Home LATEST NEWS The disappearance of the megalodon caused by the great white shark?

The disappearance of the megalodon caused by the great white shark?

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In the food chain, O. megalodon at one time occupied the highest trophic level – the rank – that of apex predator. A conclusion drawn in particular from the size of its teeth, sharp triangles easily exceeding ten centimeters, or the width of a palm of a hand. It is one of the only remains that can be used to study the animal, whose cartilaginous skeleton, like that of all sharks, does not lend itself well to fossilization.

An international team of researchers brings to NatureCommunications a new light on this giant exceeding 15 meters, which reigned in the oceans more than 3 million years ago.

The sudden disappearance, in recorded fossilsof this carnivore, among the largest that ever lived, remains an enigmaunderlines the study signed by Jeremy McCormack, geoscientist at the German Max Planck Institute.

It offers a new tool for analyzing the trophic level ofO. megalodon and its competitors, from the zinc contained in the enamel of their teeth. This metal, essential to life, is found in food and is fixed in the dentition.

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Resource competition

It is found there in the form of two isotopes – two types of atoms –, of which the greater or lesser proportion of one of them, zinc 66, has a direct link with the place of the animal in the food chain. The lower its proportion, the higher the animal is in the food chain.

The researchers tested this recent technique with the analysis of fossils from numerous museums and current species. Among the latter, the great white shark and the Mako shark are today at the highest trophic level.

But 20 million years ago, in the Miocene, that honor went to Otodus chubutensisa giant shark fond of fish and cetaceans. Otodus megalodon will succeed it as an apex predator, but at a lower trophic level, until the Pliocene era, about 5 million years ago.

Analyzes show that the megalodon then loses ground against Carcharias carcharodon, the great white shark. Although smaller in size – it does not reach more than six meters –, we know that the latter is very opportunistic in terms of food. The study in Nature notes that the two species are then at the same level in the food chain.

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We don’t know exactly why O. megalodon finally disappeared. A 2016 study saw a coincidence between the collapse of its population and a decline in the diversity of the cetaceans it fed on, with the disappearance of baleen whales in particular. The authors of the study in Nature support this hypothesis of a co-evolution and co-extinction of the two species of shark and whale.

They also see an important factor in competition with the great white shark. Their study suggests a possible competition for food resources between these two lineages of sharks. That the great white shark ended up winning.

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