Contrary to popular belief, great whites are not the long lost grandchildren of megs. But both occupy the throne at the top of the food chain—just at very different points in history. Because of this, many theories on megalodon physiology and behavior are based on great whites; however, scientists now know these two species independently developed similarities without much of a genetic connection.
To keep in tip-top shape, megalodon likely snacked on whales, dolphins, and seals, consuming a literal ton of food each day—a job made easy by serrated six-inch teeth that, en masse, have the strongest bite force of any animal in history. Even if megalodon occasionally scavenged, they were likely active predators, as evidenced by the ghastly grooves found in whale and dolphin bones scattered along the world’s shores.
Megalodon teeth have informed much of what scientists know of the creature, partially out of sheer abundance. Unlike humans, sharks cycle through teeth continuously, shedding 20,000 or more into surrounding waters in the course of a lifetime. On the heels of each sloughing event are up to five new rows of teeth arranged like concentric roulette wheels, waiting to take their predecessors’ place. According to Hans Sues, curator of vertebrate paleobiology at Smithsonian’s National Museum of Natural History, the meg teeth humans have dredged up number in the high thousands, and these fossils have been an important source of information on the beast.
Teeth are not just the most abundant meg relic; they’re also some of the only meg relics that have survived to present day. Sharks are cartilaginous fish—only a minority of their skeletons are calcified. They’re basically big, fleshy ears with fins (and in this light, much less terrifying). Lightweight and springy, a cartilage-based form is conducive to speedy swimming in pursuit of prey. But what’s good for the meg hasn’t been good for shark researchers: Cartilage simply isn’t built to survive the ages, meaning the meg’s left behind a pretty spotty fossil record.
Still, as one of the meg’s only tangible legacies, teeth are worth their salt. “Teeth are really important,” says Meghan Balk, a researcher of paleobiology at the Smithsonian’s National Museum of Natural History, who has studied megalodon. “They interact with the environment and [show] how the animal feeds. They’re the best proxy we have [for these traits].”
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Sadly, the same awe-inspiring attributes that defined megalodon existence may also have been what drove this top predator into extinction. The exact nature of its disappearance is still heavily debated, but it’s likely a number of factors contributed to the meg’s demise.
At such an indomitable size, there was little in the sea the meg couldn’t nosh on. With no predators of its own, megalodon ruled a dictatorship, dominating a cosmopolitan range of habitats. All megalodon needed to flourish were abundant, blubbery prey and coastal nurseries in which to breed. But around 2.6 million years ago, the last of them seem to have abandoned ship—right around the time of the most recent ice age.
The timing’s no coincidence: Global cooling did a number on the meg. It’s possible megalodon struggled to stay warm as waters grew chilly. But according to Catalina Pimiento, a paleobiologist and megalodon expert at Swansea University and a fellow at the Smithsonian Tropical Research Institute in Panama, a tweak of the world’s thermostat was likely of little concern to a hardy species that had conquered all but the iciest of the world’s oceans. Like great white sharks, megalodon were probably actually pretty good at maintaining a body temperature warmer than surrounding waters—a trait rare amongst fish.
Rather, Pimiento says, as sea levels fell as the oceans iced up, the availability of prey habitats gradually declined, felling with them an estimated 55 percent of marine mammals—mainstay meals for the megalodon. At the same time, other top predators like killer whales and great whites began to swim the seas, further straining the meg’s grasp on its dwindling resources. By the time temperatures began to climb, megalodon were long gone.
A common pet theory among meg fanatics is that these creatures still lurk in the unexplored depths of the world’s oceans. There, they brood in silence, biding their time until they happen upon an unlucky submarine. (This is essentially the plot of The Meg.) Most shark experts scoff at this notion. As Skomal puts it, “We’ve spent enough time fishing the world’s oceans to have a sense of what’s there and what’s not.”
To be fair, megalodon are pretty recently deceased—relatively speaking, at least. The end of the dinosaurs dates back to about 66 million years ago, while these super sharks were splashing the seas almost 64 million years later. But timing is really the meg’s only vote of confidence, and a weak one at that. A few million years is a long time to slink beneath the surface of the sea unnoticed, especially when you’re as long as a standard bowling lane.
What’s more, to remain in permanent stealth mode in those treacherous depths, megalodon would have needed to undergo some pretty drastic changes. The bottom of the sea is dark and frigid. The creatures relegated to these habitats have been forced to come up with some pretty creative ways to weather the extremes—and the further down you go, the weirder things get.
According to Skomal, great white sharks—our best living megalodon proxy—can’t tolerate the deep sea for more than a few hours at a time. Adding to this problem is the fact that the deep ocean is—compared to the shallows where most prey frolic—fairly sparsely populated. Even swaddled in the coziest of down jackets, deep-sea megalodon would be in a constant calorie deficit.
Bretton Kent, a professor at the University of Maryland who studies extinct sharks, adds that many of the ocean’s most abyssal residents tend to be slow swimmers that gum on teeny prey—a portrait incompatible with the meg’s modus operandi. If some version of this extinct shark exists in the sea’s trenches, it wouldn’t be much of a megalodon at all.