There’s a new suspect in the mystery of the megalodon’s extinction. For years, scientists have been trying to piece together why the biggest shark ever to terrorize the seas disappeared a few million years ago.
Previous research suggested the behemoth predators died out around 2.6 million years ago, along with a slew of early seals, walruses, dolphins, and whales, in a mass-extinction event caused by radiation from a nearby supernova. But a new study, published Feb. 13 in the Journal of Life and Environmental Sciences, argues that megalodons became extinct 3.6 million years ago—a million years earlier than previously thought. And the authors finger a new culprit: the great white shark.
Modern great whites—complete with the serrated teeth we now know and fear—first show up in the fossil record 6 million years ago, but it took them 2 million years to venture out of the Pacific Ocean and conquer the globe. The researchers argue that once the smaller, nimbler great whites established a foothold in their territory, the megalodons were done for.
“We propose that this short overlap (3.6-4 million years ago) was sufficient time for great white sharks to spread worldwide and outcompete O. megalodon throughout its range, driving it to extinction—rather than radiation from outer space,” said Robert Boessenecker, a paleontologist at the College of Charleston in South Carolina and the study’s lead author, in a statement.
In the paper, the researchers argue that adult great whites “would have been in the same size range and likely would have competed with juvenile Otodus megalodon.” They identified two more possible culprits: range fragmentation—when populations of a species get split up into separate areas—and declining numbers of the small whales that megalodons preyed on.
The researchers base their conclusion on a reexamination of the fossil record, which they claim has been misinterpreted in previous studies.
“We used the same worldwide dataset as earlier researchers but thoroughly vetted every fossil occurrence, and found that most of the dates had several problems—fossils with dates too young or imprecise, fossils that have been misidentified, or old dates that have since been refined by improvements in geology,” Boessenecker said.