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 unit of geologic time from 1 billion to 538.8 million years ago.^[2]

It is the last era of the Precambrian Supereon and the Proterozoic Eon; it is subdivided into the Tonian, Cryogenian, and Ediacaran periods. It is preceded by the Mesoproterozoic Era and succeeded by the Paleozoic Era of the Phanerozoic Eon.

The most severe glaciation known in the geologic record occurred during the Cryogenian, when ice sheets may have reached the equator and formed a "Snowball Earth".

The earliest fossils of complex multicellular life are found in the Ediacaran Period. These organisms make up the Ediacaran biota, including the oldest definitive animals 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]