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Megalodon, the giant fossil shark

Megalodon: the biggest shark that ever lived, known almost only from its teeth.

What megalodon was, how big it really grew, what its teeth tell us, what it ate, why it died out, how it compares with a great white, and why it is definitely not still out there. Every fact is linked to its source, and there is a quiz at the end.

Meet the shark Take the quiz

A large fossil shark tooth shaped like a broad triangle, its pale greenish-brown crown with finely serrated edges above a dark band and a wide brown root
A megalodon tooth from the Yorktown Formation, offshore North Carolina, about 5 to 4 million years old.Picture: James St. John, CC BY 2.0, via Wikimedia Commons (cropped and resized)
24.3 mpossible length, from a 2025 study NHM
18 cmthe length its teeth could reach NHM
276teeth in its jaws NHM
3.6 millionyears since it died out NHM

The short version

It is considered the largest shark, and the largest fish, that ever lived. Britannica

The word megalodon means “giant tooth”: it is made from Greek root words. Britannica

The earliest megalodon fossils date to 23 million years ago, and it became extinct 3.6 million years ago. NHM

Teeth are also the hardest part of a shark, which is why almost all megalodon fossils are teeth. NHM

Exactly why megalodon went extinct is still being worked out, but there is mounting evidence for a mix of changing climate, falling prey numbers and competition. NHM, still alive?

Because nearly all the fossils are teeth, sources often disagree, for example on how long megalodon grew, how heavy it was and exactly when it died out. Where they differ, we show each version side by side.

Reconstructed megalodon jaws hanging in a museum hall, a huge open mouth lined with rows of triangular teeth
Reconstructed megalodon jaws at the American Museum of Natural History, New York.Picture: Reinhold Möller, CC BY-SA 4.0, via Wikimedia Commons (cropped and resized)
How big? Megalodon beside a whale shark, a great white and a person, to scale. The great white length is our own working from the museum’s “about four times” comparison.Drawing: our own, simplified, to scale

Explore

The sharkName, family tree and body shape. Teeth276 in its jaws, 40,000 in a lifetime. Size and bite15, 18 or 24.3 metres? Life and nurseriesWhale hunting and warm seas. ExtinctionCooling seas and a new rival. vs great whiteSide by side, fact by fact. MythsIs megalodon still alive? No. GamesQuiz, myth or fact and the size-o-meter. Fact-check logEvery fact checked against its source.

Tile pictures are credited on their pages and on the credits page.

Try the games

A 12-question quiz, a myth-or-fact challenge, and a size-o-meter that measures you against megalodon and its giant teeth.

Play now

Megalodon is the second site in the fossils.im network. For the spiral shells of the Jurassic seas, visit ammonites.fossils.im.