Study finds dinosaurs wiped out long before asteroid impact

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The last stage of the dinosaurs – © Jorge Gonzalez

New research suggests that climate change set the dinosaurs back about 10 million years before the massive asteroid responsible for their extinction reached Earth.

Global cooling of the Earth

While paleontologists have for some time agreed on the reason for the disappearance of dinosaurs Besides birds, experts have so far been divided on whether this group was flourishing or vulnerable before the mass extinction of the Mesozoic era 66 million years ago. As part of the work published in the magazine Natural connections, an international team of researchers determined that these creatures experienced a sharp slowdown 76 million years ago, marked by high extinction rates.

This phenomenon is attributed to the global cold period of tr, where the average temperature has dropped by 7 ° C, with poor dinosaurs favoring warmer temperatures. It turns out that 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 dinosaur families during the Cretaceous Period, 150 to 66 million years ago, and found that they all clearly evolved and thrived. ‘, he explains Fabien 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 has increased, and in some cases the rate of emergence of new species has decreased.. “

The graphs show how the speciation rate (blue) and the extinction rate (red) have sharply declined over 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 impact of the asteroid 66 million years ago – © Fabien L. Condamine / ISEM / CNRS

Emergence of mammals

It was a key moment in the evolution of life The researcher continues. ” Dinosaurs ruled the world for over 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 there in the bushes. The number of these species started to increase before the dinosaurs died out, and after the impact they had the opportunity to build new types of ecosystems, which 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 of the date. decline of dinosaur fossils.

Over 1,600 carefully verified records of Cretaceous dinosaurs have been used ‘, he explains korean elephant, researcher inUniversity of Edmonton He is co-author of the study. ” I have been collecting dinosaur fossils in North America, Mongolia, China, and other areas for quite some time, and have seen massive improvements in the age of rock formations inland. This means that the data is constantly improving. The decline of 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 Sadovski / Shutterstock.com



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