This article was originally published on Nov. 15, 2021.
Sharks are survivors. An ancient lineage of animals dating back to at least the Devonian Period, from 359 to 419 million years ago, they predate much of the life we know today. They came before grass, the dinosaurs and the mammals. They came before Saturn’s rings formed (between 10 and 100 million years ago.)
Through many of Earth’s mass extinction events, these finned predators have endured. The K–T extinction that annihilated the dinosaurs only wiped out about 30 percent of sharks.
But a study published in Science this June investigated the denticles that sharks leave behind and found something rather shocking. About 19 million years ago, sharks had an extinction event of their own. Over 70 percent of the pelagic, or open-water, shark species disappeared, and their abundance dropped by 90 percent. There’s no clear answer as to why.
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