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They do not suggest any trend of changing body size with absolute latitude, or of change in size over time (although the "Carcharocles" lineage in general is thought to display a trend of increasing size over time).
The overall modal length has been estimated at , with the length distribution skewed towards larger individuals, suggesting an ecological or competitive advantage for larger body size.
Megalodon had a global distribution and fossils of the shark have been found in many places around the world, bordering all oceans of the Neogene.
Though sharks are generally opportunistic feeders, megalodon's great size, high-speed swimming capability, and powerful jaws, coupled with an impressive feeding apparatus, made it an apex predator capable of consuming a broad spectrum of animals.
It was probably one of the most powerful predators to have existed.
A study focusing on calcium isotopes of extinct and extant elasmobranch sharks and rays revealed that megalodon fed at a higher trophic level than the contemporaneous great white shark.
That is to say it was higher up in the food chain.
Fossil evidence indicates that megalodon preyed upon many cetacean species, such as dolphins, small whales, cetotheres, squalodontids (shark toothed dolphins), sperm whales, bowhead whales, and rorquals.
In addition to this, they also targeted seals, sirenians, and sea turtles.
The shark was an opportunist and piscivorous, and it would have also gone after smaller fish and other sharks.
Many whale bones have been found with deep gashes most likely made by their teeth.
Various excavations have revealed megalodon teeth lying close to the chewed remains of whales, and sometimes in direct association with them.
The feeding ecology of megalodon appears to have varied with age and between sites, like the modern great white.
It is plausible that the adult megalodon population off the coast of Peru targeted primarily cetothere whales in length and other prey smaller than itself, rather than large whales in the same size class as themselves.
Meanwhile, juveniles likely had a diet that consisted more of fish.
Megalodon faced a highly competitive environment.
Its position at the top of the food chain, probably had a significant impact on the structuring of marine communities.
Fossil evidence indicates a correlation between megalodon and the emergence and diversification of cetaceans and other marine mammals.
Juvenile megalodon preferred habitats where small cetaceans were abundant, and adult megalodon preferred habitats where large cetaceans were abundant.
Such preferences may have developed shortly after they appeared in the Oligocene.
Megalodon were contemporaneous with whale-eating toothed whales (particularly macroraptorial sperm whales and squalodontids), which were also probably among the era's apex predators, and provided competition.
Some attained gigantic sizes, such as "Livyatan", which grew from .
Fossilized teeth of an undetermined species of such physeteroids from Lee Creek Mine, North Carolina, indicate it had a maximum body length of 8–10 m and a maximum lifespan of about 25 years.
This is very different from similarly sized modern killer whales that live to 65 years, suggesting that unlike the latter, which are apex predators, these physeteroids were subject to predation from larger species such as megalodon or "Livyatan".
By the Late Miocene, around 11 mya, macroraptorials experienced a significant decline in abundance and diversity.
Other species may have filled this niche in the Pliocene, such as the fossil killer whale "Orcinus citoniensis" which may have been a pack predator and targeted prey larger than itself, but this inference is disputed, and it was probably a generalist predator rather than a marine mammal specialist.
Megalodon may have subjected contemporaneous white sharks to competitive exclusion, as the fossil records indicate that other shark species avoided regions it inhabited by mainly keeping to the colder waters of the time.
In areas where their ranges seemed to have overlapped, such as in Pliocene Baja California, it is possible that megalodon and the great white shark occupied the area at different times of the year while following different migratory prey.
Megalodon probably also had a tendency for cannibalism, much like contemporary sharks.
Sharks often employ complex hunting strategies to engage large prey animals.
Great white shark hunting strategies may be similar to how megalodon hunted its large prey.
Megalodon bite marks on whale fossils suggests that it employed different hunting strategies against large prey than the great white shark.
One particular specimen–the remains of a long undescribed Miocene baleen whale–provided the first opportunity to quantitatively analyze its attack behavior.
Unlike great whites which target the underbelly of their prey, megalodon probably targeted the heart and lungs, with their thick teeth adapted for biting through tough bone, as indicated by bite marks inflicted to the rib cage and other tough bony areas on whale remains.
Furthermore, attack patterns could differ for prey of different sizes.
Fossil remains of some small cetaceans, for example cetotheres, suggest that they were rammed with great force from below before being killed and eaten, based on compression fractures.
