What are Dinosaurs?
In simple terms, a Dinosaur can be classified as a land dwelling reptile that was born from an egg and had no fur on its body. Dinosaurs walked on straight legs tucked underneath their bodies and were thought to have evolved from early reptiles in the diapsid line (same line as snakes, crocodiles and lizards).
The term 'Dinosaur' means "terrible lizard" however, the main difference between lizards and dinosaurs are the structure of their legs and hips. Most reptiles have legs that stick out from their bodies and they move by swinging their bodies from side to side. A dinosaur however walked on straight legs similar to modern mammals. One common mistake people often make is that dinosaurs could fly. In fact they couldn't. The species that could fly were classified as Pterosaurs and were not dinosaurs at all.
Dixon, D (2007) The World of the Dinosaurs. [book] Anness Publishing Ltd, London
Natural History Museum (2007) Dino Directory [internet] London. Available http://internt.nhm.ac.uk/jdsml/nature-online/dino-directory/ [Accessed 20/11/2007]