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Related to Devonian period: Silurian period
, Carboniferous period
, Mississippian Period
, Permian period
Devonian period a geological period lasting from about 415 to 370 million years ago. Many freshwater fish existed during this period and plants became established on land. True seed plants evolved and lycopods reached the size of trees. Amphibians evolved, the first known insects, spiders and mites occurred and most graptolites became extinct. Britain still lay south of the equator with the Thames at 10 °S. See GEOLOGICAL TIME.