During the Proterozoic era, oxygen produced by photosynthesizing ... end of the era or whether they evolved into the hard-shelled life that follows. 2,500 mya: Banded iron formations Banded ...

Their research revealed how these early life forms contributed to the transition from the Proterozoic to the Phanerozoic eon.

That oxygen initially wiped out stromatolites' competition, enabling their prominence in the Archean and early Proterozoic ...