Neoproterozoic era
Geologic timescale of the Proterozoic Eon
(millions of years ago)
(expand)

The Neoproterozoic Era is the unit of geologic time from 1,000 to 542 +/- 0. The geologic time scale is a chronologic schema (or idealized Model) relating Stratigraphy to time that is used by Geologists and other The Proterozoic (ˌproʊtərəˈzoʊɪk is a geological eon representing a period before the first abundant complex life on Earth. The geologic time scale is a chronologic schema (or idealized Model) relating Stratigraphy to time that is used by Geologists and other 3 million years ago. Annum is one form of the Latin noun meaning Year, not a form normally used for derivatives in modern languages the accusative singular ^[1] The terminal Era of the formal Proterozoic Eon (or the informal "Precambrian"), it is further subdivided into the Tonian, Cryogenian, and Ediacaran Periods. The Proterozoic (ˌproʊtərəˈzoʊɪk is a geological eon representing a period before the first abundant complex life on Earth. The Precambrian ( Pre-Cambrian) is an informal name for the supereon comprising the eons of the Geologic timescale that came before the current The Tonian (from Greek tonas, "stretch" is the first Geologic period in the Neoproterozoic Era and lasted from The Cryogenian (from Greek cryos "cold" and genesis "birth" is a Geologic period that lasted from. The Ediacaran Period (ˌiːdiˈækərən named after the Ediacara Hills of South Australia) is the last geological period of the Neoproterozoic The most severe glaciation known in the geologic record occurred during the Cryogenian, when ice sheets reached the equator and formed a possible "Snowball Earth"; and the earliest fossils of multicellular life are found in the Ediacaran, including the earliest animals. "Glacial" and "Glaciation" redirect here For the geological periods see Glacial period. The equator (sometimes referred to colloquially as "the Line") is the intersection of the Earth 's surface with the plane perpendicular to the The Snowball Earth Hypothesis as it was originally proposed]] Evidence The Snowball Earth hypothesis was originally devised to explain the apparent presence of The Ediacaran Period (ˌiːdiˈækərən named after the Ediacara Hills of South Australia) is the last geological period of the Neoproterozoic

Contents 1 Geology 2 Paleobiology 3 Terminal period 4 Notes 5 References

Geology

At the onset of the Neoproterozoic the supercontinent Rodinia, which had assembled during the late Mesoproterozoic, straddled the equator. For the Genus of Metalmark butterflies, see Rodinia (butterfly. The Mesoproterozoic Era is a geologic era that occurred between 1600 Ma and 1000 Ma (million years ago During the Tonian, rifting commenced which broke Rodinia into a number of individual land masses. The Tonian (from Greek tonas, "stretch" is the first Geologic period in the Neoproterozoic Era and lasted from Possibly as a consequence of the low-latitude position of most continents, several large-scale glacial events occurred during the Era including the Sturtian and Marinoan glaciations. The Cryogenian (from Greek cryos "cold" and genesis "birth" is a Geologic period that lasted from. The Cryogenian (from Greek cryos "cold" and genesis "birth" is a Geologic period that lasted from. These glaciations are believed to have been so severe that there were ice sheets at the equator--a state known as the "Snowball Earth". The Snowball Earth Hypothesis as it was originally proposed]] Evidence The Snowball Earth hypothesis was originally devised to explain the apparent presence of

Paleobiology

Main article: Ediacaran biota

The idea of the Neoproterozoic Era came on the scene relatively recently — after about 1960. The Ediacara (ˌiːdɪˈækərə formerly Vendian) biota are ancient lifeforms of the Ediacaran Period which represent the earliest known complex Nineteenth century paleontologists set the start of multicelled life at the first appearance of hard-shelled animals called trilobites and archeocyathids. Trilobites ("three-lobes" are extinct Arthropods that form the class Trilobita. The Archaeocyatha or archaeocyathids ("ancient cups" were Sessile This set the beginning of the Cambrian period. The Cambrian is a geologic period and system that began about Ma (million years ago at the end of the Proterozoic eon and ended about Ma with In the early 20th century, paleontologists started finding fossils of multicellular animals that predated the Cambrian boundary. A complex fauna was found in South West Africa in the 1920s but was misdated. Another was found in South Australia in the 1940s but was not thoroughly examined until the late 1950s. Other possible early fossils were found in Russia, England, Canada, and elsewhere (see Ediacaran biota). The Ediacara (ˌiːdɪˈækərə formerly Vendian) biota are ancient lifeforms of the Ediacaran Period which represent the earliest known complex Some were determined to be pseudofossils, but others were revealed to be members of rather complex biotas that are still poorly understood. Pseudofossils are Inorganic objects markings or impressions that might be mistaken for Fossils Pseudofossils may be misleading as some types of mineral deposits At least 25 regions worldwide yielded metazoan fossils prior to the classical Cambrian boundary. ^[2]

A few of the early animals appear possibly to be ancestors of modern animals. Most fall into ambiguous groups of frond-like animals(?); discoids that might be holdfasts for stalked animals(?) ("medusoids"); mattress-like forms; small calcaerous tubes; and armored animals of unknown provenance. These were most commonly known as Vendian biota until the formal naming of the Period, and are currently known as Ediacaran biota. Most were soft bodied. The relationships, if any, to modern forms are obscure. Some paleontologists relate many or most of these forms to modern animals. Others acknowledge a few possible or even likely relationships but feel that most of the Ediacaran forms are representatives of (an) unknown animal type(s).

