Megalodon~

                                                                MEGALODON

The megalodon  meaning "big tooth", from Greek and (odon, "tooth")) is an extinct species of shark that lived roughly from 28 to 1.5 million years ago, during the Cenozoic Era (late Oligocene to early Pleistocene).

The taxonomic assignment of C. megalodon has been debated for nearly a century, and is still under dispute with two major interpretations; Carcharodon megalodon (under family Lamnidae) or Carcharocles megalodon (under family Otodontidae).Consequently, the scientific name of this species has been commonly abbreviated to C. megalodon in literature.

C. megalodon is regarded as one of the largest and most powerful predators in vertebrate history.C. megalodon likely had a profound impact on structuring of the marine communities. Fossil remains indicate that this giant shark reached a total length (TL) of more than 16 metres (52 ft), and also affirm that it had a cosmopolitan distribution.Scientists suggest that C. megalodon looked like a stockier version of the great white shark, Carcharodon carcharias, in life.

Identification

A Swiss naturalist, Louis Agassiz, gave this shark its scientific name, Carcharodon megalodon, in 1835, in his research work Recherches sur les poissons fossiles (Research on fossil fish), which he completed in 1843. The teeth of the C. megalodon 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 or giant white shark or even monster shark.

Fossils

C. megalodon is represented in the fossil record primarily by teeth and vertebral centra. As with all other sharks, C. megalodon's skeleton was formed of cartilage rather than bone; this results in mostly poorly preserved fossil specimens.

Fossil teeth

Megalodon tooth with slant height (diagonal length) of over 170 mm.

The most common fossils of C. megalodon are its teeth. The diagnostic characters of C. megalodon teeth include: triangular shape, robust structure, large size, fine serrations, and visible v-shaped neck.^[1] The teeth of C. megalodon 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.

Fossil vertebrae

Fossil vertebrae of C. megalodon have also been occasionally found. The most notable example is a partially preserved but associated vertebral column of a single C. megalodon specimen, which was excavated from Antwerp basin, Belgium by M. Leriche in 1926. This specimen comprises 150 vertebral centra, with the largest centra being 155 mm in diameter. However, scientists have claimed that considerably larger vertebral centra can be expected from C. megalodon. Interestingly, a partially preserved but associated vertebral column of another C. megalodon specimen was excavated from Gram clay, Denmark by Bendix-Almgeen in 1983. This specimen comprises 20 vertebral centra, with the largest centra being around 230 mm in diameter.

Fossil distribution and age

The fossils of C. megalodon have been excavated from many parts of the world, including Europe, North AmericaSouth America, Puerto Rico, Cuba Jamaica, Australia, New Zealand Japan,Africa, Malta, Grenadines, and India. C. megalodon teeth have also been excavated from regions far away from continental lands (e.g., the Mariana Trench in the Pacific).

The earliest remains of C. megalodon have been reported from late Oligocene strata, circa 28 million years old.^[ Although fossils of C. megalodon are predominantly absent in strata extending beyond the Tertiary boundary,they have been reported from subsequent Pleistocene strata. It is believed that C. megalodon became extinct in the Pleistocene, probably about 1.5 million years ago.