Megalodon shark grew to larger sizes in cooler waters
Study: Areas previously ID’d as nursery areas are in warmer water
A new shark study reveals that the iconic extinct Megalodon shark grew to larger sizes in cooler waters than in warmer areas.
DePaul University paleobiology professor Kenshu Shimada and coauthors recently took a renewed look at the body size patterns of Otodus megalodon, or megatooth shark, which lived roughly 3.6 million to 15 million years ago.
“The main conclusion of this study is that not all geographically different Megalodon individuals grew to gigantic sizes equally,” Shimada said.
Otodus megalodon is commonly portrayed as a gigantic, monstrous shark in novels and films, such as the 2018 sci-fi thriller “The Meg.” In reality, this species is only known from teeth and vertebrae in the fossil record, although it’s generally accepted scientifically that the species was indeed quite gigantic, growing to at least 50 feet and possibly as much as 65 feet.
The new study re-examined published records of geographic occurrences of Megalodon teeth along with their estimated total body lengths.
“The common notion that the species reached 18-20 m TL (60-65 feet total length) should be applied primarily to populations that inhabited cooler environments,” Shimada said.
The researchers’ findings are in line with a geographydriven ecological pattern known as Bergmann’s rule.
Introduced by German biologist Carl Bergmann in the mid-1800s, Bergmann’s rule is a broad generalization explaining that larger animals thrive in cooler climates because their size helps them retain heat more efficiently compared to animals with smaller bodies.
“Scientists constantly search for rules of life that help us predict natural patterns, and it seems that Bergmann’s rule applied to Otodus megalodon,” said co-author Victor Perez, a paleontologist at the Calvert Marine Museum in Maryland.
Some Megalodon sites were previously identified as possible nursery areas of the fossil shark because those sites yield smaller Megalodon teeth on average relative to other Megalodon localities.
However, the new study found that the previously identified nursery areas for Megalodon are located near the equator, where water is warmer.
“The results of this study have important implications for understanding how modern climate change is rapidly accelerating marine habitat shifts to more polar latitudes in apex predators such as sharks,” said co-author Michael Griffiths, a professor of environmental science at William Paterson University.
The new study — “Revisiting body size trends and nursery areas of the Neogene megatooth shark, Otodus megalodon (Lamniformes: Otodontidae) reveals Bergmann’s rule possibly enhanced its gigantism in cooler waters” — appears in the international journal Historical Biology.