A dinosaur egg unearthed in the mountains of central China has been dated to around 86 million years ago, according to scientists who applied an unprecedented approach to analyze the sample.

This groundbreaking method for dating fossil eggshells involves using a laser to vaporize mineral fragments in the shell. By determining the ratio of uranium to lead in the vapor, researchers can calculate the egg’s age — since uranium gradually decays into lead over time.

Until now, the technique had never been applied to fossil eggshells, although it has been used to determine the age of the Earth, the moon’s magma, and cave formations.

Researchers believe this unconventional dating method could help create a more precise timeline for dinosaur reproduction, fossil discoveries, and ancient environmental changes.