Geological timeline is the chronological dating of the organisms and the geological happening in the orderly manner of the years and dates. The oldest mammals lived 200 million years ago.
5 million years ago humans arrived, 200 million years ago first mammal organism, 1.5 billion years ago complex single-celled organisms and 4.5 billion years ago Earth was formed.
The geological timeline is important as it portrays the presence and arrival of the organisms and the formation of some of the structures.
Therefore, mammals arrived at option B. 200 million years ago.
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