Dinosaurs in decline before asteroids: China’s fossil record

Long before the age of the dinosaurs ended when a giant asteroid hit the Earth, they were trending downward, according to a new fossil record of dinosaur eggs from China.

It is widely accepted that there were many species of dinosaurs living around the world at the end of the Cretaceous period, 66 million years ago.

But scientists question whether dinosaurs were at their peak of dominance when the asteroid struck, or if their best days were over.

New research published Monday in the peer-reviewed journal Proceedings of the National Academy of Sciences seems to suggest that dinosaurs were on the decline.

A great deal of dinosaur research focuses on fossil records found in North America, some suggesting that dinosaurs flourished just before the asteroid hit, and others suggesting that opposite thing.

By looking at the fossil records in China and comparing them with this existing data, researchers from the Institute of Vertebrate Paleontology and Paleontology in China hope to create a picture. more complete.

They looked at more than 1,000 fossil dinosaur eggs and egg fragments unearthed from the Shenyang basin in central China.

The distinct layers of soil in which different eggshells were found allowed them to create a timeline spanning nearly two million years into the late Cretaceous, to test patterns dinosaurs were experiencing at the time. there.

What they found suggests that dinosaur diversity in the basin declined at the end of the Cretaceous. Although they found evidence of some tyrannosaurs and sauropods, the majority of the eggs belonged to just three species. And of those three, two belonged to the same group of dinosaurs, a toothless species known as oviraptors that were, ironically, believed to be egg-stealers.

This low diversity was maintained over a two-million-year period, and when the researchers compared it with data from North America, they found that it showed generally that dinosaurs declined as they went extinct. series strains.

The researchers say more research is needed to determine the cause of this decline, but they believe it could be due to global climate fluctuations and massive volcanic eruptions where they occur. what we call India and other regions, destabilizing the global ecosystem.

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