Photo of Qinglong Mountain egg fossil featured in top chemistry publication for groundbreaking dating research

The picture highlights research published in September that explained how scientists used a uranium-lead isotopic analysis of the minerals within fossilized eggshells to determine their age to be 85.91 million years old. The technique determines age directly from eggshell minerals instead of from surrounding strata, which can be disrupted over time.

Discovered in 1995, the Qinglong Mountain site is home to one of the world's largest and best-preserved collections of dinosaur eggs, numbering over 300,000.

The exact age of the egg group was unknown until late 2023, when scientists discovered three fossils filled with calcite crystals at Hall 1 of the site.

The Hubei institute partnered with the Shaanxi Institute of Geological Survey, the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences, and Xi'an Jiaotong University to conduct the research. Their findings were published in Frontiers in Earth Science.

Liu Xueru contributed to this story.