During the Pliocene, larger cetaceans appeared.
Megalodon apparently further refined its hunting strategies to cope with these large whales.
Numerous fossilized flipper bones and tail vertebrae of large whales from the Pliocene have been found with megalodon bite marks, which suggests that megalodon would immobilize a large whale before killing and feeding on it.
Megalodon, like contemporaneous sharks, made use of nursery areas to birth their young in, specifically warm-water coastal environments with large amounts of food and protection from predators.
Nursery sites were identified in the Gatún Formation of Panama, the Calvert Formation of Maryland, Banco de Concepción in the Canary Islands, and the Bone Valley Formation of Florida.
Given that all extant lamniform sharks give birth to live young, this is believed to have been true of megalodon also.
Infant megalodons were around at their smallest, and the pups were vulnerable to predation by other shark species, such as the great hammerhead shark ("Sphyrna mokarran") and the snaggletooth shark ("Hemipristis serra").
Their dietary preferences display an ontogenetic shift: Young megalodon commonly preyed on fish, sea turtles, dugongs, and small cetaceans; mature megalodon moved to off-shore areas and consumed large cetaceans.
An exceptional case in the fossil record suggests that juvenile megalodon may have occasionally attacked much larger balaenopterid whales.
Three tooth marks apparently from a long Pliocene shark were found on a rib from an ancestral blue or humpback whale that showed evidence of subsequent healing, which is suspected to have been inflicted by a juvenile megalodon.
The Earth experienced a number of changes during the time period megalodon existed which affected marine life.
A cooling trend starting in the Oligocene 35 mya ultimately led to glaciation at the poles.
Geological events changed currents and precipitation; among these were the closure of the Central American Seaway and changes in the Tethys Ocean, contributing to the cooling of the oceans.
The stalling of the Gulf Stream prevented nutrient-rich water from reaching major marine ecosystems, which may have negatively affected its food sources.
The largest fluctuation of sea levels in the Cenozoic era occurred in the Plio-Pleistocene, between around 5 million to 12 thousand years ago, due to the expansion of glaciers at the poles, which negatively impacted coastal environments, and may have contributed to its extinction along with those of several other marine megafaunal species.
These oceanographic changes, in particular the sea level drops, may have restricted many of the suitable shallow warm-water nursery sites for megalodon, hindering reproduction.
Nursery areas are pivotal for the survival of many shark species, in part because they protect juveniles from predation.
As its range did not apparently extend into colder waters, megalodon may not have been able to retain a significant amount of metabolic heat, so its range was restricted to shrinking warmer waters.
Fossil evidence confirms the absence of megalodon in regions around the world where water temperatures had significantly declined during the Pliocene.
However, an analysis of the distribution of megalodon over time suggests that temperature change did not play a direct role in its extinction.
Its distribution during the Miocene and Pliocene did not correlate with warming and cooling trends; while abundance and distribution declined during the Pliocene, megalodon did show a capacity to inhabit colder latitudes.
It was found in locations with a mean temperature ranging from , with a total range of , indicating that the global extent of suitable habitat should not have been greatly affected by the temperature changes that occurred.
This is consistent with evidence that it was a mesotherm.
Marine mammals attained their greatest diversity during the Miocene, such as with baleen whales with over 20 recognized Miocene genera in comparison to only six extant genera.
Such diversity presented an ideal setting to support a super-predator such as megalodon.
By the end of the Miocene, many species of mysticetes had gone extinct; surviving species may have been faster swimmers and thus more elusive prey.
Furthermore, after the closure of the Central American Seaway, tropical whales decreased in diversity and abundance.
The extinction of megalodon correlates with the decline of many small mysticete lineages, and it is possible that it was quite dependent on them as a food source.
Additionally, a marine megafauna extinction during the Pliocene was discovered to have eliminated 36% of all large marine species including 55% of marine mammals, 35% of seabirds, 9% of sharks, and 43% of sea turtles.
The extinction was selective for endotherms and mesotherms relative to poikilotherms, implying causation by a decreased food supply and thus consistent with megalodon being mesothermic.
Megalodon may have been too large to sustain itself on the declining marine food resources.
The cooling of the oceans during the Pliocene might have restricted the access of megalodon to the polar regions, depriving it of the large whales which had migrated there.
