Diversity of Chinese dinosaurs began to decline long before the asteroid impact

(ORDO NEWS) — The mass extinction at the end of the Cretaceous wiped out the dinosaurs, sparing only the birds – but was it the fall of a prosperous empire or the final nail in the coffin?

A new find by Chinese scientists proves that the diversity of giant lizards began to decline long before the fall of the famous asteroid.

Sixty-six million years ago, a giant asteroid crashed into the earth, triggering one of the worst mass extinctions in the history of our planet.

The reptiles that dominated the planet, including all non-avian dinosaurs, died out, making way for the modern “masters of the Earth” – mammals and birds.

Until now, scientists argue about the state of the ecosystems of the late Cretaceous period before the fall of the Chicxulub asteroid : whether the dinosaurs were in decline or flourished, unaware of their fate.

While some researchers argue that giant lizards were not going to die out at the end of the Mesozoic , others say that by that time their diversity had noticeably decreased , so that the asteroid impact only put an end to this story.

And now the supporters of the second theory have another piece of evidence found by Chinese paleontologists.

Scientists studied more than a thousand fossil egg and eggshell samples from the Shanyang Basin in central China and about 5,500 geological samples to accurately date each fossil shell sample.

They then compiled a 2-million-year time scale with a resolution of about 100,000 years that covered the very end of the Cretaceous before the mass extinction.

Based on these data, paleontologists have identified a decline in dinosaur diversity long before the asteroid impact: the entire thousand egg samples collected in Shanyang are represented by only three types, of which two belong to the toothless oviraptorid dinosaurs, and the third to the herbivorous hadrosaurid.

The bone fossils of dinosaurs of the same time do not shine with diversity either: in addition to oviraptors and hadrosaurs, predatory tyrannosaurids and long-necked sauropods also lived in Shanyang , but their diversity was significantly lower than, say, ten million years before extinction.

Diversity of Chinese dinosaurs began to decline long before the asteroid impact 2
Millions of years before the mass extinction, the diversity of Chinese dinosaurs was significantly higher: armored ankylosaurs and small predatory dromaeosaurids lived there

Given the data from North America, it can be assumed that the decline in dinosaur diversity at the end of the Cretaceous was massive, at least in the Northern Hemisphere.

Climate change, volcanic eruptions, and other factors destabilized Mesozoic ecosystems: an asteroid strike proved to be the last straw, and the back of the dinosaur empire eventually broke.


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