The Famennian is the later of two

faunal stage In chronostratigraphy, a stage is a succession of rock strata laid down in a single age on the geologic timescale, which usually represents millions of years of deposition. A given stage of rock and the corresponding age of time will by conven ...

s in the

Late Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era during the Phanerozoic eon, spanning 60.3 million years from the end of the preceding Silurian period at million years ago ( Ma), to the beginning of the succeeding ...

epoch. The most recent estimate for its duration is that it lasted from around 371.1 to 359.3 million years ago. An earlier 2012 estimate, still used by the International Commission on Stratigraphy, is that it lasted from million years ago to million years ago. It was preceded by the Frasnian stage and followed by the

Tournaisian The Tournaisian is in the ICS geologic timescale the lowest stage or oldest age of the Mississippian, the oldest subsystem of the Carboniferous. The Tournaisian age lasted from Ma to Ma. It is preceded by the Famennian (the uppermost st ...

stage.

Major events

In the seas, a novel major group of ammonoid

cephalopod A cephalopod is any member of the molluscan Taxonomic rank, class Cephalopoda (Greek language, Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral symm ...

s called clymeniids appeared, underwent tremendous diversification and spread worldwide, then just as suddenly went extinct. The beginning of the Famennian is marked by the final stages of a major

extinction event An extinction event (also known as a mass extinction or biotic crisis) is a widespread and rapid decrease in the biodiversity on Earth. Such an event is identified by a sharp fall in the diversity and abundance of multicellular organisms. It occ ...

, the Kellwasser Event, which is the largest component of the Late Devonian mass extinction. The end of the Famennian experiences a smaller but still quite severe extinction event, the

Hangenberg Event The Hangenberg event, also known as the Hangenberg crisis or end-Devonian extinction, is a mass extinction that occurred at the end of the Famennian stage, the last Stage (stratigraphy), stage in the Devonian Period (roughly 358.9 ± 0.4 million y ...

. A brief episode of glaciation, possibly linked to the Hangenberg event, occurred during the late Famennian, the first in a series of short glaciations that preceded the Late Palaeozoic ice age of the

Carboniferous The Carboniferous ( ) is a Geologic time scale, geologic period and System (stratigraphy), system of the Paleozoic era (geology), era that spans 60 million years, from the end of the Devonian Period Ma (million years ago) to the beginning of the ...

and

Permian The Permian ( ) is a geologic period and System (stratigraphy), stratigraphic system which spans 47 million years, from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.902 Mya. It is the s ...

periods.

Subdivisions

The

International Commission on Stratigraphy The International Commission on Stratigraphy (ICS), sometimes unofficially referred to as the International Stratigraphic Commission, is a daughter or major subcommittee grade scientific organization that concerns itself with stratigraphy, strati ...

divides the Famennian into four informal substages based primarily on

conodont Conodonts, are an extinct group of marine jawless vertebrates belonging to the class Conodonta (from Ancient Greek κῶνος (''kōnos''), meaning " cone", and ὀδούς (''odoús''), meaning "tooth"). They are primarily known from their hard ...

zonation. The Famennian corresponds to four historical subdivisions in German stratigraphy: the Nehdenian, Hembergian, Dasbergian, and Wocklumian (from oldest to youngest). However, these are based solely on ammonoid zonation and do not precisely correspond to the informal ICS subdivisions. The Uppermost Famennian substage (approximating the Wocklumian) is also known as the Strunian in the

Ardennes The Ardennes ( ; ; ; ; ), also known as the Ardennes Forest or Forest of Ardennes, is a region of extensive forests, rough terrain, rolling hills and ridges primarily in Belgium and Luxembourg, extending into Germany and France. Geological ...

region. North American subdivisions of the Famennian include the Chautauquan, Canadaway, Conneaut, Conneautan, Conewango and Conewangan.

Name and definition

The Famennian Stage was proposed in 1855 by Belgian geologist

André Hubert Dumont André — sometimes transliterated as Andre — is the French and Portuguese form of the name Andrew and is now also used in the English-speaking world. It used in France, Quebec, Canada and other French-speaking countries, as well in Portugal ...

and was accepted for the upper stage of the Upper Devonian by the Subcommission on Devonian Stratigraphy in 1981. It is named after Famenne, a natural region in southern Belgium. The lower GSSP, ratified in 1993, is located within the Coumiac Formation near Cessenon in southern France. Since 2017, the base of the Famennian has been defined by a distinctive turnover of conodonts, particularly the last appearance of '' Palmatolepis bogartensis,'' the first appearance of ''Palmatolepis subperlobata'', and an increase in the abundance of ''Palmatolepis ultima''. It was previously defined by the start of the ''Palmatolepis triangularis'' conodont zone, but later studies showed that ''P. triangularis'' first appeared slightly later than the main conodont turnover in the GSSP. A 2012 ICS timescale based on rough radioisotopic records estimated the Famennian began around 372.2 ± 1.6 Ma, and ended at 358.9 ± 0.4 Ma. In 2020 this was revised to a start at 371.1 ± 1.1 Ma and an end at 359.3 ± 0.3 Ma.

Major events

Subdivisions

Name and definition

References

See also