Silurian


Silurian
Silurian plate tectonics.png
Plate tectonics of Earth during the early Silurian
Chronology
Etymology
Name formalityFormal
Synonym(s)Gotlandian
Usage information
Celestial bodyEarth
Regional usageGlobal (ICS)
Time scale(s) usedICS Time Scale
Definition
Chronological unitPeriod
Stratigraphic unitSystem
First proposed byRoderick Murchison, 1835
Time span formalityFormal
Lower boundary definitionFAD of the Graptolite Akidograptus ascensus
Lower boundary GSSPDob's Linn, Moffat, UK
55°26′24″N 3°16′12″W / 55.4400°N 3.2700°W / 55.4400; -3.2700
Lower GSSP ratified1984[4][5]
Upper boundary definitionFAD of the Graptolite Monograptus uniformis
Upper boundary GSSPKlonk, Czech Republic
49°51′18″N 13°47′31″E / 49.8550°N 13.7920°E / 49.8550; 13.7920
Upper GSSP ratified1972[6]
Atmospheric and climatic data
Sea level above present dayAround 180 m, with short-term negative excursions[7]

The Silurian (/sɪˈljʊəriən, s-/ sih-LYOOR-ee-ən, sy-)[8][9][10] is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at 443.8 million years ago (Mya), to the beginning of the Devonian Period, 419.2 Mya.[11] The Silurian is the shortest period of the Paleozoic Era. As with other geologic periods, the rock beds that define the period's start and end are well identified, but the exact dates are uncertain by a few million years. The base of the Silurian is set at a series of major Ordovician–Silurian extinction events when up to 60% of marine genera were wiped out.

One important event in this period was the initial establishment of terrestrial life in what is known as the Silurian-Devonian Terrestrial Revolution: vascular plants emerged from more primitive land plants,[12][13] dikaryan fungi started expanding and diversifying along with glomeromycotan fungi,[14] and three groups of arthropods (myriapods, arachnids and hexapods) became fully terrestrialized.[15]

A significant evolutionary milestone during the Silurian was the diversification of jawed fish and bony fish.[16]

  1. ^ Jeppsson, L.; Calner, M. (2007). "The Silurian Mulde Event and a scenario for secundo—secundo events". Earth and Environmental Science Transactions of the Royal Society of Edinburgh. 93 (02): 135–154. doi:10.1017/S0263593300000377.
  2. ^ Munnecke, A.; Samtleben, C.; Bickert, T. (2003). "The Ireviken Event in the lower Silurian of Gotland, Sweden-relation to similar Palaeozoic and Proterozoic events". Palaeogeography, Palaeoclimatology, Palaeoecology. 195 (1): 99–124. doi:10.1016/S0031-0182(03)00304-3.
  3. ^ "Chart/Time Scale". www.stratigraphy.org. International Commission on Stratigraphy.
  4. ^ Lucas, Sepncer (6 November 2018). "The GSSP Method of Chronostratigraphy: A Critical Review". Frontiers in Earth Science. 6: 191. Bibcode:2018FrEaS...6..191L. doi:10.3389/feart.2018.00191.
  5. ^ Holland, C. (June 1985). "Series and Stages of the Silurian System" (PDF). Episodes. 8 (2): 101–103. doi:10.18814/epiiugs/1985/v8i2/005. Retrieved 11 December 2020.
  6. ^ Chlupáč, Ivo; Hladil, Jindrich (January 2000). "The global stratotype section and point of the Silurian-Devonian boundary". CFS Courier Forschungsinstitut Senckenberg. Retrieved 7 December 2020.
  7. ^ Haq, B. U.; Schutter, SR (2008). "A Chronology of Paleozoic Sea-Level Changes". Science. 322 (5898): 64–68. Bibcode:2008Sci...322...64H. doi:10.1126/science.1161648. PMID 18832639. S2CID 206514545.
  8. ^ Wells, John (3 April 2008). Longman Pronunciation Dictionary (3rd ed.). Pearson Longman. ISBN 978-1-4058-8118-0.
  9. ^ "Silurian". Dictionary.com Unabridged (Online). n.d.
  10. ^ "Silurian". CollinsDictionary.com. HarperCollins.
  11. ^ "International Chronostratigraphic Chart v.2015/01" (PDF). International Commission on Stratigraphy. January 2015.
  12. ^ Cite error: The named reference SilurianDevonianTerrestrialRevolution was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference SilurianDevonianTerrestrialRevolutionChina was invoked but never defined (see the help page).
  14. ^ Lutzoni, François; Nowak, Michael D.; Alfaro, Michael E.; Reeb, Valérie; Miadlikowska, Jolanta; Krug, Michael; Arnold, A. Elizabeth; Lewis, Louise A.; Swofford, David L.; Hibbett, David; Hilu, Khidir; James, Timothy Y.; Quandt, Dietmar; Magallón, Susana (21 December 2018). "Contemporaneous radiations of fungi and plants linked to symbiosis". Nature Communications. 9: 1–11. doi:10.1038/s41467-018-07849-9. PMID 30575731. S2CID 56645104. Retrieved 7 December 2022.
  15. ^ Cite error: The named reference Garwood was invoked but never defined (see the help page).
  16. ^ Brazeau, M. D.; Friedman, M. (2015). "The origin and early phylogenetic history of jawed vertebrates". Nature. 520 (7548): 490–497. Bibcode:2015Natur.520..490B. doi:10.1038/nature14438. PMC 4648279. PMID 25903631.

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