Carboniferous System
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The Carboniferous ( ) is a
geologic period 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 (the process of relating strata to time) and geochronolo ...
and
system A system is a group of interacting or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and influenced by its open system (systems theory), environment, is described by its boundaries, str ...
of the
Paleozoic The Paleozoic ( , , ; or Palaeozoic) Era is the first of three Era (geology), geological eras of the Phanerozoic Eon. Beginning 538.8 million years ago (Ma), it succeeds the Neoproterozoic (the last era of the Proterozoic Eon) and ends 251.9 Ma a ...
era An era is a span of time. Era or ERA may also refer to: * Era (geology), a subdivision of geologic time * Calendar era Education * Academy of European Law (German: '), an international law school * ERA School, in Melbourne, Australia * E ...
that spans 60 million years, from the end of the
Devonian The Devonian ( ) is a period (geology), geologic period and system (stratigraphy), system of the Paleozoic era (geology), era during the Phanerozoic eon (geology), eon, spanning 60.3 million years from the end of the preceding Silurian per ...
Period Ma (million years ago) to the beginning of the
Permian The Permian ( ) is a geologic period and System (stratigraphy), 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 251.902 Mya. It is the s ...
Period, Ma. It is the fifth and penultimate period of the Paleozoic era and the fifth period of the
Phanerozoic The Phanerozoic is the current and the latest of the four eon (geology), geologic eons in the Earth's geologic time scale, covering the time period from 538.8 million years ago to the present. It is the eon during which abundant animal and ...
eon Eon, EON or Eons may refer to: Time * Aeon, an indefinite long period of time * Eon (geology), a division of the geologic time scale Arts and entertainment Fictional characters * Eon, in the 2007 film '' Ben 10: Race Against Time'' * Eon, i ...
. In
North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...
, the Carboniferous is often treated as two separate geological periods, the earlier
Mississippian Mississippian may refer to: * Mississippian (geology), a subperiod of the Carboniferous period in the geologic timescale, roughly 360 to 325 million years ago * Mississippian cultures, a network of precontact cultures across the midwest and Easte ...
and the later
Pennsylvanian Pennsylvanian may refer to: * A person or thing from Pennsylvania * Pennsylvanian (geology) The Pennsylvanian ( , also known as Upper Carboniferous or Late Carboniferous) is, on the International Commission on Stratigraphy, ICS geologic timesc ...
. The name ''Carboniferous'' means "
coal Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other Chemical element, elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal i ...
-bearing", from the
Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...
("
coal Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other Chemical element, elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal i ...
") 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. Carboniferous is the period during which both
terrestrial animal Terrestrial animals are animals that live predominantly or entirely on land (e.g. cats, chickens, ants, most spiders), as compared with aquatic animals, which live predominantly or entirely in the water (e.g. fish, lobsters, octopuses), ...
and
land plant The embryophytes () are a clade of plants, also known as Embryophyta (Plantae ''sensu strictissimo'') () or land plants. They are the most familiar group of photoautotrophs that make up the vegetation on Earth's dry lands and wetlands. Embryophyt ...
life was well established.
Stegocephalia Stegocephali (often spelled Stegocephalia, from Greek , lit. "roofed head") is a clade of vertebrate animals containing all fully limbed tetrapodomorphs. It is equivalent to a broad definition of the superclass Tetrapoda: under this broad ...
(four-limbed
vertebrate Vertebrates () are animals with a vertebral column (backbone or spine), and a cranium, or skull. The vertebral column surrounds and protects the spinal cord, while the cranium protects the brain. The vertebrates make up the subphylum Vertebra ...
s including true
tetrapod A tetrapod (; from Ancient Greek :wiktionary:τετρα-#Ancient Greek, τετρα- ''(tetra-)'' 'four' and :wiktionary:πούς#Ancient Greek, πούς ''(poús)'' 'foot') is any four-Limb (anatomy), limbed vertebrate animal of the clade Tetr ...
s), whose forerunners (
tetrapodomorph Tetrapodomorpha (also known as Choanata) is a clade of vertebrates consisting of tetrapods (four-limbed vertebrates) and their closest sarcopterygian relatives that are more closely related to living tetrapods than to living lungfish. Advanced for ...
s) had evolved from
lobe-finned fish Sarcopterygii (; )—sometimes considered synonymous with Crossopterygii ()—is a clade (traditionally a class or subclass) of vertebrate animals which includes a group of bony fish commonly referred to as lobe-finned fish. These vertebrates ar ...
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