Competition from other predators of marine mammals, such as macropredatory sperm whales which appeared in the Miocene, and killer whales and great white sharks in the Pliocene, may have also contributed to the decline and extinction of megalodon.
Fossil records indicate that the new whale-eating cetaceans commonly occurred at high latitudes during the Pliocene, indicating that they could cope with the increasingly prevalent cold water temperatures; but they also occurred in the tropics (e.g., "Orcinus" sp.
in South Africa).
The largest macropredatory sperm whales such as "Livyatan" are best known from the Miocene, but persisted into the Pliocene, while others, such as "Hoplocetus" and "Scaldicetus", survived until the early Pleistocene.
These may have occupied a niche similar to that of orcas before eventually being replaced by them.
Recent evidence and more accurate dating methods suggest that "C. megalodon" may have died out earlier than surmised; fossils examined in North Pacific deposits imply the sharks became extinct around 3.6-4 million years ago.
This is hypothesized to have been due to both cooling surface temperatures resulting in range fragmentation for "C. megalodon" as well as competition for prey with the newly evolved modern great white shark.
Many of the species that served as megalodon's prey survived for significantly longer, contrary to a previous theory that all were swept away by a single marine mass extinction.
The extinction of megalodon set the stage for further changes in marine communities.
The average body size of baleen whales increased significantly after its disappearance, although possibly due to other, climate-related, causes.
Conversely the increase in baleen whale size may have contributed to the extinction of megalodon, as they may have preferred to go after smaller whales; bite marks on large whale species may have come from scavenging sharks.
Megalodon may have simply become coextinct with smaller whale species, such as "Piscobalaena nana".
The extinction of megalodon had a positive impact on other apex predators of the time, such as the great white shark, in some cases spreading to regions where megalodon became absent.
Megalodon has been portrayed in several works of fiction, including films and novels, and continues to be a popular subject for fiction involving sea monsters.
Three individual megalodon, two adults and one juvenile, were portrayed in BBC's 2003 TV documentary series "Sea Monsters", where it is defined as a "hazard" of the era.
The History Channel's "Jurassic Fight Club" portrays a megalodon attacking a "Brygmophyseter" sperm whale in Japan.
Several films depict megalodon, such as "" and the Mega Shark series (for instance "Mega Shark Versus Giant Octopus" and "Mega Shark Versus Crocosaurus").
The shark appears in the 2017 videogame "".
Some stories, such as Jim Shepard's "Tedford and the Megalodon", portray a rediscovery of the shark.
Steve Alten's "" portrays the shark having preyed on dinosaurs with its prologue and cover artwork depicting megalodon killing a "Tyrannosaurus" in the sea.
The sequels to the book also star megalodon: "The Trench", "Meg: Primal Waters", "Meg: Hell's Aquarium", "Meg: Nightstalkers", "Meg: Generations", and "Meg: Origins", and there is a film adaptation entitled "The Meg" released on 10 August 2018.
Animal Planet's pseudo-documentary "" included an encounter 1.6 mya between a pod of mermaids and a megalodon.
Later, in August 2013, the Discovery Channel opened its annual Shark Week series with another film for television, "", a controversial docufiction about the creature that presented alleged evidence in order to suggest that megalodon was still alive.
This program received criticism for being completely fictional; for example, all of the supposed scientists depicted were paid actors.
In 2014, Discovery re-aired "The Monster Shark Lives", along with a new one-hour program, "Megalodon: The New Evidence", and an additional fictionalized program entitled "Shark of Darkness: Wrath of Submarine", resulting in further backlash from media sources and the scientific community.
Reports of supposedly fresh megalodon teeth, such as those made by in 1873 which were erroneously dated to be around 11,000 to 24,000 years old, are probably teeth that were well-preserved by a thick mineral-crust precipitate of manganese dioxide, and so had a lower decomposition rate and retained a white color during fossilization.
Fossil megalodon teeth can vary in color from off-white to dark browns and greys, and some fossil teeth may have been redeposited into a younger stratum.
The claims that megalodon could remain elusive in the depths, similar to the megamouth shark which was discovered in 1976, are unlikely as the shark lived in warm coastal waters and probably could not survive in the cold and nutrient-poor deep sea environment.
Megalodon teeth are the state fossil of North Carolina.
Yorkshire Three Peaks
The mountains of Whernside (), Ingleborough () and Pen-y-ghent () are collectively known as the
Three Peaks.