The Devonian time period began 416 million years ago and ended 354 million years ago. Ranging about 62 million years. Devonian is in between are Carboniferous and Silurian time periods. “Its base is characterized by Monograptus uniformia a graptolite, and its top by Gattendorfia an ammonoid cephalopd.” (Mueller, Rey 2007).
Mueller, P., & Rey, P. (2007, January 1). Introduction. Retrieved April 24, 2015, from http://www.geosci.usyd.edu.au/users/prey/FieldTrips/Yass04/Devonian.html
Tectonics and climate
Many changes had occurred in the world during the period of Devonian. In the beginning of the time a large areas of North America, Europe, South America, and Australia were covered by seas. During this period, the worlds land was collected in two supercontinents Gondwana and Euramerica.
During the time period there was other changes that occurred. “The continents of North America and Europe collided, resulting in massive granite intrusions and the raising of the Appalachian Mountains of eastern North America. Vigorous erosion of these newly uplifted mountains yielded great volumes of sediment, which were deposited in vast lowlands and shallow seas nearby.” (Speer 1998).
At the end of the period a mass extinction occurred. Its not clear what caused the mass extinction, but there are some hypotheses that may have caused it. Glaciation and the lowering of the global sea level may have triggered, changing in the atmospheric carbon dioxide, meteorite impacts, and the evolutions. The change had the first animals moved on the land.
Speer, B. (1998, January 1). The Devonian Period. Retrieved April 24, 2015, from http://www.ucmp.berkeley.edu/devonian/devonian.php
