Scientists in central China have discovered a clutch of 28 fossilized dinosaur eggs dating back around 86 million years. Found in the Qinglongshan fossil reserve in the Yunyang Basin, the eggs were dated using a technique known as uranium-lead (U-Pb) analysis- a process that measures how uranium atoms in minerals decay into lead over time.The breakthrough not only helps establish the age of these eggs but could also transform how paleontologists study dinosaur reproduction.
Dating eggs with atomic precision
Source: Bi Zhao/ Frontiers
To determine their age, researchers used lasers to shave tiny fragments of calcite, a calcium carbonate mineral present in the eggshells, and then measured uranium and lead ratios. Because calcite preserves uranium well, these eggs turned out to be ideal candidates for U-Pb dating. According to the team, this is the first time fossils from the Qinglongshan reserve have been reliably dated.The eggs, mostly belonging to the species Placoolithus tumiaolingensis, are slightly flattened spheres about 4.7 to 6.7 inches long with shells just 2.4 millimeters thick. Their porous texture may reveal how dinosaurs living in this region adapted to Earth’s cooling climate during the late Cretaceous period.
Why this discovery matters
Traditionally, fossils are dated based on the surrounding sediment, which can sometimes misrepresent their true age. Direct U-Pb dating of fossils themselves, however, is considered the most precise technique. “We decided to give it a try on the Qinglongshan eggs, not expecting such clear and reliable results,” said Bi Zhao, a researcher at the Hubei Institute of Geosciences.The success of this method could allow paleontologists to build stronger timelines of how dinosaurs reproduced and adapted over millions of years. With over 200 dinosaur egg sites identified worldwide, most of them not yet dated accurately, the potential applications are vast.