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The Ediacaran Period , named after the Ediacara Hills of South Australia, is the last geological period of the Neoproterozoic Era and of the Proterozoic Eon, immediately preceding the Cambrian Period, the first period of the Paleozoic Era and of the Phanerozoic Eon. The Ediacaran Period's status as an official geological period was ratified in 2004 by the International Union of Geological Sciences (IUGS), making it the first new geological period declared in 120 years.〔 Although the Period takes its name from the Ediacara Hills where geologist Reg Sprigg first discovered fossils of the eponymous Ediacara biota in 1946, the type section is located in the bed of the Enorama Creek〔 Accessed 27 December 2010.〕 within Brachina Gorge〔(South Australian Museum Newsletter April 2005 ) Accessed 9 August 2010.〕 in the Flinders Ranges of South Australia, at . ==Ediacaran and Vendian== The Ediacaran Period overlaps, but is shorter than the Vendian Period, a name that was earlier, in 1952, proposed by Russian geologist and paleontologist Boris Sokolov. The Vendian concept was formed stratigraphically top-down, and the lower boundary of the Cambrian became the upper boundary of the Vendian.〔Sokolov, B.S. (1997). "Essays on the Advent of the Vendian System." 153 pp. KMK Scientific Press, Moscow. (in Russian)〕 Paleontological substantiation of this boundary was worked out separately for the siliciclastic basin (base of the Baltic Stage of the Eastern European Platform〔Sokolov B. S. (1965) "Abstracts of All-Union Symposium on Paleontology of the Precambrian and Early Cambrian." Nauka, Novosibirsk.〕) and for the carbonate basin (base of the Tommotian Stage of the Siberian Platform). The lower boundary of the Vendian was suggested to be defined at the base of the Varanger (Laplandian) tillites.〔〔 In: (82mb)〕 The Vendian in its type area consists of large subdivisions such as Laplandian, Redkino, Kotlin and Rovno Regional stages with the globally traceable subdivisions and their boundaries, including its lower one. The Redkino, Kotlin and Rovno regional stages have been substantiated in the type area of the Vendian on the basis of the abundant organic-walled microfossils, megascopic algae, metazoan body fossils and ichnofossils.〔 The lower boundary of the Vendian could have a biostratigraphic substantiation as well taking into consideration the worldwide occurrence of the Pertatataka assemblage of giant acanthomorph acritarchs.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Ediacaran」の詳細全文を読む スポンサード リンク
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