The global extinction of dinosaurs was caused by an asteroid hitting Earth 66 million years ago.
Dinosaurs lived around the world just before their extinction, according to scientists. Dinosaurs were either at their peak or already in decline before they died. Dinosaurs went out with either a bang or a whimper.
The answer has been found by researchers from the IVPP of the Chinese Academy of Sciences and their partners. Evidence shows that dinosaurs were not very diverse before their extinction and that they declined during the last part of the dinosaur's life.
The findings were published in PNAS.
The data on the last days of the dinosaurs comes from North America. Some studies suggest that dinosaur populations were thriving before extinction, but other studies suggest that they were in decline and that mass extinction was inevitable.
The Chinese researchers wanted to know if the declining trend extended to Asia.
Over 1000 dinosaur eggs and eggshells were studied by the researchers. The fossils were made from rock with a thickness of 150 meters. The researchers used computer modeling to estimate the age of the rock layers. The scientists were able to create a time line of nearly two million years at the end of the Cretaceous. Data from around the world can be compared with this timelines.
The scientists were able to identify a decline in dinosaur diversity. There are only three different dinosaur species that are represented in the 1,000 dinosaur egg fossils collected from the basin. Two of the dinosaur eggs are from a group of toothless dinosaurs known as oviraptors, while the other is from the plant-eating hadrosaurid group.
Between 66.4 and 68.2 million years ago, tyrannosaur and sauropods lived in the area. Before the mass extinction, there was a low diversity of dinosaur species in central China. The small number of dinosaurs depicted in the movie are far from the real thing.
Dinosaurs were probably declining before their extinction, according to these results.
The long-term decline in dinosaur diversity may have been caused by climate fluctuations and volcanic eruptions in India. Non-bird dinosaurs are vulnerable to mass extinction due to these factors.
More information: Low dinosaur biodiversity in central China 2 million years prior to the end-Cretaceous mass extinction, Proceedings of the National Academy of Sciences (2022). DOI: 10.1073/pnas.2211234119 Journal information: Proceedings of the National Academy of Sciences
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