Dr. Mette Elstrup holding a 10.8-million-year-old vertebral fossil specimen of the extinct megatooth shark, Otodus megalodon, from the Gram Formation of Denmark featured in the new study, and a reconstructed O. megalodon jaw model in the background.

Museum of Southern Jutland, Gram, Denmark

In the late 1970s, workers digging clay in Denmark unearthed something extraordinary: a collection of enormous fossil vertebrae belonging to the extinct megatooth shark, Otodus megalodon. The fossils were studied, photographed and recognized as some of the largest shark vertebrae ever found. Then, during a museum move in the 1980s, they disappeared. Scientists assumed they were lost forever, but they were hidden among forgotten boxes in a museum collection and parts of those legendary fossils were recently rediscovered. Their return is more than a happy ending to a decades-old mystery of “whodunit?” or “whereisit?” as they are providing new clues about the size, lifespan and feeding habits of one of the most famous predators in Earth’s history.

Megalodon lived between roughly 15 million and 3.6 million years ago and has become a cultural icon, appearing in documentaries, novels, blockbuster films and nightmares. Despite its fame, scientists still know remarkably little about it. Unlike most bony fish, sharks have skeletons made primarily of cartilage, which rarely fossilizes; as a result, most of what we know about Megalodon comes from its teeth, which can reach more than 7 inches (18 centimeters) in length. Complete skeletons of this great predator do not exist — in fact, even partial skeletons are incredibly rare.

That makes every vertebra, every fragment and every clue exceptionally valuable! The rediscovered fossils come from the Upper Miocene Gram Formation in Denmark, a marine deposit that formed about 10.8 million years ago. At the time, the area was covered by a deep offshore sea more than 328 feet (100 meters) deep and teeming with life. We know this because fossils from the site include sharks, rays, fishes, marine mammals, seabirds and even sea turtles. The Megalodon specimen from here originally consisted of around 20 vertebrae but unfortunately, much of the material deteriorated over time. Still, enough survived for researchers to confirm a critical detail: some of the vertebrae measured an astonishing 9 inches (23 centimeters) in diameter. That measurement matters because it forms the basis of current estimates for the shark’s maximum size. Earlier research by the lead author, Dr. Kenshu Shimada, compared these giant vertebrae with those from a more complete Megalodon specimen from Belgium using proportions derived from living and extinct shark species. The 2025 publication estimated that the Danish individual could have reached approximately 79.7 feet (24.3 meters) in length. For perspective, that is nearly three times longer than a modern white shark and longer than many city buses! The rediscovered fossils support this 2025 estimate. In fact, they may suggest the animal had the potential to grow even larger. But the researchers remain cautious. Without a complete skeleton, there is still uncertainty as body size estimates depend on assumptions about anatomy and growth patterns. “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,” cautioned Shimada. Nevertheless, the Danish vertebrae represent the largest known shark vertebral specimen ever discovered and quite possibly the largest vertebrae known from any fish.

The team also used high-resolution micro-CT scanning to look inside the fossils! Similar to counting rings in a tree trunk, scientists can sometimes examine growth bands preserved within shark vertebrae to estimate age. The scans revealed at least 64 growth bands, suggesting the shark was at least 64 years old when it died. A theoretical growth model indicated it may have been capable of living as long as 96 years. If these estimates are correct, they paint a picture of a predator that grew slowly, lived for decades and occupied the top of the food web for much of its life… very similar to the life-history traits often associated with large marine animals today, including whales and many shark species.

But perhaps the most surprising discovery came from the sediment surrounding the vertebrae.

The team found tiny scales and gill-related structures belonging to a basking shark. At first, they considered whether the giant vertebrae themselves might belong to a basking shark but the anatomy did not match as basking shark vertebrae have a different shape and proportions than those of Megalodon. So, instead, the team proposed a fascinating alternative explanation: the basking shark remains may represent stomach contents. If correct, this would be the first direct evidence of prey preserved alongside Megalodon remains! Modern basking sharks are gentle filter feeders, but they can grow to impressive sizes, so finding evidence that a giant Megalodon may have consumed one reinforces the idea that Megalodon likely hunted or scavenged a wide range of large marine animals.

We often speak about Megalodon as if we understand it completely. Yet scientists are still debating its maximum size, growth rates, lifespan and feeding ecology. The answers to many questions around this animal remain elusive. For now, the rediscovered Danish vertebrae provide one of the strongest pieces of evidence yet that Megalodon truly was among the largest predators Earth has ever produced. And until a more complete skeleton emerges from the fossil record, these fossils will continue to shape our understanding of a shark that has captivated human imagination for generations.