the event may not be solely to blame for the dinosaur’s demise.
Lead researcher Manabu Sakamoto, University of Reading, said they were not expecting that 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.”
This strongly disputes previous thinking, in which dinosaurs flourished right up until a massive meteorite impact wiped them out. It also shows that the patterns of decline were different among the various dinosaur species, with some in more rapid declines than others.
The scientists drilled into a huge meteor scar on the Earth’s surface on the Gulf of Mexico, thought to be ground zero for the mass extinction of dinosaurs, among other Earth species. They statistically analyzed the fossil record to determine the rate at which new species were evolving from the dinosaurs, and the rate at which species were going extinct. They found that the dinosaurs were declining for a long time.
For 50 million years before the big event, species were becoming extinct faster than new ones were appearing. However, the decline was not species-wide, with some types of dinosaurs, such as duck-bills, actually on the rise just before the extinction event.
The researchers are not sure what might have been causing this decline, but think it might have had to do with a cooling climate.