The Proterozoic 's a geological eon representing a period before the first abundant complex life on Earth. The name Proterozoic comes from the Greek "earlier life." The Proterozoic Eon extended from 2500 Ma to 542.0 ± 1.0 Ma (million years ago), and's the most recent part of the old, informally named ‘Precambrian’ time. The Proterozoic consists of 3 geologic eras, from oldest to youngest: Paleoproterozoic Mesoproterozoic Neoproterozoic The well-identified events were: The… (More on Proterozoic)