You might know the Cretaceous Period for big animals such as Tyrannosaurus rex and Triceratops ... It lasted a long time, nearly 80 million years, making it the longest geological period of the ...

The Proterozoic eon was the gathering up of oxygen in Earth's atmosphere, and the Phanerozoic eon coincides with the major diversification of animals, plants, and fungi.

including plants and animals, and the chemical environment in the current Phanerozoic Eon, which began approximately 540 million years ago. At the start of the Phanerozoic, carbon dioxide levels ...