Question

Origin of first mammals occurred?
(A) 500 million years ago
(B) 220 million years ago
(C) 1600 million years ago
(D) Over 1600 million years ago

Answer 1

Hint: Evolution is the process in which different kinds of living organisms are believed to have developed from earlier forms during the history of the earth. It is the gradual development of something. It shows us different forms of a single organism after evolution. Organisms adapt new forms of life according to the situation around them.

Complete answer:
(A) 500 million years ago: According to the geologic time scale, it is the Paleozoic era and present in the Cambrian period. During this period invertebrates are formed and active. Before this Precambrian era was present. It was the beginning of the earth.
(B) 220 million years ago: According to the geologic time scale, it is in the Mesozoic era and present in the Triassic period. It is the period between the extinction of the Dinosaurs and the present day is called the age of mammals or Cenozoic. The first mammals were shrews. Their fossils are small-sized and protect their offspring inside their body. They evolved in a better manner according to their survival.
(C) 1600 million years ago: It is the Mesoproterozoic era which occurred between 1600-1000 million years ago. The major events of this era are the evolution of sexual reproduction, the formation of the Rodinia supercontinent and the breakup of the Columbia supercontinent. It was the high point of the stromatolites before the decline of Neoproterozoic.
(D) Over 1600 million years ago: it is the Paleoproterozoic era which occurred between 2500-1600 million years ago. It is under the Proterozoic aeon. It is the largest era in history.

So, (B) is the correct answer.

Note:
In the above we detailed the evolution of organisms and geology in different eras according to geological time scale. It showed us the history of developed organisms and geology. Evolution is important for survival because only the fittest can survive to the last and weak one gets eliminated.