demise dinosaurs It has long captivated paleontologists. The mass extinction after a fiery meteorite hit the Earth some 66 million years ago, with volcanoes erupting and global temperatures rising and falling, was a turbulent end to the reign of these once-dominant monsters.
But now another study suggests that dinosaurs were already on their way out millions of years before the meteor hit the predator, according to an analysis of more than 1,000 fossilized eggshells discovered in central China.
“Dinosaurs gradually became extinct over millions of years, rather than ending abruptly by sudden disasters,” said study author Qiang Wang of the Chinese Academy of Sciences. Tell The South China Morning Newspaper.
Expect to test these conclusions. Weigh the study in a long and poetic discussion Between paleontologists about whether non-avian dinosaurs faced an abrupt end or if they were already teetering on the brink of extinction 10 kilometers before asteroid seal their fate.
The new research, conducted by a team of geologists and paleontologists working in China, suggests dinosaur Biodiversity was fading at least two million years before the dinosaurs went extinct, at the end of the Cretaceous period, leaving birds as their only living descendants.
Her conclusions are based on a collection of egg fossils, including many complete and incomplete dinosaur eggs, preserved in 150-meter-thick layers of rock that were deposited between 68.2 and 66.4 million years ago, just before the curtain came down on the dinosaurs.
The Shanyang Basin, where the egg fossils were found, is home to one of the most abundant records of dinosaurs from the late Cretaceous period. However, researchers found only three species of dinosaur represented in fossilized eggshells – a clear reduction in biodiversity compared to ancient fossil records.
Researchers believe that this decline in variance may have weakened the dinosaurs’ collective ability to recover from Chicxulub asteroid impact that struck modern Mexico or adapted to Troubled environmental conditions at that time. With fewer options in their evolutionary playbook, they were exposed to snooker.
“Our results support a long-term decline in global dinosaur biodiversity 66 million years ago, which likely paved the way for the mass extinction of non-avian dinosaurs at the end of the Cretaceous,” researcher at China University of Geosciences Fei Han and colleagues Type in their published paper.
Despite their claims, the team is right Notes That the extinction of the dinosaurs remains disputed for a range of reasons, such as “sampling biases in the fossil record, differences in the analytical methods used, and the paucity of high-accuracy geo-dating of dinosaur fossils.”
In their work, Han and colleagues used a combination of techniques to classify the thousands of rock samples that encase fossilized eggshells, estimate the age of those samples, and create a timeline of that data with an accuracy of 100,000 years.
Two of the three “oospace” dinosaur eggs (the species category for dinosaurs, when you only have eggs) were identified in this mix from a group of toothless, parrot-like dinosaurs called oviraptors, with the third group identified as laying dinosaurs. Like herbivorous hadrosaurs.
The low species diversity the researchers found matches with the remains of ancient dinosaur skeletons also discovered in the Shanyang Basin, and is comparable to other fossil deposits in southern and eastern China, as well as some bones in North Amarica This also indicates a decline in dinosaur diversity over the same period.
All of this “indicates lower diversity and general decline among dinosaurs on a global scale,” Han and colleagues arguesuggesting that the decline may be caused by global climate fluctuations and volcanic eruptions.
Other studies that also indicated that dinosaurs were at risk of extinction suggested that their diversification may have begun. dwindles up to 10 million years before the meteor hits the earth.
However, previous studies have found otherwise. One recent, far-reaching analysis that simulates dinosaur species – the rate at which new species emerge – found that less than 20 percent of dinosaurs were in terminal decline before the asteroid impact, while Other species were thriving.
The only way to resolve these conflicting interpretations, Han and colleagues deduceis to find, sample and analyze more fossils and combine existing data from fossil sites around the world to better understand extinction patterns.
Certainly not an easy task, but one that may finally help settle what happened in light of the fading of the reign of the dinosaurs.
“Our study in Asia of the abundant and geologically dated fossils is a major step in that direction,” the researchers said. Type.
The study was published in PNAS.