Shark fossils first appear in the Silurian period, around 450 million years ago. That’s millions of years before dinosaurs first walked the Earth. The Golden Age of prehistoric sharks, though, began about 360 million years ago when sharks became the largest predators in the sea. They had already begun to perfect their torpedo-shaped bodies, fins, and sharp teeth. Sharks continued to survive mass extinctions, leading to the massive Megalodon, the largest shark ever, perhaps two to three times as long as a great white shark. Scientists doubt great whites are direct descendants of Megalodon, but the two do share some common features.