Megalodon was no Cold-blooded Killer
Published:17 Jul.2023 Source:University of California - Los Angeles
After analyzing isotopes in the tooth enamel of the ancient shark, which went extinct about 3.6 million years ago, the scientists concluded the megalodon could maintain a body temperature that was about 13 degrees Fahrenheit (about 7 degrees Celsius) warmer than the surrounding water. That temperature difference is greater than those that have been determined for other sharks that lived alongside the megalodon and is large enough to categorize megalodons as warm-blooded. The paper, published in Proceedings of the National Academy of Sciences, suggests that the amount of energy the megalodon used to stay warm contributed to its extinction. And it has implications for understanding current and future environmental changes.
In the new study, the scientists looked for answers in the megalodon’s most abundant fossil remains: its teeth. A main component of teeth is a mineral called apatite, which contains atoms of carbon and oxygen. Like all atoms, carbon and oxygen can come in “light” or “heavy” forms known as isotopes, and the amount of light or heavy isotopes that make up apatite as it forms can depend on a range of environmental factors. So the isotopic composition of fossil teeth can reveal insights about where an animal lived and the types of foods it ate, and — for marine vertebrates — information like the chemistry of the seawater where the animal lived and the animal’s body temperature.
The researchers collected teeth from the megalodon and other shark contemporaries from five locations around the world, and analyzed them using mass spectrometers at UCLA and UC Merced. Using statistical modeling to estimate sea water temperatures at each site where teeth were collected, the scientists found that megalodons’ teeth consistently yielded average temperatures that indicated it had an impressive ability to regulate body temperature.Its warmer body allowed megalodon to move faster, tolerate colder water and spread out around the world. But it was that evolutionary advantage that might have contributed to its downfall, the researchers wrote.