Story at a glance:
- Dinosaur species were in decline long before the asteroid hit what is now known as Mexico, a new study posits.
- Non-avian dinosaurs died during the global climate cooling.
- Dinosaurs competed for survival.
Although an asteroid strike wiped out the dinosaurs 66 million years ago, it was fate that the dinosaurs were going to be extinct.
A new study shows that dinosaur species were in decline long before the asteroid hit what is now known as Mexico, which caused the climate to change and killed three quarters of life on the planet, CNN reported.
The asteroid, estimated to be 6.2 miles long, caused the 125-mile-wide Chicxulub crater on the Earth.
However, researchers analyzed 1,600 dinosaur fossils, representing 247 dinosaur species, and they assessed the rate of dinosaurs becoming less diverse.
"We looked at the six most abundant dinosaur families through the whole of the Cretaceous (period), spanning from 150 to 66 million years ago, and found that they were all evolving and expanding and clearly being successful," study lead author, Fabien Condamine, said in a news release.
Condamine is a researcher from the Institut des Sciences de l'Evolution de Montpellier in France.
"Then, 76 million years ago, they show a sudden downturn. Their rates of extinction rose and in some cases, the rate of origin of new species dropped off," he added.
Decline of non-avian – avian or bird-like dinosaurs managed to survive the asteroid strike and evolved into the common day birds – dinosaurs might have occurred during the Late Cretaceous period, which was 146-65 million years ago, when global climate cooling began, according to a study published in the journal Nature Communications on Tuesday.
Dinosaurs competed for survival, with some families like hadrosaurs outlasting other herbivores.
Using computer modeling techniques, researchers determined the unpredictability.
"In the analyses, we explored different kinds of possible causes of the dinosaur decline," Mike Benton, the other co-author of the study, said.
Benton is a University of Bristol's School of Earth Sciences professor.
"It became clear that there were two main factors, first that overall climates were becoming cooler, and this made life harder for the dinosaurs which likely relied on warm temperatures,” Benton said. “Then, the loss of herbivores made the ecosystems unstable and prone to extinction cascade. We also found that the longer-lived dinosaur species were more liable to extinction, perhaps reflecting that they could not adapt to the new conditions on Earth."
CNN notes that other paleontologists have published contradictory studies that concluded dinosaurs were actually thriving when the asteroid hit. One of those scientists said the new study is limited by a patchy fossil record, while another scientist said the new study puts too much emphasis on the global cooling effect.
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