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The Late Series 3, Stage 4 to Furongian (Upper Cambrian) Orsten fauna includes fossilized organisms preserved in Orsten〔''Orsten'' means "stinking stone": the alum shale matrix is rich in organics.〕 lagerstätten, notably at Kinnekulle and on the island of Öland, all in Sweden. The initial site, discovered in 1975 by Klaus Müller and his assistants, exceptionally preserves soft-bodied organisms, and their larvae, who are preserved uncompacted in three dimensions. The fossils are phosphatized and silicified, thus the delicate chitinous cuticle and soft parts are not affected by acids, which act upon the limestone nodules within which the fossils have survived. Acids dissolve the limestone, revealing the microfossils in a recovery process called "acid etching". To recover the fossils, more than one and a half tons of Orsten limestone have been dissolved in acid, originally in a specifically designed laboratory in Bonn, more recently moved to Ulm. The insoluble residue is scanned by electron microscope.〔(C.O.R.E. Örsten site )〕 The Orsten fauna has improved our understanding of metazoan phylogeny and evolution, particularly among the arthropods, thanks in part to unique preservation of larval stages. The Orsten sites reveals the oldest well-documented benthic meiofauna in the fossil record. For the first time, fossils have been found of tardigrades ("water bears") and apparently free-living pentastomids.〔Modern pentastomids, or "tongue worms" are internal parasites of most modern terrestrial vertebrates.〕 The Cambrian stratum consists of alum shales with limestone nodules, which are interpreted as the products of an oxygen-depleted ("dysoxic")〔The distribution of pyrites in the limestone, together with the organic content indicate levels of oxygen that prevented normal decomposition.〕 marine bottom water habitat of a possibly offshore seashelf at depths of perhaps 50–100 m.〔 The bottom was rich in organic detritus, forming a soft muddy zone with floc in its surface layer. Further Orsten fauna have been found by Dieter Waloszek〔(Dieter Waloszek ).〕 in the outback of the Northern Territory of Australia. ==Notes== 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「Orsten」の詳細全文を読む スポンサード リンク
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