The Famennian is the latter 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 convent ...

s in the

Late Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, wher ...

Epoch. The most recent estimate for its duration estimates that it lasted from around 371.1 million years ago to 359.3 million years ago. An earlier 2012 estimate, still used by the International Commission on Stratigraphy, estimated that it lasted from million years ago to million years ago. It was preceded by the

Frasnian The Frasnian is one of two faunal stages in the Late Devonian Period. It lasted from million years ago to million years ago. It was preceded by the Givetian Stage and followed by the Famennian Stage. Major reef-building was under way during th ...

stage and followed by the

Tournaisian The Tournaisian is in the ICS geologic timescale The geologic time scale, or geological time scale, (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy ...

stage.

Major events

In the seas, a novel major group of

ammonoid Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttlefish) ...

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

s called clymeniids appeared, underwent tremendous

diversification Diversification may refer to: Biology and agriculture * Genetic divergence, emergence of subpopulations that have accumulated independent genetic changes * Agricultural diversification involves the re-allocation of some of a farm's resources to ...

and spread worldwide, then just as suddenly went

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

. 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 change in the diversity and abundance of multicellular organisms. I ...

, the

Kellwasser Event The Late Devonian extinction consisted of several extinction events in the Late Devonian Epoch, which collectively represent one of the five largest mass extinction events in the history of life on Earth. The term primarily refers to a major ex ...

, 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 in the Devonian Period (roughly 358.9 ± 0.4 million years ago). It is usuall ...

. 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 period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carbonifero ...

and

Permian The Permian ( ) is a geologic period and 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 251.9 Mya. It is the last period of the Paleoz ...

periods.

Subdivisions

The

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

divides the Famennian into four informal substages based primarily on

conodont Conodonts (Greek ''kōnos'', "cone", + ''odont'', "tooth") are an extinct group of agnathan (jawless) vertebrates resembling eels, classified in the class Conodonta. For many years, they were known only from their tooth-like oral elements, which ...

zonation. The Famennian corresponds to four historical subdivisions in

German German(s) may refer to: * Germany (of or related to) ** Germania (historical use) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizens of Germany, see also German nationality law **Ge ...

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 (french: Ardenne ; nl, Ardennen ; german: Ardennen; wa, Årdene ; lb, Ardennen ), also known as the Ardennes Forest or Forest of Ardennes, is a region of extensive forests, rough terrain, rolling hills and ridges primarily in Be ...

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. It is a variation ...

and was accepted for the upper stage of the Upper Devonian by the Subcommission on Devonian Stratigraphy in 1981. It is named after

Famenne Famenne (; wa, Fåmene, ) is a natural region in Wallonia (southern Belgium). Together with The Fagne or la Fagne, west of the river Meuse, it is part of the Fagne-Famenne natural region. The two regions are often grouped together because they ...

, a natural region in southern Belgium. The lower GSSP, ratified in 1993, is located within the

Coumiac Formation The Coumiac Formation is a geologic formation in France. It preserves fossils dated to the Devonian period. The Global Boundary Stratotype Section and Point (GSSP) for the base of the Famennian The Famennian is the latter of two faunal stage ...

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