Overview

• A Frontiers in Earth Science study reports an age of about 85.9 ± 1.7 million years for a clutch of 28 eggs at the Qinglongshan site in China’s Yunyang Basin.
• The team used in‑situ carbonate U–Pb dating via laser ablation mass spectrometry, directly measuring uranium–lead ratios in the eggshell.
• Biogenic eggshell calcite produced more consistent ages than the calcite infill originally targeted for analysis, an unexpected result that boosts the method’s prospects.
• Only a few fragments from one egg were analyzed, and the authors say they will sample across additional layers and nearby basins to build a regional timeline.
• Some paleontologists warn that post‑burial alteration could skew ages, and while the authors note good preservation, they frame links to Late Cretaceous cooling and eggshell porosity as hypotheses to be tested.