The dinosaur eggs, mainly classified as Placoolithus tumiaolingensis, are about 85 million years old, meaning they were laid around a time when the global climate was changing.
Bi ZhaoFor the first time, researchers dated a dinosaur egg itself, rather than relying on nearby sediment to estimate its age.
Paleontologists have directly dated fossilized dinosaur eggs for the first time ever using carbonate uranium-lead (U-Pb) dating.
Typically, in order to estimate the age of a dinosaur egg, researchers must use the surrounding rock layers or volcanic ash to approximate the fossil’s age. However, this method risks a much rougher estimate, because depending on the environment and the region, those rock layers or volcanic ash may not necessarily be the same age as the egg.
Now, for the first time, experts have been able to directly date the eggs themselves, with a method that had already been successfully used on other types of fossils. The innovation may also offer more insights into the environment and climate of the Late Cretaceous Period.
The First Dinosaur Eggs From Qinglongshan To Be Reliably Dated
Bi ZhaoChina’s Qinglongshan site has over 3,000 dinosaur egg fossils.
The researchers described their findings in a new Frontiers in Earth Science study, in which they determined fossilized dinosaur eggs from China’s Qinglongshan site in the Hubei Province were around 85 million years old.
They used U-Pb dating on the eggs, a method where researchers must first fire micro-lasers at eggshell fragments in order to remove minerals and deposits that developed during the fossilization process. Then, the experts have to count the uranium and lead atoms present.
“Since uranium decays into lead at a fixed rate, we were able to calculate the age by measuring accumulated lead — it’s like an atomic clock for fossils,” explained study co-author Bi Zhao.
U-Pb dating has been used to date rocks, minerals, and other fossils in the past, but using it to examine dinosaur eggs is new.
“To the best of our knowledge, this is the first time that in situ isotopic ages have been reported for dinosaur eggshells both in China and, very likely, worldwide,” study co-author Xing Cheng told Nature.
Notably, the results of the U-Pb dating matched the approximated dates of the rocks surrounding the eggs. The newly dated fossils are the first precisely dated dinosaur eggs uncovered from the Qinglongshan site.
Qinglongshan, located in central China, is the country’s first national dinosaur egg fossil reserve. With over 3,000 confirmed fossilized eggs at the reserve, 28 of them were dated as part of the study. Most of the eggs are classified as Placoolithus tumiaolingensis, part of the Dendroolithidae family.
The Dinosaur Eggs Could Help Provide A Closer Look At The Late Cretaceous Climate
Bi ZhaoMost of the eggs the researchers dated were classified as Placoolithus tumiaolingensis.
Along with providing more exact dating information on dinosaur eggs, the researchers’ work can also shed more light on life during the Late Cretaceous Period. By the time these eggs were laid over 85 million years ago, the global climate was in a period of transition.
Temperatures were growing cooler, and dinosaurs were going to have to start adapting in order to survive. Researchers believe that this cooling climate may have contributed to dwindling biodiversity amongst the creatures, and the fossilized dinosaur eggs themselves may even point to that.
“Dendroolithids’ specialized pore structures may represent evolutionary adaptations to this climatic shift, as novel egg types emerged worldwide during cooling,” Bi Zhao said in a statement. “P. tumiaolingensis may represent an evolutionary dead end where the egg-laying dinosaur population failed to adapt successfully to cooling climates.”
The research team is looking to expand their research into what the specific climate may have looked like in different areas and different times by dating fossilized eggs found at various rock layers, in the hopes of constructing a regional timeline of the local dinosaur population during a changing climate. Researchers also believe that studying other Dendroolithid eggs in nearby basins could help put together a clearer picture of dinosaur migrations.
“Our achievement holds significant implications for research on dinosaur evolution and extinction, as well as environmental changes on Earth during the Late Cretaceous,” Zhao explained. “Such findings can transform fossils into compelling narratives about Earth’s history.”
Next, read about the perfectly preserved, 70-million-year-old dinosaur embryo found curled up in its egg. Then, learn about the catastrophic mass extinction event that killed the dinosaurs.
