| Middle Devonian | |
| Color: | Middle devonian |
| Time Start: | 393.3 |
| Time Start Uncertainty: | 1.2 |
| Time End: | 382.7 |
| Time End Uncertainty: | 1.6 |
| Caption Map: | A map of Earth as it appeared 390 million years ago during the Middle Devonian Epoch, Eifelian Age |
| Timeline: | Devonian |
| Name Formality: | Formal |
| Celestial Body: | Earth |
| Usage: | Global (ICS) |
| Timescales Used: | ICS Time Scale |
| Chrono Unit: | epoch |
| Strat Unit: | series |
| Timespan Formality: | Formal |
| Lower Boundary Def: | Fad of the Conodont Polygnathus costatus partitus |
| Lower Gssp Location: | Wetteldorf Richtschnitt, Eifel hills, Germany |
| Lower Gssp Accept Date: | 1985 |
| Upper Boundary Def: | FAD of the Conodont Ancyrodella rotundibola |
| Upper Gssp Location: | Col du Puech de la Suque, Montagne Noire, France |
| Upper Gssp Accept Date: | 1986 |
In the geological timescale, the Middle Devonian epoch (from 393.3 ± 1.2 million years ago to 382.7 ± 1.6 million years ago) occurred during the Devonian period, after the end of the Emsian age.
The Middle Devonian epoch is subdivided into two stages: Eifelian and Givetian.
In the middle Devonian the armored jawless fish known as ostracoderms were declining in diversity and instead the jawed fish were thriving and increasing in diversity in both the oceans and freshwater. The shallow, warm, oxygen-depleted waters of Devonian inland lakes, surrounded by primitive plants, provided the environment necessary for certain early fish to develop essential characteristics such as well developed lungs, ability to crawl out of the water and onto the land for short periods of time, possibly in search of food which would be developed by the tetrapods later in the Late Devonian which are descendents of these early fish.
The earliest forest grew in the Middle Devonian (Eifelian) time. This new environment was formed by cladoxylopsid trees including Calamophyton.[1]
The Taghanic event took place near the end of the Middle Devonian.