The Famennian is the latter of two faunal stages 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 stage and followed by the Tournaisian 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 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 ...

. 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. It ...

, 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. 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 ''Carboniferou ...

and Permian periods.

Subdivisions

The International Commission on Stratigraphy 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 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 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