What is a dinosaur?

When first learning about prehistoric animals, it is sometimes easy to get confused about what exactly is and isn't a dinosaur. Dinosaurs belonged to a group of reptiles that includes birds, crocodiles and other prehistoric animals such as pterosaurs. All of these animals are called the 'archosaurs', a group of reptiles that first appeared about 250 million years ago.

Like other reptiles, dinosaurs had a tough scaly skin, although smaller species sometimes had a soft feathery down similar to ducks. Most dinosaurs laid shelled eggs in nests and some may have cared for their young.

Dinosaurs were animals, closely related to crocodiles and birds, that lived in the Mesozoic era between 230 and 65 million years ago. All dinosaurs had four limbs, lived on land and breathed air. Dinosaurs walked on two or four legs. Some ate plants, others were fearsome carnivores. Many dinosaurs bore great armour plates and shields, which helped them fend off predatory dinosaurs.

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