86-Million-Year-Old Fossil Eggs Reveal Clues to Cretaceous Life   

• A clutch of 28 dinosaur eggs discovered in central China is helping scientists better understand how ancient reptiles adapted to a changing planet. Dated to about 86 million years ago, the find was reported from the Qinglongshan fossil reserve, which holds more than 3,000 preserved specimens. The research team used a precise method called uranium-lead dating to measure the age of the fossilized eggs. After using a laser to shave off tiny shell fragments, the scientists analyzed the fragments for uranium and lead atoms. Hinging on the fact that uranium naturally decays into lead over time, the method calculates the sample’s age by looking at the ratio between the two. The eggs, each about the size of a grapefruit, were discovered to have thin, porous shells. While the exact dinosaur that laid them remains unknown, scientists say the porousness of the shells could offer crucial clues about the ancient ecosystem, how these animals nested, and how they adapted as the Earth cooled during the Cretaceous period. Researchers hope to apply the technique to other fossil sites, building a clearer timeline of dinosaur reproduction and evolution. Yesel Kang Copy Editor junior/1760056312/1613367813