Late Proterozoic climate and life
A 580 million year old fossil of Spriggina floundensi , an animal from the Ediacaran period. Such life forms could have been ancestors to the many new forms that originated in the Cambrian Explosion . The end of the Proterozoic saw at least two Snowball Earths, so severe that the surface of the oceans may have been completely frozen. This happened about 716.5 and 635 Ma, in the Cryogenian period . The intensity and mechanism of both glaciations are still under investigation and harder to explain than the early Proterozoic Snowball Earth.Most paleoclimatologists think the cold episodes were linked to the formation of the supercontinent Rodinia.Because Rodinia was centered on the equator, rates of chemical weathering increased and carbon dioxide (CO 2 ) was taken from the atmosphere. Because CO 2 is an important greenhouse gas, climates cooled globally.In the same way, during the Snowball Earths most of the continental surf...