amphibian Amphibians are ectothermic, anamniote, anamniotic, tetrapod, four-limbed vertebrate animals that constitute the class (biology), class Amphibia. In its broadest sense, it is a paraphyletic group encompassing all Tetrapod, tetrapods, but excl ...
s such as the
temnospondyl Temnospondyli (from Greek language, Greek τέμνειν, ''temnein'' 'to cut' and σπόνδυλος, ''spondylos'' 'vertebra') or temnospondyls is a diverse ancient order (biology), order of small to giant tetrapods—often considered Labyrinth ...
s, which became dominant land vertebrates, as well as the first appearance of
amniote Amniotes are tetrapod vertebrate animals belonging to the clade Amniota, a large group that comprises the vast majority of living terrestrial animal, terrestrial and semiaquatic vertebrates. Amniotes evolution, evolved from amphibious Stem tet ...
s including
synapsid Synapsida is a diverse group of tetrapod vertebrates that includes all mammals and their extinct relatives. It is one of the two major clades of the group Amniota, the other being the more diverse group Sauropsida (which includes all extant rept ...
s (the
clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...
to which modern
mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...
s belong) and
sauropsid Sauropsida ( Greek for "lizard faces") is a clade of amniotes, broadly equivalent to the class Reptilia, though typically used in a broader sense to also include extinct stem-group relatives of modern reptiles and birds (which, as theropod dino ...
s (which include modern reptiles and birds) during the late Carboniferous. Land
arthropod Arthropods ( ) are invertebrates in the phylum Arthropoda. They possess an arthropod exoskeleton, exoskeleton with a cuticle made of chitin, often Mineralization (biology), mineralised with calcium carbonate, a body with differentiated (Metam ...
s such as
arachnid Arachnids are arthropods in the Class (biology), class Arachnida () of the subphylum Chelicerata. Arachnida includes, among others, spiders, scorpions, ticks, mites, pseudoscorpions, opiliones, harvestmen, Solifugae, camel spiders, Amblypygi, wh ...
s (e.g.
trigonotarbid The Order (biology), order Trigonotarbida is a group of extinct arachnids whose fossil record extends from the late Silurian to the early Permian (Pridoli epoch, Pridoli to Sakmarian).Dunlop, J. A., Penney, D. & Jekel, D. 2020A summary list of fos ...
s and ''
Pulmonoscorpius ''Pulmonoscorpius'' is an extinct genus of scorpion from the Mississippian (Early Carboniferous) of Scotland. It contains a single named species, ''Pulmonoscorpius kirktonensis''. It was one of the largest scorpions to have ever lived, with the ...
''),
myriapod Myriapods () are the members of subphylum Myriapoda, containing arthropods such as millipedes and centipedes. The group contains about 13,000 species, all of them terrestrial. Although molecular evidence and similar fossils suggests a diversifi ...
s (e.g. ''
Arthropleura ''Arthropleura'', from Ancient Greek ἄρθρον (''árthron''), meaning "joint", and πλευρά (''pleurá''), meaning "rib", is an extinct genus of massive myriapoda, myriapod that lived in what is now Europe and North America around 344 t ...
'') and especially insects (particularly
flying insects Pterygota ( ) is a subclass of insects that includes all winged insects and groups who lost them secondarily. Pterygota group comprises 99.9% of all insects. The orders not included are the Archaeognatha (jumping bristletails) and the Zygent ...
) also underwent a major
evolutionary radiation An evolutionary radiation is an increase in taxonomic diversity that is caused by elevated rates of speciation, that may or may not be associated with an increase in morphological disparity. A significantly large and diverse radiation within ...
during the late Carboniferous. Vast swaths of forests and swamps covered the land, which eventually became the coal beds characteristic of the Carboniferous
stratigraphy Stratigraphy is a branch of geology concerned with the study of rock layers (strata) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks. Stratigraphy has three related subfields: lithost ...
evident today. The later half of the period experienced
glaciations A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate betw ...
, low sea level, and
mountain building Mountain formation occurs due to a variety of geological processes associated with large-scale movements of the Earth's crust (List of tectonic plates, tectonic plates). Fold (geology), Folding, Fault (geology), faulting, Volcano, volcanic acti ...
as the continents collided to form
Pangaea Pangaea or Pangea ( ) was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from the earlier continental units of Gondwana, Euramerica and Siberia during the Carboniferous period approximately 335 mi ...
. A minor marine and terrestrial extinction event, the
Carboniferous rainforest collapse The Carboniferous rainforest collapse (CRC) was a minor extinction event that occurred around 305 million years ago in the Carboniferous period. The event occurred at the end of the Moscovian and continued into the early Kasimovian stages of th ...
, 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%.


