CHICAGO — An associated set of gigantic vertebrae belonging to the iconic extinct Megalodon or megatooth shark that had been missing since the 1980s was recently rediscovered, providing new information about the shark’s lifestyle in Palaeontologia Electronica. 

The 10.8-million-year-old vertebral specimen was originally discovered in the late 1970s, but was misplaced recently after its discovery, leaving behind only photographic evidence in the scientific literature. The rediscovery of the specimen, which was the foundation of size and weight estimates of Otodus megalodon, has allowed researchers to review the specimen after forty-plus years of building scientific understanding of the shark’s lifestyle.

“The rediscovery of the vertebrae was a true delight because it empirically confirms the maximum vertebral diameter of 23 cm reported in the literature,” said the lead author of the new study, Kenshu Shimada, who is a paleobiology professor at DePaul University in Chicago. “The specimen not only represents the largest shark vertebrae known to date but also the largest fish vertebrae ever recorded to our knowledge.”

Although no complete skeletons of Megalodon exist, current size measurements originate from a reasonably complete string of trunk vertebrae in Belgium, which is thought to have come from a 16.4-meter-long individual. 

“The sharks’ cartilaginous skeletons make their preservation potential generally very low except for their highly mineralized teeth,” said Trine Sørensen, a natural history conservator at the Museum of Southern Jutland, who prepared the vertebral specimen. “The Gram Formation exposed in the claypit is special in that, besides one known gigantic Megalodon tooth, we have multiple examples of well-preserved fossilized shark vertebrae, although the specimen in our study remains the only Megalodon vertebra from the site.”

Mette Elstrup, the Head of the Natural History section of the museum, added, “The giant Megalodon vertebrae are of great importance because size matters when it comes to understanding the biology, ecological impact, and geographic distribution pattern of this extinct giant predator. The Gram claypit site also represents the scientifically verifiable latitudinally highest Megalodon locality in the world, which does not contradict the previous observation that larger Megalodon remains are more common in cooler regions relative to warmer regions.”

The research team also analyzed incremental growth bands, indicators of growth similar to tree rings, in the Megalodon vertebrae, which revealed that the Megalodon individual was at least 64 years old when it died, with a possible theoretical longevity of 96 years. 

The rocks surrounding the Megalodon vertebrae were found to contain fragmentary gill-associated structures and tiny scales of another shark, the basking shark. 

“This led us to interpret the basking shark elements to represent the stomach contents of the Megalodon, which is the first documentation for the Megalodon fossil record,” said coauthor Mikael Siversson, a paleontologist at the Western Australian Museum in Welshpool.

Deciphering the body size of large extinct carnivores like Megalodon is important in the context of ecology and evolution. “Although our growth model suggests that Megalodon could have theoretically grown even slightly larger, the length of 24.3 meters is currently the largest possible scientifically justifiable estimate for O. megalodon,” said Shimada. This new study, “Rediscovery of the associated gigantic vertebrae of the extinct megatooth shark, Otodus megalodon, from the Upper Miocene Gram Formation in Denmark, and comments on its paleobiological significance and the maximum possible size of the species,” authored by Shimada, Elstrup, Lauridsen, Sørensen, and Siversson is available online: https://palaeo-electronica.org/content/2026/5872-otodus-megalodon-vertebrae-from-denmark