Orsten

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Orsten
Stratigraphic range: Miaolingian–Furongian
Hesslandona angustata, a phosphatocopine, showing exceptional preservation in 3D
TypeGeological formation
Unit ofAlum Shale Formation
Lithology
PrimaryShale and limestone
Location
RegionKinnekulle and island of Öland
CountrySweden
Type section
Named forOrsten[1]
Named byKlaus J. Müller, 1975

The Orsten fauna are fossilized organisms preserved in the Orsten lagerstätte of Cambrian (Late Miaolingian[2] to Furongian) rocks, 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.[3] The phosphorus used to replace the fossils with calcium phosphate is presumed to be derived from fecal pellets.[4]

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.[5]

The Cambrian strata consist of alum shales with limestone nodules (the Alum Shale Formation), which are interpreted as the products of an oxygen-depleted ("dysoxic")[6] marine bottom water habitat of a possibly offshore seashelf at depths of perhaps 50–100 m.[3] The bottom was rich in organic detritus, forming a soft muddy zone with floc in its surface layer.

Other Orsten-type preservation fauna have been found in Nevada, eastern Canada, England, Poland, Siberia, China and the Northern Territory of Australia.[7]

Paleobiota[edit]

Based on data from C.O.R.E website.[3]

Animals
Genus Notes Images
Agnostus An agnostid
Cambropycnogon A sea spider
Cambropachycope A monocular arthropod of uncertain affinities, possibly placed in stem-Mandibulata
Goticaris A monocular arthropod of uncertain affinities, possibly placed in stem-Mandibulata
Rehbachiella A crustacean
Martinssonia A pancrustacean
Musacaris A pancrustacean
Bredocaris A pancrustacean
Skara A pancrustacean
Sandtorpia A pancrustacean
Henningsmoenicaris A pancrustacean
Walossekia A pancrustacean
Aengapentastomum A pentastomid parasitic crustacean
Boeckelericambria
Heymonsicambria
Haffnericambria
Oelandocaris A stem-group crustacean or stem-group mandibulate or megacheiran[8]
Hesslandona A bivalved arthropod belonging to Phosphatocopina
Trapezilites
Waldoria
Veldotron
Falites
Vestrogothia
Orstenotubulus A lobopodian

Orsten-type fauna found elsewhere[edit]

Animals
Genus Notes Images
Skara Two additional species known from Poland and China
Heymonsicambria One additional species known from Ordovician of Canada
Vestrogothia Two additional species known from China
Markuelia A possible member of Cycloneuralia, known from Australia
Shergoldana
Orstenoloricus A loriciferan larva[9] from Australia
Cambrocaris A crustacean, known only from Poland
Unnamed tardigrade Only known from Siberia
Wujicaris A pancrustacean known from China
Yicaris
Dabashanella A member of Phosphatocopina from China
Klausmuelleria A member of Phosphatocopina from England

Notes[edit]

  1. ^ Orsten means "stinking stone": the alum shale matrix is rich in organics.
  2. ^ Maas, A.; Mayer, G.; Kristensen, R. M.; Waloszek, D. (2007). "A Cambrian micro-lobopodian and the evolution of arthropod locomotion and reproduction". Chinese Science Bulletin. 52 (24): 3385. doi:10.1007/s11434-007-0515-3. S2CID 83993887.
  3. ^ a b c C.O.R.E. Örsten site
  4. ^ Maeda, Haruyoshi; Tanaka, Gengo; Shimobayashi, Norimasa; Terufumi, Ohno; MATSUOKA, HIROSHIGE (2011-03-30). "Cambrian Orsten Lagerstätte from the Alum Shale Formation: fecal pellets as a probable source of phosphorous preservation". PALAIOS. 26 (3/4): 225–231. doi:10.2110/palo.2010.p10-042r. JSTOR 25835620. S2CID 131428775.
  5. ^ Modern pentastomids, or "tongue worms" are internal parasites of most modern terrestrial vertebrates.
  6. ^ The distribution of pyrites in the limestone, together with the organic content indicate levels of oxygen that prevented normal decomposition.
  7. ^ Waloszek, Dieter (19 February 2016). "'Orsten' on World-Wide Scale". Center of 'Orsten' Research and Exploration. Retrieved 29 November 2016.
  8. ^ Aria, Cédric; Caron, Jean-Bernard; Gaines, Robert (2015). Zhang, Xi-Guang (ed.). "A large new leanchoiliid from the Burgess Shale and the influence of inapplicable states on stem arthropod phylogeny". Palaeontology. 58 (4): 629–660. doi:10.1111/pala.12161. S2CID 86443516.
  9. ^ Peel, John S.; Stein, Martin; Kristensen, Reinhardt Møbjerg (2013-08-09). "Life Cycle and Morphology of a Cambrian Stem-Lineage Loriciferan". PLOS ONE. 8 (8): e73583. doi:10.1371/journal.pone.0073583. ISSN 1932-6203. PMC 3749095. PMID 23991198.

References[edit]