Geological Time Scale of Earth

By the study of fossils and different layers of rocks on earth geologists have formed time scale of earth. They have divided this period as Eon, Era, Period and Epoch among which eon is the longest one. Here we study about following era.

• Cenozoic Era: During this period, all types of variety of plants evolved. Humans dominated the era. The era began from 65 million years ago to till now.
• Mesozoic Era: During this period, evolution of coniferous and flowering plants took place. Reptiles i.e. Dinosaurs dominated the era. The era began from 225 million years ago and ended about 65 million years ago.
• Palaezoic Era:  Some marine vertebrate appeared. Some green plants on land appeared. Flying insects originated on land. Origin and development of ferns. Extinction of many animals and development of reptiles.
• Pre Cambrian Era: origin of bacteria and algae. Developments of many unicellular and multicellular primitive organisms.