When palaeobiologist Elizabeth Sibert set out to build a record of fish and shark populations over millions of years, she didn't expect to be solving a mysterious disappearance case.
This revealed that the number of different shark groups had dropped by around 70 per cent.
But the mysterious extinction event discovered by Dr Sibert and Ms Rubin resulted in a decline that was twice as severe for sharks compared to what they experienced during the Cretaceous-Paleogene event. "We weren't expecting this, because this period is not known for rapid extinctions or major global change," Dr Sibert said.
"It's an example of the biology telling us that this is a really important interval in Earth's history that we've been overlooking," Dr Sibert said.Sharks have been cruising the oceans for over 400 million years, making them older than the earliest trees.Today, more than 400 species of sharks inhabit the oceans, with 180 of these living in Australian waters."What we see today is a tiny fraction of the diversity that they once knew," Dr Sibert said.
"Losing 90 per cent of the abundance of a really important predator group is a huge deal to an ecosystem, and can really derail how the ocean works," Dr Sibert said.
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