A new study published in the journal Earth and Planetary Science Letters reveals that Otodus megalodon, the prehistoric giant shark, had a more versatile diet than previously thought, feeding on a broader range of prey including large fish and marine mammals. An international team of scientists, including Dr. Jeremy McCormack from Goethe University Frankfurt, conducted an analysis of the zinc isotopic composition in fossilized teeth of megalodon to determine its position in the food chain, as reported by Science Alert.
"Our investigation paints a picture of megalodon as an ecologically versatile generalist," McCormack, the lead author of the study, stated, according to Science Alert. He noted the shark's diverse diet and flexibility in feeding on both large and small prey, which had important implications for revising the idea that it focused exclusively on hunting whales.
"We studied fossil teeth from deposits in Sigmaringen and Passau, Germany, that 18 million years ago were part of a shallow estuary next to the Alps. There coexisted species of sharks and fish, from those that fed on mollusks on the seafloor to large predators like Otodus megalodon," McCormack detailed, as reported by Science Daily.
By examining the zinc isotopic composition in the teeth, the researchers were able to reconstruct predator-prey relationships from about 18 million years ago. Zinc isotopes served as a valuable tool for paleoecological reconstructions, helping to determine an animal's position in the food chain. "When animals eat, some metals in their food replace some of the calcium in their teeth and bones, leaving a tracer," Science Alert explained.
The study found that megalodon occupied the top level of the food pyramid but was flexible enough to switch to prey from lower levels, depending on availability. This opportunistic feeding strategy indicates that megalodon was not a specialized predator exclusively hunting whales but rather fed on a much wider range of prey, including marine mammals measuring two to eight meters in length and large fish.
"The megalodon was flexible enough to feed on marine mammals and large fish, both from the top of the food chain and from lower levels, depending on availability," McCormack emphasized, according to Agencia SINC.
"It gives us important insights into how the marine communities have changed over geologic time, but more importantly the fact that even 'supercarnivores' are not immune to extinction," commented Kenshu Shimada, a paleobiologist at DePaul University in Chicago, as cited by Science Alert.
Otodus megalodon swam through the world's oceans from around 23 million to 3 million years ago, occupying a prime position at the top of the food web during the Miocene and Pliocene epochs. The giant shark could grow up to 20 meters in length, making it longer than a truck with a trailer, and is considered the largest predatory fish in Earth's history.
Megalodon is known primarily from its fossilized teeth and a few vertebrae, as its skeleton was mostly cartilage. The name megalodon means "big tooth." Embedded in its jaws were triangular teeth the size of a human hand.
The zinc isotopic analysis allowed the researchers to compare the trophic levels of megalodon and other prehistoric sharks. Fish at the top of the food chain had the least zinc-66 compared to zinc-64, indicating their high position in the trophic hierarchy. The data showed that megalodon had a lower ratio of zinc-66 to zinc-64, consistent with its role as a top predator but also suggesting dietary flexibility.
The study also reconstructed a model of the marine food web in the region, revealing that sea bream, which fed on mussels, snails, and crustaceans, formed the lowest level of the food chain studied. Above them were smaller shark species such as requiem sharks and ancestors of today's cetaceans, dolphins, and whales. Larger sharks such as sand tiger sharks were further up the food pyramid, and at the top were giant sharks like Otodus megalodon.
"The isotopic signals of the megalodon also show that it occasionally fed on prey located at lower levels in the food web," McCormack explained, according to Agencia SINC.
Despite its flexibility in prey hunting, megalodon was not spared from extinction. The scarcity of large prey and the emergence of smaller, more efficient predators, such as the modern great white shark (Carcharodon carcharias), may have contributed to its decline. Previous work led by McCormack indicated that the rise of the great white shark was likely one of the drivers that led megalodon to extinction.
The preparation of this article relied on a news-analysis system.