Carboniferous

EtymologyName formalityFormalNickname(s)Age of Amphibians or ReptilesUsage informationCelestial bodyEarthRegional usageGlobal (ICS)Time scale(s) usedICS Time ScaleDefinitionChronological unitPeriodStratigraphic unitSystemFirst proposed byWilliam Daniel Conybeare and William Phillips, 1822Time span formalityFormalLower boundary definitionFAD of the ConodontSiphonodella sulcata (discovered to have biostratigraphic issues as of 2006)Lower boundary GSSPLa Serre, Montagne Noire, France
43°33′20″N3°21′26″E / 43.5555°N 3.3573°E / 43.5555; 3.3573Lower GSSP ratified1990Upper boundary definitionFAD of the ConodontStreptognathodus isolatus within the morphotypeStreptognathodus wabaunsensis chronoclineUpper boundary GSSPAidaralash, Ural Mountains, Kazakhstan
50°14′45″N57°53′29″E / 50.2458°N 57.8914°E / 50.2458; 57.8914Upper GSSP ratified1996Atmospheric and climatic dataSea level above present dayFalling from 120 m to present-day level throughout the Mississippian, then rising steadily to about 80 m at end of period

The Carboniferous ( ) is a geologic period and system of the Paleozoicera that spans 60 million years, from the end of the Devonian Period 358.86 Ma (million years ago) to the beginning of the Permian Period, 298.9 Ma. It is the fifth period of the Phanerozoiceon. In North America, the Carboniferous is often treated as two separate geological periods, the earlier Mississippian and the later Pennsylvanian.

The name Carboniferous means "coal-bearing", from the Latin ("coal") and ("bear, 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 the period during which both terrestrial animal and land plant life was well established. 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. The period is sometimes called the Age of Amphibians because of the diversification of early amphibians such as the temnospondyls, which became dominant land vertebrates, 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. Land arthropods such as arachnids (e.g. trigonotarbids and Pulmonoscorpius), myriapods (e.g. Arthropleura) and especially insects (particularly flying insects) 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. Atmospheric oxygen levels, originally thought to be consistently higher than today throughout the Carboniferous, have been shown to be more variable, increasing from low levels at the beginning of the Period to highs of 25–30%.