180 m; rising to 220 m in Caradoc and falling sharply to 140 m in end-Ordovician glaciations[8]
The Ordovician (/ɔːrdəˈvɪʃi.ən,-doʊ-,-ˈvɪʃən/or-də-VISH-ee-ən, -doh-, -VISH-ən)[9] is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period 485.4 Ma (million years ago) to the start of the Silurian Period 443.8 Ma.[10]
The Ordovician, named after the Welsh tribe of the Ordovices, was defined by Charles Lapworth in 1879 to resolve a dispute between followers of Adam Sedgwick and Roderick Murchison, who were placing the same rock beds in North Wales in the Cambrian and Silurian systems, respectively.[11] Lapworth recognized that the fossil fauna in the disputed strata were different from those of either the Cambrian or the Silurian systems, and placed them in a system of their own. The Ordovician received international approval in 1960 (forty years after Lapworth's death), when it was adopted as an official period of the Paleozoic Era by the International Geological Congress.
Life continued to flourish during the Ordovician as it did in the earlier Cambrian Period, although the end of the period was marked by the Ordovician–Silurian extinction events. Invertebrates, namely molluscs and arthropods, dominated the oceans, with members of the latter group probably starting their establishment on land during this time, becoming fully established by the Devonian. The first land plants are known from this period. The Great Ordovician Biodiversification Event considerably increased the diversity of life. Fish, the world's first true vertebrates, continued to evolve, and those with jaws may have first appeared late in the period. About 100 times as many meteorites struck the Earth per year during the Ordovician compared with today.[12]
^Wellman, C.H.; Gray, J. (2000). "The microfossil record of early land plants". Phil. Trans. R. Soc. B. 355 (1398): 717–732. doi:10.1098/rstb.2000.0612. PMC 1692785. PMID 10905606.
^Korochantseva, Ekaterina; Trieloff, Mario; Lorenz, Cyrill; Buykin, Alexey; Ivanova, Marina; Schwarz, Winfried; Hopp, Jens; Jessberger, Elmar (2007). "L-chondrite asteroid breakup tied to Ordovician meteorite shower by multiple isochron 40 Ar- 39 Ar dating". Meteoritics & Planetary Science. 42 (1): 113–130. Bibcode:2007M&PS...42..113K. doi:10.1111/j.1945-5100.2007.tb00221.x.
^Lindskog, A.; Costa, M. M.; Rasmussen, C.M.Ø.; Connelly, J. N.; Eriksson, M. E. (2017-01-24). "Refined Ordovician timescale reveals no link between asteroid breakup and biodiversification". Nature Communications. 8: 14066. doi:10.1038/ncomms14066. ISSN 2041-1723. PMC 5286199. PMID 28117834. It has been suggested that the Middle Ordovician meteorite bombardment played a crucial role in the Great Ordovician Biodiversification Event, but this study shows that the two phenomena were unrelated
^"Chart/Time Scale". www.stratigraphy.org. International Commission on Stratigraphy.
^Cooper, Roger; Nowlan, Godfrey; Williams, S. H. (March 2001). "Global Stratotype Section and Point for base of the Ordovician System" (PDF). Episodes. 24 (1): 19–28. doi:10.18814/epiiugs/2001/v24i1/005. Archived (PDF) from the original on 11 January 2021. Retrieved 6 December 2020.
^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.
^Holland, C. (June 1985). "Series and Stages of the Silurian System" (PDF). Episodes. 8 (2): 101–103. doi:10.18814/epiiugs/1985/v8i2/005. Archived (PDF) from the original on 19 January 2022. Retrieved 11 December 2020.
^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.
^"International Chronostratigraphic Chart v.2015/01" (PDF). International Commission on Stratigraphy. January 2015. Archived (PDF) from the original on 2015-04-02. Retrieved 2015-05-30.
