Chapter 23, Problem 9SA

Summary Introduction

To explain:

The mass extinctions have shaped the ecological landscape.

Introduction:

Most of the organisms that have ever lived on the earth are extinct. As the ecological niche changes, the new species are evolved to fit in it and the older species fade away. Over past $\text{500}$ million years, the animal diversity in the oceans is decreased both rapidly and substantially. The extinctions also occurred on land which is known as mass extinction. In these extinctions, ecologically important taxa are eliminated and evolutionary opportunities are provided for the survivors.