Development of ozone layer which absorbs harmful UV radiation End of banded iron formations which only formed in low, fluctuation O2 Beginning of red beds - red beds are clastic sedimentary rocks such as sandstones and siltstones with red iron oxide cement. The presence of iron oxide indicates that there was a relatively abundant, constant level of oxygen in the atmosphere at the time the rocks were deposited. Proterozoic life Extensive stromatolites . May have been more resistant to UV radiation because of sediment covering. First fossil eukaryotic cells appeared by at least 1.6 - 1.4 by.
Eukaryotes are cells which have a nucleus and organelles .
They are larger than prokaryotes. Ediacaran Fauna Metazoans appeared in the Late Proterozoic. Metazoans are multicellular animals with various types of cells organized into tissues and organs. Preserved as impressions of soft-bodied organisms in sandstones. May be related to the accumulation of oxygen in the atmosphere.