Carboniferous
The Carboniferous (/ˌkɑːrbəˈnɪfərəs/ KAR-bə-NIF-ər-əs)[6] is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period 358.9 Ma (million years ago) to the beginning of the Permian Period, 298.9 Ma. In North America, the Carboniferous is often treated as two separate geological periods, the earlier Mississippian and the later Pennsylvanian.[7]
For the album, see Carboniferous (album).Carboniferous
Formal
Age of Amphibians
Global (ICS)
ICS Time Scale
William Daniel Conybeare and William Phillips, 1822
Formal
FAD of the Conodont Siphonodella sulcata (discovered to have biostratigraphic issues as of 2006)[2]
1990[3]
FAD of the Conodont Streptognathodus isolatus within the morphotype Streptognathodus wabaunsensis chronocline
1996[4]
Falling from 120 m to present-day level throughout the Mississippian, then rising steadily to about 80 m at end of period[5]
The name Carboniferous means "coal-bearing", from the Latin carbō ("coal") and ferō ("bear, carry"), and refers to the many coal beds formed globally during that time.[8] The first of the modern "system" names, it was coined by geologists William Conybeare and William Phillips in 1822,[9] based on a study of the British rock succession.
Carboniferous is the period during which both terrestrial animal and land plant life was well established.[10] Stegocephalia (four-limbed vertebrates including true tetrapods), whose forerunners (tetrapodomorphs) had evolved from lobe-finned fish during the preceding Devonian period, became pentadactylous during the Carboniferous.[11] The period is sometimes called the Age of Amphibians[12] because of the diversification of early amphibians such as the temnospondyls, which became dominant land vertebrates,[13] as well as the first appearance of amniotes including synapsids (the clade to which modern mammals belong) and sauropsids (which include modern reptiles and birds) during the late Carboniferous. Due to the raised atmospheric oxygen level, land arthropods such as arachnids (e.g. trigonotarbids and Pulmonoscorpius), myriapods (e.g. Arthropleura) and insects (e.g. Meganeura) also underwent a major evolutionary radiation during the late Carboniferous. Vast swaths of forests and swamps covered the land, which eventually became the coal beds characteristic of the Carboniferous stratigraphy evident today.
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.[14]
Etymology and history[edit]
The development of a Carboniferous chronostratigraphic timescale began in the late 18th century. The term "Carboniferous" was first 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. 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 then into the Carboniferous System by Phillips in 1835. The Old Red Sandstone was later considered Devonian in age.[15]
The similarity in successions between the British Isles and Western Europe led to the development of a common European timescale with the Carboniferous System divided into the lower Dinantian, dominated by carbonate deposition and the upper Silesian with mainly siliciclastic deposition.[16] The Dinantian was divided into the Tournaisian and Viséan stages. The Silesian was divided into the Namurian, Westphalian and Stephanian stages. The Tournaisian is the same length as the International Commission on Stratigraphy (ICS) stage, but the Viséan is longer, extending into the lower Serpukhovian.[15]
North American geologists recognised a similar stratigraphy but divided it into two systems rather than one. These are the lower carbonate-rich sequence of the Mississippian System and the upper siliciclastic and coal-rich sequence of the Pennsylvanian. The United States Geological Survey officially recognised these two systems in 1953.[17] In Russia, in the 1840s British and Russian geologists divided the Carboniferous into the Lower, Middle and Upper series based on Russian sequences. In the 1890s these became the Dinantian, Moscovian and Uralian stages. The Serpukivian was proposed as part of the Lower Carboniferous, and the Upper Carboniferous was divided into the Moscovian and Gzhelian. The Bashkirian was added in 1934.[15]
In 1975, the ICS formally ratified the Carboniferous System, with the Mississippian and Pennsylvanian subsystems from the North American timescale, the Tournaisian and Visean stages from the Western European and the Serpukhovian, Bashkirian, Moscovian, Kasimovian and Gzhelian from the Russian.[15] With the formal ratification of the Carboniferous System, the Dinantian, Silesian, Namurian, Westphalian and Stephanian became redundant terms, although the latter three are still in common use in Western Europe.[16]
Geology[edit]
Stratigraphy[edit]
Stages can be defined globally or regionally. For global stratigraphic correlation, the 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. Only the boundaries of the Carboniferous System and three of the stage bases are defined by global stratotype sections and points because of the complexity of the geology.[18][15] The ICS subdivisions from youngest to oldest are as follows:[19]
Aviculopecten subcardiformis; a bivalve from the Logan Formation (lower Carboniferous) of Wooster, Ohio (external mold)
Bivalves (Aviculopecten) and brachiopods (Syringothyris) in the Logan Formation (lower Carboniferous) in Wooster, Ohio
Syringothyris sp.; a spiriferid brachiopod from the Logan Formation (lower Carboniferous) of Wooster, Ohio (internal mold)
Palaeophycus ichnosp.; a trace fossil from the Logan Formation (lower Carboniferous) of Wooster, Ohio
Crinoid calyx from the lower Carboniferous of Ohio with a conical platyceratid gastropod (Palaeocapulus acutirostre) attached
Conulariid from the lower Carboniferous of Indiana
Tabulate coral (a syringoporid); Boone Limestone (lower Carboniferous) near Hiwasse, Arkansas
Typhloesus was a bizarre invertebrate that lived in Montana. It is possibly a mollusk related to gastropods.
Essexella was a cnidarian that lived in Northern Illinois. It was long considered a scyphozoan, but is now regarded as a Sea anemone
Concavicaris was a long lasting genus of thylacocephalan arthropod that lived from the Devonian to the Carboniferous.
Triproetus was a genus of proetid trilobite, which were the only order that survived the end-Devonian extinction
Syllipsimopodi was the earliest known vampyropod cephalopod, originating from Carboniferous rocks of Montana.
