Meet the crocodilians
Crocodilians are a group of big reptiles that live in the tropics. There are about 23 types of crocodilian. These include crocodiles, alligators, caimans and gavial.
All crocodilians are carnivores. They have very powerful jaws filled with lots of sharp teeth.
Crocodilians live in swamps and rivers. They have sharp claws that help them grip when running on muddy riverbanks. They also have webbed toes to help them swim.
Another special thing about crocodilians is their skin. It is thick and works like armour plating. These reptiles are very tough.
The first crocodilians appeared about 220 million years ago. Because modern crocodilians look almost exactly the same as their dinosaur ancestors, they are called living fossils.
A big difference between dinosaurs and modern crocodilians is that the dinosaurs were bigger. A 12-metre long animal nicknamed SuperCroc lived in North Africa some 112 million years ago. If SuperCroc stood on its tail, it could look into the window of a fourth storey flat!