Ancient clam reveals a 372-day year and a faster Earth
Researchers analyzed daily growth rings in the Cretaceous clam Torreites sanchezi from Oman to estimate that ~70 million years ago a year contained about 372 days, with each day ~23.5 hours long. This implies Earth spun faster then, slowed by tidal interactions with the Moon (which was closer and is receding today at ~3.8 cm/year). The study’s high-resolution method—combining daily laminae counts and chemistry—could be applied to other well-preserved shells to refine the history of Earth's rotation.