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Related to Silurian period: Permian period
, Devonian period
, Carboniferous period
Silurian period the period of the PALAEOZOIC ERA lasting from 445 million BP to 415 million BP, during which trilobites declined. The first land plants appeared, though they probably evolved in the Ordovician. Armoured jawless fish and eurypterids were common. see GEOLOGICAL TIME.