PROTEROZOIC

[Pro.te.ro.zo.ic] adj [Gk proteros former, earlier (fr. pro before) + ISV -zoic--more at for] (1899): of, relating to, or being the eon of geologic time or the corresponding system of rocks that includes the interval between the Archean and Phanerozoic eons, perhaps exceeds in length all of subsequent geological time, and is marked by rocks that contain fossils indicating the first appearance of eukaryotic organisms (as algae) -- Proterozoic n