The Devonian is a geologic period and system of the Paleozoic Era spanning from 416 to 359.2 ẹgbẹgbẹ̀rún ọdún sẹ́yìn (ICS, 2004, chart). It is named after Devon, England, where rocks from this period were first studied. During the Devonian Period the pectoral and pelvic fins of lobe-finned fish evolved into legs as they started to walk on land as tetrapods around 397 Ma. Various terrestrial arthropods also became well-established. Image:Sauerstoffgehalt-1000mj.svg Image:Phanerozoic Carbon Dioxide.png Image:All palaeotemps.png Haq, B. U.; Schutter, SR (2008). "A Chronology of Paleozoic Sea-Level Changes". Science 322 (5898): 64–68. doi:10.1126/science.1161648. PMID 18832639.  Gradstein, Felix M.; Ogg, J. G.; Smith, A. G. (2004). A Geologic Time Scale 2004. Cambridge: Cambridge University Press. ISBN 0521786738.  See Tiktaalik. [1] Fossil tracks record 'oldest land-walkers' - BBC News