User:Hemiauchenia/sandboxCarboniferous

Carboniferous
Chronology
Etymology
Name formality	Formal
Nickname(s)	Age of Amphibians
Usage information
Celestial body	Earth
Regional usage	Global (ICS)
Time scale(s) used	ICS Time Scale
Definition
Chronological unit	Period
Stratigraphic unit	System
First proposed by	William Daniel Conybeare and William Phillips, 1822
Time span formality	Formal
Lower boundary definition	FAD of the Conodont Siphonodella sulcata (discovered to have biostratigraphic issues as of 2006)
Lower boundary GSSP	La Serre, Montagne Noire, France 43.5555°N 3.3573°E / 43.5555; 3.3573
Lower GSSP ratified	1990
Upper boundary definition	FAD of the Conodont Streptognathodus isolatus within the morphotype Streptognathodus wabaunsensis chronocline
Upper boundary GSSP	Aidaralash, Ural Mountains, Kazakhstan 50.2458°N 57.8914°E / 50.2458; 57.8914
Upper GSSP ratified	1996
Atmospheric and climatic data
Mean atmospheric O2 content	c. 32.3 vol % (162 % of modern)
Mean atmospheric CO2 content	c. 800 ppm (3 times pre-industrial)
Mean surface temperature	c. 14 °C (0 °C above modern)
Sea level above present day	Falling from 120 m to present-day level throughout the Mississippian, then rising steadily to about 80 m at end of period

The Carboniferous (/ˌkɑːr.bəˈnɪf.ər.əs/ KAHR-bə-NIF-ər-əs) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period 358.9 million years ago (Mya), to the beginning of the Permian Period, 298.9 Mya. The name Carboniferous means "coal-bearing", from the Latin carbō ("coal") and ferō ("I bear, I carry"), and refers to the many coal beds formed globally during that time.

The first of the modern 'system' names, it was coined by geologists William Conybeare and William Phillips in 1822, based on a study of the British rock succession. The Carboniferous is often treated in North America as two geological periods, the earlier Mississippian and the later Pennsylvanian.

Terrestrial animal life was well established by the Carboniferous period. Tetrapods (four limbed vertebrates), which had originated from lobe-finned fish during the preceeding Devonian, diversified during the Carboniferous, including early amphibian lineages such as temnospondyls, with the first appearance of amniotes, including synapsids (the group to which modern mammals belong) and reptiles during the late Carboniferous. The period is sometimes called the Age of Amphibians, during which amphibians became dominant land animals and diversified into many forms including lizard-like, snakelike and crocodile-like.

Insects would undergo a major radiation during the late Carboniferous. Vast swaths of forest covered the land, which would eventually be laid down and become the coal beds characteristic of the Carboniferous stratigraphy evident today. The atmospheric content of oxygen reached its highest levels in geological history, 35% compared with 21% today, allowing terrestrial invertebrates, which breathe by diffusion of oxygen through spiracles, to grow very large.

The later half of the period experienced glaciations, low sea level, and mountain building as the continents collided to form Pangaea. A minor marine and terrestrial extinction event, the Carboniferous rainforest collapse, occurred at the end of the period, caused by climate change.

Etymology and history

The term "Carboniferous" had first been used as an adjective by Irish geologist Richard Kirwan in 1799, and later used in a heading entitled “Coal-measures or Carboniferous Strata” by John Farey Sr in 1811, becoming an informal term referring to coal-bearing sequences in Britain and elsewhere in Western Europe. Four units were originally ascribed to the Carboniferous, in ascending order, the Old Red Sandstone, Carboniferous Limestone, Millstone Grit and the Coal Measures. These four units were placed into a formalised Carboniferous unit by William Conybeare and William Phillips in 1822, and later into the Carboniferous System by Phillips in 1835. The Old Red Sandstone was later considered Devonian in age. Subsequently, separate stratigraphic schemes were developed in Western Europe, North America, and Russia. The first attempt to build an international timescale for the Carboniferous was during the Eighth International Congress on Carboniferous Stratigraphy and Geology in Moscow in 1975, when all of the modern ICS stages were proposed.

