Paleoproterozoic

Paleoproterozoic Era ( /pælioʊˌproʊtərəˈzoʊɪk-/;), spanning the time period from 2,500 to 1,600 million years ago (2.5–1.6 Ga), is the first of the three sub-divisions (eras) of the Proterozoic Eon. The Paleoproterozoic is also the longest era of the Earth's geological history.

Occurred: 2,500 million years ago - 1,600 million years ago