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These old life forms were simple but helped to change the atmosphere of early Earth.
They helped to produce more oxygen, making the atmosphere more similar to what we have today.
Following the increased production of oxygen, there was an increase in the number of organisms on Earth.The clothes that you wore longer ago will be towards the bottom, while clothes that you just wore will be near the top.This same idea is used to determine the relative age of rock layers and of the fossils within those rocks.We will look at the major eons and eras of Earth's history along with important characteristics of each.
Generally, when you think about history, you may think of learning about things like wars, invasions and empires.
Let's look at a few general things on this timeline first.