When dinosaurs still left fresh footprints on the mud, our planet twirled around faster than it does today. Chronicled in the rings of an ancient timekeeper is a story of days half an hour shorter and years a week longer than they are today, according to a new study.
That ancient timekeeper is an extinct rudist clam, one of a group of mollusks that once dominated the role that corals fill today in building reefs. The clam belonged to the species Torreites sanchezi and lived 70 million years ago in a shallow tropical seabed, which is now dry land in the mountains of Oman in the Middle East.
This ancient clam grew extremely fast from its home in a dense reef, creating a growth ring on its shell for every day of the nine years that it lived. A group of researchers analyzed the clam’s shell to get a snapshot of what time and life was like in the Late Cretaceous period, about 5 million years before the story of both the dinosaurs and these clams ended.