Was Megalodon a dinosaur?

Sharp teeth, an enormous body, extinct for a very long time. Megalodon looks like a dinosaur in almost every film and toy box. But it was something completely different, and it lived in a completely different time. Here is the whole story.

A gap of more than 40 million years

The last dinosaurs, such as Tyrannosaurus rex and Triceratops, died out about 66 million years ago. The oldest reliable megalodon fossils are around 23 million years old, and the last ones disappeared roughly 3.6 million years ago.

That means no dinosaur ever saw a megalodon. When the first megalodon swam the seas, the dinosaurs had already been gone for more than 40 million years. We humans actually live closer in time to megalodon than megalodon lived to the dinosaurs.

A shark, not a lizard

The word dinosaur does not mean "big, dangerous and extinct". Dinosaurs were a particular group of land animals with their legs straight under the body, the way a bird or a dog stands, not sprawling out to the sides like a crocodile. Birds are in fact dinosaurs that are still alive today.

Megalodon was a shark. Sharks are fish with skeletons of cartilage instead of bone, gills instead of lungs and fins instead of legs. That is why scientists find almost only teeth and a few vertebrae from it; the rest of the body decayed. Not even the great sea reptiles that lived alongside the dinosaurs, such as the mosasaurs, count as dinosaurs. The sea simply had no dinosaurs.

How big was it really?

Very big. Its teeth could reach almost 18 centimetres tall, about the size of an adult's hand. From the teeth and a few vertebrae, scientists estimate that a full-grown megalodon could reach around 15 to 20 metres, three times the length of a great white shark. It hunted whales, seals and large fish.

Compared with the dinosaurs it still was not the biggest. An Argentinosaurus could grow to more than 30 metres. But in the sea, for many millions of years, megalodon was the mightiest predator there was.

Why did it die out?

Nobody knows for certain, but the clues point the same way. The oceans grew colder, many of the whales it hunted became scarcer or moved to cold water where it did not thrive, and new rivals such as the great white shark and early killer whales took their share. About 3.6 million years ago it was gone.

How to remember the difference

Dinosaur: a land animal with legs under its body, alive from 252 to 66 million years ago. Megalodon: a shark, alive from 23 to 3.6 million years ago. Both are extinct, both are amazing, but they never met.