Etymology and history

The development of a Carboniferous
chronostratigraphic Chronostratigraphy is the branch of stratigraphy that studies the ages of rock strata in relation to time. The ultimate aim of chronostratigraphy is to arrange the sequence of deposition and the time of deposition of all rocks within a geological ...
timescale began in the late 18th century. The term "Carboniferous" was first used as an adjective by Irish geologist
Richard Kirwan Richard Kirwan, LL.D, Fellow of the Royal Society, FRS, FRSE Membership of the Royal Irish Academy, MRIA (1 August 1733 – 22 June 1812) was an Irish geologist and chemist. He was one of the last supporters of the theory of Phlogiston theory, ...
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 Old Red Sandstone, abbreviated ORS, is an assemblage of rocks in the North Atlantic region largely of Devonian age. It extends in the east across Great Britain, Ireland and Norway, and in the west along the eastern seaboard of North America. It ...
, Carboniferous Limestone,
Millstone Grit Millstone Grit is any of a number of coarse-grained sandstones of Carboniferous age which occur in the British Isles. The name derives from its use in earlier times as a source of millstones for use principally in watermills. Geologists refer to ...
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 The Devonian ( ) is a period (geology), geologic period and system (stratigraphy), system of the Paleozoic era (geology), era during the Phanerozoic eon (geology), eon, spanning 60.3 million years from the end of the preceding Silurian per ...
in age. 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 The Dinantian is a series or epoch from the Lower Carboniferous system in western Europe between 359.2 and 326.4 million years ago. It can stand for a series of rocks in Europe or the time span in which they were deposited. The Dinantian is eq ...
, dominated by
carbonate A carbonate is a salt of carbonic acid, (), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word "carbonate" may also refer to a carbonate ester, an organic compound containing the carbonate group ...
deposition and the upper Silesian with mainly
siliciclastic Siliciclastic (or ''siliclastic'') rocks are clastic noncarbonate sedimentary rocks that are composed primarily of silicate minerals, such as quartz or clay minerals. Siliciclastic rock types include mudrock, sandstone Sandstone is a Clastic ...
deposition. The Dinantian was divided into the
Tournaisian The Tournaisian is in the ICS geologic timescale the lowest stage or oldest age of the Mississippian, the oldest subsystem of the Carboniferous. The Tournaisian age lasted from Ma to Ma. It is preceded by the Famennian (the uppermost st ...
and
Viséan The Visean, Viséan or Visian is an age in the ICS geologic timescale or a stage in the stratigraphic column. It is the second stage of the Mississippian, the lower subsystem of the Carboniferous. The Visean lasted from to Ma. It follows ...
stages. The Silesian was divided into the
Namurian The Namurian is a stage in the regional stratigraphy of northwest Europe, with an age between roughly 331 and 319 Ma (million years ago). It is a subdivision of the Carboniferous system or period, as well as the regional Silesian series. The Na ...
, Westphalian and Stephanian stages. The Tournaisian is the same length as the
International Commission on Stratigraphy The International Commission on Stratigraphy (ICS), sometimes unofficially referred to as the International Stratigraphic Commission, is a daughter or major subcommittee grade scientific organization that concerns itself with stratigraphy, strati ...
(ICS) stage, but the Viséan is longer, extending into the lower
Serpukhovian The Serpukhovian is in the ICS geologic timescale the uppermost stage or youngest age of the Mississippian, the lower subsystem of the Carboniferous. The Serpukhovian age lasted from Ma to Ma. It is preceded by the Visean and is followed ...
. 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 Mississippian may refer to: * Mississippian (geology), a subperiod of the Carboniferous period in the geologic timescale, roughly 360 to 325 million years ago * Mississippian cultures, a network of precontact cultures across the midwest and Easte ...
System and the upper siliciclastic and coal-rich sequence of the
Pennsylvanian Pennsylvanian may refer to: * A person or thing from Pennsylvania * Pennsylvanian (geology) The Pennsylvanian ( , also known as Upper Carboniferous or Late Carboniferous) is, on the International Commission on Stratigraphy, ICS geologic timesc ...
. The
United States Geological Survey The United States Geological Survey (USGS), founded as the Geological Survey, is an agency of the U.S. Department of the Interior whose work spans the disciplines of biology, geography, geology, and hydrology. The agency was founded on Mar ...
officially recognised these two systems in 1953. 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 Moscovian may refer to: *An inhabitant of Moscow, the capital of Russia *Something of, from, or related to Moscow *Moscovian (Carboniferous) The Moscovian is in the International Commission on Stratigraphy, ICS geologic timescale a stage (strat ...
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 Gzhelian ( ) is an age in the ICS geologic time scale or a stage in the stratigraphic column. It is the youngest stage of the Pennsylvanian, the youngest subsystem of the Carboniferous. The Gzhelian lasted from to Ma. It follows the Ka ...
. The
Bashkirian The Bashkirian is in the International Commission on Stratigraphy geologic timescale the lowest stage (stratigraphy), stage or oldest age (geology), age of the Pennsylvanian (geology), Pennsylvanian. The Bashkirian age lasted from to Mega annu ...
was added in 1934. 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 The Kasimovian is a geochronologic age or chronostratigraphic stage in the ICS geologic timescale. It is the third stage in the Pennsylvanian (late Carboniferous), lasting from to Ma.; 2004: ''A Geologic Time Scale 2004'', Cambridge Unive ...
and Gzhelian from the Russian. 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.


Geology


Stratigraphy

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 A Global Boundary Stratotype Section and Point (GSSP), sometimes referred to as a golden spike, is an internationally agreed upon reference point on a stratigraphic section which defines the lower boundary of a stage on the geologic time scale. ...
(GSSP) from a single
formation Formation may refer to: Linguistics * Back-formation, the process of creating a new lexeme by removing or affixes * Word formation, the creation of a new word by adding affixes Mathematics and science * Cave formation or speleothem, a secondary ...
(a
stratotype In geology, a stratotype or type section is the physical location or outcrop of a particular reference exposure of a stratigraphic sequence or stratigraphic boundary. If the stratigraphic unit is layered, it is called a stratotype, whereas the ...
) 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. The ICS subdivisions from youngest to oldest are as follows:Cohen, K.M., Finney, S.C., Gibbard, P.L. & Fan, J.-X. (2013; updated
The ICS International Chronostratigraphic Chart
Episodes 36: 199–204.


