Scientists find a new clue that led to the demise of the megalodon | CNN

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A new study reveals that the ancient Otodus megalodon shark (illustrated here) was partially warm-blooded. This trait may have played a role in the extinction of the dangerous apex predator.

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Megalodon, one of the most fearsome sharks that ever lived, was not the cold-blooded killer it was made out to be – at least not in the literal sense.

By analyzing fossilized megalodon teeth, scientists have discovered that the extinct shark was a semi-warm-blooded shark with a body temperature about 7 degrees Celsius (44 degrees Fahrenheit) warmer than the estimated seawater temperature at the time, according to a study published last week. journal Proceedings of the National Academy of Sciences.

“We found that O. megalodon had a significantly elevated body temperature compared to other sharks, consistent with it having the same degree of internal heat production as modern warm-blooded (endothermic) sharks. animals do,” study co-author Robert Eagle, UCLA professor of marine science and geobiology, said in an email.

The results suggest that this distinctive feature played a key role in the evolution of ancient carnivores frightening size and its eventual disappearance.

Otodus megalodon, also known as the megatooth shark, is believed to be at least 15 meters long and was one of the largest apex marine predators since the Mesozoic era and became extinct around 3.6 million years ago. Eagle.

Scientists previously theorized that megalodons were warm-blooded, but the new study is the first to provide concrete evidence of this.

The researchers observed how closely the carbon-13 and oxygen-18 isotopes found in the fossilized teeth of the ancient shark were bound together, a data point that can reveal how warm the body was. From this finding, they concluded that the megalodon’s average body temperature was about 27 C (80 F).

Like today’s great whites and mako sharks, megalodons were regionally endothermic, meaning they had the ability to regulate the temperature of certain parts of their bodies, the study suggests. In contrast, the body temperature of other cold-blooded apex predators is regulated by the temperature of the surrounding water.

According to the study’s senior author Kenshu Shimada, a paleobiologist at DePaul University in Chicago, this could be one of the main factors contributing to megalodon’s enormous size and general predatory abilities.

“A large body promotes prey capture efficiency with wider spatial coverage, but requires a lot of energy to maintain,” Shimada said in an email. “We know that Megalodon had huge incisors used for feeding on marine mammals such as cetaceans and seals, based on the fossil record. The new study is consistent with the idea that warm-blooded evolution was the gateway to Megalodon’s gigantism to keep up with the high metabolic demands.”

The need to continuously consume so much energy to regulate the body temperature of such a huge animal may have contributed to its collapse as the world changed. The researchers noted that the timing of the megalodon’s extinction coincided with a cooling of the Earth’s temperature.

“The fact that Megalodon disappeared suggests a possible vulnerability of warm-bloods, as the presence of warm-bloods requires constant food intake to maintain a high metabolism,” Shimada said. “There may have been changes in the marine ecosystem due to climate cooling,” causing sea levels to drop, altering the habitats of food megalodon populations fed on, such as marine mammals, and leading to their extinction.

Compared to other apex predators, Megalodon was much larger and therefore more vulnerable to changes in prey populations, said lead study author Michael Griffiths, a professor of environmental science, geochemist and paleoclimatologist at William Paterson University in New Jersey.

But by learning more about the ancient shark, scientists could still better understand the threats similar marine animals face today.

“One of the big implications of this work is that it highlights the vulnerability of large predators, such as today’s great white sharks, to climate change, given their biological similarities to Megalodon,” Griffiths said.

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