Megalodon is definitely extinct—and great white sharks may be to blame

Megalodon were the rulers of the ancient oceans. The massive creatures grew up to 60 feet long and sported jaws more than six feet wide. FERNANDO G. BAPTISTA, DAISY CHUNG, RYAN T. WILLIAMS, CHIQUI ESTEBAN, AND JAIME HRITSIK, NG STAFF; FANNA GEBREYESUS

Megalodon were the rulers of the ancient oceans. The massive creatures grew up to 60 feet long and sported jaws more than six feet wide. FERNANDO G. BAPTISTA, DAISY CHUNG, RYAN T. WILLIAMS, CHIQUI ESTEBAN, AND JAIME HRITSIK, NG STAFF; FANNA GEBREYESUS

The beaches were deserted near Santa Cruz, California, on December 23, 2007. Temperatures were cool for Cali standards, and the wind whipped unpleasantly across the sandy expanse.

But that didn't stop paleontologist Robert Boessenecker from avidly trolling the chilly shores. A senior at Montana State University at the time, Boessenecker was on the hunt for fossils, and he soon found his prize: a dark greenish blue tooth the size of his hand—“about as big as they come,” he says—peeking out of a cliff.

This rare find came from the ancient Otodus megalodon, the largest shark to ever glide through Earth's oceans. Though movies continue to stoke the conspiracy that these nearly 60-foot-long beasts still lurk in the inky depths,the megalodon is unquestionably extinct. Boessenecker's find on that wintery day instead kicked off his decade-long quest to figure out exactly when these behemoths made their earthly exit. (Explore how humans size up to sharks in our interactive graphic.)

Now, he finally has his answer: The megalodon vanished some 3.6 million years ago, around a million years earlier than previous estimates. The new date, published February 12 in the journal PeerJ, coincides with the rise of the modern great white shark, hinting that this shakeup in the marine hierarchy may have spelled doom for the mighty “meg.”

Hunting the megalodon

To solve the cold case, Boessenecker, now an adjunct lecturer at the College of Charleston, and his colleagues started searching for more traces of the megalodon in California, creating a compendium of West Coast finds. They quickly expanded their search to other regions, to take a broader look at this ancient disappearing act.

The samples in their growing list were not only ones the researchers found themselves, but also fossils from the published literature and freshly scrutinized discoveries in museum collections. Several times throughout this hunt, the team tried to publish their work. And though reviews were generally positive, Boesenecker says, there always seemed to be a reason for rejection, including concerns about the paper's length (the final version is 47 pages, not counting appendices).

Still, they weren't the only ones hunting for clues. In 2014, Catalina Pimientoof the University of Florida and Christopher Clements of the University of Zurich published their analysis of the megalodon's extinction using available records. That team concluded that these creatures could have lingered in the oceans until sometime around 2.6 million years ago, a mere half million years or so before our ancient human relatives Homo erectus took their first wobbly steps.

Deadly detective work

For the latest study, Boessenecker and his colleagues combined their sleuthing with the 2014 study's data into one mega-catalog. But they were suspicious of some of the more recently described teeth and vertebrae. Some samples were broken or chemically altered by the element phosphorus—evidence that they hadn't stayed put through the millennia and could be feigning a younger age. Others seemed to have iffy origins, making it impossible to accurately position them in time. Still others needed date readjustments that took more recent analyses of those samples into account.

Boessenecker estimates that they excluded 10 to 15 percent of the samples that lacked the necessary exactness in space and time. And as they pored through the remaining records one by one, a pattern started to emerge.

“It wasn’t quite Woodward and Bernstein sitting in the Library of Congress in All the President's Men,” Boessenecker says. “But it’s a lot of boring but classic detective work.” In the end, the results were clear: It's likely the megalodonwas gone by 3.6 million years ago, with margins of error that mean the date could be as young as 3.2 million years ago and possibly as old as 4.1 million years ago.

Read the full story on National Geographic’s website