|Regional usage||Global (ICS)|
|Time scale(s) used||ICS Time Scale|
|First proposed by||Roderick Murchison, 1835|
|Time span formality||Formal|
|Lower boundary definition||FAD of the Graptolite Akidograptus ascensus|
|Lower boundary GSSP||Dob's Linn, Moffat, UK|
|Lower GSSP ratified||1984|
|Upper boundary definition||FAD of the Graptolite Monograptus uniformis|
|Upper boundary GSSP||Klonk, Czech Republic|
|Upper GSSP ratified||1972|
|Atmospheric and climatic data|
|Sea level above present day||Around 180 m, with short-term negative excursions|
The Silurian (/ -/, sih-LYOOR-ee-ən, sy-) 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. 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, dikaryan fungi started expanding and diversifying along with glomeromycotan fungi, and three groups of arthropods (myriapods, arachnids and hexapods) became fully terrestrialized.
SilurianDevonianTerrestrialRevolutionwas invoked but never defined (see the help page).
SilurianDevonianTerrestrialRevolutionChinawas invoked but never defined (see the help page).
Garwoodwas invoked but never defined (see the help page).
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