The megatooth shark, Otodus megalodon, is an iconic shark represented primarily by its gigantic teeth in the Neogene fossil record, but the lack of well-preserved skeletons has hampered the understanding of various aspects of its biology. In new research, paleontologists reassessed some of its biological properties using a new approach, based on known vertebral specimens of Otodus megalodon and 165 species of extinct and living sharks across ten orders. Their results show that Otodus megalodon could have had a slender body and possibly reached about 24.3 m in length.
Otodus megalodon went extinct 3.6 million years ago. Image credit: Alex Boersma / PNAS.
Otodus megalodon, also referred to as Carcharocles megalodon, is a gigantic megatooth shark that lived in the world’s oceans from 23 to 3.6 million years ago.
This creature is typically portrayed as a super-sized monster in popular culture, with recent examples in the sci-fi films.
“Otodus megalodon is represented primarily by its gigantic teeth measuring up to at least 16 cm and possibly as much as about 20 cm in height from Neogene marine deposits nearly worldwide,” said DePaul University’s Professor Kenshu Shimada and colleagues.
“Some vertebrae, placoid scales, and fragments of tessellated cartilage have also been reported up to now.”
“However, the lack of complete fossil specimens has resulted in uncertainty regarding the true size of this prehistoric shark.”
In their study, the authors examined an incomplete vertebral specimen of Otodus megalodon, mostly consisting of trunk vertebrae was 11.1 m, from the Miocene of Belgium as well as specimens of 165 species of extinct and living neoselachian sharks.
“Assuming that Otodus megalodon had a body plan consistent with the vast majority of sharks, we determined that its head length and tail length possibly occupied about 16.6% and 32.6%, respectively, of the total body length,” they said.
“Because the Belgian specimen measures 11.1 m, its head and tail were calculated to be about 1.8 m and 3.6 m long, respectively, making the estimated total length of 16.4 m for the specific Otodus megalodon individual.”
“The largest vertebra of the Belgian specimen measures 15.5 cm in diameter, but putative Otodus megalodon vertebrae measuring as much as 23 cm in diameter are reported from Denmark.”
“If the Danish vertebrae represent the largest vertebrae in the body, that individual could have measured about 24.3 m long.”
Based on comparisons of their body part proportions, they determined that the body form of Otodus megalodon likely resembled superficially the modern lemon shark (Negaprion brevirostris), which has a more slender body than the modern great white shark.
They also noticed that modern-day gigantic sharks, such as the whale shark (Rhincodon typus) and basking shark (Cetorhinus maximus), as well as many other gigantic aquatic vertebrates like whales, have slender bodies because large stocky bodies are hydrodynamically inefficient for swimming.
In contrast, the great white shark with a stocky body that becomes even stockier as it grows can be large but cannot be gigantic (no more than 7 m) because of hydrodynamic constraints.
“Our new study has solidified the idea that Otodus megalodon was not merely a gigantic version of the modern-day great white shark, supporting our previous study,” said Phillip Sternes, an educator at SeaWorld San Diego.
“What sets our study apart from all previous papers on body size and shape estimates of Otodus megalodon is the use of a completely new approach that does not rely solely on the modern great white shark,” added Jake Wood, a doctoral student at the Florida Atlantic University.
According to the team, a 24.3-m-long Otodus megalodon may have weighed around 94 tons, with an estimated cruising speed of 2.1-3.5 km per hour.
“The growth patterns recorded in the vertebral specimen from Belgium suggested that Otodus megalodon gave live birth to newborns measuring about 3.6-3.9 m long and that embryos nourished themselves through egg-eating behavior,” the authors said.
“Additional newly inferred growth patterns along with the known fossil record of Otodus megalodon and the white shark lineage support the idea that the rise of the great white shark roughly 5 million years ago likely played a role in the ultimate demise of Otodus megalodon due to competition.”
“Many interpretations we made are still tentative, but they are data-driven and will serve as reasonable reference points for future studies on the biology of Otodus megalodon,” Professor Shimada said.
The study was published online in the journal Palaeontologia Electronica.
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Kenshu Shimada et al. 2025. Reassessment of the possible size, form, weight, cruising speed, and growth parameters of the extinct megatooth shark, Otodus megalodon (Lamniformes: Otodontidae), and new evolutionary insights into its gigantism, life history strategies, ecology, and extinction. Palaeontologia Electronica 28 (1): a12; doi: 10.26879/1502
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