The Devonian is a geologic period and system of the Paleozoic era spanning from 416 to ±2.8 million years ago to 359.2 to ±2.5 million years ago. It is named after Devon, England, where rocks from this period were first studied.

During the Devonian Period, which occurred in the Paleozoic era, the first fish evolved legs and 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 bony fish. 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.

Mantell's Iguanodon restoration
Paleozoic era
Devonian period
Lower/Early Devonian Middle Devonian Upper/Late Devonian
Lochkovian | Pragian
Eifelian | Givetian Frasnian | Famennian
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