The megatooth shark, Otodus megalodon, which likely reached at least 15 m in total length, is an iconic extinct shark represented primarily by its gigantic teeth in the Neogene fossil record. This ancient species is largely known only from its teeth and vertebrae in the fossil record. Thus, the living great white shark (Carcharodon carcharias) has traditionally been used as a model for the body form of Otodus megalodon in previous studies. The new study, however, illuminates that Otodus megalodon had a body form that was more elongated than the great white shark.
Also referred to as Carcharocles megalodon, Otodus 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. Previous studies assume that the shark likely reached lengths of at least 15 m.
However, Otodus megalodon is largely known only from its teeth and vertebrae in the fossil record — a rather incomplete set of data from which to draw assumptions.
Thus, the modern great white shark was traditionally used as a model for Otodus megalodon bodies in previous studies. That model led paleontologists to conclude that the shark was round and stocky like great whites.
“Previous research depicted the shark species with a stocky body shape like that of the white shark and other lamnid species, but with the new study disputing this body shape interpretation,” said Dr. Mikael Siversson, a researcher at the Western Australian Museum.
“The mismatch between the stocky build of Otodus megalodon in published paleoartistic reconstructions and the surprisingly small diameter of the largest known vertebral centra of this species has bothered me for a long time.”
“The species had in fact an unusually slender vertebral column, which is at odds with previous reconstructions depicting megalodon as a girthy shark.”
“The only fossil material available of this enormous shark comprises associated dentitions, a relatively complete vertebral column and isolated vertebrae and shed teeth.”
“Although we have a very good idea about the size of the mouth from associated dentitions seemingly including all tooth positions, other anatomical features such as the shape of the fins and tail are unknown.”
“It was refreshing to see such broad and strong support among my peers for a more strictly evidence-based view on the anatomy of this iconic species of extinct shark.”
“Going forward, any meaningful discussion on the anatomy of this shark other than the size and robustness of the jaws would require the discovery of more-or-less complete skeletons.”
Otodus megalodon body shape comparison. Image credit: Western Australian Museum.
“Our team reexamined the fossil record, and discovered Otodus megalodon was more slender and possibly even longer than we thought. Therefore, a better model might be the modern mako shark,” said Dr. Phillip Sternes, a researcher at the University of California Riverside.
“It still would have been a formidable predator at the top of the ancient marine food chain, but it would have behaved differently based on this new understanding of its body.”
“Despite the major scientific advancement in our new study, the fact that we still don’t know exactly how Otodus megalodon looked keeps our imagination going,” said DePaul University’s Professor Kenshu Shimada.
“The continued mystery like this makes paleontology, the study of prehistoric life, a fascinating and exciting scientific field.”
The study was published in the journal Palaeontologia Electronica.
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Phillip C. Sternes et al. 2024. White shark comparison reveals a slender body for the extinct megatooth shark, Otodus megalodon (Lamniformes: Otodontidae). Palaeontologia Electronica 27 (1): a7; doi: 10.26879/1345