Megalodon, the famed prehistoric shark, is the stuff of legends. Their huge teeth – as big as the palm of a hand – fuel unquenchable rumours of their continued survival, a plethora of implausible YouTube videos, and the devoted fascination of a legion of children.

Megalodon presents as a formidable prehistoric predator of epic proportions. But just how big was it? Like the fish that got away, giant creatures get bigger and bigger with the telling, leading to frequent exaggeration and misrepresentation, even in the driest scientific accounts.

The title of Big Meg: The story of the largest and most mysterious predator that ever lived plays right into this Meg-mythology. While hyperbole may be an effective marketing tool, in this case the subtitle is simply wrong. Even the largest estimates of megalodon (twenty metres long and fifty tonnes) are on a par with sizes reported for modern whale sharks or prehistoric marine reptiles such as Kronosaurus and slightly smaller than either modern sperm whales or prehistoric Livytan sperm whales. Megalodon would be dwarfed by the modern blue whale, which reaches a maximum of thirty metres long and two hundred tonnes. All of these are predators – animals which feed on other animals. Such looseness with the truth casts a disturbing pall over the reliability of what should be a factual, science-based book.