Earth’s temperatures changed and oxygen levels in the ocean plummeted some 252 million years ago, most life on the planet was doomed. The number of Sharks has dropped. Some estimates suggest the extinction event, a mass extinction known as the Great Dying, killed off up to 70% of all land species but marine animals felt the impact even greater. As much as 96% of all species in the world’s oceans perished.
Sibert said that something happened that knocked out 90% of them overnight. Something remains uncertain, but it was devastating. The asteroid that wiped out the dinosaurs resulted in the extinction of just 30 to 35% of all shark species; this event was two to three times worse. The ocean floor is a graveyard for all of the life that’s living anywhere in the water column. Tiny pieces of the fallen, like the scales, present on a shark and teeth from fish rain down upon the ocean floor and, over time, pile up in the sediment.