Ancient Giant Sharks Were Warm-Blooded

Being warm-blooded can support larger body size and ancient giant sharks called megalodons were among them. Most fish and reptiles are cold blooded.

Otodus megalodon (center in this illustration, preying on a seal) was warmer-blooded than the great white shark (top left). That warm-bloodedness may have helped it grow so large, but also ultimately spelled its doom as food sources dwindled.

Massive, megatoothed Otodus megalodon ran hot — the ancient shark was at least somewhat warm-blooded, new evidence shows.

Chemical measurements from fossil O. megalodon teeth suggest the sharks had higher body temperatures than their surrounding waters, researchers report June 26 in Proceedings of the National Academy of Sciences. Analyses of carbon and oxygen in the teeth of these and other sharks, both living and extinct, revealed that the giant shark’s body temperature was about 7 degrees Celsius warmer than estimated seawater temperatures at the time.

From Science News citing three papers:

* M. Griffiths et al., Endothermic physiology of extinct megatooth sharks. Proceedings of the National Academy of Sciences (June 26, 2023). doi: 10.1073/pnas.2218153120.

* J. A. Cooper et al. The extinct shark Otodus megalodon was a transoceanic superpredator: Inferences from 3D modeling. Science Advances (August 17, 2022). doi: 10.1126/sciadv.abm9424.

* H. Ferrón. Regional endothermy as a trigger for gigantism in some extinct macropredatory sharks. PLOS ONE (September 22, 2017). doi: 10.1371/journal.pone.0185185.