Crossword clues for proterozoic
Douglas Harper's Etymology Dictionary
WordNet
adj. formed in the later of two divisions of the Precambrian era; "proterozoic life forms"
Wikipedia
The Proterozoic is a geological eon representing the time just before the proliferation of complex life on Earth. The name Proterozoic comes from Greek and means "earlier life",the Greek root protero-,means "former, earlier" and zoic-,means "animal, living being". The Proterozoic Eon extended from to (million years ago), and is the most recent part of the Precambrian. It is subdivided into three geologic eras (from oldest to youngest): the Paleoproterozoic, Mesoproterozoic, and Neoproterozoic.
The well-identified events of this eon were the transition to an oxygenated atmosphere during the Paleoproterozoic; several glaciations, including the hypothesized Snowball Earth during the Cryogenian period in the late Neoproterozoic; and the Ediacaran Period (635 to 542 Ma) which is characterized by the evolution of abundant soft-bodied multicellular organisms.
Usage examples of "proterozoic".
Others divide the Precambrian into two eras, the very ancient Archean and the more recent Proterozoic.
Proterozoic Era and, before that, the Archeozoic Era, each estimated to have been 650 million years in duration.