| Abstract from DBPedia | The Ediacaran Period ( /iːdiˈækərən, ɛdi-/ ee-dee-AK-ər-ən, ed-ee-) is a geological period that spans 96 million years from the end of the Cryogenian Period 635 million years ago (Mya), to the beginning of the Cambrian Period 538.8 Mya. It marks the end of the Proterozoic Eon, and the beginning of the Phanerozoic Eon. It is named after the Ediacara Hills of South Australia. 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 Ediacaran biota in 1946, the type section is located in the bed of the Enorama Creek within Brachina Gorge in the Flinders Ranges of South Australia, at 31°19′53.8″S 138°38′0.1″E / 31.331611°S 138.633361°E. The Ediacaran marks the first appearance of widespread multicellular fauna following the end of Snowball Earth glaciation events, the so-called Ediacaran biota, which is represented by now-extinct relatively simple animal phyla such as Proarticulata (bilaterians with articulation including Dickinsonia and Spriggina), Petalonamae (sea pen-like animals including Charnia), Disc-shaped forms (radial-shaped animals including Cyclomedusa) and Trilobozoa (animals with tri-radial symmetry including Tribrachidium). Most of those organisms appeared during or after the Avalon explosion event 575 million years ago and died out during an End-Ediacaran extinction event 539 million years ago. Some modern groups of animals also appeared during this period, including cnidarians and early bilaterians such as Xenacoelomorpha. Mollusc-like Kimberella also lived during Ediacaran. Fossilized organisms with shells or skeletons were yet to evolve in the Cambrian, the superseding period of the Phanerozoic eon. The supercontinent Pannotia formed and broke apart by the end of the period. The Ediacaran also witnessed several glaciation events, such as the Gaskiers and Baykonurian glaciations. The Shuram excursion also occurred during this period, but its glacial origin is unlikely.エディアカラン（Ediacaran period、エディアカラ紀）とは、地質時代の区分の1つである。新原生代クライオジェニアンの終わりから古生代カンブリア紀の始まりまでの約6億2000万年前〜約5億4200万年前である。原生代の最後の区分である。2004年に国際地質科学連合（IUGS）が、先カンブリア時代層序小委員会の勧告に基づきその基底 (Enorama Creek GSSP) を公式に批准した。 (Source: http://dbpedia.org/resource/Ediacaran) |
