Question

What are fossils? How are they formed? Describe in brief two methods of determine the age of fossils. State any one role of fossils in the study of the process of evolution.

Answer 1

• Fossils are the preserved traces of the organisms that once existed and now they are extinct. Fossils are formed because some organisms failed to decay completely and have remained preserved till today.
  
• The age of the fossils can be determined by the following way:
  

1. Radiometric dating :

In this method, the age of the fossil can be determined by tracing the radioactive elements present in the rocks and examining it chemically.

2. Relative dating :

The fossils are found in the sedimentary rocks in the form of layers accumulated over large span of time. So, using this fact, the geologist find the age of fossils in the way that the fossil found at the bottom of those layers are found to be older than that found above those.

• Fossils have a significant role in evolution as they help in creating evolutionary relationships with the earlier organisms and the present day organisms.