^Charles Lapworth (1879) "On the Tripartite Classification of the Lower Palaeozoic Rocks"[permanent dead link], Geological Magazine, new series, 6 : 1-15. From pp. 13-14: "North Wales itself — at all events the whole of the great Bala district where Sedgwick first worked out the physical succession among the rocks of the intermediate or so-called Upper Cambrian or Lower Silurian system; and in all probability, much of the Shelve and the Caradoc area, whence Murchison first published its distinctive fossils — lay within the territory of the Ordovices; … Here, then, have we the hint for the appropriate title for the central system of the Lower Paleozoic. It should be called the Ordovician System, after this old British tribe."
^"New type of meteorite linked to ancient asteroid collision". Science Daily. 15 June 2016. Archived from the original on 3 April 2019. Retrieved 20 June 2016.
The Ordovician (/ɔːrdəˈvɪʃi.ən, -doʊ-, -ˈvɪʃən/ or-də-VISH-ee-ən, -doh-, -VISH-ən) is a geologic period and system, the second of six periods of the...
Cap Late D O–S The Late Ordovician mass extinction (LOME), sometimes known as the end-Ordovician mass extinction or the Ordovician-Silurian extinction, is...
The Late Ordovician, also called the Upper Ordovician by geologists, is the third epoch of the Ordovician period. At this time Western and Central Europe...
The Early Ordovician is the first epoch of the Ordovician period, corresponding to the Lower Ordovician series of the Ordovician system. It began after...
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...
subdivided into six geologic periods (from oldest to youngest): Cambrian Ordovician Silurian Devonian Carboniferous Permian Some geological timescales divide...
The Great Ordovician Biodiversification Event (GOBE), was an evolutionary radiation of animal life throughout the Ordovician period, 40 million years after...
appearing in the Ordovician include: Cyclopyge (Early to Late Ordovician) Selenopeltis (Early to Late Ordovician) Parabolina (Early Ordovician) Cheirurus (Middle...
Sacabambaspis is an extinct genus of jawless fish that lived in the Ordovician period. Sacabambaspis lived in shallow waters on the continental margins...
The Ordovician meteor event was a dramatic increase in the rate at which L chondrite meteorites fell to Earth during the Middle Ordovician period, about...
Ediacaran period 538.8 Ma (million years ago) to the beginning of the Ordovician Period 485.4 Ma. Most of the continents lay in the southern hemisphere...
the Mexican amber by García-Villafuerte (2018). Redescription of the Ordovician malacostracan Wuningia multisegmenlata is published by Lin (2018). A member...
[citation needed] As such, it's not until the Ordovician that the first crown-group members arise. By the Ordovician period the gastropods were a varied group...
and extending southwest to Longford and south to Navan is a province of Ordovician and Silurian rocks, with similarities to the Southern Uplands province...
Southeastern United States. The age is from the Late Cambrian to the Early Ordovician. Predominantly, it is composed of carbonates, chiefly dolomite, with some...
; Owen, A. W. (2002), Palaeobiogeography and Biodiversity Change: The Ordovician and Mesozoic–Cenozoic Radiations, Geological Society Special Publication...
into the super-continent Gondwana. The Ordovician spans from 485 million to 444 million years ago. The Ordovician was a time in Earth's history in which...
endocerid cephalopod which lived in equatorial oceans during the entire Ordovician period. Like other endocerids, it was an orthocone, meaning that its shell...
coast Ordovician genus, in prior times it was employed as a general name given to all straight-shelled nautiloids that lived from the Ordovician to the...
short range in the Middle Ordovician period. If rocks of unknown age have traces of E. pseudoplanus, they have a mid-Ordovician age. Such index fossils...
malacology known as teuthology. Cephalopods became dominant during the Ordovician period, represented by primitive nautiloids. The class now contains two...
Iapetus Ocean and Khanty Ocean. The Ordovician period started at a major extinction event called the Cambrian–Ordovician extinction event some time about...
protozoa. They were thought to have appeared as early as the mid-late Ordovician period as an adaptation of early land plants. Bacterial spores are not...
chondrichthyan and acanthodian traits. Dating back to the Middle and Late Ordovician Period, many isolated scales, made of dentine and bone, have a structure...
in the Middle Ordovician period. If rocks of unknown age are found to have traces of E. pseudoplanus, they must have a mid-Ordovician age. Such index...