A restoration of Carcharocles megalodon at the San Diego Natural History Museum

A restoration of Carcharocles megalodon at the San Diego Natural History Museum. Although such restorations are based on teeth and the anatomy of modern great white sharks, new evidence indicates that the two sharks were only distant cousins separated by millions of years of evolution. Photo: Brian Switek / Wired

Few predators terrorize our imaginations as fiercely as the great white shark. The immense fish is sublimely attuned to an environment that is alien to us, and, despite the rarity of accidents, the nightmare of slipping down the shark’s throat has obscured the fact that we have done far worse things to these apex predators. And, in a culture where bigger is frequently confused with better, the great white’s prehistoric cousin Carcharocles megalodon has gained almost as much fame. A 15-foot-long white shark is imposing enough, but the 50-foot-long version has inspired even more awful novels and blood-soaked b-movies than its living relative.

Today’s Carcharodon carcharias and the extinct Carcharocles megalodon have often been linked together on account of their teeth. With the exception of rare vertebrae, that’s really all we know of the “megashark.” The rest of the shark’s cartilaginous frame has never been found, and may forever remain that way. Still, since the triangular, finely serrated teeth of Carcharocles megalodon roughly resembled the more coarsely serrated teeth of today’s great white sharks, some ichthyologists and paleontologists connected the two together as close relatives – if not actually ancestor and descendant. The great white shark could be a dwarfed version of its massive, whale-crunching forerunner, or a very close cousin.

Not everyone has agreed that the two sharks were close kin, though. In fact, recent analyses have underscored a different scenario that drives a wider gap between the two sharks.