Neoproterozoic

Neoproterozoic
1000 – 538.8 ± 0.2 Ma Pha. Proterozoic Archean Had.
Clockwise, from top left: Otavia, a multicellular organism from Tonian period, Snowball Earth glaciations from Cryogenian period, Ediacaran biota from Ediacaran period
Chronology
−1000 — – −950 — – −900 — – −850 — – −800 — – −750 — – −700 — – −650 — – −600 — – −550 — – P r o t e r o z o i c P Mesoproterozoic N e o p r o t e r o z o i c Paleozoic Tonian Cryogenian Ediacaran   An approximate timescale of key Neoproterozoic events. Axis scale: millions of years ago.
Proposed redefinition(s)	850–541 Ma Gradstein et al., 2012
Proposed subdivisions	Cryogenian Period, 850–630 Ma Gradstein et al., 2012 Ediacaran Period, 630–541.0 Ma Gradstein et al., 2012
Etymology
Name formality	Formal
Usage information
Celestial body	Earth
Regional usage	Global (ICS)
Time scale(s) used	ICS Time Scale
Definition
Chronological unit	Era
Stratigraphic unit	Erathem
Time span formality	Formal
Lower boundary definition	Defined Chronometrically
Lower GSSA ratified	1991[1]
Upper boundary definition	Appearance of the Ichnofossil Treptichnus pedum
Upper boundary GSSP	Fortune Head section, Newfoundland, Canada 47°04′34″N 55°49′52″W / 47.0762°N 55.8310°W / 47.0762; -55.8310
Upper GSSP ratified	1992[citation needed]

The Neoproterozoic Era is the last of the three geologic eras of the Proterozoic eon, spanning from 1 billion to 538.8 million years ago,^[2] and is the last era of the Precambrian "supereon". It is preceded by the Mesoproterozoic era and succeeded by the Paleozoic era of the Phanerozoic eon, and is further subdivided into three periods, the Tonian, Cryogenian and Ediacaran.

One of the most severe glaciation event known in the geologic record occurred during the Cryogenian period of the Neoproterozoic, when global ice sheets may have reached the equator and created a "Snowball Earth" lasting about 100 million years. The earliest fossils of complex life are found in the Tonian period in the form of Otavia, a primitive sponge, and the earliest fossil evidence of metazoan radiation are found in the Ediacaran period, which included the namesaked Ediacaran biota as well as the oldest definitive cnidarians and bilaterians in the fossil record.

According to Rino and co-workers, the sum of the continental crust formed in the Pan-African orogeny and the Grenville orogeny makes the Neoproterozoic the period of Earth's history that has produced most continental crust.^[3]