Explain the importance of fossils in deciding evolutionary relationships.

Fossil provide us evidence about

(i) The organisms that lived long ago such as the time period during which they lived, their structure etc.
(ii)Evolutionary development of species i.e., line of their development.

(iii) Connecting links between two groups. For example, feathers present in some dinosaurs means that birds are very closely related to reptiles.

(iv) Which organisms evolved earlier and which later.

(v) Development of complex body designs from the simple body designs.