Big whites may have condemned the largest shark that ever lived, exposing fossil teeth – KION546

Author: Katie Hunt, CNN

Megalodon, a huge shark that lived more than 23 million years ago and was the inspiration for “The Meg,” was almost four times the size of the great white shark that crosses our oceans today.

However, these two species of sharks, which once coexisted, probably hunted the same prey. This competition could potentially be one of the reasons why the 65-foot-long (20-meter-long) megalodon has become extinct, a new study suggests.

To achieve this finding, the researchers involved in the study used a new technique. They analyzed the dietary traits found in the teeth of 13 extinct shark species and 20 modern sharks to understand where they fit into the food chain – also known as their trophic level.

“Megalodon is typically portrayed as a super-large, monstrous shark in novels and movies, but the reality is that we still know very little about the extinct shark,” said study author Kenshu Shimada, a professor of paleobiology at DePaul University in Chicago. researcher at the Sternberg Museum of Natural History in Kansas.

“Our new study shows that the dietary range of the early white shark pliocene is very similar to that of the megalodon, suggesting that our data do not contradict the competition hypothesis,” he said in an email.

The researchers were able to obtain this information by monitoring the presence of various isotopes or variants of the chemical element zinc preserved in sharks. tooth enamel.

Zinc is essential for living organisms and plays a key role in bone development. The ratio of heavy to light zinc isotopes in the teeth keeps track of the type of animal the sharks ate.

“Zinc isotopes can be used as ecological indicators because the ratio of these two different isotopes varies as you progress through the food chain,” said co-author Michael Griffiths, a geochemist and professor in the Department of Environmental Science. at William Paterson University in New Jersey.

For example, if a megalodon ate large white sharks, its higher position in the food chain would be reflected in the isotope record. But the study found two types they overlapped to some extent, suggesting that they shared similar prey items. However, the authors warned that they could not rule out that the megalodon hunts large whites, given that the values ​​of its isotopes, and especially its close relative, called Chubutensis megalodon, had lower values ​​than any modern and fossil marine vertebrate measured..

Feeding at the same trophic level does not necessarily mean direct competition between the megalodon and great white sharks for the same prey, as both species could specialize in different prey. However, at least some food overlap between the two species was likely, the study said.

“Like today’s whites, they probably ate big fish. The smaller big whites probably didn’t require as much food as the megalodon, so they would have a competitive advantage if they fed similar prey, “Griffiths said in an email.

The research was published Tuesday in the journal Nature Communications.

This study was the first case to show that diet-related zinc isotopes are stored in fossilized shark teeth.

A similar technique, using nitrogen isotopes to study dietary signatures for other groups of animals, is well established, the study said. However, the nitrogen in the dentin of the teeth is not stored well enough to be able to study animals that became extinct millions of years ago.

The technique using zinc isotopes could be applied to other extinct animals to understand their diet and ecology.

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