The Paleoproterozoic era was the first era in the Proterozoic eon. It lasted from 2.5 bya to 1.6 bya. Most of the bacteria was anaerobic and lived in oxygen-free environments. During this era, the first eukaryotes formed.
Dinopedia
The Paleoproterozoic era was the first era in the Proterozoic eon. It lasted from 2.5 bya to 1.6 bya. Most of the bacteria was anaerobic and lived in oxygen-free environments. During this era, the first eukaryotes formed.