Megalodon, the sea monster defeated by the climate

The second paradox about Megalodon is its disappearance. The beast gives the impression of omnipotence: yet it has disappeared. Appearing in the Lower Miocene 23 million years ago, this cosmopolitan fish flourished in all waters of the world with an acme of about -16 million years. Then again, it’s a recession. “Its traces disappeared after the Upper Pliocene between -3.6 and -2.6 million years ago”, Guillaume Guinot explains. Did the Achilles Heel do its damage early? What if there was Megalodon – already! Victim of climate change? This suggests a study published last November. The Royal Society Journal Biology Letters . The work, carried out exclusively by scientists from the University of Valencia in Spain, is based on the analysis of a collection of fossil teeth. (see box p. 84) Megalodon housed in the Cau del Touro Museum in Tarragona. These are small fangs found around this town on the northeastern coast of Spain, which belonged to young individuals. To scientists, this is a sign that there was a nursery near the shore where . had children Otodus Megalodon . And the site won’t be rare: In the process scientists identified four other “shark nurseries”—two in the United States, two in Panama—evidence that they would be present everywhere on the planet.

podcast. Find this article from here Science and Avenir – Research 892, dated June 2021, In France culture program “La Méthode Scientifique” presented by Nicolas Martin and hosted by Sidonie Bonec with France Bleu, “Minute Papillon!”, Olivier Lasker, Editor-in-Chief of the Digital Centre.

Nursery to rescue and feed baby sharks

Megalodon Nursery.This is an attractive scenario for these species with slow growth, low fertility rates and late sexual maturity.Judge Alain Pradel, in charge of preserving the collection of fossil fish at the National Museum of Natural History in Paris. There are so many features typical for large animals that scientists attribute it to the megalodon’s analogy: “They justify that adults pay special attention to the young, which are born in small numbers, to ensure the continuation of the species.”, the lecturer continues. Thus, nurseries such as the nursery in Tarragona seem to be the ideal location for the development of the young: a bay of warm and shallow water, protected by coral reefs, and therefore inaccessible to large predators but small fish and marine mammals including baby sharks. Make them regular filled with. A true paradise under the sea that ended one day. A planetary-scale event has shattered Megalodon Haven: the climate cooling that occurred between the end of the Miocene and the beginning of the Pliocene. This resulted in a fall in the sea level. Enough to empty your water nursery until it disappears; And leave the “baby” shark at the mercy of outside attacks. “The role of nurseries in the extinction of the megalodon remains a hypothesis.Angry Guillaume Guinot. For the scientist, it is really hard to imagine that a regression of ocean levels could completely deplete the nursery, given that “Even today we are at sea level. Yet many extant sharks use nurseries.”

“It is possible that it is not able to sustain itself in the face of a lack of resources and its preferred habitat,” according to paleontologist Guillaume Guinot.

But there may have been other effects contributing to explain the disappearance of cooling.Otodus Megalodon. Of course, his own body was able to adapt to it: “Megalodon was mesothermal, i.e. it was able to regulate its body temperature, Note Jack Cooper, paleontologist at Swansea University, UK. Thus he was able to adapt to the cold water to some extent”. On the other hand, climate change has also led to a lack of prey for giant sharks. Because the giant animal was in great need of food: it fed on primitive whales present in all the oceans of our planet. In any case, unless the generalized cooling, accompanied by tectonic changes such as the expansion of the ice cap at the poles and the closure of the Isthmus of Panama between North America and South America, has completely disturbed the circulation of ocean currents. The result: a drastic decline in biodiversity in the Pliocene, resulting in a decline in whale numbers in the tropics and intertropics, where megalodon preferentially evolved. “So their only option was to compete with other sharks such as the great white: because they are so small – the megalodon was three times the size of the largest white shark! -, they can swim fast, move in shallow water and meet their energy needs by feeding on small prey”, Analysis Jack Cooper. very, “The megalodon appears to have not been able to sustain itself in the face of dwindling resources and the lack of its preferential habitat., concludes Guillaume Guinot. “When species become extinct it is due to many factors, Abundant Alan Pradel . There are many influences on many other parameters of the climate.”

So how can we further refine the scenario of the monster’s disappearance? Perhaps by discovering, finally, a megalodon fossil…which is something other than teeth (which sharks constantly lose and renew over the course of their lives). “There is a rule in paleontology: the less we find, the more we can tell”, Alan Pradel laughs. The discovery of a more complete fossil would undoubtedly make it possible to deduce theories. Such a discovery isn’t impossible: After all, megalodon had enormous muscles and a wonderfully developed skeleton capable of activating its challenging jaws, capable of biting prey. Somewhere at the bottom of an ocean, beneath its sediment burial, is an entire skeleton waiting to be excavated under the water that might wake it. and talk to him.

Long thought to be the ancestor of the white shark and represented as such, Megalodon is actually related to another extinct family, the otodontids, as revealed by recent studies (artist's view).

Long thought to be the ancestor of the white shark and represented as such, Megalodon is actually related to another extinct family, the otodontids, as revealed by recent studies (artist’s view). (HUGO SALAS / METAZOA STUDIO / AFP)

A shark of about 15 meters!
Today only rare fragments of vertebrae and teeth remain from Megalodon. But what a tooth! “He had a sequence of saws, giant knives in his mouthsays Guillaume Guinot from the Institute for Evolutionary Sciences in Montpellier. Some can reach 16 cm, it is huge. By working on large species of fossil sharks, you get used to the impressive teeth. But compared to Megalodon, everything turns out to be ridiculous ”. If Megalodon’s skeleton is not made of bones – like ours – but from cartilage, a material that fossilizes badly, in contrast, its teeth are highly mineralized. One characteristic that enabled them to remain near us as fossils: several thousand specimens enrich the Palaeolithic registers around the world. Clearly triangular, they are characterized by serrated edges: an evolutionary adaptation to improve their bite power. “It shows a pattern of hunting towards larger organisms”, Guillaume Guinot continues. And it is from them that experts now know everything about extinct sharks. First, its size: since 2019, an estimate reference to American Kenshu Shimada (DePaul University, Chicago, USA). This gives the megalodon a maximum length of between 14.2 and 15.3 metres. Slight decrease compared to previous forecasts which raised it to 20m.

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