Question

Which of the following is commonly called ‘Age of Mammals’
A. Mesozoic
B. Cenozoic
C. Paleozoic
D. Azoic

Answer 1

Hint: The various periods on earth can be divided into various eras known as the geologic eras. Era can be obtained by further division of a bigger period known as eons. The Phanerozoic eon can be divided into Paleozoic, Mesozoic, and Cenozoic eras.

Complete answer:
The Cenozoic era is known as the ‘Age of Mammals’, more precisely it can be called the ‘Age of Mammals and Birds’. This period started about sixty-six million years ago and is continued till the present. The start of this period is marked by the extinction of dinosaurs. The age is called so because it is assumed that mammals are the largest land animals surviving at this time. The name Cenozoic means ‘Recent life’. This era marked the extinction of many other animals so that the mammals could dominate the earth. During this time, the atmosphere of the earth started to cool down.
Considering the other options:
-The Mesozoic era existed about sixty-six million years ago. This period is known as ‘The Age of Reptiles’ or ‘The Age of Conifers’. The largest reptiles to have ever existed on earth, the dinosaurs lived in this era. It had massive climatic changes as well as tectonic activities. Birds and mammals also first appeared in this period but were a minority.
-The paleozoic era is the oldest among the eras belonging to the Phanerozoic eon. The organisms to have lived in the era are amphibians, mollusks, arthropods, crustaceans, and many other primitive organisms. Life in this period is said to have originated in the ocean, but it slowly got extended into the land.
-The Azoic era represents the period where no life existed on Earth. It is also known as ‘The Age of Rocks’. Azoic means without animals.
Thus, from the given set of options, the most correct answer is Option (B), i.e., Cenozoic Era.

Note: The eras are further classified into different Time Periods. For example, the Mesozoic Era is further divided into the Cretaceous, Jurassic and Triassic periods. And the Cenozoic Era is divided into Quaternary, Neogene, and Paleogene periods.