Early Devonian
| Early Devonian | |||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
 Sample from the Lower DevonianRhynie chert | |||||||||||||||||
| Chronology | |||||||||||||||||
| |||||||||||||||||
| Etymology | |||||||||||||||||
| Chronostratigraphic name | Lower Devonian | ||||||||||||||||
| Geochronological name | Early Devonian | ||||||||||||||||
| 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 | FADof thegraptoliteMonograptus uniformis | ||||||||||||||||
| Lower boundary GSSP | Klonk,Czech Republic 49°51′18″N13°47′31″E/ 49.8550°N 13.7920°E | ||||||||||||||||
| Lower GSSP ratified | 1972[5] | ||||||||||||||||
| Upper boundary definition | FADof theconodontPolygnathus costatus partitus | ||||||||||||||||
| Upper boundary GSSP | Wetteldorf Richtschnitt section,Wetteldorf,Eifel,Germany 50°08′59″N6°28′18″E/ 50.1496°N 6.4716°E | ||||||||||||||||
| Upper GSSP ratified | 1985[6] | ||||||||||||||||
TheEarly Devonianis the first of threeepochscomprising theDevonianperiod, corresponding to theLower Devonianseries.It lasted from419.2± 3.2to393.3± 1.2and began with theLochkovianStage419.2± 3.2to410.8± 1.2,which was followed by thePragianfrom410.8± 3.2to407.6± 1.2and then by theEmsian,which lasted until theMiddle Devonianbegan,393.3± 1.2 million years ago.[7] During this time, the firstammonoidsappeared, descending frombactritoidnautiloids.Ammonoids during this time period were simple and differed little from their nautiloid counterparts. These ammonoids belong to the orderAgoniatitida,which in later epochs evolved to new ammonoid orders, for exampleGoniatitidaandClymeniida.This class ofcephalopodmolluscs would dominate the marine fauna until the beginning of theMesozoicEra.
References
[edit]- ^Parry, S. F.; Noble, S. R.; Crowley, Q. G.; Wellman, C. H. (2011)."A high-precision U–Pb age constraint on the Rhynie Chert Konservat-Lagerstätte: time scale and other implications".Journal of the Geological Society.168(4). London: Geological Society: 863–872.doi:10.1144/0016-76492010-043.
- ^Kaufmann, B.; Trapp, E.; Mezger, K. (2004). "The numerical age of the Upper Frasnian (Upper Devonian) Kellwasser horizons: A new U-Pb zircon date from Steinbruch Schmidt(Kellerwald, Germany)".The Journal of Geology.112(4): 495–501.Bibcode:2004JG....112..495K.doi:10.1086/421077.
- ^Algeo, T. J. (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.
- ^"Chart/Time Scale".stratigraphy.org.International Commission on Stratigraphy.
- ^Chlupáč, Ivo; Hladil, Jindrich (January 2000)."The global stratotype section and point of the Silurian-Devonian boundary".CFS Courier Forschungsinstitut Senckenberg:1–8.Retrieved7 December2020.
- ^Ziegler, W.; Klapper, G. (June 1985)."Stages of the Devonian System"(PDF).Episodes.8(2): 104–109.doi:10.18814/epiiugs/1985/v8i2/006.Retrieved18 December2020.
- ^Cohen, K.M.; Finney, S.C.; Gibbard, P.L.; Fan, J.-X. (2013)."The ICS International Chronostratigraphic Chart"(PDF).Episodes.36(3): 199–204.doi:10.18814/epiiugs/2013/v36i3/002.Retrieved7 January2021.