Mississippian

The Mississippian was proposed by
Alexander Winchell Alexander Winchell (December 31, 1824, in North East, New York – February 19, 1891, in Ann Arbor, Michigan) was an American geologist who contributed to this field mainly as an educator and a popular lecturer and writer. His views on evolutio ...
in 1870 named after the extensive exposure of lower Carboniferous
limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...
in the upper
Mississippi River The Mississippi River is the main stem, primary river of the largest drainage basin in the United States. It is the second-longest river in the United States, behind only the Missouri River, Missouri. From its traditional source of Lake Ita ...
valley. During the Mississippian, there was a marine connection between the Paleo-Tethys and
Panthalassa Panthalassa, also known as the Panthalassic Ocean or Panthalassan Ocean (from Greek "all" and "sea"), was the vast superocean that encompassed planet Earth and surrounded the supercontinent Pangaea, the latest in a series of supercontinent ...
through the
Rheic Ocean The Rheic Ocean (; ) was an ocean which separated two major paleocontinents, Gondwana and Laurussia ( Laurentia- Baltica- Avalonia). One of the principal oceans of the Paleozoic, its sutures today stretch from Mexico to Turkey and its closure r ...
resulting in the near worldwide distribution of marine faunas and so allowing widespread correlations using marine
biostratigraphy Biostratigraphy is the branch of stratigraphy which focuses on correlating and assigning relative ages of rock strata by using the fossil assemblages contained within them.Hine, Robert. "Biostratigraphy." ''Oxford Reference: Dictionary of Biology ...
. However, there are few Mississippian
volcanic rock Volcanic rocks (often shortened to volcanics in scientific contexts) are rocks formed from lava erupted from a volcano. Like all rock types, the concept of volcanic rock is artificial, and in nature volcanic rocks grade into hypabyssal and me ...
s, and so obtaining radiometric dates is difficult. The Tournaisian Stage is named after the Belgian city of
Tournai Tournai ( , ; ; ; , sometimes Anglicisation (linguistics), anglicised in older sources as "Tournay") is a city and Municipalities in Belgium, municipality of Wallonia located in the Hainaut Province, Province of Hainaut, Belgium. It lies by ...
. It was introduced in scientific literature by Belgian geologist André Dumont in 1832. The GSSP for the base of the Carboniferous System, Mississippian Subsystem and Tournaisian Stage is located at the
La Serre La Serre (; ) is a commune in the Aveyron department in southern France. Population The GSSP Golden Spike for the Tournaisian is in La Serre, with the first appearance of the conodont ''Siphonodella sulcata''. In 2006 it was discovered ...
section in
Montagne Noire The Montagne Noire (; , known as the 'Black Mountain' in English) is a mountain range in central southern France. It is located at the southwestern end of the Massif Central at the juncture of the Tarn, Hérault and Aude departments. Its highe ...
, southern France. It is defined by the first appearance of the
conodont Conodonts, are an extinct group of marine jawless vertebrates belonging to the class Conodonta (from Ancient Greek κῶνος (''kōnos''), meaning " cone", and ὀδούς (''odoús''), meaning "tooth"). They are primarily known from their hard ...
''
Siphonodella sulcata ''Siphonodella'' is an extinct genus of Conodont, conodonts. ''Siphonodella banraiensis'' is from the Late Devonian of Thailand. ''Siphonodella nandongensis'' is from the Early Carboniferous of the Baping Formation in China.New material of the ...
'' within the evolutionary lineage from '' Siphonodella praesulcata'' to ''Siphonodella sulcata''. This was ratified by the ICS in 1990. However, in 2006 further study revealed the presence of ''Siphonodella sulcata'' below the boundary, and the presence of ''Siphonodella'' ''praesulcata'' and ''Siphonodella sulcata'' together above a local
unconformity An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval ...
. This means the evolution of one species to the other, the definition of the boundary, is not seen at the La Serre site making precise correlation difficult.The Viséan Stage was introduced by André Dumont in 1832 and is named after the city of
Visé Visé (; , ; ) is a city and municipality of Wallonia, located on the river Meuse in the province of Liège, Belgium. The municipality consists of the following districts: Argenteau, Cheratte, Lanaye, Lixhe, Richelle, and Visé. In the ...
,
Liège Province Liège ( ; ; ; ; ) is the easternmost province of the Wallonia region of Belgium. Liège Province is the only Belgian province that has borders with three countries. It borders (clockwise from the north) the Dutch province of Limburg, the ...
, Belgium. In 1967, the base of the Visean was officially defined as the first black limestone in the Leffe
facies In geology, a facies ( , ; same pronunciation and spelling in the plural) is a body of rock with distinctive characteristics. The characteristics can be any observable attribute of rocks (such as their overall appearance, composition, or con ...
at the Bastion Section in the Dinant Basin. These changes are now thought to be ecologically driven rather than caused by evolutionary change, and so this has not been used as the location for the GSSP. Instead, the GSSP for the base of the Visean is located in Bed 83 of the sequence of dark grey
limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...
s and
shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of Clay mineral, clay minerals (hydrous aluminium phyllosilicates, e.g., Kaolinite, kaolin, aluminium, Al2Silicon, Si2Oxygen, O5(hydroxide, OH)4) and tiny f ...
s at the Pengchong section,
Guangxi Guangxi,; officially the Guangxi Zhuang Autonomous Region, is an Autonomous regions of China, autonomous region of the China, People's Republic of China, located in South China and bordering Vietnam (Hà Giang Province, Hà Giang, Cao Bằn ...
, southern China. It is defined by the first appearance of the
fusulinid The Fusulinida is an extinct order within the Foraminifera in which the tests are traditionally considered to have been composed of microgranular calcite. Like all forams, they were single-celled organisms. In advanced forms the test wall was d ...
''Eoparastaffella simplex'' in the evolutionary lineage ''Eoparastaffella ovalis – Eoparastaffella simplex'' and was ratified in 2009. The Serpukhovian Stage was proposed in 1890 by Russian stratigrapher Sergei Nikitin. It is named after the city of
Serpukhov Serpukhov ( rus, Серпухов, p=ˈsʲerpʊxəf) is a types of inhabited localities in Russia, city in Moscow Oblast, Russia, located at the confluence of the Oka River, Oka and the Nara (Oka), Nara Rivers, 99 kilometers (62 miles) south fro ...
, near Moscow and currently lacks a defined GSSP. The Visean-Serpukhovian boundary coincides with a major period of glaciation. The resulting sea level fall and climatic changes led to the loss of connections between marine basins and
endemism Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...
of marine fauna across the Russian margin. This means changes in biota are environmental rather than evolutionary making wider correlation difficult. Work is underway in the
Urals The Ural Mountains ( ),; , ; , or simply the Urals, are a mountain range in Eurasia that runs north–south mostly through Russia, from the coast of the Arctic Ocean to the river Ural (river), Ural and northwestern Kazakhstan.
and Nashui,
Guizhou ) , image_skyline = , image_caption = , image_map = Guizhou in China (+all claims hatched).svg , mapsize = 275px , map_alt = Map showing the location of Guizhou Province , map_caption = Map s ...
Province, southwestern China for a suitable site for the GSSP with the proposed definition for the base of the Serpukhovian as the first appearance of conodont '' Lochriea ziegleri.''


