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The history of the Earth is divided broadly into 3 stretches of time called eons, these are Archean, Proterozoic, and Phanerozoic. The Phanerozoic eon is split into eras which are Paleozoic Era, Mesozoic Era and Cenozoic Era. The first two eons lasted over the first 4 billion years after the creation of our planet. During this time, the rock crust was formed, and the oceans and atmosphere were formed. Fossils from this period consist of primitive bacteria and towards the later end of worms, jellyfish, corals, and other primitive invertebrates.
The Paleozoic era began 570 million years ago. There was the development of plants during this period. 240 million years ago the Mesozoic era began. In this period the fish, reptiles and other creatures that live in the water started to appear. Warm blooded creatures made an entry right at the end of this era. The Cenozoic Era which is still going on began 65 million years ago. During this period, the continents as we know them today were formed by the movement of the crust, mountain ranges appeared and volcanoes were formed.
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