Nearly 19 million years ago something caused the death of 90% of the world’s open-ocean sharks.
What happened to cause the massive kill off is a mystery to scientists.
Researchers say that fossils found in sediment in the Pacific helped them see that some 19 million years ago the population of sharks plunged, but they can’t say what it was that killed the ocean predator, according to an article in Science published earlier this month.
“It’s a great mystery,” Elizabeth Sibert, a paleobiologist and oceanographer at Yale University, told Science News. “Sharks have been around for 400 million years. They’ve been through hell and back. And yet this event wiped out (up to) 90% of them.”
According to Sibert, there is no obvious climate event that could have affected sharks in such a dramatic fashion.
“Nineteen million years ago is not known as a formative time in Earth’s history,” Sibert said.
Sibert, along with colleague Leah Rubin, a marine scientist at the State University of New York College of Environmental Science and Forestry in Syracuse, discovered the evidence of the shark extinction event by studying fish teeth and shark scales that were found in sediment in the Pacific Ocean.
“We stumbled into this thing completely by accident because what we saw was everything was pretty stable until about 20 million years when sharks dropped off in abundance by over 90%,” Sibert told CNN.
“We found that sharks were doing incredibly well in the open ocean until this one moment in time when they virtually disappeared.
“We had no idea because no one had ever looked.”
Sibert said it is unclear how long the event that killed the sharks lasted, saying it could have been as rapid as one day or could have taken years.
“It’s possible something big happened, but whatever it was it was very rapid,” Sibert said. “The Earth’s system was able to correct it, but these big predators, these sharks that were living in the open ocean, must have been very susceptible to this rapid environmental change. But this is still just a hypothesis.”
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