- Megalodon is a species of shark, which first appeared on Earth some 23 million years ago and went extinct about 3.6 million years ago.
- It remains the largest known fish species to ever roam on Earth waters.
- It is believed that they went extinct because of the global cooling trend and the rise of great white sharks.
The whale shark, currently the largest surviving shark species, measures about 18.8 meters in length and weigh more than 11,000 kg. In contrast, megalodon sharks could have been anywhere between 15 to 18 meters in length. Few believe that it could be much larger, about 25 meters.
Megalodon first appeared on Earth some 23 million years ago and went extinct about 3.6 million years ago. Its name – megalodon (short for Carcharocles megalodon) means “giant tooth.”
Below, we will take a look at some of the most interesting aspects of the long-extinct sea creature and try to uncover the reason why it suddenly vanished for the world’s oceans. We will also investigate the possibility of its existence.
What Megalodon Looked Like?
Reconstructed skeleton of a megalodon at Calvert Marine Museum in Maryland
While the scientific community is split of the exact appearance of the long-extinct shark species, the one thing they all agree on is that it had a large, robust body. Many believe that megalodon may have looked like a great white shark, albeit much larger and with wider jaws.
Others have concluded that the ancient shark closely resembled the whale shark, the largest living fish species. The setting of its fins and other anatomical features (crescent-like tail fins, smaller second dorsal, and cloacal fin) may have been identical to that of whales and other extant shark species.
How Big Were The Megalodons?
A megalodon tooth alongside two great white shark teeth for comparison | Wikimedia Commons
Much of what we know about this long-gone gigantic shark species is based on the analysis of its teeth. The largest tooth specimen found is close to 18 centimeters (7.1 inches) in length. Simulations, based on the recovered teeth specimen, indicate that megalodon had a robust dental structure with somewhere up to 250 teeth and jaws extending about 2 meters.
Several attempts were made towards its jaws reconstruction, based on which the actual size of the shark could be estimated. In 2002, Kenshu Shimada, a paleontologist from DePaul University, came up with an improved model for predicting a specimen size based on the length of their teeth.
Using the model, Shimada predicted total lengths of various specimens discovered in Panama’s Gatún Formation. The largest was estimated to be around 17.9 meters.
In 2019, Shimada made specific changes in his model, in which he stated that analysis of the upper anterior teeth of a specimen yields more accurate results. With the help of these alterations, he estimated that megalodon sharks more than 15.3 meters in length were extremely rare.
On the other hand, according to the Natural History Museum in London, the largest specimen could have extended up to 18 meters.
Reconstructed Megalodon jaws on display at National Aquarium, Baltimore
According to medieval texts, the large teeth, which were often found embedded in rocks, are believed to be petrified dragon tongues. It was only in 1667 that Nicolas Steno was able to identify them as shark teeth.
Its Range and Habitat
The species most likely had a cosmopolitan distribution, meaning it was found around the world in suitable habitats. Megalodon remains have been discovered form Africa, the Americas, Australia, and Europe.
Based on the general location of recovered fossils, it appears that the shark inhabited mostly in shallow marine environments, including coastal waters and lagoons, but also navigated in deep seas. Adult megalodon hunted and stayed most of their lives in deep waters but migrated to shallow regions to spawn.
Their latitudinal range extended to 55 degrees in both the hemispheres. Like most other shark species, it preferred warmer temperatures. However, mesothermy (ability to regulate heat by conserving energy) allowed them to cope with colder temperatures in the temperate region to some extent.
Nursery areas for juveniles are located in or near shallow and temperate coastal waters, where food is in abundance. The Bone Valley Formation in Florida and Calvert Formation in Maryland are few examples of such sites.
When and How the Megalodon Went Extinct?
In 2014, researchers from the University of Zurich conducted a study to determine the age of megalodon fossils using a method called Optimal Linear Estimation. The study revealed that the shark species went extinct about 2.6 million years ago, that’s about 200,000 years before H. habilis (earliest known ancestors of H. Sapiens) first appeared on the Earth.
In 1873, HMS Challenger, a British survey vessel, unearthed a pair of well-preserved megalodon teeth. Their analysis erroneously indicated them to be around 10,000 to 15,000 years old; that’s no way near the established range. This discrepancy is most possibly due to the presence of manganese dioxide, which could effectively lower the decomposition rate.
During the period when megalodon existed, the planet experienced some drastic climatic changes. A global cooling trend that started about 35 million years ago led to the glaciation of poles while the temperatures fell by 8 °C worldwide.
Earth’s decreasing temperatures and expansion of glaciers at poles disrupted the marine habitats, ultimately leading to the loss of various aquatic species, including the megalodon. It could have contributed towards the extinction in multiple ways.
Since megalodon sharks were dependent on warm waters, a sudden drop in temperatures likely to have constricted their habitat. Their food may also have become scarce (either migrated to the colder regions or were gone entirely).
Great white shark in waters of Mexico | Image Courtesy: Wikimedia Commons
An interesting theory behind megalodon’s extinction is the rise of great white sharks. According to a new study conducted by a group of international researchers, the youngest megalodon fossil dates back to 3.6 million years; that is a million years earlier than previously thought.
The study further points out that the dates coincide with the first appearance of the great white shark on earth. Though smaller, the great whites may have out-competed the juveniles to the point where the entire species is exterminated.
Could Megalodon Still Be Alive?
From time-to-time, megalodon is portrayed in media fiction, including TV shows and films. Unfortunately, several documentaries (docufiction) have given rise to a false notion that the ancient shark species could still be alive.
In a 2013 pseudo-documentary named Megalodon: The Monster Shark Lives, the creators make a case for the possible survival of species. A sequel, Megalodon: The New Evidence, was released the next year. These claims are fueled mainly by supposed, unverified sightings.
To answer the initial question, no, megalodons are no longer alive and gone for good. Those who still believe that the ancient beast is lurking somewhere in the ocean, here are few arguments that may help you reach a different conclusion.
Artist’s impression of a megalodon chasing two Eobalaenoptera whales | Image Courtesy: Karen Carr
No direct observation of a megalodon specimen has been made to date. What we have are claims of unverified sightings. One of the most controversial of them was a doctored image of shark’s dorsal and tail fin (about 20 m. apart) next to a submarine. It was aired on Discovery Channel as part of a “documentary.”
The reported sightings of giant sharks washed up on shores are highly unreliable as megalodons could easily be mistaken for whale sharks or are likely to be overstated great whites.
A popular argument people often cite in favor of their existence is the unanticipated discovery of megamouth shark in 1976. Planktivorous by nature, the megamouth sharks, eluded detection for years as they navigate mostly in deep waters. It doesn’t mean, in any way, that megalodon sharks may still exist.
To miss something as substantial as an 18-meter long megalodon, it had to be way deep inside the ocean, where food is scarce, and large marine life is extremely rare.