Stratigraphy

The Carboniferous is divided into two subsystems, the lower Mississippian and upper Pennsylvanian, which are sometimes treated as separate geological periods in North American stratigraphy.

Stages can be defined globally or regionally. For global stratigraphic correlation, the International Commission on Stratigraphy (ICS) ratify global stages based on a Global Boundary Stratotype Section and Point (GSSP) from a single formation (a stratotype) identifying the lower boundary of the stage. The ICS subdivisions from youngest to oldest are as follows:

Series/epoch		Stage/age	Lower boundary
Permian		Asselian	298.9 ±0.15 Mya
Pennsylvanian	Upper	Gzhelian	303.7 ±0.1 Mya
		Kasimovian	307.0 ±0.1 Mya
	Middle	Moscovian	315.2 ±0.2 Mya
	Lower	Bashkirian	323.2 ±0.4 Mya
Mississippian	Upper	Serpukhovian	330.9 ±0.2 Mya
	Middle	Visean	346.7 ±0.4 Mya
	Lower	Tournaisian	358.9 ±0.4 Mya

ICS units

The Mississippian was first proposed by Alexander Winchell, and the Pennsylvanian was proposed by J. J. Stevenson in 1888, and both were proposed as distinct and independent systems by H. S. Williams in 1881.

The Tournaisian was named after the Belgian city of Tournai. It was introduced in scientific literature by Belgian geologist André Hubert Dumont in 1832. The GSSP for the base of the Tournaisian is located at the La Serre section in Montagne Noire, southern France. It is defined by the first appearance datum of the conodont Siphonodella sulcata, which was ratified in 1990. However, the GSSP was later shown to have issues, with Siphonodella sulcata being shown to occur 0.45 m below the proposed boundary.

The Viséan stage was introduced by André Dumont in 1832. Dumont named this stage after the city of Visé in Belgium's Liège Province. The GSSP for the Visean is located in Bed 83 at the Pengchong section, Guangxi, southern China, which was ratified in 2012. The GSSP for the base of the Viséan is the first appearance datum of fusulinid (an extinct group of forams) Eoparastaffella simplex.

The Serpukhovian stage was proposed in 1890 by Russian stratigrapher Sergei Nikitin. It is named after the city of Serpukhov, near Moscow. The Serpukhovian stage currently lacks a defined GSSP. The proposed definition for the base of the Serpukhovian is the first appearance of conodont Lochriea ziegleri.

The Bashkirian was named after Bashkiria, the then Russian name of the republic of Bashkortostan in the southern Ural Mountains of Russia. The stage was introduced by Russian stratigrapher Sofia Semikhatova in 1934. The GSSP for the base of the Bashkirian is located at Arrow Canyon in Nevada, USA, which was ratified in 1996. The GSSP for the base of the Bashkirian is defined by the first appearance of the conodont Declinognathodus noduliferus.

The Moscovian is named after Moscow, Russia, and was first introduced by Sergei Nikitin in 1890. The Moscovian currently lacks a defined GSSP.

The Kasimovian is named after the Russian city of Kasimov, and originally included as part of Nikitin's original 1890 definition of the Moscovian. It was first recognised as a distinct unit by A.P. Ivanov in 1926, who named it the "Tiguliferina" Horizon after a kind of brachiopod.

The Gzhelian is named after the Russian village of Gzhel (Russian: Гжель), nearby Ramenskoye, not far from Moscow. The name and type locality were defined by Sergei Nikitin in 1890. The base of the Gzhelian currently lacks a defined GSSP.

The GSSP for the base of the Permian is located in the Aidaralash River valley near Aqtöbe, Kazakhstan, which was ratified in 1996. The beginning of the stage is defined by the first appearance of the conodont Streptognathodus postfusus.

European Succession

The Tournasian and Visean units

Tetrapods

The oldest known temnospondyls are known from the Viséan of Europe, including Balanerpeton from Scotland and an indeterminate form from Germany.