Carcharodon Megalodon first appeared about 16 million years ago and was traditionally thought to be the giant ancestor of the Great White Shark. The newest view is that Megalodon belongs in a separate genus (Carcharocles) and family (Otodontidae) from the Great White Shark.
It is thought to have reached lengths as long as 40 feet. Large teeth, some over 6 inches in length, are most often found as evidence of this shark. Its teeth have been found on both sides of North America and in many other parts of the world. Most modern great white sharks are less then half the size of Megalodon.
An actual Carcharodon Megalodon tooth over 6 inches long.
Protospinax is a relative of modern rays. These fish grew to approximately 5 feet in length. They swam in the lagoons of southern Germany 150 million years ago.
150 million year old Protospinax fossil.