Answer: Mass extinction selectively removes poorly adapted animals.
A mass extinction is a catastrophic event in which a disaster occurs to limit or decrease in living communities. This results in decrease in biodiversity on Earth. Mass extinction plays an important role in evolution of the animal as the remaining group of species will have to follow their ecological niche in a unsuitable land for survival as mass extinction not only affect living community but also result in drastic changes in abiotic (non-living) factors like water, air, food, shelter on which living organisms are dependent upon. Some animals undergo several adaptations to tolerate changing environment conditions but others cannot. Therefore, poorly adapted animals do not survive. Hence, mass extinction selectively removes poorly adapted animals.