Pennsylvanian

The Pennsylvanian was proposed by J.J.Stevenson in 1888, named after the widespread coal-rich strata found across the state of Pennsylvania. The closure of the Rheic Ocean and formation of Pangea during the Pennsylvanian, together with widespread glaciation across
Gondwana Gondwana ( ; ) was a large landmass, sometimes referred to as a supercontinent. The remnants of Gondwana make up around two-thirds of today's continental area, including South America, Africa, Antarctica, Australia (continent), Australia, Zea ...
led to major climate and sea level changes, which restricted marine fauna to particular geographic areas thereby reducing widespread biostratigraphic correlations. Extensive volcanic events associated with the assembling of Pangea means more radiometric dating is possible relative to the Mississippian. The Bashkirian Stage was proposed by Russian stratigrapher Sofia Semikhatova in 1934. It was named after Bashkiria, the then Russian name of the republic of
Bashkortostan Bashkortostan, officially the Republic of Bashkortostan, sometimes also called Bashkiria, is a republic of Russia between the Volga river and the Ural Mountains in Eastern Europe. The republic borders Perm Krai to the north, Sverdlovsk Oblast ...
in the southern Ural Mountains of Russia. The GSSP for the base of the Pennsylvanian Subsystem and Bashkirian Stage is located at
Arrow Canyon An arrow is a fin-stabilized projectile launched by a bow. A typical arrow usually consists of a long, stiff, straight shaft with a weighty (and usually sharp and pointed) arrowhead attached to the front end, multiple fin-like stabilizers call ...
in
Nevada Nevada ( ; ) is a landlocked state in the Western United States. It borders Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the seventh-most extensive, th ...
, US and was ratified in 1996. It is defined by the first appearance of the conodont '' Declinognathodus noduliferus''. Arrow Canyon lay in a shallow, tropical seaway which stretched from Southern California to Alaska. The boundary is within a
cyclothem In geology, cyclothems are alternating stratigraphy, stratigraphic sequences of marine and non-marine Sedimentary structures, sediments, sometimes interbedded with coal seams. The cyclothems consist of repeated sequences, each typically several m ...
sequence of
transgressive Transgressive may mean: *Transgressive art, a name given to art forms that violate perceived boundaries *Transgressive fiction, a modern style in literature *Transgressive Records, a United Kingdom-based independent record label *Transgressive (l ...
limestones and fine
sandstone Sandstone is a Clastic rock#Sedimentary clastic rocks, clastic sedimentary rock composed mainly of grain size, sand-sized (0.0625 to 2 mm) silicate mineral, silicate grains, Cementation (geology), cemented together by another mineral. Sand ...
s, and regressive
mudstone Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from ''shale'' by its lack of fissility.Blatt, H., and R.J. Tracy, 1996, ''Petrology.'' New York, New York, ...
s and
breccia Breccia ( , ; ) is a rock composed of large angular broken fragments of minerals or Rock (geology), rocks cementation (geology), cemented together by a fine-grained matrix (geology), matrix. The word has its origins in the Italian language ...
ted limestones. The Moscovian Stage is named after shallow marine limestones and colourful
clay Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolinite, ). Most pure clay minerals are white or light-coloured, but natural clays show a variety of colours from impuriti ...
s found around Moscow, Russia. It was first introduced by Sergei Nikitin in 1890. The Moscovian currently lacks a defined GSSP. The fusulinid ''Aljutovella aljutovica'' can be used to define the base of the Moscovian across the northern and eastern margins of Pangea, however, it is restricted in geographic area, which means it cannot be used for global correlations. The first appearance of the conodonts ''Declinognathodus donetzianus'' or ''Idiognathoides postsulcatus'' have been proposed as a boundary marking species and potential sites in the Urals and Nashui, Guizhou Province, southwestern China are being considered. The Kasimovian is the first stage in the Upper Pennsylvanian. It is named after the Russian city of
Kasimov Kasimov (; ;, Ханкирмән Latinized : Kasıym, Hankirmən,Ханкирмән, Хан-Кермень, means " Khan's fortress" historically Gorodets Meshchyorsky, Novy Nizovoy) is a town in Ryazan Oblast, Russia, located on the left bank of ...
, and was originally included as part of Nikitin's 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 type of
brachiopod Brachiopods (), phylum (biology), phylum Brachiopoda, are a phylum of animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear e ...
. The boundary of the Kasimovian covers a period of globally low sea level, which has resulted in disconformities within many sequences of this age. This has created difficulties in finding suitable marine fauna that can used to correlate boundaries worldwide. The Kasimovian currently lacks a defined GSSP; potential sites in the southern Urals, southwest USA and Nashui, Guizhou Province, southwestern China are being considered. The Gzhelian is named after the Russian village of
Gzhel (selo), Moscow Oblast Gzhel ( rus, Гжель, p=ɡʐelʲ) is a rural locality (a '' selo'') in Ramensky District of Moscow Oblast, Russia, located southeast from the center of Moscow. As of the 2010 Census, its population was 1,006.Moscow Oblast Territorial ...
, near Ramenskoye, not far from Moscow. The name and type locality were defined by Sergei Nikitin in 1890. The Gzhelian currently lacks a defined GSSP. The first appearance of the fusulinid ''Rauserites rossicus'' and ''Rauserites'' ''stuckenbergi'' can be used in the Boreal Sea and Paleo-Tethyan regions but not eastern Pangea or Panthalassa margins. Potential sites in the Urals and Nashui, Guizhou Province, southwestern China for the GSSP are being considered. The GSSP for the base of the Permian is located in the Aidaralash River valley near
Aqtöbe Aktobe (, ; ) is a major city located on the Ilek River in western Kazakhstan. It serves as the administrative center of the Aktobe Region and is an important cultural, economic, and industrial hub in the region. As of 2023, the city has a popu ...
, Kazakhstan and was ratified in 1996. The beginning of the stage is defined by the first appearance of the conodont '' Streptognathodus postfusus.''


