The Devonian is the period of the Paleozoic era from about 419 million years ago (mya) to about 359 mya. It is named after Devonshire, England, where rocks from this period were first studied.
Sea levels were high, and there was a great variety of fish and other marine organisms. The Devonian fish included the Agnatha (jawless fish), the Acanthodii (spiny fish), the Placoderms (armoured fish), the Chondrichthyes (cartilaginous fish), and the early Osteichthyes (bony fish). The Devonian strata are divided into lower, middle and upper subdivisions.
During the Devonian the evolution of fish into tetrapods occurred. Various terrestrial arthropods also became established. The first seed-bearing plants spread across dry land, forming huge forests.
Tectonic and volcanic activity was high. A series of extinction events occurred towards the end of the Devonian, including a major event at the Frasnian-Famennian boundary in the Late Devonian, about 364 mya. The supercontinent Pangaea was just starting to form.
Images for kids
The rocks of Lummaton Quarry in Torquay in Devon played an early role in defining the Devonian period.
Spindle diagram for the evolution of fish and other vertebrate classes. The diagram is based on Michael Benton, 2005.
The Devonian period marks the beginning of extensive land colonization by plants. With large land-dwelling herbivores not yet present, large forests grew and shaped the landscape.