megalodon
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What was the megalodon?
The megalodon, Carcharocles megalodon, meaning "giant tooth," was the largest shark and fish ever known. It lived from the early Miocene Epoch (23.03 million years ago) to the end of the Pliocene Epoch (2.58 million years ago).
Megalodon was an apex predator that preyed on fish, baleen whales, toothed whales, sirenians, and seals. Adults likely had no predators, while juveniles were vulnerable to large predatory sharks.
Debate continues about the taxonomy and evolution of megalodon and its relationship to modern white sharks. Some scientists believe that megalodon and modern white sharks evolved within the same lineage, while others classify megalodon within the lineage of megatooth sharks.
Megalodon's extinction may be attributed to climate change and shifting food-chain dynamics.
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When did the megalodon live?
The megalodon (Carcharocles megalodon) lived from the early Miocene Epoch (beginning about 23.03 million years ago) to the end of the Pliocene Epoch (2.58 million years ago). It is considered to be the largest shark and fish that ever lived.
The megalodon's geographic distribution expanded throughout the Miocene but declined during the Pliocene. Scientists initially thought that the decline was due to climate change, but studies suggest that shifting food-chain dynamics may have been the primary factor in the megalodon's demise.
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How big was the megalodon compared to modern sharks?
The megalodon was the largest fish ever known. Based on the size of fossil teeth, the megalodon likely resembled the modern great white shark in appearance. However, megalodon teeth were much larger, with the largest tooth measuring 17.8 cm (6.9 inches) in length, almost three times longer than those of modern white sharks.
Estimates suggest that adult megalodons reached a mean length of between 13 and 14 metres (roughly 42.7 and 45.9 feet), with the largest specimens measuring up to an estimated 24.3 metres (79.7 feet) long. The largest of the modern predatory sharks is the great white shark, at 6 metres (20 feet).
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What did the megalodon eat?
The megalodon (Carcharocles megalodon) was one of the largest marine carnivores and the largest fish in Earth's history. As an apex predator, it preyed on various marine animals, including fish, baleen whales, toothed whales, sirenians, and seals.
Young megalodons likely consumed smaller prey, while adults hunted larger whales. Mature megalodons likely had no predators, but newborn and juvenile megalodons may have been vulnerable to other large predatory sharks, such as great hammerhead sharks.
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How do scientists learn about megalodon if it is extinct?
Scientists learn about the extinct megalodon primarily through its fossilized teeth. The word megalodon means "giant tooth" in Greek. Since sharks lack bones, these teeth are the most abundant remains, providing key insights into megalodon's size, estimated at up to 58.7 feet long.
By studying the shape and size of these teeth, scientists can infer relationships to modern sharks, diet, and even potential nursery areas. The largest megalodon tooth ever found was 6.9 inches long, almost three times longer than the average tooth of a modern great white shark. Additionally, fossil remains have been found off the coast of every continent except Antarctica.
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What are some reasons scientists think the megalodon became extinct?
Scientists suggest that the megalodon shark became extinct about 2.6 million years ago. The reasons for this are likely linked to a mix of environmental changes and shifting food-chain dynamics.
The closing of seaways separating North and South America disrupted marine food chains. This likely affected baleen whales, which scientists believe were the megalodon's main food source. Additionally, competition from smaller predatory sharks, such as the great white shark, and early killer whales likely contributed to the megalodon's decline.
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megalodon, (Carcharocles megalodon), member of an extinct species of megatooth shark (Otodontidae) that is considered to be the largest shark, as well as the largest fish, that ever lived. Fossils attributed to megalodon have been found dating from the early Miocene Epoch (which began 23.03 million years ago) to the end of the Pliocene Epoch (2.58 million years ago). The word megalodon, a compound of Greek root words, means “giant tooth.”