Cyclothems

A cyclothem is a succession of non-marine and marine
sedimentary rock Sedimentary rocks are types of rock (geology), rock formed by the cementation (geology), cementation of sediments—i.e. particles made of minerals (geological detritus) or organic matter (biological detritus)—that have been accumulated or de ...
s, deposited during a single sedimentary cycle, with an erosional surface at its base. Whilst individual cyclothems are often only metres to a few tens of metres thick, cyclothem sequences can be many hundreds to thousands of metres thick and contain tens to hundreds of individual cyclothems. Cyclothems were deposited along
continental shelves A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea. Much of these shelves were exposed by drops in sea level during glacial periods. The shelf surrounding an island ...
where the very gentle gradient of the shelves meant even small changes in sea level led to large advances or retreats of the sea. Cyclothem lithologies vary from
mudrock Mudrocks are a class of fine-grained siliciclastic sedimentary rocks. The varying types of mudrocks include siltstone, claystone, mudstone and shale. Most of the particles of which the stone is composed are less than and are too small to ...
and carbonate-dominated to coarse siliciclastic sediment-dominated sequences depending on the paleo-topography, climate and supply of sediments to the shelf. The main period of cyclothem deposition occurred during the Late Paleozoic Ice Age from the Late Mississippian to early Permian, when the waxing and waning of
ice sheet In glaciology, an ice sheet, also known as a continental glacier, is a mass of glacier, glacial ice that covers surrounding terrain and is greater than . The only current ice sheets are the Antarctic ice sheet and the Greenland ice sheet. Ice s ...
s led to rapid changes in
eustatic sea level The eustatic sea level (from Greek εὖ ''eû'', "good" and στάσις ''stásis'', "standing") is the distance from the center of the Earth to the sea surface. An increase of the eustatic sea level can be generated by decreasing glaciation, inc ...
. The growth of ice sheets led global sea levels to fall as water was locked away in glaciers. Falling sea levels exposed large tracts of the continental shelves across which river systems eroded channels and valleys and vegetation broke down the surface to form
soil Soil, also commonly referred to as earth, is a mixture of organic matter, minerals, gases, water, and organisms that together support the life of plants and soil organisms. Some scientific definitions distinguish dirt from ''soil'' by re ...
s. The non-marine sediments deposited on this erosional surface form the base of the cyclothem. As sea levels began to rise, the rivers flowed through increasingly water-logged landscapes of swamps and lakes. Peat mires developed in these wet and oxygen-poor conditions, leading to coal formation. With continuing sea level rise, coastlines migrated landward and
deltas A river delta is a landform, wikt:archetype#Noun, archetypically triangular, created by the deposition (geology), deposition of the sediments that are carried by the waters of a river, where the river merges with a body of slow-moving water or ...
,
lagoon A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into ''coastal lagoons'' (or ''barrier lagoons'') an ...
s and esturaries developed; their sediments deposited over the peat mires. As fully marine conditions were established, limestones succeeded these marginal marine deposits. The limestones were in turn overlain by deep water black shales as maximum sea levels were reached. Ideally, this sequence would be reversed as sea levels began to fall again; however, sea level falls tend to be protracted, whilst sea level rises are rapid, ice sheets grow slowly but melt quickly. Therefore, the majority of a cyclothem sequence occurred during falling sea levels, when rates of
erosion Erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust and then sediment transport, tran ...
were high, meaning they were often periods of non-deposition. Erosion during sea level falls could also result in the full or partial removal of previous cyclothem sequences. Individual cyclothems are generally less than 10 m thick because the speed at which sea level rose gave only limited time for sediments to accumulate. During the Pennsylvanian, cyclothems were deposited in shallow, epicontinental seas across the tropical regions of
Laurussia Laurasia () was the more northern of two large landmasses that formed part of the Pangaea supercontinent from around (Million years ago, Mya), the other being Gondwana. It separated from Gondwana (beginning in the late Triassic period) during ...
(present day western and central US, Europe, Russia and central Asia) and the
North North is one of the four compass points or cardinal directions. It is the opposite of south and is perpendicular to east and west. ''North'' is a noun, adjective, or adverb indicating Direction (geometry), direction or geography. Etymology T ...
and
South China cratons South is one of the cardinal directions or compass points. The direction is the opposite of north and is perpendicular to both west and east. Etymology The word ''south'' comes from Old English ''sūþ'', from earlier Proto-Germanic ''*sunþaz' ...
. The rapid sea levels fluctuations they represent correlate with the glacial cycles of the Late Paleozoic Ice Age. The advance and retreat of ice sheets across Gondwana followed a 100 kyr
Milankovitch cycle Milankovitch cycles describe the collective effects of changes in the Earth's movements on its climate over thousands of years. The term was coined and named after the Serbian geophysicist and astronomer Milutin Milanković. In the 1920s, he pr ...
, and so each cyclothem represents a cycle of sea level fall and rise over a 100 kyr period.


