Great white shark and the megalodon are not related after all?

This picture show how big were the jaws of the biggest and most voracious shark that ever swam in our oceans: the megalodon.

The extinct giant shark known as Megalodon is sometimes mistakenly referredto as a great-white shark. However, the lineage that produced this gigantic shark came from a different group. We know this because Megalodon (Carcharocles megalodon) and its ancestors can be traced through a nearly complete series of fossil beds found right here in Virginia.

The difference is in the teeth.

When the lineage first appeared 60 million years ago, its tooth shape was different from its often mistaken cousin, the great white. It had a central tall cusp of about 2½ inches (a cusp is the pointed end of the tooth) was not serrated (notched like the edge of a saw).

At 50 million years ago it continued this same tooth shape and size but began to develop fine serrations. Eventually the tooth's center cusp began to widen and the two smaller cusps became much smaller.

Between 18 and 15 million years ago the side cusps were much smaller and appeared only as bumps on the much wider central cusp. The serration of the teeth increased to about 4 inches. By the time Megalodon became extinct, the teeth were about 6 inches high and 5 inches fish.

The modern-day great-white shark has a lineage that started at the same time as the Megalodon lineage, about 60 million years ago. But the great white's lineage, Carcharodon, lacked side cusps and had much coarser serrations.