Extinction of species is an accepted fact. Anything which is created is destined to come into extinction at some period of time which is true in several cases of species and the fossil records are the most existed proof of it. From millions of years back, the cases of extinction have been witnessed and scientists have found five extinction in Earth’s history out of which some cases were so severe that almost 90% of the species were extinguished. The Cretaceous –Tertiary event is the most popular that happened some 63 million years ago and killed off all the dinosaurs to give rise to the birth of mammals. This event was the result of asteroid attack on the earth.