| System (period) | Series | Stage (age) | Lower boundary, Ma | ||
|---|---|---|---|---|---|
| Carboniferous | Mis. | Lower | Tournaisian | 358.9±0.4 | |
| Devonian | Upper | Famennian |  372.2±1.6
| ||
| Frasnian | 382.7±1.6
| ||||
| Middle | Givetian | 387.7±0.8
| |||
| Eifelian | 393.3±1.2
| ||||
| Lower | Emsian | 407.6±2.6
| |||
| Pragian | 410.8±2.8
| ||||
| Lochkovian | 419.2±3.2
| ||||
| Silurian | Pridoli | older | |||
| Subdivisions and "golden spikes" according to IUGS as of September 2023[1] | |||||
The Eifelian is a first stage of the Middle Devonian series, corresponding to the Eifelian age of the Middle Devonian epoch. It lasted from approximately 393.3 Ma to around 387.7 Ma (million years ago). It is preceded by the Emsian age of the Early Devonian and is followed by the Givetian age of the Middle Devonian.
The oldest land forest and tetrapodomorph trackways are known from this stage.
Definition[]
The GSSP of the Emsian stage was ratified in 1985. The lower boundary is fixed in the base of sample station WP30 in Wetteldorf, Eifel Hills, Germany, and related to the first appearance of the conodont subspecies Polygnathus costatus partitus.[2]
Eifelian life[]
Calamophyton reconstruccion
Numerous brachiopods (Anoplotheca) and molluscs including gastropods (Loxonema), bivalves (Panenka, Nucula) and cephalopods (Bactrites) lived in the ocean. Trilobites like Dechenella and Burmeisteria crawled along the bottom. The number of eurypterids decreased in Eifelian, and many of them, such as Cyrtoctenus, had adapted to life in fresh waters. At that time, a wide variety of arachnids already lived on land. They include mites like Protochthonius and Devonacarus from the Eifelian of Schoharie County, New York. Animals managed to adapt to life on land thanks to the development of terrestrial flora. Plants of that time included not only low-growing forms, but also trees. From the deposits of this century, the oldest forest that grew in England is known. This forest consisted of cladoxylopsid trees like Calamophyton.[3]
Glyptolepis
Vertebrates of that time still lived in water. Among fish, many primitive forms like Schizosteus and Pycnosteus still remained. Placoderms (Homostius, Coccosteus, Actinolepis, Byssacanthus) were numerous in the seas, rivers and lakes. Bony fish were also varied. Palaeonisciforms (Orvikuina) and cheirolepidiforms (Cheirolepis) could become victims of large predators like Onychodus. Some fish like Dipterus and possibly Glyptolepis could breathe both underwater and atmospheric air; this feature helped them wait out droughts by burying themselves in silt. Thursius was a tetrapod relative but it could not yet walk on land. True tetrapodomorphs probably already appeared, since traces left by amphibian animal during Eifelian are known.[4]
References[]
- ↑ "Latest version of international chronostratigraphic chart". International Commission on Stratigraphy. https://stratigraphy.org/chart#latest-version.
- ↑ "GSSP Table - Paleozoic Era". https://timescalefoundation.org/gssp/index.php?parentid=77.
- ↑ 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". Journal of the Geological Society. DOI:10.1144/jgs2023-204
- ↑ Grzegorz Niedźwiedzki; Piotr Szrek; Katarzyna Narkiewicz; Marek Narkiewicz; Per E. Ahlberg (2010). "Tetrapod trackways from the early Middle Devonian period of Poland". Nature. 463 (7277): 43–8. Bibcode:2010Natur.463...43N. doi:10.1038/nature08623