Q.What is Mass extinction ?

Mass extinction is a geologically sudden event in which a large percentage of the world's species become extinct together, usually due to a catastrophic global environmental disturbance.

Unlike the slow, continuous 'background' rate of extinction that occurs normally, a mass extinction is characterised by the loss of a very large fraction (often 50-95%) of existing species over a geologically short interval - thousands to a few million years - cutting across many unrelated taxonomic groups simultaneously. Such events are generally linked to severe environmental upheavals, for example massive volcanic activity, asteroid impact, drastic climate change, or sea-level change. The fossil record shows five major mass extinctions, the largest being the end-Permian extinction (~252 mya, over 90% of species lost) and the best known being the end-Cretaceous (K-T) extinction (~65 mya) that ended the reign of the dinosaurs. Present-day biodiversity loss caused by habitat …