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However, it is possible that two species of sharks, which once coexisted, caught some of the same prey. A new study has suggested that this competition may be one reason for the extinction of the 65-foot (20-meter) megalodon.
To reach this result, the researchers involved in the study used a new technique. They analyzed the food signatures in the teeth of 13 extinct shark species and 20 modern shark species to understand where they fit in the food chain – also known as the trophic level.
“Megalodon is usually depicted as a huge, awful-sized shark in novels and movies, but the truth is that we still know very little about the extinct shark,” said study author Kensho Shimada, professor of paleobiology at DePaul University in Chicago. Research Associate at the Sternberg Museum of Natural History in Kansas.
“Our new study shows that the food range of the great white shark in the early Pliocene is very similar to that of megalodon, indicating that our data do not contradict the competition hypothesis,” he said by email.
The researchers were able to gather this information by looking at the presence of different isotopes, or variants, of the chemical element zinc preserved in sharks. Tooth enamel.
Zinc is essential to living organisms and plays a critical role in bone development. The ratio of heavy and light zinc isotopes in the teeth keeps a record of the type of animal matter the sharks ate.
“Zinc isotopes can be used as environmental indicators because the ratio of these two different isotopes changes as you move up the food chain,” said co-author Michael Griffiths, a geochemist and professor in the Department of Environmental Sciences. at William Paterson University in New Jersey.
For example, if megalodon ate great white sharks, its higher position in the food chain would be reflected in the isotopic record. But the study found both types Some overlap, indicating that they shared similar prey items. However, the authors cautioned that they could not rule out megalodon that preyed on large eggs, given that the values of its isotopes, especially a relative of Megalodon, called Chupotensis megalodon, were worth less than any modern and fossil marine vertebrates that have been measured..
Feeding at the same trophic level does not necessarily imply direct competition between megalodon sharks and great white sharks for the same prey, as both species would have specialized on different prey. However, the study said, at least some overlap in nutrients between both types is likely.
Griffiths said via email.
This study was the first time that the preservation of zinc isotopes associated with diet had been demonstrated in the teeth of fossilized sharks.
A similar technique, using nitrogen isotopes to study the nutritional signatures of other groups of animals, is well established, the study said. However, the nitrogen in dentin is not preserved well enough to study animals that became extinct millions of years ago.
The technique that uses zinc isotopes can be applied to other extinct animals to understand their diet and ecology.
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