Megalodon

Otodus megalodon ( MEG-əl-ə-don; meaning "big tooth"), commonly known as megalodon, is an extinct species of giant mackerel shark that lived approximately 23 to 3.58 million years ago (Mya), from the Early Miocene to the Early Pliocene epochs. It was once considered a member of the family Lamnidae and a close relative of the great white shark (Carcharodon carcharias), but is now classified in the extinct family Otodontidae, which diverged from the lineage leading to modern great white sharks during the Early Cretaceous.

Megalodon is regarded as one of the largest and most powerful predators to have ever lived, although its fragmentary fossil record leaves its appearance and maximum size uncertain. Scientists have debated whether its body was more robust or elongated than that of modern lamniform sharks. Proposed maximum length estimates range from 14.2 to 24.3 m (47 to 80 ft), while the estimated modal length across juveniles and adults is approximately 10.5 m (34 ft). Its thick, robust teeth were adapted for grasping prey and breaking bone, and its large jaws are thought to have exerted a bite force of 108,500 to 182,200 newtons (24,390 to 40,960 lbf).

Megalodon likely played a significant role in shaping marine ecosystems and had a cosmopolitan distribution, as indicated by the fossil record. It probably preyed on large marine animals, including whales, seals and sea turtles, while juveniles inhabited warm coastal waters and fed on fish and small whales. Unlike great white sharks, which often attack prey from beneath, megalodon may have used its powerful jaws to crush the thoracic region of its prey, damaging the heart and lungs.

The animal faced competition from whale-eating cetaceans, such as Livyatan and other macroraptorial sperm whales and possibly smaller ancestral killer whales (Orcinus), although the inclusion of early Orcinus as a direct competitor is uncertain, as species such as Orcinus citoniensis were likely adapted for feeding on small fish and cephalopods rather than large marine mammals. As the shark preferred warmer waters, it is thought that oceanic cooling associated with the onset of the ice ages, coupled with the lowering of sea levels and resulting loss of suitable nursery areas, may have contributed to its decline. A reduction in the diversity of baleen whales and a shift in their distribution toward polar regions may have reduced megalodon's primary food source. The shark's extinction coincides with a gigantism trend in baleen whales.

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