US researchers have found that Megalodon was the most massive shark that ever lived, even among living sharks.
Most Megalodon fossils date to around 15 million years ago, however, little is known about its anatomy; since shark skeletons are made of cartilage rather than bone, they are extremely scarce in the fossil record, save for their plentiful fossilized teeth, which were used by a research group led study author Kenshu Shimada, a professor of paleobiology at DePaul University in Chicago, to estimate the size of the animal.
In the study published Monday in the journal Historical Biology, Shimada and his colleagues generated a new tool for calculating body length: an equation representing the actual quantitative relationship between body length and tooth size in lamniform. They based it on the teeth and known body lengths from 32 specimens of living, predatory lamniform sharks, representing all shark species including Megalodon.
The researchers found that many extinct lamniform sharks were quite large, and the Megalodon was the biggest among them, estimated to have measured up to 50 feet (15 meters) in length, about as long as a bowling lane. It was also substantially bigger than the next-biggest extinct shark in the Lamniformes order by at least 23 feet (7 meters).
While the Megalodon picture is now a little clearer than it was before, many fundamental questions about the size of the massive super-shark are still unanswered. Why Megalodon became extinct is another big fundamental question that remains unsettled, Shimada said.
Speaking about the value of the new findings, Shimada said understanding body sizes of extinct organisms is important in the context of ecology and evolution. "Lamniform sharks have represented major carnivores in oceans since the age of dinosaurs, so it is reasonable to assert that they must have played an important role in shaping the marine ecosystems we know today. This is why we need further information about them," he added.
