The Devonian is a geologic period and system of the Paleozoic era spanning from 416 to 359.2 million years ago (ICS, 2004). It is named after Devon, England, where rocks from this period were first studied. It is proceeded by the Silurian

During the Devonian Period, which occurred in the Paleozoic era, the first fish evolved legsand started to walk on land as tetrapods around 365 Ma. Various terrestrial arthropods also became well-established.

The first seed-bearing plants spread across dry land, forming huge forests. In the oceans, primitive sharks became more numerous than in the Silurian and the late Ordovician, and the first lobe-finned and ray finned (both are types of bony fish) evolved. The first ammonite mollusks appeared, and trilobites, the mollusc-like brachiopods, as well as great coral reefs were still common. The Late Devonian extinction severely affected marine life.

The paleogeography was dominated by the supercontinent of Gondwana to the south, the continent of Siberia to the north, and the early formation of the small supercontinent of Euramerica in between.

It was succeeded by the Carboniferous