The Megalodon: What Happened to the Ocean’s Fiercest Predator?

The largest shark to have ever lived is the mighty Otodus megalodon, which might have been up to 80 feet long. These enormous creatures required a lot of food to survive, and they nourished themselves by eating large prey such as whales, dolphins and possibly other megalodons. Their teeth were the size of human hands, and these giant chompers are the most prominent fossil that megalodons left behind after they disappeared.

Megalodons have recently captured people’s imaginations, with the action movies The Meg (2018) and The Meg 2: The Trench (2023) portraying fictional versions of megalodons living in the modern day. Some conspiracy theorists have even wondered if megalodons might still exist. However, paleontologists agree that megalodons are definitely extinct. They lived between 23 million and 3.6 million years ago, long before modern humans walked the earth.

What caused their extinction—and why are paleontologists certain that megalodons are no longer alive?

The name “megalodon” is a Greek-derived word meaning “giant tooth.” It's an apt name, considering megalodons’ teeth could be up to 7 inches long. Megalodons had hundreds of these giant teeth lining their ferocious jaws. Like modern sharks, megalodons regularly shed their teeth, meaning that just one megalodon could have left thousands of teeth on the ocean floor.

Megalodon teeth have fascinated humans for millennia, and they make up the vast majority of known megalodon fossils (the only other known megalodon fossils are vertebrae). Researchers often find these teeth in geologic formations that are currently above sea level but used to be below it, like the Calvert Cliffs that line part of Maryland’s shoreline along the Chesapeake Bay.

Megalodons’ triangular teeth featured serrated edges that helped them slice into large prey. We know megalodon ate whales and dolphins because researchers have found megalodon teeth embedded in ancient whale and dolphin bones, says Stephen J. Godfrey, curator of paleontology at the Calvert Marine Museum in Maryland.

Although rarer, researchers have also found megalodon teeth that were bitten by other megalodon teeth.

“It’s possible that those teeth were bitten only because they were scavenging an already dead megalodon,” says Godfrey, who has co-authored a paper on this phenomenon. “But there is evidence of cannibalism in modern sharks, and so it’s not impossible that large megalodons could have been preying on smaller megalodons.”

So how did such a formidable apex predator go extinct? That’s something paleontologists are still trying to figure out.

Researchers have theorized that competition with other predators like great white sharks (Carcharodon carcharias) for food sources could have led megalodons to die out. Cooling global temperatures might also have played a role, as could changing geographic factors like the formation of the Isthmus of Panama, which might have fragmented megalodon populations, Godfrey says. Most likely, a combination of factors led to the megalodon’s extinction.

But one thing that’s firmly settled among paleontologists is that megalodons are extinct, and there are very clear reasons why.

“If megalodon was still alive today, people wouldn’t be wondering if they saw a megalodon, they would know for sure that they saw a megalodon,” Godfrey says. “It’s hard to hide an 80-foot-long predator that has to live in the photic zone [where light penetrates], because that’s where its prey are.”

Godfrey’s point gets at one of the problems with conspiracy theories about megalodons secretly lurking in the deep. (In The Meg, a megalodon is living at the bottom of the Mariana Trench, the deepest part of the ocean.) Even though megalodons could breathe underwater, their prey couldn’t. The whales and dolphins that megalodons hunted are marine mammals that need to live near the ocean’s surface to breathe. In turn, megalodons lived closer to the surface to have ready access to their next meals.

There are modern sharks that are comparable in size to megalodons, and we already know about them: The largest recorded length of a whale shark (Rhincodon typus) is over 60 feet. These sharks have tiny teeth and feed on much smaller prey, so they don’t leave the same signs of hunting that megalodons would.

“If megalodon still existed…we would know it,” says Nick Pyenson, curator of fossil marine mammals at the Smithsonian National Museum of Natural History in Washington, D.C. “And the best way we’d know it is we’d find whales that were bitten in half.”

With all the modern interest in megalodons, the Calvert Marine Museum is campaigning for Maryland to designate the extinct species as its state shark. This would make Maryland the first state to have its own official shark and draw attention to the state’s extensive fossil record of megalodon teeth. (Incidentally, Maryland already has a state fossil.)

“There are over 60 different kinds of sharks that are found as fossils in Maryland, and so we have a rich history of sharks having lived here,” Godfrey says, who adds that the museum is singling out the megalodon for its campaign because it’s an “amazing iconic shark” that left fossils in at least seven Maryland counties.

“Maryland is famous for its marine fossils, which have been found for several hundred years,” Pyenson says. These include lots of fossilized shark teeth, and “the most spectacular examples of those fossil shark teeth is megalodon.”