Why aren’t pterosaurs classed as dinosaurs?

Pterosaurs (flying prehistoric reptiles) and dinosaurs (also reptiles) share a common reptilian ancestor that lived some 240 million years ago, but the two groups then followed different evolutionary paths.

Dinosaurs are characterised by distinctive features of the skeleton, including a window-like opening in the pelvis where the thigh bone connects. Pterosaurs don’t have this joint, and they have their own unique features such as extra-long fourth fingers that support their wings. Pterosaurs are no more dinosaurs than we are chimpanzees.

Read more:

• What’s the largest flying animal?
• What did dinosaurs evolve from?
• What was the first dinosaur?
• What if the dinosaurs had survived?