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Lower ProterozoicStromatolites from Bolivia, South America (polished vertical section through rock)
TheProterozoiceon comes before thePhanerozoic. It was a period before the first abundant complex life onEarth. The name Proterozoic comes from the Greek "earlier life". The Proterozoic Eon extended from 2500 million years ago (mya) to 541 mya. It is the most recent part of the formerPrecambrian.
The Proterozoic consists of 3 geologiceras, from oldest to youngest:
TheEdiacaran period (635 to 542mya) which is characterized by the evolution of abundant soft-bodied multicellular organisms.[2]
Study of these rocks shows that the eon featured massive, rapidcontinental accretion (unique to the Proterozoic), supercontinent cycles, andmountain building.[3]
