The formidable Megalodon was the largest shark species that ever lived. This prehistoric mega-shark prowled Earth’s oceans from the beginning of the Miocene some 23 million years ago until the end of the Pliocene and the dawn of the Pleistocene, as previously reported by the Inquisitr.
Scientifically known as Carcharocles megalodon, the massive shark species was recently reclassified as Otodus megalodon, notes Science Alert. A distant relative of the great white shark (Carcharodon carcharias), Megalodon could reach incredible lengths of up to 60 feet and weigh as much as 60 tons.
The general consensus is that this mega-shark went extinct some 2.6 million years ago, during the transition from the Pliocene to the Pleistocene. However, the exact cause of Megalodon’s demise remains a mystery.
For a long time, the extinction of this great prehistoric beast was put down to climate change. As the Inquisitr reported earlier today, a newly emerged theory suggests that the extinction of Earth’s aquatic megafauna, Megalodon included, may have been brought on by massive supernova explosions recorded shortly after the start of the Pleistocene.
Yet a more recent study, presented on Monday at the annual meeting of the American Geophysical Union, points to another — even more surprising — reason that could have triggered the downfall of Megalodon. According to this latest research, the giant, school-bus-sized predator of Earth’s ancient oceans may have died off due to its high body temperature, reports Live Science.
Similar to the mighty sharks of modern times, such as the great white and the mako shark (Isurus), Megalodon was believed to be endowed with thermoregulation, therefore being able to adjust its body temperature in order to adapt to a warmer or cooler environment.
To find out more about its body temperature in comparison with that of modern sharks, the authors of the new study conducted a geochemical analysis of shark teeth belonging to both Megalodon and the great white. The fossils were unearthed from Pliocene deposits in Japan; meanwhile, the modern shark teeth came from great whites that had been either bred in aquariums or caught in the wild, in the waters of the Pacific and Atlantic Oceans.
The team examined rare carbon and oxygen isotopes, known as clumped isotopes, found within both types of shark teeth samples. These isotopes create different bonds that are influenced by body temperature when teeth begin to form, explained study co-author Michael Griffiths, an associate professor in the Department of Environmental Science at William Paterson University in New Jersey.
“This project uses ‘isotopic fingerprinting’ of teeth of megalodon and other marine vertebrates to determine not only their body temperatures but also their dietary behavior and ambient seawater chemistry during the past 15 million years,” study co-author Kenshu Shimada, a paleobiology professor at DePaul University in Chicago, Illinois, told Eos.
The results revealed that Megalodon “maintained a higher body temperature” compared with the great white shark, which was likely due to its massive size. More specifically, the researchers uncovered that Otodus megalodon was more warm-blooded, with body temperatures ranging between 95 degrees and 104 degrees Fahrenheit.
In contrast, ancestors of modern-day mako and great white sharks that shared the oceans with Megalodon were significantly more cold-blooded — in the literal sense of the word — and had body temperatures of 68 degrees to 86 degrees Fahrenheit.
The revelation that Otodus megalodon was “quite warm,” as Griffiths puts it, led to the speculation that the prehistoric mega-shark most likely had a very active metabolism. This meant that Megalodon had no choice but to gorge on vast amounts of prey in order to maintain its high body temperature.
“However, cooling of ocean temperatures during the Pliocene would have constrained the species to lower latitudes where ocean temperatures were warmer, whilst its preferred prey (e.g., whales) evolved traits to adapt to cooler temperatures of the higher latitudes,” the authors wrote in their paper.
“Therefore, large climatic shifts combined with evolutionary limitations may provide the ‘smoking gun’ for the extinction of the largest shark species to ever roam the planet.”