Egg research says dinosaurs went extinct when asteroid hit

Most information about dinosaurs at the end of the Cretaceous period comes from the present-day United States, in particular Hell Creek formation, This presents a picture of relatively rich dinosaur diversity during the last million years of that period.

However, the fossil record from that period in other regions is thinner, and it is not known whether the pattern seen in North America is representative of global dinosaur diversity. after.

To fill this gap in the fossil record, researchers in China studied more than 1,000 fossilized dinosaur eggs from Shanyang. central China basin. At the end of the Cretaceous period, dinosaur diversity was already declining. Scientific journal of the National Academy of Sciences.

Eggs and eggshell fragments represent the last 2 million years of the dinosaur era, and fossils represent every 100,000 year interval. The research involved obtaining detailed age estimates of rock layers by analyzing and applying computer modeling to more than 5,500 geological samples.

Analysis found whole eggs and eggshell pieces There were only three species of dinosaurs during this time period, indicating low dinosaur biodiversity, the researchers said.

Macroolithus yaotunensis and Elongatoolithus elongatus belonged to a group of toothless dinosaurs known as oviraptors, while the third Stromatoolithus pinglingensis, was a member of the plant-eating hadrosaur or duck-billed dinosaur group.

A fragment of the asteroid that killed the dinosaurs may have been found

Researchers found that their findings from fossilized eggs were consistent with fossilized dinosaur bones found in the same and surrounding region, although they discovered several additional dinosaur bones from the region. Between 66.4 million and 68.2 million years ago, tyrannosaurs and sauropods also lived in the area.

The photo shows a fossilized egg of Macroolithus yaotunensis, which was examined as part of the study.

“Our results support a long-term decline in global dinosaur biodiversity up to 66 million years ago,” he said, “which likely triggered the mass extinction of non-avian dinosaurs during the Cretaceous.”

Most of the dinosaurs are gone, though some of the smaller, bird-like ones survived and evolved into the birds we see today.

Opponents of the theory of sudden death by an asteroid point out a period of global cooling that made life difficult for many dinosaur species. Their dismissal was also linked to a year A series of massive volcanic eruptions in the Deccan Traps now in the territory of India.

Paleontologist Alfio Alessandro Chiarenza postdoctoral researcher at the University of Vigo, Spain, who worked on paleoclimate records He said that the eggs were fossilized from that time is not a reliable record of dinosaur diversity. He was not involved in the study.

He drew attention to recent studies dinosaurs probably had soft-shelled eggs fossilization would be unlikely. Moreover, eggs were not found for many dinosaurs species, even famous ones like Tyrannosaurus rex, Chiarenza said.

The asteroid that destroyed the dinosaurs collided in the spring

“These results also conflict with what we know based on the North American record (and) what emerges from egg fossils and the variety of bones, teeth and other remains found in places like Spain,” he said via email. “So I believe these authors are misinterpreting these signals.”

He is convinced that the asteroid impact was the real driver the extinction of the dinosaurs.

“Dinosaurs were probably beautiful and diverse, and if not for the end, the Cretaceous asteroid (they) might still dominate today as we know it.”