Study finds that dinosaurs were wiped out long before the asteroid impact

The last step of the dinosaurs – © Jorge Gonzalez

New research suggests that climate change caused the dinosaurs to recede about 10 million years before the massive asteroid responsible for their extinction hit Earth.

Global cooling of the Earth

While paleontologists agreed for some time on the reason for the disappearance of dinosaurs Other than birds, experts have so far been divided over whether this group was thriving or vulnerable before the mass extinction of the Mesozoic Era 66 million years ago. In the context of the work published in the magazine Nature Connections, an international team of researchers determined that these creatures experienced an abrupt slowdown 76 million years ago, marked by high rates of extinction.

This phenomenon is attributed to the global cold period of tr, where the average temperature dropped by 7°C, with the deprived dinosaurs favoring warmer temperatures. As it turns out, herbivorous species tend to go extinct first, making ecosystems unstable and leading to the collapse of other dinosaur families.

« We looked at the six most abundant families of dinosaurs during the Cretaceous period, 150 to 66 million years ago, and found that they were all evolving, and clearly thriving. ‘, he explains Fabian Condamine, researcher inMontpellier Institute of Evolutionary Sciences and lead author of the study. ” Then, 76 million years ago, they slowed down sharply. The rate of their extinction increased, and in some cases the rate of emergence of new species decreased.. »

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The graphs show how the rate of speciation (blue) and the rate of extinction (red) declined sharply during the last 10 million years of the age of the dinosaurs. All correspond to a rapid decline in the number of species (in black) before the asteroid impact 66 million years ago – © Fabien L. Condamine / ISEM / CNRS

Mammal emergence

« It was a key moment in the evolution of life The researcher continues. ” Dinosaurs dominated the world for more than 160 million years, and as they declined other groups began to take over, most notably mammals. Dinosaurs were often so huge that they probably didn’t know the small, furry mammals were right there in the bushes. The number of these species began to increase before the disappearance of the dinosaurs, and after the impact they had the opportunity to build new types of ecosystems, which is what we see today.. »

The researchers said they took into account fossil-related uncertainties, including incomplete fossil records and dating discrepancies, by running modeling programs millions of times before agreeing on the most likely date for the dinosaur fossils’ decline.

« More than 1,600 carefully verified records of Cretaceous dinosaurs have been used ‘, he explains korean elephant, researcher inUniversity of Edmonton He co-authored the study. ” I’ve been collecting dinosaur fossils in North America, Mongolia, China and other regions for some time, and have seen massive improvements in the age of the rock formations inland. This means that the data is constantly improving. The decline of the dinosaurs over the past 10 million years makes sense, and is the best sampled part of the fossil record.. »

Recent research has proven that The asteroid that killed the dinosaurs gave birth to the Amazon rainforest – Vadim Sadovsky / Shutterstock.com

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