A disaster on a spring day 66 million years ago

How dinosaurs left the world "in the prime of their youth"

The skull of a predatory dinosaur that lived 85 million years ago.

«Getty»

The age of the dinosaurs ended in disaster one spring day 66 million years ago, when a 12-kilometre-wide asteroid struck Mexico's Yucatan Peninsula, wiping out the giant creatures along with about three-quarters of Earth's species.

But were the dinosaurs already on the way to extinction, with faltering diversity and poor rates of evolution, according to some scientists' perceptions?

The answer is definitely "no".

The researchers studied 18 million years before the asteroid impact that ended the Cretaceous period and four million years after that at the beginning of the Paleogene period, when mammals asserted their dominance after the dinosaurs disappeared, regardless of the bird lineages that belonged to this extinct giant lineage.

Drawing on more than 1,600 fossils, researchers have reconstructed the food chains and habitat preferences of land and freshwater vertebrates, including the likes of the giant carnivorous Tyrannosaurus, Triceratops, Ankylosaurus, crocodiles, turtles, frogs, fish, and the many small mammals that lived beneath the dinosaurs' feet. The researchers found that the dinosaurs were holed up in a stable, favorable environment that they adapted well to.

“In other words, the dinosaurs were eliminated at the height of their prosperity,” or in the prime of their youth, if the translation is correct, said Jorge Garcia Giron, an ecologist at the Universities of Oulu in Finland and Leon in Spain, senior author of the study published in the journal Science Advances.

García-Girón added that mammals began to lay the foundation for their ensuing evolution, diversifying their ecological habitats and developing more diverse and climate-adapted diets and behaviors.

The study concluded that dinosaurs continued to evolve and adapt during their existence with the emergence of new species and the disappearance of old ones.

Some of the major plant-eaters, such as the horned and duck-billed dinosaurs, were replaced by a larger group of medium-sized herbivores.

Some previous research indicated that dinosaur biodiversity declined long before the asteroid impact, based on the fossil record of different dinosaur families.

"There was this nagging thought that maybe the dinosaurs were going extinct anyway, in the midst of a protracted decline, when the asteroid put them out of their misery," said University of Edinburgh paleontologist Steve Brusatte, co-author of the study.

We can now say with conviction that dinosaurs were getting stronger with stable ecosystems until the asteroid killed them suddenly.” Perhaps the good adaptation of dinosaurs to their climate and environment was the reason for their extinction.

"When the asteroid hit, it threw everything into chaos, and the dinosaurs couldn't deal with the sudden change of a world they were so used to," Brusatte said.

And after the mass extinction, new mammals appeared.

"Mammals and dinosaurs have the same origin story," Brusatte said. "They both originated and began diversifying in the Triassic period, about 230 million years ago, on the supercontinent Pangea."

And from there they went their separate ways;

Dinosaurs headed towards larger sizes and mammals towards smaller sizes in the shade, but their fate will remain interconnected forever, as mammals were present at the asteroid collision and survived it.

An “asteroid” 12 kilometers wide led to the extinction of giant organisms, along with about three-quarters of all species on Earth.

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