A giant megalodon shark which lived in oceans around the world over between 15 and 3.6 million years ago was "off the charts," and likely to have measured over 50ft long.
New research examining measurements taken from the same group of sharks as the Otdodus megalodon suggests the animal could have reached 15m or 50ft in length.
In comparison, great white sharks can grow to more than 6m or 20ft, whereas the blue whale, a mammal, can reach 30m.
Kenshu Shimada, a paleobiologist at DePaul University in Chicago and lead author of a new megalodon study said the shark was "off the charts in the shark world."
Scientists do not have a complete fossilised skeleton of the beast and paleontologists have to rely on studying teeth, the toughest part of any shark’s body.
Dr Shimada' research shows exactly how uniquely gigantic the megalodon was and says they "must have played an important role in shaping the marine ecosystems" known today.
Dr Shimada said: "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."
Fossil records indicate the megalodon species dominated oceans during that period, before eventually dying out.
The new study also proposes a reproductive strategy with a unique cannibalistic egg-eating behaviour among early hatched embryos, which takes place while still inside the mother.
Scientists said this could nourish early-hatched embryos and be a cause for the gigantism achieved by megalodon sharks.
Co-author Michael Griffiths, a professor of environmental science at William Paterson University in Wayne, New Jersey said: "This is compelling evidence for the truly exceptional size of megalodon."