The megalodon shark (Carcharocles megalodon) is an extinct species of giant shark that lived during the late Oligocene epoch and through out the Neogene period. Most scientists believe it became extinct between 1-2 million years ago.
A close relative of today's great white sharks, megalodon could have grown up to 50 feet long and weighed well over 10 tons. Its immensely strong jaws and massive serrated teeth enabled it to hunt almost anything in the ocean. The hunting method of megalodon is probably the same as it's great white cousins as today: attack from below and crushand tear them with their dozen rows of teeth. Scientists suggest that being a close cousin of the white shark, megalodon could have possed the same hunting technique while hunting large sea mammals of its time, such as sperm whales.
Megalodon is represented in the fossil record primarily by teeth and vertebral centra. As with all sharks, megalodon's skeleton was formed of cartilage rather than bone; this results in mostly poorly preserved fossil specimens. According to Renaissance accounts, gigantic, triangular fossil teeth often found embedded in rocky formations were once believed to be the petrified tongues, or glossopetrae, of dragons and snakes. This interpretation was corrected in 1667 by Danish naturalist Nicolaus Steno, who recognized them as shark teeth, and famously produced a depiction of a shark's head bearing such teeth. He described his findings in the book The Head of a Shark Dissected, which also contained an illustration of a C. megalodon tooth.
 Megalodon tooth with slant height (diagonal length) of over 170 mm. Megalodon tooth with two great white shark teeth.The most common megalodon fossils are its teeth. Diagnostic characteristics include: triangular shape, robust structure, large size, fine serrations, and visible v-shaped neck. Megalodon teeth can measure over 180 millimetres (7.1 in) in slant height or diagonal length, and are the largest in size of any known shark species.
Some fossil vertebrae have been found. The most notable example is a partially preserved vertebral column of a single specimen, excavated in Antwerp basin, Belgium by M. Leriche in 1926. It comprises 150 vertebral centra, with the largest centra stretching 155 millimetres (6.1 in) in diameter. However, scientists have claimed that considerably larger vertebral centra can be expected. A partially preserved vertebral column of another megalodon specimen was excavated from Gram clay, Denmark by Bendix-Almgeen in 1983. This specimen comprises 20 vertebral centra, with the largest centra around 230 millimetres (9.1 in) in diameter.
Distribution and age
Megalodon fossils have been excavated from many parts of the world, including Europe, Africa and both North and South America, as well as Puerto Rico, Cuba, Jamaica, Australia, New Zealand, Japan, Malta, Grenadines and India. Megalodon teeth have been excavated from regions far away from continental lands, such as the Mariana Trench in the Pacific Ocean.
The earliest megalodon remains were reported from late Oligocene strata, circa 28 million years old. Although fossils are mostly absent in strata extending beyond the Tertiary boundary, they have been reported from subsequent Pleistocene strata. It is believed that megalodon became extinct in the Pleistocene, probably about 1.5 million years ago.
Swiss naturalist Louis Agassiz gave the shark its initial scientific name, Carcharodon megalodon, in 1835, in his research work Recherches sur les poissons fossiles (Research on fossil fish), which he completed in 1843. Megalodon teeth are morphologically similar to the teeth of the great white shark. On the basis of this observation, Agassiz assigned the genus Carcharodon to the megalodon. While the scientific name is C. megalodon, it is often informally dubbed the "megatooth shark", "giant white shark" or "monster shark".
Taxonomy and evolution
The taxonomic assignment of C. megalodon has been debated for nearly a century, and is still under dispute. The two major interpretations are Carcharodon megalodon (under family Lamnidae) or Carcharocles megalodon (under family Otodontidae). Consequently, the scientific name of this species is commonly abbreviated C. megalodon in the literature. Even after decades of research and scrutiny, controversy over megalodon phylogeny persists. Several shark researchers (e.g. J. E. Randall, A. P. Klimley, D. G. Ainley, M. D. Gottfried, L. J. V. Compagno, S. C. Bowman, and R. W. Purdy) insist that megalodon is a close relative of the great white shark. However, others (e.g. D. S. Jordan, H. Hannibal, E. Casier, C. DeMuizon, T. J. DeVries, D. Ward, and H. Cappetta) cite convergent evolution as the reason for the dental similarity. Such Carcharocles advocates have gained noticeable support. However, the original taxonomic assignment still has wide acceptance.
In The Land Before Time
A megalodon briefly appears as an enemy in the game The Land Before Time: Into the Mysterious Beyond for the GameBoy Advance. It appears in the second to last level of the game, where it serves as an obstacle to the player by jumping out of the water in an attempt to hit the player on a log. Due to this, it can only be avoided, not killed.