Carcharodon megalodon (8) Fossil Shark's Tooth Dogfishes Cartilaginous Fishes Chondrichthyes Selachians Elasmobranchs Otodontidae

The megalodon (Carcharodon megalodon or Carcharocles megalodon, Louis Agassiz, 1843) is an extinct species of large sharks, known for large fossil teeth, some of which are also found in Sardinia. The scientific name megalodon comes from greek and means "big tooth". Fossils of C. megalodon are found in the Pliocene sediments dall'Eocene (between 55 and 1.8 million years ago).
The classification is the subject of scientific debate among experts. In the past this animal was placed in the genus Carcharodon, like the current white shark. In 1995, the new genus Carcharocles (belonging to the family Otodontidae) was proposed to classify the animal. Many paleontologists now supports the latter theory.
It was considered a close relative of the better known, and still living, great white shark (Carcharodon carcharias), especially for the great similarity in form and structure of the teeth. However, a growing number of researchers are questioning this relationship, instead embracing the idea that convergent evolution why white sharks and C. megalodon teeth have a similar time. In any case, the appearance and size of C. megalodon are reconstructed precisely from this similarity.
The dimensions of the fossil record (mostly up to 17 cm long teeth, although teeth seem to have been found 20 cm) suggest an animal whose length would exceed 17 meters. Estimates indicate that the weight could reach 45 tons. Based on the metabolism of the white shark, it is believed that the C. megalodon would need to eat on average one fifth of its weight every day, or 4 tonnes of meat. He had an opening of the jaw than 2 meters and it seems that his diet could also include the great whales.
C. megalodon was a predator common in all oceans from southern latitudes to northern ones, more suited to more environments and climates (but tend to those preferring warm temperate), probably preferred the relatively coastal areas, where it was easy to meet the large mammals marine which certainly ate (fingerprints of bites, even healed, tend to confirm this theory.) Remains of this large shark were also found in areas of open sea at the time, or in fields located in small remote islands of the Pacific Ocean and Indian Ocean, which demonstrate how the animal lived in open sea environments . It should, however, added that he was, in all likelihood, a predator specialized in the hunt for little depth. The Miocene is the period of greatest diversity of cetaceans to large size (20 kinds of whales against the current six), and has known a great diffusion of other potential prey (dugongs  and big Sirenia, sea turtles, pinnipeds large size, Penguins on larger, other predatory sharks, whale sharks, tuna) in the cold waters abounded the ancestors of the orca, in those hot instead ruled the C. megalodon.