ABSTRACT
In the history of 4.6 billion years, Earth has experienced many mysterious and unexplained events of obliteration, which demarcates the boundaries among geological periods. Fossil records are fundamental to the interpretation of these past geological events. Earth was punctuated by five major extinction events. Each event eliminated most of the flourishing species and raised the curtain for new species after. These five major mass extinctions, which occurred during Late Ordovician, Late Devonian, Permian–Triassic transition, Triassic–Jurassic transition, and Cretaceous–Tertiary transition, are often referred to as the five largest Phanerozoic mass extinctions. Climate change and global oceanic circulation played a significant role in these “Big Five” events that wiped out more than half of the pervasive biota. Global ecosystem was disturbed and ruptured many times due to phenomenon like marine transgressions and regressions, global warming and climate change, ocean anoxia, asteroid impact, and intense volcanic activities in the total Earth’s history. This chapter focuses on “Mass Extinction,” which is perhaps the most perplexing event on Earth, and emphasizes on its relative causes and consequences.
