What are fossils? How are fossils formed and how is their age determined? State the importance of fossils in the study of evolution?
(i) Dead remains of plants and animals that are embedded in sedimentary rocks of hundred
of years ago.
(ii) When a plant or an animals dies, it remains fall on the ground and its body gets covered by sediments brought by river, winds etc., over a period of time and resulting in the formation of fossils.
(iii)
- Radiometric dating: In this method, age of fossils can be determined by tracing the radioactive elements in the rocks.
- Relation dating: Fossils are found in sedimentary rocks in the form of layers accumulated over a large span of time, considering the fact that fossils found in the bottom layers are older than those found in the layers above them, geologists find the age of fossils.
(iv) Importance:
- They can help in finding the connecting links between different organism.
- The depth at which fossils are fourd tells us their age and the period of existence.