Search Results for: Fish preserved in forms
crust and the oldest earth rocks - million years ago (mya) and continuing until its boundary at mya, with the proterozoic eon. the archean-proterozoic boundary is defined chronometrically, unlike the boundaries separating many other geologic time periods, which are defined based on noticeable changes in
divided, from earliest to most recent, into the hadean, archean, and proterozoic eons. the origin of life has been traced to the archean eon, with fossils of prokaryotes (non-nucleated single-celled organisms) known from mya. during the archean eon, prokaryotes spread over much of earth's surface, often in...
https://www.newworldencyclopedia.org/entry/Archean