Dinosaurs refer to the nearest common ancestor of Triceratops, modern birds and Diplodocus and all their descendants.

For the convenience of research, dinosaurs can be divided into birds and non bird dinosaurs. Among them, non bird dinosaurs only lived in the Mesozoic (Triassic, Jurassic and Cretaceous), and were completely extinct 65 million years ago. This entry mainly introduces non bird dinosaurs.

The vigorous limbs, long tail and huge body are the portraits of some non bird dinosaurs. They mainly inhabit forests or open areas on the lake shore plain (or coastal plain).

In 1841, when Richard Owen, a British scientist, studied several lizard like bone fossils, he thought they were left by some prehistoric animal and named them dinosaurs, which means "horrible lizards"