摘要

<正>When dinosaurs walked the Earth,days on our planet were a little bit shorter than the full 24 hours we know today.Earth turned more quickly,meaning that a day lasted about 23.5 hours and a year equated(等同) to 372 days,according to a new study.Researchers discovered this fact from a surprising resource:ancient shells,dated to the Late Cretaceous(白垩纪)period 70 million years ago.