Early Devonian
| Early Devonian | |
|---|---|
Epoch | |
| Stratigraphic unit | Series |
| Time span formality | Formal |
| Lower boundary definition | FAD of the graptolite Monograptus uniformis |
| Lower boundary GSSP | Klonk, Czech Republic 49°51′18″N 13°47′31″E / 49.8550°N 13.7920°E |
| Lower GSSP ratified | 1972[5] |
| Upper boundary definition | FAD of the conodont Polygnathus costatus partitus |
| Upper boundary GSSP | Wetteldorf Richtschnitt section, Wetteldorf, Eifel, Germany 50°08′59″N 6°28′18″E / 50.1496°N 6.4716°E |
| Upper GSSP ratified | 1985[6] |
The Early Devonian is the first of three
epochs comprising the Devonian period, corresponding to the Lower Devonian series. It lasted from 419.2 ± 3.2 to 393.3 ± 1.2 and began with the Lochkovian Stage 419.2 ± 3.2 to 410.8 ± 1.2, which was followed by the Pragian from 410.8 ± 3.2 to 407.6 ± 1.2 and then by the Emsian, which lasted until the Middle Devonian began, 393.3± 1.2 million years ago.[7]
During this time, the first nautiloids. Ammonoids during this time period were simple and differed little from their nautiloid counterparts. These ammonoids belong to the order Agoniatitida, which in later epochs evolved to new ammonoid orders, for example Goniatitida and Clymeniida. This class of cephalopod molluscs would dominate the marine fauna until the beginning of the Mesozoic
Era.
References
- .
- doi:10.1086/421077.
- .
- ^ "Chart/Time Scale". www.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. Retrieved 7 December 2020.
- . Retrieved 18 December 2020.
- . Retrieved 7 January 2021.
| Authority control databases: National |
|---|
