Main Page | See live article | Alphabetical index This period is part of the Proterozoic era. Hadean Archaean Paleoproterozoic Mesoproterozoic Neoproterozoic The Paleoproterozoic is the first of the three sub-divisions of the Proterozoic occurring between 2500 to 1600 million years ago. This is when the continents first stabilized. This is also when the atmospheric oxygen increased. Cyanobacteria were responsible for the increase. This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.