The ancient Otodus megalodon, the largest shark to ever swim in our planet’s oceans, still inhabited the sea up to around 3.6 million years ago. The exact cause of the species’ extinction is still debated, likely a combination of environmental change and competition with smaller shark species played a role.

Despite its fame in pop-culture, surprisingly little is known about the life-appearance of the megalodon. Sharks have only a cartilaginous skeleton that quickly decays after death, only their hard teeth survive the long and ardeous fossilization process. Megalodon was formerly thought to be a close relative of the great white shark (Carcharodon carcharias) based on similarities observed between fossil teeth and current-day Carcharodon teeth. The great white shark often measures more than 19 feet (or 6 meters) in length. So megalodon was depicted as a very big white shark with length estimates ranging from 80-100 feet (25-30 meters). However, it is now classified into the extinct family Otodontidae, which diverged from the great white shark lineage during the Early Cretaceous, some 100 million years ago. As the two species are not closely related, the teeth – body size relationship of C. carcharias alone can’t be used to reconstruct the body size of the extinct relative.

A study published in the journal Scientific Reports uses the growth curves of five current-day shark species – the great white shark C. carcharias, the mako shark species Isurus oxyrinchus and Isurus paucus (megalodon’s closest living relatives), the salmon shark Lamna ditropis and the porbeagle Lamna nasus – for a body size estimation in the extinct species O. megalodon. The study notes that as modern sharks grow bigger, their body proportions remain the same, a shared character likely found also in their extinct relative. Applying the growth curves of the five modern forms and project the overall shape as they get larger and larger on their precedessor, the researchers reconstruced the complete body of Otodus megalodon.

The results suggest a full-grown megalodon is likely to have had a head about 15.2 feet long, a dorsal fin 5.3 feet tall and a tail 12.6 feet long, reaching a total length of 52.5 feet (or 16 meters). The new body size proportions fit well with research published last year, arguing that the scientifically justifiable maximum size for megalodon was around 50 feet (15 meters).