Overview

• Researchers used in‑situ micro‑laser uranium‑lead dating on carbonate within the eggshells to determine absolute ages.
• The dated clutch from the Qinglongshan reserve in central China falls in the Late Cretaceous at roughly 85–86 million years old with about ±1.7 million years uncertainty.
• These are the first reliably dated fossils from the site, and the results align with independent ages from the enclosing strata.
• Most eggs at Qinglongshan are attributed to Placoolithus tumiaolingensis of the Dendroolithidae, whose highly porous shells inform interpretations of nesting environments.
• The team links high pore density to regional cooling during the Late Cretaceous and proposes expanding the method to build broader egg chronologies across additional layers and basins.