Question

What are fossils? How do they act as an evidence for organic evolution?

Answer 1

Fossils are the dead remains of plants and animals that are embedded in sedimentary rocks, preserved and petrified. They represent the ancestors of the plants and animals that are alive today. They provide evidence of evolution by revealing the characteristics of the past organisms and the changes that have occurred in these organisms to give rise to the present organisms. Let us explain the importance of fossils in deciding evolutionary history with the help of the following example.

Around 100 million years ago, some invertebrates died and got buried in the soil. More sediments got accumulated on top of the soil, turning it into sedimentary rock.
At the same place, millions of years later, some dinosaurs died and their bodies got buried on top of the sedimentary rock. The mud containing dinosaurs also turned into a rock.
Then, millions of years later, some horse-like creatures died in that area and got fossilised in rocks above the dinosaur fossils.
Sometime later, due to soil erosion or floods in that area, the rocks containing horse-like fossils get exposed. If that area is excavated deeper, then the dinosaur and invertebrate fossils can also be found. Thus, by digging that area, scientists can easily predict that horse-like animals evolved later than the dinosaurs and the invertebrates.