He was clearly a giant – but what physical features did Megalodon have, of which almost only the teeth have been preserved? A new model now shows what proportions the primeval mega-shark could have had. It is based on evaluations of the body shapes and growth characteristics of today’s shark species with reference to the extinct giant. Among other things, the model shows that the dorsal fin of an adult megalodon about 16 meters long could reach approximately the size of an adult human.
Huge teeth, which have been discovered in many places around the world, bear witness to a gigantic shark that roamed the seas of the earth until about three million years ago. The triangular walkers are sometimes larger than a human hand and suggest that megalodon (Otodus megalodon) was more than twice as large as the great white shark (Carcharodon carcharias), which can be up to seven meters long. Tooth marks on the fossil bones of whales suggest that what is probably the largest shark of all time has primarily eaten marine mammals. Why it died out remains largely unclear. There are, however, suspicions that the smaller, but more adaptable great white shark might have ousted it.
What did the monstrous shark look like?
Since no further megalodon fossils have been found apart from the teeth and isolated vertebrae, details of the physique of the former kings of the sharks remain unclear. When modeling the size and anatomy of extinct animals, palaeontologists orientate themselves on the comparison of found body parts with those of relatives that still exist today. For a long time, the great white shark was regarded as the closest living counterpart to the megalodon within the group of jack sharks (Lamnidae) and thus served as a model for the extinct giant. A detailed examination of the tooth features, however, called the particularly close relationship of these two species into question. “Megalodon is not a direct ancestor of the great white shark, but probably related to other representatives of the jackshark as well,” says co-author Catalina Pimiento from Swansea University in the UK.
For this reason, the scientists included other mackerel shark species in their modeling of the giant’s appearance, which have a way of life similar to what the megalodon probably once did. In addition to the great white shark, these were the long-fin mako (Isurus paucus), the short-fin mako (Isurus oxyrinchus), the salmon shark (Lamna ditropis) and the porbeagle (Lamna nasus). The researchers recorded the anatomical features of these shark species at certain developmental stages in order to develop a model of the body proportions of their extinct cousins from the entirety of the information.
Details of the anatomy emerge
In doing so, they first recorded an aspect that was fundamentally important for the model: “Before we could continue, we first had to clarify whether the proportions of these five modern sharks during theirs
Change as you grow up, ”says co-author Michael Benton of the University of Bristol. This effect is very pronounced in humans, for example: babies have comparatively large heads and short legs. “If there was something similar with the sharks, we would have had difficulties projecting the proportions of the adults onto the extinct shark,” explains Benton. “But we were able to document within the scope of the study that the babies of the modern predatory sharks examined are born like small adults and do not change their proportions when they get bigger,” reports the scientist. The researchers were able to use the growth curves of the five modern mackerel sharks as a basis for their projections of the dimensions of the body shapes with increasing size.
As they report, they assume a maximum size of the megalodon of around 16 meters. This falls in the middle range of previous estimates of the size of the shark. Newborns were probably around three meters long and young animals eight meters, write the researchers. As can be seen from the new model, a fully grown megalodon had a 4.65 meter long head area and there were about six meters between the tip of the nose and the transition into the dorsal fin. This trademark of the sharks was about 1.62 meters high in the megalodon and about two meters wide at the base, according to the calculations. The pectoral fins reached a length of about three meters and a caudal fin about 3.85 meters high provided the propulsion of the giant. The traits presumably enabled the animal to move quickly and swim stamina, the researchers write.
They now hope that their study can contribute to further research into these spectacular sea predators of the past. Reconstructing the size of the megalodon’s body parts represents a fundamental step towards a better understanding of the physiology of these giants and could also provide clues as to what made its success or its decline, the scientists sum up.
Source: Swansea University, Article: Scientific Reports, doi: 10.1038 / s41598-020-71387-y