Prehistoric mega-shark had fin the size of human, study reveals

Researchers compared 16-metre ocean monster to modern-day relatives to estimate its full size for first time

Megalodon had a dorsal fin the size of an adult human (Getty Images/iStockphoto)

A prehistoric giant shark that once ruled the seas had fins as large as a person and teeth bigger than a human hand, according a study that claims to reveal the ocean monster’s vast size for the first time.

The scale of the megalodon, a relative of the Great White shark that lived from around 23 million to three million years ago, had previously only been estimated.

Researchers at University of Bristol and Swansea University now say the fearsome predator grew to more than 16 metres long and had a bite force of 10 tonnes. That is more than twice as big as a Great White, which has a typical bite force of two tonnes.

Research into the megalodon has previously been limited by the fact little remains of it except fossilised teeth.

But Jack Cooper, a postgraduate palaeobiologist at the University of Bristol’s School of Earth Sciences, and colleagues from Bristol and Swansea, used mathematical modelling to compare the mega-shark to other living relatives with ecological and physiological similarities and pin down its size and proportions.

Mr Cooper said: “Megalodon was actually the very animal that inspired me to pursue palaeontology in the first place at just six years old, so I was over the moon to get a chance to study it.

“This was my dream project. But to study the whole animal is difficult considering that all we really have are lots of isolated teeth.”

Previously, researchers had only compared the fossil shark, known formally as Otodus megalodon, with the Great White. The new study, published in the journal Scientific Reports, expanded this analysis to include four other modern-day sharks to which it is also related: the shortfin mako, longfin mako, porbeagle, and salmon shark.

They pooled detailed measures of all five species to make predictions about the megalodon, which has inspired Hollywood films, books and TV documentaries.

The shark’s fin is thought to have been the size of a person (Oliver E. Demuth)

Professor Mike Benton, a Bristol University palaeontologist who supervised the project, said: “Before we could do anything, we had to test whether these five modern sharks changed proportions as they grew up. If, for example, they had been like humans, where babies have big heads and short legs, we would have had some difficulties in projecting the adult proportions for such a huge extinct shark.

“But we were surprised, and relieved, to discover that in fact that the babies of all these modern predatory sharks start out as little adults, and they don’t change in proportion as they get larger.”

This mean the team could “simply take the growth curves of the five modern forms and project the overall shape as they get larger and larger – right up to a body length of 16 metres,” Mr Cooper added.

The results suggest that a 16-metre-long megalodon likely had a head round 4.65 metres long, a dorsal fin approximately 1.62 metres tall and a tail around 3.85 metres high.

These dimensions offer new insights into the megalodon’s life and habits, the researchers said. The shape and size of its fin meant it was probably well-adapted for swiftly attacking prey and long-distance swimming, but its vast proportions suggest it was unlikely to have been capable of swimming fast for a long time.

Previously studies have suggested the megalodon may have gone extinct due to growing competition from its smaller cousin, the great white.