When many think of the prehistoric Megalodon (Otodus megalodon), they often think of the fierce predator being super-sized. Previous studies suggest that the shark, which has a cosmopolitan range roughly 15-3.6 million years ago, likely reached lengths of at least 50 feet (15 meters) and possibly as much as 65 feet (20 meters). Yet a new scientific study, led by University of California Ph.D. candidate Phillip Sternes, shows that all previously proposed body forms of this giant still remain in the realm of speculations. “There are currently no scientific means to support or refute the accuracy of any of the previously published body forms of O. megalodon,” stated Sternes in a press release.
The most common way that Megalodon is portrayed is… well, like this. A shark that looks like a … [+]
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“The study may appear to be a step backward in science, but the continued mystery makes paleontology, the study of prehistoric life, a fascinating and exciting scientific field,” said Dr. Kenshu Shimada, DePaul University paleobiology professor and a coauthor of the study. Sternes graduated from DePaul in 2019 and was mentored by Shimada; this new study, appearing in an issue of Historical Biology, also includes Shimada’s current graduate student Jake Wood.
Traditionally the great white shark (Carcharodon carcharias) was used as a body form model for Megalodon. The great white is part of the Lamnidae shark family, which include species like mako, porbeagle, and salmon sharks. These species are known to be regionally endothermic (partially warm-blooded), allowing them to be active predators even in colder waters. While Megalodon was not a lamnid shark, it was thought to have been regionally endothermic when it was alive and ruling our oceans. Based on this information, a previous study saw researchers using a two-dimensional geometric shape analyses on the body forms of modern lamnids to propose an inferred body form for “The Meg.”
But was this the right way to go about inferring body shape? The new study by Sternes, Wood and Shimada examined whether this approach could differentiate the body forms represented by modern endothermic (warm-blooded) species from those of modern ectothermic (cold-blooded) ones within the shark order called Lamniformes, which also includes the great Megalodon. The results showed that there is no relationship between thermophysiology and body form in lamniforms. “Although it is still possible that O. megalodon could have resembled the modern great white shark or lamnids, our results suggest that the two-dimensional approach does not necessarily decisively allow the body form reconstruction for O. megalodon,” Wood explained. “All previously proposed body forms of Otodus megalodon should be regarded as speculations from the scientific standpoint,” Sternes added.
Traditionally the great white shark (Carcharodon carcharias) was used as a body form model for … [+]
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Many wonder why scientists can’t just recreate the shark’s body form, but it isn’t as easy as it sounds. While shark teeth are among the most common vertebrate fossils, fossilized shark skeletons are much harder to come by. That is because they are made of cartilage, which doesn’t typically fossilize as well as bone because it doesn’t mineralize as much. So it is no surprise that Otodus megalodon is known only from its teeth and very few vertebrae in the fossil record. “Any meaningful discussion about the body form of O. megalodon would require the discovery of at least one complete, or nearly complete, skeleton of the species in the fossil record,” said Wood.
While this seems like a setback, Shimada disagrees: “The fact that we still don’t know exactly how O. megalodon looked keeps our imagination going. This is exactly why the science of paleontology continues to be an exciting academic field. We’ll continue looking for more clues in the fossil record.”
