The largest shark that ever lived, the prehistoric—and certainly extinct—megalodon, might have been driven to extinction by a smaller and nimbler competitor that still roams the seas today: the great white shark.
The giant Otodus megalodon once reached lengths of 50 feet. While not the only large shark to swim ancient seas, it was the biggest and has grabbed modern imagination. The fixation on the beast springs from a strong foundation: Megalodon's jaws could open wide enough to swallow two adults standing side-by-side, writes Josh Davis for the Natural History Museum in London, UK.
Megalodon's physical length is accompanied by a long fossil record; the shark reigned in the oceans for about 13 million years. Research pegged the behemoth's extinction to around 2.6 million years ago. But a new study challenges that date, writes Nicolas Rivero for Quartz.
Robert Boessenecker, a paleontologist at the College of Charleston in South Carolina and lead author of the new study, and his colleagues revisited various fossils of megalodon. Their new analysis, published in the journal PeerJ, pushes megalodon's extinction date back about a million years earlier than previously thought.
The researchers used the same dataset that earlier work had relied upon to date megladon's death. But all the fossils tagged as younger than 3.6 million years had problems: they had imprecise dates, had been misidentified or the dating has since been refined based on better geology methods, a press statement from the University of Wisconsin, Oshkosh explains.
"After making extensive adjustments to this worldwide sample and statistically re-analyzing the data, we found that the extinction of O. megalodon must have happened at least one million years earlier than previously determined," Boessenecker says in the statement.
The new date offers a big clue as to how megalodon went extinct. It coincides with the rise of the great white shark, writes Maya Wei-Haas for National Geographic. Scientists had previously tied the megalon's disappearance from the fossil record to a marine extinction at the end of the Pliocene epoch, perhaps triggered by a supernova that sent harmful radiation toward earth. With the new dates, there aren't any events or changes that were widespread enough to explain the megalodon's die out—just the appearance of the great white shark on the scene.
"Nothing else is that cosmopolitan," Boessenecker tells National Geographic.
Great white sharks are smaller than the megalodon was, but they could have competed against juvenile megalodons. Other changes in the ocean at the time could have been just enough to make the difference. The megalodon was dealing with dwindling populations of the small whales they ate and shrinking into smaller, more fragmented populations, writes Melissa Cristina Márquez for Forbes. Under those threats, the appearance of great white sharks spelled the larger predators doom.
The great white shark has to survive about 10 million more years to beat megalodon's record, but from a more inclusive point of view both creatures can enjoy a reputation of adaptive success. All sorts of sharks have roamed the world's oceans for more than 350 million years. What's a little squabbling among species against that impressive record?