But what was their life like before that happened? Whether they thrived or actually teetered on the edge of a cliff has long been a matter of debate for paleontologists.
A new study suggests that the dinosaurs suffered a decline of up to 10 million years before the city-sized asteroid that hit the coast of what is now Mexico suffered its final knockdown and this decline hampered their ability to recover from the asteroid impact. .
The attack created the 125 -mile -wide Chicxulub crater, releasing climate -changing gases into the atmosphere, which ultimately killed three -quarters of life on the planet.
The researchers studied a total of 1,600 dinosaur fossils representing 247 dinosaur species to assess the species diversity and extinction rates of six dinosaur families.
“We looked at the six most abundant dinosaur families during the entire Cretaceous period, which spanned from 150 to 66 million years ago, and found that they all evolved and evolved and were clearly successful,” said the study’s lead author, Fabian. Condamine, a researcher from the Institute of Evolutionary Sciences in Montpellier, France, said in a press release.
“Then, 76 million years ago, they showed a sudden decline. Their rate of extinction is increasing, and in some cases the rate of emergence of new species is falling.”
Global climate cooling during the Late Cretaceous (100 to 66 million years ago) may have contributed to the decline of non-avian dinosaurs, the authors of the study, published Tuesday in the journal Nature Communications, said. (Dinosaurs that looked like birds or birds survived an asteroid strike and evolved into the birds we see today.)
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They also say that highly successful dinosaur families such as the hadrosaurs may have outperformed other herbivores, reducing the diversity of the dinosaurs.
The researchers used computer modeling techniques that account for uncertainties including an incomplete fossil record to estimate the most likely outcome.
“In the analysis, we explored different types of potential causes of dinosaur decline,” said Mike Benton, one of the study’s authors and professor from the University of Bristol’s School of Earth Sciences.
“It became clear that there were two main factors, the first being that the overall climate was getting colder, and that made life more difficult for dinosaurs who likely depended on warmer temperatures.” Then the loss of herbivores makes the ecosystem unstable and vulnerable to extinction. . We also found that longer-lived dinosaur species were more likely to go extinct, perhaps reflecting their inability to adapt to new conditions on Earth.”
Alvio Alessandro Chiarenza, a paleontologist and postdoctoral researcher at the University of Vigo in Spain, who was not involved in the study, said the authors attach great importance to the cooling trend at the end of the Cretaceous period. He said that the dinosaurs had survived the same climatic fluctuations during the 165 million years they roamed the Earth.
“There is a significant bias in the fossil record due to a number of factors (mainly geographic and economic, but also more personal biases such as paleontologists focused on searching for single species for example, such as Tyrannosaurus),” he said by email. .
“The fact that several groups of scientists working on the exact same question at the same time can produce completely opposite results reinforces this, namely that there is a great need to collect more data, which is to find more dinosaurs and find out where they lived. and how successful they really are.”.
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