Neoproterozoic

Proposed redefinition(s)850–541 Ma
Gradstein et al., 2012
Proposed subdivisionsCryogenian Period, 850–630 Ma

Gradstein et al., 2012
Ediacaran Period, 630–541.0 Ma

Gradstein et al., 2012
EtymologyName formalityFormalUsage informationCelestial bodyEarthRegional usageGlobal (ICS)Time scale(s) usedICS Time ScaleDefinitionChronological unitEraStratigraphic unitErathemTime span formalityFormalLower boundary definitionDefined ChronometricallyLower GSSA ratified1990Upper boundary definitionAppearance of the IchnofossilTreptichnus pedumUpper boundary GSSPFortune Head section, Newfoundland, Canada
47°04′34″N55°49′52″W / 47.0762°N 55.8310°W / 47.0762; -55.8310Upper GSSP ratifiedAugust 1992 (as base of Cambrian)

The Neoproterozoic is the last of the three geologic eras of the Proterozoiceon, spanning from 1 billion to 538.8 million years ago, 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 events 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 metazoanradiation 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.