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LIFE BEGINS ON EARTH:
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The four EONS of time comprise the entire history of Earth from the moment our planet accreted 
from debris of the solar disk, to the moment in which we presently live.
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(Observe how life in the sea begins shortly after Earth cools and forms a crust.)
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Note:  All charts in this series work backward in time, flowing from the oldest time (left) to the more recent time (right)..
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Hadean Eon:         800-million years of cooling, Earth's crust is forming.   Earlist Precambrian.
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Archean Eon:       The first igneous and metamorphic rocks develop.  Life begins, the first marine microorganisms appear, including a one-celled
                              protozoan-type ancestor of the chicken -- sometimes called the amoeba chicken.
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Proterozoic Eon:   Development of sedimentary rock, shallow seas, and the first soft-bodied, marine invertebrates.  Late Precambrian.
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Phanerozoic Eon:  Subdivided into the Paleozoic, Mesozoic, and Cenozoic eras.   Amphibian chickens arise -- no beaks or feathers,  but plenty of
                               scales, a scum-slimed belly, a dragging tail, and a long olfactory tongue.
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Next,  we explore the Phanerozoic Eon and its three eras, encompassing the most recent 570-million years of time.
The next  episode is called,  Hard Shelled Creatures Appear on Earth.