 | This article includes a list of references, related reading, or external links, but its sources remain unclear because it lacks inline citations. (December 2023) |
| Middle Devonian | |||||||||||||||||
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.png) A map of Earth as it appeared 390 million years ago during the Middle Devonian Epoch, Eifelian Age | |||||||||||||||||
| Chronology | |||||||||||||||||
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| Etymology | |||||||||||||||||
| Name formality | Formal | ||||||||||||||||
| Usage information | |||||||||||||||||
| Celestial body | Earth | ||||||||||||||||
| Regional usage | Global (ICS) | ||||||||||||||||
| Time scale(s) used | ICS Time Scale | ||||||||||||||||
| Definition | |||||||||||||||||
| Chronological unit | Epoch | ||||||||||||||||
| Stratigraphic unit | Series | ||||||||||||||||
| Time span formality | Formal | ||||||||||||||||
| Lower boundary definition | Fad of the Conodont Polygnathus costatus partitus | ||||||||||||||||
| Lower boundary GSSP | Wetteldorf Richtschnitt, Eifel hills, Germany 50°08′59″N 6°28′18″E / 50.1496°N 6.4716°E | ||||||||||||||||
| Lower GSSP ratified | 1985 | ||||||||||||||||
| Upper boundary definition | FAD of the Conodont Ancyrodella rotundibola | ||||||||||||||||
| Upper boundary GSSP | Col du Puech de la Suque, Montagne Noire, France 43°30′12″N 3°05′12″E / 43.5032°N 3.0868°E | ||||||||||||||||
| Upper GSSP ratified | 1986 | ||||||||||||||||
In the geological timescale, the Middle Devonian epoch (from 393.47 ± 0.99 million years ago to 382.31 ± 1.36 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.
Life in the Middle Devonian
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.[5]
The Taghanic event took place near the end of the Middle Devonian.
References
- ^ Kaufmann, Bernd; Trapp, Endres; Mezger, Klaus (July 2004). "The numerical age of the Upper Frasnian (Upper Devonian) Kellwasser horizons: A new U-Pb zircon date from Steinbruch Schmidt (Kellerwald, Germany)" (PDF). The Journal of Geology. 112 (4): 495–501. Bibcode:2004JG....112..495K. doi:10.1086/42107. eISSN 1537-5269. ISSN 0022-1376. JSTOR 421077. LCCN 25013118. OCLC 1608377. S2CID 129963970. Archived from the original (PDF) on 10 February 2024. Retrieved 16 December 2025.
- ^ Algeo, Thomas; Scheckler, Stephen E. (29 January 1998). "Terrestrial-marine teleconnections in the Devonian: links between the evolution of land plants, weathering processes, and marine anoxic events". Philosophical Transactions of the Royal Society B: Biological Sciences. 353 (1365): 113–130. doi:10.1098/rstb.1998.0195. eISSN 1471-2970. PMC 1692181. S2CID 84656565.
- ^ Parry, Stephen F.; Noble, Stephen R.; Crowley, Quentin C.; Wellman, Charles H. (15 June 2011). "A high-precision U–Pb age constraint on the Rhynie Chert Konservat-Lagerstätte: time scale and other implications" (PDF). Journal of the Geological Society. 168 (4). Geological Society of London: 863–872. Bibcode:2011JGSoc.168..863P. doi:10.1144/0016-76492010-043. eISSN 2041-479X. ISSN 0016-7649. LCCN 79641612. OCLC 1934542. S2CID 128679831. Archived (PDF) from the original on 11 July 2025. Retrieved 16 December 2025.
- ^ "International Chronostratigraphic Chart" (PDF). International Commission on Stratigraphy. December 2024. Retrieved 23 October 2025.
- ^ Davies, Neil S., McMahon, William J. and Berry, Christopher M. (2024). "Earth's earliest forest: fossilized trees and vegetation-induced sedimentary structures from the Middle Devonian (Eifelian) Hangman Sandstone Formation, Somerset and Devon, SW England" (PDF). Journal of the Geological Society. doi:10.1144/jgs2023-204. Archived (PDF) from the original on 9 March 2024.
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