Feed Item
Added a post  to  , sharks

Fossil records show that roughly 90 percent of the planet's open-ocean sharks inexplicably vanished.

Sharks are some of nature’s greatest survivors. For more than 400 million years, the marine predators have plied Earth’s waters, from shallow reefs to the heart of the open ocean. Sharks are older than the oldest fossil forest. They’ve made it through at least four mass extinctions.

And yet, 19 million years ago, something mysteriously dealt open-ocean sharks a huge blow—one from which they’ve never recovered.

Records of this extinction, detailed for the first time in the journal Science, come in the form of shark scales, called denticles, found in seafloor samples from the Pacific Ocean. Based on the shapes and abundance of denticles in the samples, the researchers estimate that the planet’s open-ocean shark populations suddenly and inexplicably fell by more than 90 percent. By contrast, during the extinction event that killed off the non-avian dinosaurs 66 million years ago, sharks suffered losses of roughly 30 percent.

Full Article >>