Natural history
Distribution
Fossil remains of megalodon have been found in shallow tropical and temperate seas along the coastlines and continental shelf regions of all continents except Antarctica. During the early and middle parts of the Miocene Epoch (which lasted from 23 million to 5.3 million years ago), large seaways separated North America from South America and Europe and Asia from Africa and the Middle East, which likely facilitated movement from one ocean basin to another. Throughout the Miocene, megalodon distribution expanded from pockets located in the Caribbean and Mediterranean seas, in the Bay of Bengal, and along the coasts of California and southern Australia to encompass waters off the coasts of northern Europe, South America, southern Africa, New Zealand, and east Asia. During the Pliocene Epoch, however, megalodon’s geographic range contracted significantly, and it was extinct by the end of the epoch.
Physical features
Megalodon was the largest fish ever known, a designation based on discoveries of hundreds of fossil teeth, two vertebral columns, and a handful of individual vertebrae. Tooth-shape similarities between megalodon and modern great white sharks (Carcharodon carcharias) suggest that the two species may have been close relatives, and thus megalodon likely resembled that species in appearance—that is, as a bulky torpedo-shaped fish with a conical snout, large pectoral and dorsal fins, and a strong crescent-shaped tail. Estimates of body length are calculated using the statistical relationship between the size of megalodon’s fossil teeth and the teeth and body mass of modern white sharks and other living relatives. This data suggests that mature adult megalodons had a mean length of between 13 and 14 metres (about 42.7 and 45.9 feet), with the largest specimens measuring up to an estimated 24.3 metres (79.7 feet) long. Studies estimate that adult body mass ranged from roughly 30 metric tons (1 metric ton = 1,000 kg; about 66,000 pounds) to more than 65 metric tons (about 143,000 pounds), adult females being larger (in both length and mass) than adult males.
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However, some scientists note that Megalodon may have possessed a sleeker body, possibly with a shape closer to that of a lemon shark. They argue that a large, bulky shark with the proportions described above may have had more difficulty moving through the water than a shark with more slender body shape. Size estimates suggest that such a sleek-bodied form was larger than previously thought, possibly measuring as much as 24.3 meters (about 80 feet) long and weighing about 94 tonnes (103 tons).
Megalodon teeth are similar to those of modern white sharks in that they are triangular, serrated, and symmetrical. They differ from modern white shark teeth in that they are larger and thicker, the serrations on each tooth occur in regular intervals, and they possess a bourlette (a darker, chevron-shaped region near the tooth’s root). The largest extant megalodon tooth measures 17.8 cm (6.9 inches) in length, almost three times longer than those of modern white sharks (which are typically about 5.4 cm [2.1 inches] long). In addition, megalodon possessed a ferocious bite; its bite diameter was 3 metres (about 9.8 feet), several times larger than the bite diameter of averaged-sized white sharks.
Megalodon is thought to have managed its body temperature in a manner similar to that of modern white sharks, in that it was not exclusively cold-blooded like most fish. White sharks generate heat through the contraction of their swimming muscles, and this heat raises the temperature of parts of the shark’s body above that of the surrounding water, an adaptation called regional endothermy (which is a type of warm-bloodedness). This adaptation might have allowed megalodon to swim and hunt in colder waters, giving it exclusive access to prey in those locations.
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Reproduction and territoriality
Megalodon is thought to have produced live young. It is not known, however, whether the species was ovoviviparous (in which eggs are retained within the mother until they hatch) or viviparous (in which fertilized embryos derive continuous nourishment from the mother). Estimates of body size using juvenile teeth suggest that newly birthed young may have been at least 2 metres (6.6 feet) in length.
Few details are known about megalodon courtship, but the species appears to have used nurseries for its young. A 2010 study identified a megalodon nursery along the Panamanian coast, which was characterized by the presence of juvenile teeth from various stages of life. Scientists posit that this shallow warm-water nursery provided young megalodons with access to a diverse array of smaller, more-abundant prey and enabled adults to better intercept attacks from other predatory shark species, such as hammerhead sharks. As the young sharks grew older, it is thought that they would make forays into deeper water to pursue larger animals.
Little is known about how individuals dispersed after they matured. Since megalodon is thought to have occupied an ecological niche similar to that of the white shark, some studies have assumed that megalodon likely ranged over areas comparable in size to the range of modern white sharks—about 1,000 square km (386 square miles).