Fossils
What are fossils:-
Fossils are the remains or evidence of ancient plants or animals that have been preserved in the rocks of the earth’s crust. Most fossils represent the hard parts of prehistoric organisms that lived in the area in which their remains were collected.
With the help of fossils the paleontologist is able to form a visible picture of past age. He does this by studying bones, teeth, shells, foot prints or any other indication of presence of past life.
The majority of fossils are found in marine sedimentary rocks. Only rarely fossils occur in igneous and metamorphic rocks.
Requirements of Fossilization:- There are certainly a few requirements of fossilization.
1. The organism should possess hard parts:
Possession of hard part is very importan requirement. These hard parts might be shell, bones, teeths or the woody tissue of plants.
2. The organic remains must escape immediate destruction after death:
If the body parts of an organism are crushed, decayed , badly weathered, or otherwise greatly changed, this may result in the alteration or complete destruction of the fossil record of that particular organism.
3. Rapid burial must take place in a material capable of retarting decomposition.
The type of material burying the remains usually depends upon where the organism lived. The remains of marine animals are common as fossils because they to the ocean bottom after death, and here they are covered by soft muds which are converted into the shales and limestones of later geologic ages.
Ash falling from near by volcanoes has been known to cover entire forests. Some of these fossil forests have been found with the trees still standing and in excellent state of preservation.
Uses of fossils:-
(1) The fossils are commonly used for correlating the strata and determining their relative age.
(2) Fossils indicate wether the rock is a fresh water deposit or a marine deposit.
(3) Fossils give information about the climate of the times in which they lived.
(4) The fossils have helped in understanding the evolution of plants and animals.