By: Pei-Yu Tsai

Megalodons, ancient gigantic sharks with mysterious and awe-inspiring features, have become a hot topic in many Hollywood movies due to their terrifying nature. Recently, more and more research, based on novel geochemical techniques, have revealed that this cold-blooded killer was actually more warm-blooded than previously thought. This feature set megalodons on a path to the apex of the food chain, but also led to their extinction.

Previous studies have suggested that megalodons, formally called Otodus megalodon, lived in oceans worldwide from 23 million to 3.6 million years ago. With a length reaching at least 15 meters, their massive size made them the largest predators in the marine food chain. They were likely warm-blooded or regionally endothermic, similar to a group of sharks called mackerel sharks, which includes modern members such as the great white and thresher sharks.

While most fish are ectothermic, meaning their body temperature matches the surrounding water, megalodon sharks can thrive and hunt in both colder and warmer water. This indicates that they are endothermic animals, controlling their body temperature by promoting metabolism. (Source by: Science News Explores)

The claim that megalodons are endothermic is further supported by empirical evidence from a new study published in the peer-reviewed journal Proceedings of the National Academy of Sciences. The study, conceived and led by Professors Michael Griffiths and Martin Becker of William Paterson University’s Environmental Science department, used fossilized teeth to analyze the megalodon’s body temperature. They found that it was significantly higher than previously expected.

This warm-blooded characteristic helped give the megalodon swift swimming abilities, extensive range of activity in the ocean, and high hunting capabilities. However, the energy-demanding nature of maintaining metabolism through consuming large amounts of food is also a double-edged sword and may have contributed to its eventual extinction.

“Maintaining an energy level that would allow for megalodon’s elevated body temperature would require a voracious appetite. That may not have been sustainable in a time of changing marine ecosystem balances when it may have even had to compete against newcomers such as the great white shark,” said Randy Flores, a UCLA (University of California–Los Angeles) doctoral student who worked on the study.

Scientists believe that the extinction of the megalodon occurred during the Pliocene Epoch, approximately 5.3 million to 2.6 million years ago. During the period, significant climate change led to sharp decline in the population of marine mammals, resulting in a scarcity of the megalodon primary food sources.

To study how warm the body temperature of ancient sharks was, the team utilized techniques involving ‘clumped isotope thermometry’ and ‘phosphate oxygen isotope thermometry.’ They measured clumped isotopes in the dentin of the teeth to determine the body temperature of Megalodon. Additionally, scientists analyzed cold-blooded animals that lived in the same period to uncover the ocean’s water temperature.

“You can think of the isotopes preserved in the minerals that make up teeth as a kind of thermometer, but one whose reading can be preserved for millions of years. Because teeth form in the tissue of an animal when it’s alive, we can measure the isotopic composition of fossil teeth in order to estimate the temperature at which they formed and that tells us the approximate body temperature of the animal in life,” said Flores.

This new discovery reveals the advantages and vulnerabilities of large marine apex predators. For more detailed research, please refer to “Endothermic physiology of extinct megatooth sharks.”

Source:

 https://www.snexplores.org/article/megalodon-fossil-warm-blooded-predator

 https://newsroom.ucla.edu/releases/megalodon-warm-blooded-extinct-shark

 https://www.sciencefocus.com/news/megalodons-warm-blooded-demise/

 https://www.newswise.com/articles/megalodon-shark-was-warm-blooded-confirm-researchers-using-geochemical-technique

 https://scitechdaily.com/megalodon-was-no-cold-blooded-killer-and-that-spelled-its-doom/

 https://scitechdaily.com/the-warm-blooded-megalodon-geochemistry-and-fossil-teeth-illuminate-the-prehistoric-predator/?expand_article=1

 https://www.sciencefocus.com/news/megalodons-warm-blooded-demise/