Researchers from Stellenbosch University and other institutions utilized advanced uranium-lead (U-Pb) dating along with elemental mapping to analyze traces of uranium and lead in the calcite of fossilized dinosaur eggshells discovered in the United States and Mongolia.
An artist’s reconstruction of a troodontid dinosaur that had just hatched from a fragment of an egg shell. Image credit: Eva Utsukiyouhei.
The ages of numerous fossil remains globally remain uncertain.
Without precise geological age data for fossils, paleontologists face challenges in comprehending the relationships among different species and ecosystems over time and across regions.
Traditionally, they depend on dating minerals like zircon and apatite found alongside fossils, but these minerals are not always available.
Efforts to date fossils such as bones and teeth often lead to ambiguous results.
Dr. Ryan Tucker and his team at Stellenbosch University adopted a novel strategy. They applied advanced U-Pb dating and elemental mapping to identify trace quantities of uranium and lead in the calcite of fossilized dinosaur eggshells.
These isotopes function as a natural clock, enabling scientists to ascertain when an egg was buried.
Studies of dinosaur eggs sourced from Utah in the United States and Mongolia’s Gobi Desert have indicated that the eggshells can accurately reflect their ages to about 5% in comparison to the true ages of volcanic ash.
In Mongolia, researchers have for the first time directly dated a significant area where dinosaur eggs and nests have been preserved, tracing back to approximately 75 million years ago.
“Eggshell calcite is remarkably adaptable,” states Dr. Tucker.
“This introduces a fresh method for dating fossil sites lacking volcanic layers, which has posed a challenge for paleontology for many years.”
By demonstrating that dinosaur eggshells can reliably record geological time, this research bridges biology and earth sciences, providing scientists with a powerful tool for dating fossil remains worldwide.
“Directly dating fossils is a dream for paleontologists,” remarked Dr. Lindsay Zanno, a paleontologist at North Carolina State University and the North Carolina Museum of Natural Sciences.
“With this innovative technology, we can tackle previously insurmountable riddles of dinosaur evolution.”
The team’s study was published in the journal Communication Earth and Environment.
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RT Tucker et al. 2025. U-Pb calcite dating of fossil eggshells as an accurate deep-earth chronometer. Communication Earth and Environment 6,872; doi: 10.1038/s43247-025-02895-w
Source: www.sci.news
