Tooth analysis confirms the megalodon - a huge ancient shark - was warm-blooded

Analysis of megalodon teeth are providing a fuller understanding the mineral makeup of their enamel-like tissue which confirms that the ancient shark was warm-blooded

The megalodon, a huge shark that was the scourge of the ancient oceans and is a star in modern movie theaters, is named for its "large tooth" - and for good reason. Its serrated teeth - up to about 7 inches long (18 cm) - could tear through any prey in the deep blue sea.

Those teeth now are providing a fuller understanding of this extinct predator, with an analysis of the mineral makeup of their enamel-like tissue confirming that megalodon was warm-blooded - a trait scientists suspect contributed both to its tremendous success and eventual downfall.

Researchers estimated that megalodon, which reached at least 50 feet (15 meters) and possibly 65 feet (20 meters) long while hunting marine mammals including whales, boasted an overall average body temperature of about 81 degrees Fahrenheit (27 degrees Celsius) and could keep it at about 13 degrees F (7 degrees C) above that of the surrounding seawater.

This may have made megalodon a more dynamic predator - a strong swimmer able to digest food in an energetically efficient manner and, importantly, tolerate colder water, letting it broaden its range to nearly worldwide.

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Most fish are cold-blooded - ectothermic - with body temperatures matching the surrounding water. But a few are warm-blooded - endothermic - generating their own body heat. Examples include certain sharks including the largest modern one, the great white.

"The only comparable living species today in terms of both diet and body temperature are the great white shark and, to a lesser extent, the mako shark. Though, as shown in our study, megalodon was quite a bit warmer than both of these modern apex predators, which makes megalodon unique," said geochemist and paleoclimatologist Michael Griffiths of William Paterson University in New Jersey, lead author of the research published in the journal Proceedings of the National Academy of Sciences.