Britannica Presents: The Megalodon

The creature's full scientific name is Carcharocles megalodon. Megalodon means simply giant tooth derived from Greek fossil. Evidence of the megalodon occurs most often as giant shark teeth. Adult megalodon teeth may be as big as one's palm, some are even larger. Fossil suggests that megalodons lived in tropical and temperate oceans worldwide. The megalodon is often compared to the great white shark, but both species have descended along different, albeit closely related lines. Sharks are known for their stability through evolution, and so scientists believe that a day in a Megalodon's life would resemble that of other top predator sharks here. The Isthmus of Panama, the land that would connect North America with South America, has not yet emerged from the ocean. A female megalodon surveys the area. She's pregnant. She came here to give birth. While we don't know for how long, her pregnancy could have taken over a year as some other large sharks do. Today the mother shark gives birth to live young. The mother shark is truly giant, about the size of a bus, and so these infant sharks are similarly big, about two meters or more from nose to tail. The mother may stay near her young, but her actions may not be about mothering. Instead, she's more about defending an area she may have used as a feeding ground. Hammerhead sharks feed here too, and so as she keeps territory for herself, she also keeps her babies safe from the hammer heads. Even at birth, the infant sharks are formidable. They'll prey on smaller fish mollusks and on small marine mammals if they're present. The mother, however, seeks larger prey. She is easily capable of killing sizable marine mammals like whales because she is far bigger than they are. Tooth marks on fossil whale bones indicate deep Megalodon bites. The female bites and then shakes her prey. The serrated edges of her teeth cut heavy flesh like giant steak knives. If Megalodons behaved like other large predatory sharks, her male mate likely remained apart and independent. While he is still larger than the great white sharks we know today, he is only about half the female's size among megalodons. If sheer size was any indication, females rule the cycle of mating, birth, and hunting continued in these shallow seas until about 2.6 million years ago. In the time of the megalodons, continents drifted together. Sea currents and sea levels changed. The abundance of prey rose and fell throughout Megalodon's reign. But as the Pliocene epic went on, sharks became more competitive, possibly even quicker and more agile. These factors, and perhaps others, spelled the end of the megalodon. Why is there so little material evidence of megalodons today? Well, they were sharks, and all sharks are cartilaginous fish. Megalodon skeletons had few hard bones and were mostly cartilage. A dinosaur leaves bones when it dies. Bones enable one to estimate a body's size, structure and function. But since shark skeletons are almost totally cartilage, and cartilage decomposes easily after death, almost nothing of a megalodon is left behind. Shark teeth, however, fossilize easily, so scientists use fossil megalodon teeth to estimate other details about the animals. The enormous size of Megalodon teeth compared to the teeth of living sharks is a significant reason why scientists think the megalodon was so large. But fossil teeth paint an incomplete picture of this magnificent animal, and the scarcity of other hard evidence continues to challenge scientists. For now, some ideas about the Megalodon are based on assumptions of how it could have resembled today's sharks in form, ecology and behavior.