Shark Week was every week for Megalodon

New research shows that prehistoric megatooth sharks, the biggest sharks that ever lived, were at the very highest rung of the prehistoric food chain — what scientists call the highest “trophic level.” Indeed, their trophic signature is so high that they must have eaten other predators and predators-of-predators in a complicated food web, say the researchers.

“We’re used to thinking of the largest species — blue whales, whale sharks, even elephants and diplodocuses — as filter feeders or herbivores, not predators,” said Emma Kast, a 2019 Ph.D. graduate in geosciences who is the first author on the study in the June 22, 2022, issue of Science Advances. “But Megalodon and the other megatooth sharks were genuinely enormous carnivores that ate other predators, and Meg went extinct only a few million years ago.”

To reach these conclusions, Kast, along with her adviser Danny Sigman, Princeton’s Dusenbury Professor of Geological and Geophysical Sciences, and their colleagues used a novel technique to measure the nitrogen isotopes in the sharks’ teeth. Several lines of evidence point to cannibalism in both megatooth sharks and other prehistoric marine predators.

“If Megalodon existed in the modern ocean, it would thoroughly change humans’ interaction with the marine environment,” Sigman said.

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