An illustration shows the large extinct shark megalodon, Otodus megalodon, preying on a seal in this picture obtained by Reuters on June 27, 2023. Alex Boersma/PNAS/Handout via REUTERS.
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. Megalodon, perhaps the largest shark of all time, appeared about 23 million years ago, then disappeared about 3.6 million years ago amid declining ocean temperatures and sea levels."Yet, the fact that the species became extinct suggests the probable vulnerability - or the cost - of being warm-blooded because warm-bloodedness requires constant high food intake to sustain high metabolism," paleobiologist and study co-author Kenshu Shimada of DePaul University in Chicago said.