Researchers have discovered a massive die-off of sharks roughly 19 million years ago.
It came at a period in history when there were more than 10 times as many sharks patrolling the world’s oceans than there are today. For now, researchers don’t know the cause of the shark die-off.
“We happened upon this extinction almost by accident,” says Elizabeth Sibert, a postdoctoral associate in Yale University’s earth and planetary sciences department and the Yale Institute for Biospheric Studies. Sibert is lead author of the new study in
“I study microfossil fish teeth and shark scales in deep-sea sediments, and we decided to generate an 85-million-year-long record of fish and shark abundance, just to get a sense of what the normal variability of that population looked like in the long term,” Sibert says.