Having been on Earth for more than 400 million years, sharks have learned how to survive natural disasters. Along with hurricanes, tornadoes and volcanic eruptions that ravage our planet today, sharks have also survived the Big Five— the series of mass extinction events that wiped out swathes of animals and plants over millions of years.
The most catastrophic of them all, the Permian-Triassic extinction of 252 million years ago, is named the Great Dying for good reason: It wiped out a staggering 90 percent of marine life and 70 percent of land wildlife. It took 10 million years for the planet to recover.
And yet, sharks remained.
While studying sites that had once been an ocean floor during the Cretaceous period, paleontologists discovered fossilized teeth of the tiny Cladodontomorph shark, according to research published in 2013. Until this point, researchers believed this shark was a victim of the Great Dying. But they had survived by leaving their natural shallow waters for "deep-sea refuge environments," the study concludes.
