A clutch of 28 dinosaur eggs unearthed in the Qinglongshan fossil reserve in central China has been dated to around 86 million years ago using an “atomic clock” method known as uranium-lead (U-Pb) dating. The findings, published in Frontiers in Earth Science, mark the first reliable dating of fossils from the site, which contains over 3,000 eggs, reported CNN.
Researchers used a micro-laser to remove fragments of eggshell, then measured uranium and lead atom ratios to determine the age. The process was made possible by the discovery of calcite in the shells, a calcium carbonate mineral suitable for U-Pb analysis. “We decided to give it a try on the Qinglongshan eggs, not expecting such clear and reliable results,” said Bi Zhao of the Hubei Institute of Geosciences.
Most of the eggs belong to the species Placoolithus tumiaolingensis, of the Dendroolithidae family. Measuring 12 to 17 cm long with porous shells, they may provide insights into how dinosaurs in the Yunyang Basin adapted as Earth cooled, during the Cretaceous period.
Experts say U-Pb dating could transform fossil studies. With over 200 dinosaur egg sites globally, but few accurately dated, the method may help establish timelines for nesting behavior and reproductive evolution. “If widely applied, this approach could help establish a robust chronological framework for dinosaur reproduction behavior,” Zhao noted.
