In March 2025, a team of 29 researchers from nine countries published a study that revised the accepted reconstruction of the megalodon, one of the largest predatory sharks ever known. Their work suggests that the animal was not a larger version of the great white shark, the form long used in museums, films, and textbooks, but a longer, more slender creature whose closest living anatomical match is the lemon shark.

The difficulty in reconstructing the megalodon comes down to a basic property of its biology. Its skeleton was made of cartilage, which decomposes and rarely fossilizes. After more than 150 years of searching, no complete megalodon skeleton has ever been found. What survives in collections are primarily teeth, which a single shark could shed and regrow by the tens of thousands over its lifetime. Alongside the teeth, researchers have found some vertebrae and microscopic scales. That is the full physical record of the largest macropredatory shark known to science.

Because so little of the body remained, early scientists used the teeth to build an image of the animal. In 1843, naturalist Louis Agassiz classified megalodon into the same genus as the modern great white shark. The teeth looked similar, only larger, and the assumption followed that the body must have looked similar as well. That reasoning shaped every reconstruction that came after it.

Later size estimates were built on the same logic. In 1973, a researcher calculated a length of roughly 43 feet by applying the tooth-to-body ratio of a great white shark to megalodon teeth. In 1996, two researchers refined the method and produced a model of a 52-foot shark weighing around 48 tons. That figure became the standard reference, and the accompanying image, a great white blown up to enormous size, was widely reproduced.

The first major problem with that model surfaced in 2022. A team in Wales built a three-dimensional digital model of the megalodon using real skeletal material, including a substantial set of 141 vertebrae recovered from a single animal in Belgium in 1926. That specimen preserved a continuous stretch of the backbone in life order. When two scientists measured the vertebral column directly, they found it was about 36 feet long. The accepted model, however, estimated the entire animal at roughly 30 feet. The preserved trunk alone was longer than the whole shark was supposed to be, a contradiction that indicated the great white template was fundamentally incorrect.

The 2025 study took a different approach. The researchers examined measurements from 165 shark species, including 20 extinct ones, to understand how body proportions vary across the shark family tree. They then applied those patterns to the known megalodon fossils rather than assuming a shape in advance. The result was a body plan in which the head made up about 17 percent of the animal, the trunk about 51 percent, and the tail about 33 percent. That combination describes a long, streamlined shape more suited to slow, efficient cruising than to sudden bursts of speed. The nearest living comparison was not the great white but the lemon shark, a slender coastal species with a much less imposing silhouette.

The revised proportions also changed the size estimate. Applied to the Belgian vertebral column, they produced a shark of roughly 54 feet. Using a larger vertebra found in Denmark, about nine inches across, the model suggested a possible length of around 80 feet and a weight near 94 metric tons. That approaches the length of a blue whale.

The physical requirements of moving through water support the new shape. Large aquatic animals tend to become more slender as they grow because bulk creates drag that demands too much energy to sustain. Great whites, which become stockier with age, reach a limit around 23 feet. The largest creatures in the ocean, such as whale sharks and blue whales, are all long and thin. A very large animal built like a great white would not be able to move efficiently enough to survive, while a long, tapered form could.

The revised reconstruction also fits with other known details about the species. Isotope studies indicate megalodon was warm-blooded, keeping its body temperature about 13 degrees Fahrenheit above the surrounding water. Growth rings in the Belgian vertebrae suggest a lifespan of roughly 74 to 89 years. Its young were born at 12 to 13 feet long, already the size of an adult great white, and evidence indicates it fed at the highest trophic level recorded for any marine animal, with some signs it preyed on its own kind.

The species went extinct between five and three million years ago as the planet cooled. Its warm-water habitat shrank, and its prey moved toward the poles. At the same time, great white sharks appeared in the same seas and competed with juvenile megalodons for a reduced food supply. The megalodon, slow to reproduce and too large to adapt quickly, declined until it disappeared.

The scientific debate is not fully settled. One researcher involved in the 2022 model has argued that the drag comparisons rely too heavily on whales, and no formal rebuttal to the 2025 paper had been published as of early 2026. Both sides agree that a complete skeleton would settle the question, but none has been found. For now, the best available evidence describes a predator that was not a giant great white, but a warm-blooded, whale-sized shark of a different and more slender build.