What are fossils ? What do they tell us about the process of evolution ?

Fossils : Fossils are the remains or traces of a dead organism. These are formed through the formation of sedimentary rocks. They provide following information on the process of evolution. They tell about the changes that occured on the earth’s surface and the corresponding organisms. They tell about the gradual development of complex structured organisms from simple structured organisms. It is known through them that birds are evolved from reptiles. They state that angiosperms are developed from pteriodophytes and gymnosperms. They exhibit the process of humana evolution.