In addition to Ediacaran biota, later two other types of biota were discovered in China (the so-called Doushantuo formation and Hainan formation). The Ediacara (ˌiːdɪˈækərə formerly Vendian) biota are ancient lifeforms of the Ediacaran Period which represent the earliest known complex The Doushantuo Formation is a lagerstätte in Guizhou Province China that is notable for being one of the oldest Fossil beds to contain highly

Terminal period

Main article: Ediacaran

The nomenclature for the terminal period of the Neoproterozoic has been unstable. The Ediacaran Period (ˌiːdiˈækərən named after the Ediacara Hills of South Australia) is the last geological period of the Neoproterozoic Russian geologists referred to the last period of the Neoproterozoic as the Vendian, and the Chinese called it the Sinian, and most Australians and North Americans used the name Ediacaran. The Ediacaran Period (ˌiːdiˈækərən named after the Ediacara Hills of South Australia) is the last geological period of the Neoproterozoic The Ediacaran Period (ˌiːdiˈækərən named after the Ediacara Hills of South Australia) is the last geological period of the Neoproterozoic However, in 2004, the International Union of Geological Sciences ratified the Ediacaran age to be a geological age of the Neoproterozoic, ranging from 630 +5/-30 to 542 +/- 0. "MMIV" redirects here For the Modest Mouse album see " Baron von Bullshit Rides Again " The Ediacaran Period (ˌiːdiˈækərən named after the Ediacara Hills of South Australia) is the last geological period of the Neoproterozoic 3 million years ago. ^[1] The Ediacaran boundaries are the only Precambrian boundaries defined by biologic Global Boundary Stratotype Section and Points, rather than the absolute Global Standard Stratigraphic Ages. A Global Boundary Stratotype Section and Point, abbreviated GSSP, is an internationally agreed upon stratigraphic section which serves as the reference section for In the Stratigraphy sub-discipline of Geology, a Global Standard Stratigraphic Age, officially abbreviated GSSA, is a chronological reference point and

Notes

References

• Gradstein, F. M. ; Ogg, J. G. ; Smith, A. G. (eds. ) (2005). A Geologic Time Scale 2004. Cambridge University Press. ISBN 0-521-78673-8.  
• Knoll, A. H. ; Walter, M. ; Narbonne, G. ; Christie-Blick, N. (2006). "The Ediacaran Period: a new addition to the geologic time scale". Lethaia 39: 13-30. doi:10.1080/00241160500409223. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.   PDF here.

Proterozoic eon
Paleoproterozoic era				Mesoproterozoic era			Neoproterozoic era
Siderian	Rhyacian	Orosirian	Statherian	Calymmian	Ectasian	Stenian	Tonian	Cryogenian	Ediacaran

The Proterozoic (ˌproʊtərəˈzoʊɪk is a geological eon representing a period before the first abundant complex life on Earth. The Paleoproterozoic (ˌpeɪlɪoʊˌproʊtərəˈzoʊɪk also spelled Palaeoproterozoic) is the first of the three sub-divisions ( eras) of the The Mesoproterozoic Era is a geologic era that occurred between 1600 Ma and 1000 Ma (million years ago The Siderian (saɪˈdɪəriən sideros meaning "iron" is the first Geologic period in the Paleoproterozoic Era and lasted from 2500 The Rhyacian (raɪˈeɪsiən Ρυαξ ( rhyax) meaning "stream of Lava " is the second Geologic period in the Paleoproterozoic The Orosirian (ˌɒroʊˈsɪəriən oroseira - ὀροσειρά, meaning "mountain range" is the third Geologic period in the The Statherian (stəˈθɪəriən statheros, meaning "stable firm" is the final Geologic period in the Paleoproterozoic Era The Calymmian (from Greek calymma, "cover" is the first Geologic period in the Mesoproterozoic Era and lasted The Ectasian (from Greek ectasis, "extension" is the second Geologic period in the Mesoproterozoic era and lasted The Stenian (from Greek stenos, "narrow" is the final Geologic period in the Mesoproterozoic Era and lasted The Tonian (from Greek tonas, "stretch" is the first Geologic period in the Neoproterozoic Era and lasted from The Cryogenian (from Greek cryos "cold" and genesis "birth" is a Geologic period that lasted from. The Ediacaran Period (ˌiːdiˈækərən named after the Ediacara Hills of South Australia) is the last geological period of the Neoproterozoic

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