Dinosaurs are a huge and diverse group of ancient animals. They first appeared during the Triassic period and evolved rapidly during the Jurassic and Cretaceous periods.

They left a very distinct impression on the Earth, not only because of the enormous size and incredible diversity, but also because they left behind an extremely well-preserved fossil record.

Dinosaur fossils have been found in rocks of various ages, all over the world. They have been found in the Jurassic, Cretaceous, and Triassic periods. Some of the most well-preserved and best-known dinosaur fossils have been found in the Jehol fossil beds in China, the Palaeogene era fossil beds in Europe, and the Oguigarano Formation in South America.

There are hundreds of different species of dinosaurs. However, only a few have been classified as living things. The vast majority of species are extinct, and the ones that are still alive today are extremely rare.