Megalodon (Otodus megalodon) just got a tentative makeover thanks to new research that has estimated its body form. The study leaned on "three critical pieces of information" that have become available in recent years, and it paints a very different picture of this enormous bloodthirsty fish.
The first piece in the tryptic puzzle was the temperature of the megalodon's blood, with researchers concluding that it was warm-blooded, just like the modern great white shark its body form has previously been modeled off. However, it wasn’t the only one to join the warm-blooded club.
Basking sharks that feed on plankton and are still alive today were also found to be warm-blooded, which was interesting because they’re slow, sluggish swimmers – a trait typically associated with cold-blooded animals. This told researchers that being warm-blooded didn’t necessarily make megalodon a fast swimmer.
The third piece of critical information was that megalodon was found to like be a slow-cruising shark based on an analysis of its scales. In short, two out of the three cast doubt on the great white’s body form being a suitable comparison for megalodon.
“The previously published reconstruction of the vertebral column of Megalodon based on an incomplete set of fossil vertebrae of the species from Belgium was measured to be 11.1 meters [36.4 feet] without accounting for the length of the head or tail,” study co-lead Kenshu Shimada, a palaeobiologist at DePaul University in Chicago, told IFLScience. Shimada co-led a huge team of well-known shark experts with Phillip Sternes, a doctoral candidate at the University of California at Riverside.
“However, the same megalodon individual was previously calculated to be just 9.2 meters [30.2 feet], including the head and the tail, based on the size ratio of the largest vertebral diameters between the modern great white shark individuals of known body lengths and the megalodon fossil," he continued.
“While the previous studies were stuck with the idea that megalodon ought to have looked like the modern great white shark, our new study highlights the discrepancy in size estimates and emphasizes the empirical fossil evidence – the fact that the megalodon individual could not have measured less than 11.1 meters where that measurement does not even account for the head and tail lengths. Therefore, our general conclusion is that megalodon must have had a slender body compared to the body proportion seen in the modern great white shark.”
Like modern sharks, megalodon’s skeleton would’ve been made up of cartilage. This doesn’t preserve well in the fossil record, which is why confidently concluding what they looked like is a tricky task. For now, at least, it seems we should be more open-minded about what this ancient apex predator might have looked like.
That is, until we find one crucial thing...
“Our study suggests that we need to think 'outside the box' when it comes to inferring the biology of Megalodon, where the modern great white shark may not necessarily serve as a good modern analog for assessing at least certain aspects of its biology,” concluded Kenshu. “The reality is that we need the discovery of one or more complete Megalodon skeletons to be confident of megalodon's body form.”
The study is published in the journal Palaeontologia Electronica.