Coal formation

Coal forms when organic matter builds up in waterlogged,
anoxic Anoxia means a total depletion in the level of oxygen, an extreme form of hypoxia or "low oxygen". The terms anoxia and hypoxia are used in various contexts: * Anoxic waters, sea water, fresh water or groundwater that are depleted of dissolved ox ...
swamps, known as peat mires, and is then buried, compressing the peat into coal. The majority of Earth's coal deposits were formed during the late Carboniferous and early Permian. The plants from which they formed contributed to changes in the Carboniferous Earth's atmosphere. During the Pennsylvanian, vast amounts of organic debris accumulated in the peat mires that formed across the low-lying, humid equatorial wetlands of the
foreland basin A foreland basin is a structural basin that develops adjacent and parallel to a mountain belt. Foreland basins form because the immense mass created by crustal thickening associated with the evolution of a mountain belt causes the lithospher ...
s of the
Central Pangean Mountains The Central Pangean Mountains were an extensive northeast–southwest trending mountain range in the central portion of the supercontinent Pangaea during the Carboniferous, Permian and Triassic periods. They were formed as a result of collision be ...
in Laurussia, and around the margins of the North and South China cratons. During glacial periods, low sea levels exposed large areas of the continental shelves. Major river channels, up to several kilometres wide, stretched across these shelves feeding a network of smaller channels, lakes and peat mires. These wetlands were then buried by sediment as sea levels rose during
interglacial An interglacial period (or alternatively interglacial, interglaciation) is a geological interval of warmer global average temperature lasting thousands of years that separates consecutive glacial periods within an ice age. The current Holocene i ...
s. Continued crustal
subsidence Subsidence is a general term for downward vertical movement of the Earth's surface, which can be caused by both natural processes and human activities. Subsidence involves little or no horizontal movement, which distinguishes it from slope mov ...
of the foreland basins and continental margins allowed this accumulation and burial of peat deposits to continue over millions of years resulting in the formation of thick and widespread coal formations. During the warm interglacials, smaller coal swamps with plants adapted to the temperate conditions formed on the
Siberian craton Siberia, also known as Siberian Craton, Angaraland (or simply Angara) and Angarida, is an ancient craton in the heart of Siberia. Today forming the Central Siberian Plateau, it formed an independent landmass prior to its fusion into Pangea during ...
and the western Australian region of Gondwana. There is ongoing debate as to why this peak in the formation of Earth's coal deposits occurred during the Carboniferous. The first theory, known as the delayed fungal evolution hypothesis, is that a delay between the development of trees with the wood fibre
lignin Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidit ...
and the subsequent evolution of lignin-degrading fungi gave a period of time where vast amounts of lignin-based organic material could accumulate. Genetic analysis of
basidiomycete Basidiomycota () is one of two large divisions that, together with the Ascomycota, constitute the subkingdom Dikarya (often referred to as the "higher fungi") within the kingdom Fungi. Members are known as basidiomycetes. More specifically, Basid ...
fungi, which have
enzyme An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...
s capable of breaking down lignin, supports this theory by suggesting this fungi evolved in the Permian. However, significant Mesozoic and Cenozoic coal deposits formed after lignin-digesting fungi had become well established, and fungal degradation of lignin may have already evolved by the end of the Devonian, even if the specific enzymes used by basidiomycetes had not. The second theory is that the geographical setting and climate of the Carboniferous were unique in Earth's history: the co-occurrence of the position of the continents across the humid equatorial zone, high biological productivity, and the low-lying, water-logged and slowly subsiding sedimentary basins that allowed the thick accumulation of peat were sufficient to account for the peak in coal formation.


Palaeogeography

During the Carboniferous, there was an increased rate in
tectonic plate Plate tectonics (, ) is the scientific theory that the Earth's lithosphere comprises a number of large tectonic plates, which have been slowly moving since 3–4 billion years ago. The model builds on the concept of , an idea developed durin ...
movements as the
supercontinent In geology, a supercontinent is the assembly of most or all of Earth's continent, continental blocks or cratons to form a single large landmass. However, some geologists use a different definition, "a grouping of formerly dispersed continents", ...
Pangea assembled. The continents themselves formed a near circle around the opening Paleo-Tethys Ocean, with the massive Panthalassic Ocean beyond. Gondwana covered the south polar region. To its northwest was Laurussia. These two continents slowly collided to form the core of Pangea. To the north of Laurussia lay
Siberia Siberia ( ; , ) is an extensive geographical region comprising all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has formed a part of the sovereign territory of Russia and its predecessor states ...
and
Amuria Amuria is a town in the Eastern Region of Uganda. It is the chief municipal, administrative, and commercial center of Amuria District, in the Teso sub-region. Location Amuria is located , by road, north of Soroti, the largest city in the Tes ...
. To the east of Siberia,
Kazakhstania Kazakhstania (), the Kazakh terranes, or the Kazakhstan Block, is a geological region in Central Asia which consists of the area roughly centered on Lake Balkhash, north and east of the Aral Sea, south of the Siberian craton and west of the Alta ...
, North China and South China formed the northern margin of the Paleo-Tethys, with Annamia laying to the south.


