Reptiles represent the first class of vertebrates fully adapted for life in dry places on land. They have no obvious diagnostic characteristics of their own that immediately separate them from other classes of vertebrates. The characters of reptiles are in fact a combination of characters that are found in fishes and amphibians on one hand and in birds and mammals on the other. The class name refers to the mode of locomotion (Latin, repere=to creep or crawl). The study of reptiles is called Herpetology (Greek, herpeton=reptiles). They dominated the world as dinosaurs once which can now be seen only in Spielberg movies.