Devonian

359.2-416 mya

The Devonian Period

Adam Sedgwick and Roderick Murchison, in 1839, proposed the name "Devonian" for the marine rocks they encountered. The Devonian Period occurred 359.2 - 416 mya and was before the Silurian period and after the Carboniferous Period. Studies of Devonian corals show that a year during the Devonian Period was about 400 days rather than 365.

Devonian Life

The Devonian Period is called the "Age of Fishes" because of the abundant and diverse types of creatures that swam in seas. Jawless fish lived between 500-360 mya. The first fish with a jaw occurred around 440 mya called acanthodians. 360 - 440 mya were the second group of jawed fish to appear called placoderms (bottom-dwellers that developed from the first gill arch and enabled them to prey on other animals.) Forests and Ammonites first appeared early in this period. The late Devonian first four-legged amphibians appeared indicating that colonization of land by vertebrates. Many plants started evolving during early Devonian like Lycophytes, horsetails and ferns.

Devonian Geography

During the Devonian Period there were no glaciers and it was relatively warm and dry. There were no glaciers until the late Devonian when ice began to cover the south polar region. There were two supercontinents called Gondwana (South America, Africa, India, Australia, and Antartica) and Euramerica (North American, Greenland, and Europe) which later collided during the Permian Period creating Pangea. During this time 85% of the Earth was covered by water.
Devonian Period: The Age of Fish