Megalodon was an ancient shark that may have been 12 m or more long. Some scientists estimate (from many fossilized teeth and a few fossilized vertebrae that have been found) that it could have been 15.5 to 31 m long! This is at least 2-3 times longer than the Great White Shark. The giant fossilized teeth are the size of a person's hand! Since Megalodon's teeth are very similar to those of the Great White Shark (but bigger and thicker), it is thought that Megalodon may have looked like a huge, streamlined version of the Great White Shark. 'Megalodon' is Greek for 'big teeth'.
(Source: "W H A L E E C H O E S - From South African Shores", Official Newsletter of the Whale Mark Organisation, September 2009)