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It’s a quagmire debate in paleontology. an act A Huge Asteroid Hit Earth 66 Million Years Ago Are you exterminating a thriving and diverse group of dinosaurs, or were they already struggling to survive when that disastrous day dawned?
Most dinosaur information comes from the late Cretaceous period of what is now the United States, especially Hell’s Stream formation – compositionAnd the which paints a picture of the relatively rich diversity of dinosaurs over the last few million years of this period.
However, information on fossils from this era in other regions is much scarcer, and it is unclear whether the pattern seen in North America represents global dinosaur diversity. so what.
To fill this gap in the fossil record, Chinese researchers studied more than 1,000 fossilized dinosaur eggs from Shanyang. Central basin of China. The study, published in Sept. Scientific journal Proceedings of the National Academy of Sciences.
The egg and eggshell fragments represent the last two million years of the age of the dinosaurs, with the fossils representing all 100,000 years. The study included obtaining detailed estimates of the age of rock layers, analyzing and applying computer modeling to more than 5,500 geological samples.
analysis found Full Eggs and eggshell fragments of According to the researchers, there were only three types of dinosaurs, indicating a decline in dinosaur biodiversity during this period.
Macroolithus yaotunensis and Elongatoolithus elongatus belong to a group of toothless dinosaurs known as oviraptors, while the third belongs to, Stromatoolithus was pinglingensis Herbivorous hadrosaur or member of the group of duck-billed dinosaurs.
researchers They said their discovery of fossilized eggs was consistent with fossilized dinosaur bones found in and around the same area, although they found other dinosaur bones from the area showing Tyrannosaurs and sauropods also lived in the area between 66.4 and 68.2 million years ago.
“Our results support a long-term decline in global dinosaur biodiversity 66 million years ago,” the study says, likely paving the way for the mass extinction of non-Cretaceous dinosaurs in the Late Cretaceous.
Most dinosaurs are extinct, but Some of the smaller birds survived and evolved into the birds we see today.
Opponents of the sudden asteroid death theory refer to A period of global cold that may have made life difficult for many species of dinosaurs. His death was also associated with a A series of massive volcanic eruptions at the Deccan Traps in what is now India.
Paleontologist Alvio Alessandro Chiarenza, Postdoctoral researcher at the University of Vigo in Spain where he worked paleoclimate records Of that time he says petrified eggs This is not a reliable record of dinosaur diversity. He did not participate in the study.
He pointed out that there is a lot of recent research Dinosaurs can have soft-shelled eggs It is unlikely to decompose. Also, no eggs have been found for many dinosaurs. Species, even well-known species like Tyrannosaurus rex, Chiarinza said.
“These findings also run counter to what comes out of egg remains and the diversity of bones, teeth and other remains found in places like Spain (and) what we know based on of the North American file,” he said by email. . “So I think these authors are misinterpreting these signals.”
Still convinced the asteroid impact was the real reason since the extinction of the dinosaurs.
“Maybe the dinosaurs were good and varied, and if the Cretaceous asteroid (they) weren’t coming to an end, they might be dominant today as far as we know.”