The fossil evidence places its disappearance around 3.6 million years ago. There is no credible scientific evidence that it survives in today’s oceans.
Part of me is sad for that, but as I sometimes venture below the waves to scuba dive, I am really, really grateful!
But the real animal is every bit as fascinating as the imagined sea monster. With enormous teeth and an appetite to match, this ancient shark left us clues to a remarkable life beneath the waves.
How big did it grow? What did it eat? And how can scientists piece together its story from fossils? Let’s sink our teeth into ten big questions about the biggest shark that ever lived.
1. WHAT WAS MEGALODON?
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It belonged to an extinct group called the megatooth sharks. The image here will give you a sense of the scale of this massive fellow. If you think Great White Sharks are scary, this is the one they would be scared of!
Terrifying and mysterious as it is an animal known to us mainly through the hard clues it left behind, rather than a complete skeleton waiting neatly in a museum drawer.
2. HOW BIG COULD MEGALODON GROW?
Very big—but the exact maximum is still debated. Earlier studies commonly estimated the largest individuals at roughly 15–20 metres long. A 2025 study proposed a possible maximum of about 24.3 metres, using fossil vertebrae and comparisons with other sharks.
These are reconstructions, not measurements of a complete animal. They depend on assumptions about the missing head, trunk and tail. The larger estimate is a working hypothesis, not a settled length for every megalodon.
Either way, imagine a shark stretching well beyond the length of a school bus. Then imagine trying to work out its full shape from only a few pieces of the puzzle.
3. HOW BIG WERE ITS TEETH?
Look closely at a tooth and you can see a broad root, a pointed crown and, where preserved, fine serrations along the cutting edges.
Different positions in the mouth produced different tooth shapes and sizes. One loose tooth is therefore not a simple ruler for the whole shark.
Try this: sketch the outline of each tooth in a comparison photograph. Where is the biggest difference—the root, the crown, or both?
4. WHAT DID MEGALODON EAT?
Marine mammals, including whales, were part of its menu. Fossil bite marks and the chemistry preserved in teeth help researchers investigate its place in ancient ocean food webs.
In one study, scientists analysed zinc isotopes—different forms of the same element—in fossil tooth tissue. Their results suggest that some megalodon and early great white populations occupied similar positions high in the food web.
That does not mean every individual ate the same meals. It gives us evidence about feeding patterns that would otherwise be very difficult to recover.
5. WHERE DID MEGALODON LIVE?
Its fossils occur in ancient marine deposits around the world. This was an ocean-going shark with a wide distribution, rather than an animal confined to one small corner of the sea.
A fossil tooth found on land today can record a place once covered by seawater. The landscape may have changed enormously since the shark lost its tooth.
6. DID MEGALODON LIVE ALONGSIDE DINOSAURS?
Not dinosaurs such as Tyrannosaurus rex or Triceratops. Those non-avian dinosaurs disappeared about 66 million years ago, long before megalodon appeared.
Birds are living dinosaurs, so there is a little scientific twist to the answer. But a meeting between megalodon and T. rex belongs in imagination, not the fossil record.
7. WAS IT A GIANT GREAT WHITE SHARK?
No. Megalodon and the great white belonged to different shark families. Similar-looking teeth once encouraged a closer connection, but megalodon is placed in the extinct family Otodontidae.
Nor can we assume that its entire body was simply a great white enlarged. Research into its proportions suggests it may have been more slender than that familiar reconstruction. Its precise appearance remains an active scientific question.
8. WHY DO WE FIND TEETH MORE OFTEN THAN SKELETONS?
Sharks replace teeth throughout their lives, leaving many opportunities for a lost tooth to be buried and preserved.
Their skeletons are made mainly of cartilage rather than bone. Cartilage generally preserves less readily than the hard tissues of teeth. Fossil vertebrae and other skeletal remains do exist, but complete megalodon skeletons have not been found.
That imbalance explains why a single tooth can be such an important window into an enormous animal.
9. WHY DID MEGALODON BECOME EXTINCT?
Scientists are still investigating the combination of pressures involved. Changes in ocean environments, prey availability and competition with other predators are among the proposed factors.
The dietary overlap suggested by zinc-isotope research makes competition with great white sharks one possibility. It does not prove that great whites alone caused megalodon’s extinction. An animal’s disappearance can have several interacting causes.
10. COULD IT STILL BE HIDING IN THE DEEP OCEAN?
There is no credible evidence for that. The ocean contains many discoveries still to be made, but unexplored water is not evidence that an extinct species survives.
The case for extinction comes from examining the ages and reliability of fossil occurrences. A giant living shark would require positive evidence—not simply the possibility of a place to hide.
The real mystery is how megalodon lived, grew and responded to a changing ocean. Fossils give us a way to investigate those questions.
YOUR TURN: READ A TOOTH LIKE A FOSSIL DETECTIVE
Choose a clear tooth photograph. Find the root, follow the crown towards its tip and look for the serrated edges. What is preserved? What is worn or missing? Which observations can you make confidently, and which questions need more evidence?
A tooth cannot tell us everything. But it can open the door to an entire vanished ocean.
Explore another Fossil Huntress story in Megalodon: Apex Predator of the Deep, or practise recording fossil observations with the ammonite guide.
READ THE RESEARCH
- Shimada and colleagues (2025): Megalodon’s possible size, shape and biology. The authors explicitly present their reconstructions as working hypotheses.
- Boessenecker and colleagues (2019): The Early Pliocene extinction of Otodus megalodon.
- McCormack and colleagues (2022): Megalodon and great white shark feeding ecology revealed by zinc isotopes.
- Natural History Museum: Is megalodon still alive? and the largest shark that ever lived.
