Los tiburones Megalodón podrían haberse convertido en megapredadores al calentarse.

The team used this technique on teeth from the different sharks, as well as fossil samples from other ancient ocean contemporaries including whales and mollusks. (Mollusks, being entirely cold-blooded, represent the ocean water temperature, Eagle says). The data show that both sharks were a bit endothermic, but not only was O. megalodon’s average body temperature (about 27⁰ C) higher than its surrounding waters, it was also higher than the average body temperature of great whites (about 22⁰ C) living in similar waters. Neither shark was as warm-blooded as marine mammals, such as the whale groups Odontoceti and Mysticeti, the team determined.

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It’s “a very interesting finding, and it is fantastic that we have more evidence for regional endothermy in megalodon,” Cooper says. O. megalodon’s higher body temperature would have allowed it “to swim further and faster, increasing its chances of encountering prey,” he says. “But it also means that if food availability declines, megalodon would not have been able to meet its huge energetic requirements.” And when changing sea levels in the Pliocene led to a decline in the sharks’ prey about 3 million years ago, “it may well have starved into extinction.”

Eagle and colleagues are now delving into the chicken-or-egg question of which came first for O. megalodon: warm-bloodedness or apex predator status. “You need a high trophic level to become gigantic,” Eagle says. But is warm-bloodedness necessary to get to that high trophic level (apex predator status)? “We’re hoping to fit it all together into an evolutionary story as to what drives what.”

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