Archean is a geologic eon, 4,000 to 2,500 million years ago (4 to 2.5 billion years), that followed the hadean Eon and preceding the Proterozoic Eon.
The archean atmosphere is thought to have nearly free lacked oxygen.
There is a substantial evidence that life came into existence either near the end of hadean Eon or early in the Archean Eon.
This time period was around to 541 to 252.17 million years ago.
The Earths, atmosphere has changed over billions of years, but for the past 200 million years it's been much as it today.
Two great animal faunas dominated the seas during the paleozoic.... gave rise the reptiles and synapsids by the end of paleozoic.
the main events were permian, Devonian.
the time period was 225 million years ago
during the trassic oxygen levels in the atmosphere fell to a little 15%
diversified rapidly and a giant reptiles, dinosaurs and other monstrous beast roamed the earth.
This time period 65 millions years.
Quaternary period (2.6 millions years ago to the present), consisting the pleistocene and Holocene epoch).
cave lions, sabre- toothed cats, cave bears, giant deer, wolly rhinoceroses, and wolly mammoths were prevailing species of the quaternary period.