| 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 Famennian is a second and upper stage of the Upper Devonian series, corresponding to the Famennian age of the Late Devonian epoch. It lasted from approximately 372.2 Ma to around 358.9 Ma (million years ago). It is preceded by the Frasnian age of the Late Devonian and is followed by the Tournaisian age of the Mississippian (Carboniferous). It started with the mass Late Devonian extinction and it is the last age from wchich most of the trilobite groups as well as the placoderm fish are known since the Famennian-Tournaisian boundary corresponds to another extinction, the end-Devonian.
Definition[]
The GSSP of the Famennian stage was ratified in 1993. The lower boundary is fixed in the Coumiac Quarry, Montagne Noire, France, and related to the first appearance of the conodont species Palmatolepis subperlobata as well as the extinction of several conodont taxa (Ancyrodella, Palmatolepis bogartensis and Ozarkodina) and goniatit ammonite families (Gephuroceratidae and Beloceratidae).[2]
Famennian life[]
Various brachiopods (Douvillina, Chonetes, Productella), bivalves (Edmondia, Spathella, Leptodesma) and gastropods (Platyceras, Euryzone, Mesocoelia) lived in the seas and coastal waters. Numerous cephalopods like Lobobactrites, Pseudorthoceras and Cyrtogomphus hunted in the water column. Among cephalopods, ammonites reached a significant number. Famennian genera include Crickites, Armatites, Tornoceras, Oxytornoceras, Lobotornoceras and Exotornoceras. Trilobites after the end-Frasnian crisis became less numerous. Babinops, Trimerocephalus and Cyrtosymbole were found in the Famennian sediments of Canning Basin, Australia. Malacostracan crustaceans Dithyrocaris and Palaeopalaemon lived in the open ocean. Eurypterids of this age include likely freshwater Adelophthalmus and Cyrtoctenus. Pterygotids possibly became extinct at the beginning of the Famennian.
On land, life evolved more and more actively. Fossils of plants of the groups Archaeopteridaceae (Archaeopteris), Sigillariaceae (Sigillaria), Calamopityaceae (Calamopitys), Selaginellaceae (Heliosporites) and Cordaitales (Callixylon) are known from deposits of this age. The fully terrestrial animals of that time were arthropods: centipedes, arachnids and insects such as Strudiella from the Upper Famennian of Namur Province, Belgium.
Dunkleosteus skull
A wide variety of chordates lived in the water. Conodonts like Palmatolepis lived at great depths. Many groups of fish lived both in the seas and in fresh water bodies. Ichthyofauna of the Famennian include cartilagenous (Antarctilamna, Plesioselachus, Devononchus) and numerous placoderms, from small Remigolepis and Bothriolepis to large carnivorous Dunkleosteus. Various bony fish of the time include coelacanthimorphs (Chagrinia) and dipnomorphs (Holoptychius, Glyptolepis, Andreyevichthys). Osteolepiformes is a group that include such animals as Eusthenodon and, cladistically, semiaquatic tetrapodomorphs like the Famennian Acanthostega, Tulerpeton and Ichthyostega. These animals not only could breathe atmospheric oxygen, but also had developed limbs with fingers, although, most likely, they moved slowly on land.
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.