Geologic Time Scale: Devonian Period
(419.2 to 358.9 million years ago)
The Devonian Period (The Age of Fishes) is named after Devon, England, where rocks from this period were first studied. The first significant adaptive radiation of life on dry land ocurred during the Devonian. An introduction of free-sporing vascular and the first seed-bearing plants appeared by the end of the period. Placoderms began dominating almost every aquatic environment. The ancestors of all four-limbed vertebrates (tetrapods) began adapting to walk on land, as their strong pectoral and pelvic fins gradually evolved into legs.