Part of the Paleozoic Era
Ordovician Period - Silurian Period - Devonian Period
The Silurian Period is the third period of the Paleozoic Era and of the Phanerozoic Eon. The period begins with the Ordovician-Silurian extinction event and ends at the time from which the earliest Monograptus uniformis graptolite fossils in Bed 20 of the Klonk Section, located near modern Prague, Czech Republic are known. Life began to become more evident on land during the Silurian, though it had already existed since the Cambrian Period. Sixty percent of marine genera went extinct during the extinction event that began this period.
During the Silurian, Gondwana continued to move southward towards the South Pole. Avalonia, Baltica, and Laurentia began to combine into a new supercontinent known as Euramerica, while Siberia remained distinct. The collision caused the Caledonian orogeny in modern North America and Europe. The giant ocean of Panthalassa covered much of the Northern Hemisphere. The Proto-Tethys was among a number of smaller oceans and became the Paleo-Tethys before the period came to an end, though a remnant of the Proto-Tethys would exist until the Carboniferous Period. Other oceans included the Rheic, Iapetus, and the new Ural Ocean.
The Silurian is characterized by overall climatic stability and warm temperatures, while the preceding Ordovician Period was glaciated and the succeeding Devonian Period featured intense heat. Sea levels rose again after having fallen in the later part of the Ordovician, but would fall again at the end of the Silurian. The Silurian featured the first large terrestrial fossils, with all previous large fossils having been aquatic. Cooksonia and Baragwanathia were among the planet's dominant plant species during this period. Bony fish, which compose the class Osteichthyes, first appeared during the Silurian. Sea scorpions were relatively common in the fossil record. Reefs varied from either being widespread or rare at different points throughout the period.
The Silurian is subdivided into four epochs: the Llandovery, Wenlock, Ludlow, and Pridoli.
Silurian Timescale:
Silurian Period - 443.8-419.2 MYA
-Llandovery Epoch - 443.8-433.4 MYA
--Rhuddanian Age - 443.8-440.8 MYA
--Aeronian Age - 440.8-438.5 MYA
--Telychian Age - 438.5-433.4 MYA
-Wenlock Epoch - 433.4-427.4 MYA
--Sheinwoodian Age - 433.4-430.5 MYA
--Homerian Age - 430.5-427.4 MYA
-Ludlow Epoch - 427.4-423 MYA
--Gorstian Age - 427.4-425.6 MYA
--Ludfordian Age - 425.6-423 MYA
-Pridoli Epoch - 423-419.2 MYA