This isn’t to say that all sharks have weathered these last few hundred million years. On the contrary, many species have died out and new ones have evolved over the Earth’s cycles of growth and extinction. A period known as the Carboniferous Period some 359 million years ago is said to have been the Golden Age of Sharks. About 3/4 of all the Earth’s species had recently died out – including many fish – so sharks were free to dominate.
And dominate they did. Uninhibited by predators, a number of strange new shark species evolved: the stethacanthus with its unusual fin sticking out of its back; the helicoprion with its spiral saw-like lower jaw; and the falcatus with a spike-like protrusion reaching over its head, to name just a few.