Silurian

The Silurian ( ) is a geologic period and system spanning 23.5 million years from the end of the Ordovician Period, at Ma (million years ago) to the beginning of the Devonian Period, Ma. The Silurian is the third and shortest period of the Paleozoic Era, and the third of twelve periods of the Phanerozoic Eon. 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 we

mass extinction event at the end of the Ordovician period and the beginning of the Silurian period in the Paleozoic era, around 444 million years ago

mass extinction event in the Ludfordian age of the Silurian period, ca. 424 Ma

first of three relatively minor extinction events (the Ireviken, Mulde, and Lau events) during the Silurian period; occurred at the Llandovery/Wenlock boundary

anoxic event causng mass extinctions, coinciding with a global drop in sea level, and is closely followed by an excursion in geochemical isotopes, during the Silurian period