Variscan-Alleghanian-Ouachita orogeny

The Central Pangean Mountains were formed during the
Variscan The Variscan orogeny, or Hercynian orogeny, was a geologic mountain-building event caused by Late Paleozoic continental collision between Euramerica (Laurussia) and Gondwana to form the supercontinent of Pangaea. Nomenclature The name ''Variscan ...
- Alleghanian- Ouachita orogeny. Today their remains stretch over 10,000 km from the
Gulf of Mexico The Gulf of Mexico () is an oceanic basin and a marginal sea of the Atlantic Ocean, mostly surrounded by the North American continent. It is bounded on the northeast, north, and northwest by the Gulf Coast of the United States; on the southw ...
in the west to
Turkey Turkey, officially the Republic of Türkiye, is a country mainly located in Anatolia in West Asia, with a relatively small part called East Thrace in Southeast Europe. It borders the Black Sea to the north; Georgia (country), Georgia, Armen ...
in the east. The orogeny was caused by a series of continental collisions between Laurussia, Gondwana and the Armorican terrane assemblage (much of modern-day Central and Western Europe including
Iberia The Iberian Peninsula ( ), also known as Iberia, is a peninsula in south-western Europe. Mostly separated from the rest of the European landmass by the Pyrenees, it includes the territories of peninsular Spain and Continental Portugal, compri ...
) as the
Rheic Ocean The Rheic Ocean (; ) was an ocean which separated two major paleocontinents, Gondwana and Laurussia ( Laurentia- Baltica- Avalonia). One of the principal oceans of the Paleozoic, its sutures today stretch from Mexico to Turkey and its closure r ...
closed and Pangea formed. This mountain building process began in the Middle Devonian and continued into the early Permian. The Armorican
terrane In geology, a terrane (; in full, a tectonostratigraphic terrane) is a crust fragment formed on a tectonic plate (or broken off from it) and accreted or " sutured" to crust lying on another plate. The crustal block or fragment preserves its d ...
s
rift In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics. Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-graben ...
ed away from Gondwana during the Late
Ordovician The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era, and the second of twelve periods of the Phanerozoic Eon (geology), Eon. The Ordovician spans 41.6 million years f ...
. As they drifted northwards the Rheic Ocean closed in front of them, and they began to collide with southeastern Laurussia in the Middle Devonian. The resulting Variscan orogeny involved a complex series of oblique collisions with associated
metamorphism Metamorphism is the transformation of existing Rock (geology), rock (the protolith) to rock with a different mineral composition or Texture (geology), texture. Metamorphism takes place at temperatures in excess of , and often also at elevated ...
,
igneous Igneous rock ( ), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rocks are formed through the cooling and solidification of magma or lava. The magma can be derived from partial ...
activity, and large-scale deformation between these terranes and Laurussia, which continued into the Carboniferous. During the mid Carboniferous, the South American sector of Gondwana collided obliquely with Laurussia's southern margin resulting in the Ouachita orogeny. The major
strike-slip faulting In geology, a fault is a Fracture (geology), planar fracture or discontinuity in a volume of Rock (geology), rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust (geology ...
that occurred between Laurussia and Gondwana extended eastwards into the
Appalachian Mountains The Appalachian Mountains, often called the Appalachians, are a mountain range in eastern to northeastern North America. The term "Appalachian" refers to several different regions associated with the mountain range, and its surrounding terrain ...
where early deformation in the Alleghanian orogeny was predominantly strike-slip. As the West African sector of Gondwana collided with Laurussia during the Late Pennsylvanian, deformation along the Alleghanian orogen became northwesterly-directed
compression Compression may refer to: Physical science *Compression (physics), size reduction due to forces *Compression member, a structural element such as a column *Compressibility, susceptibility to compression * Gas compression *Compression ratio, of a ...
.


Uralian orogeny

The
Uralian orogeny The Uralian orogeny refers to the long series of linear deformation and mountain building events that raised the Ural Mountains, starting in the Late Carboniferous and Permian periods of the Palaeozoic Era, 323–299 and 299–251 million years ...
is a north–south trending
fold and thrust belt A fold and thrust belt is a series of mountainous foothills adjacent to an orogenic belt, which forms due to contractional tectonics. Fold and thrust belts commonly form in the forelands adjacent to major orogens as deformation propagates outwards ...
that forms the western edge of the Central Asian Orogenic Belt. The Uralian orogeny began in the Late Devonian and continued, with some hiatuses, into the
Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...
. From the Late Devonian to early Carboniferous, the
Magnitogorsk Magnitogorsk ( rus, Магнитого́рск, p=məɡnʲɪtɐˈɡorsk, ) is an industrial city in Chelyabinsk Oblast, Russia, on the eastern side of the extreme southern extent of the Ural Mountains by the Ural River. Its population is curre ...
island arc Island arcs are long archipelago, chains of active volcanoes with intense earthquake, seismic activity found along convergent boundary, convergent plate tectonics, tectonic plate boundaries. Most island arcs originate on oceanic crust and have re ...
, which lay between Kazakhstania and Laurussia in the Ural Ocean, collided with the
passive margin A passive margin is the transition between Lithosphere#Oceanic lithosphere, oceanic and Lithosphere#Continental lithosphere, continental lithosphere that is not an active plate continental margin, margin. A passive margin forms by sedimentatio ...
of northeastern Laurussia ( Baltica craton). The suture zone between the former island arc complex and the continental margin formed the
Main Uralian Fault The Main Uralian Fault (MUF) runs north–south through the middle of the Ural Mountains for over 2,000 km. It separates both Europe from Asia and the three, or four, western megazones of the Urals from the three eastern megazones: namel ...
, a major structure that runs for more than 2,000 km along the orogen.
Accretion Accretion may refer to: Science * Accretion (astrophysics), the formation of planets and other bodies by collection of material through gravity * Accretion (meteorology), the process by which water vapor in clouds forms water droplets around nucl ...
of the island arc was complete by the Tournaisian, but subduction of the Ural Ocean between Kazakhstania and Laurussia continued until the Bashkirian when the ocean finally closed and continental collision began. Significant strike-slip movement along this zone indicates the collision was oblique. Deformation continued into the Permian and during the late Carboniferous and Permian the region was extensively intruded by
granite Granite ( ) is a coarse-grained (phanerite, phaneritic) intrusive rock, intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly coo ...
s.


Laurussia

The Laurussian continent was formed by the collision between
Laurentia Laurentia or the North American craton is a large continental craton that forms the Geology of North America, ancient geological core of North America. Many times in its past, Laurentia has been a separate continent, as it is now in the form of ...
,
Baltica Baltica is a paleocontinent that formed in the Paleoproterozoic and now constitutes northwestern Eurasia, or Europe north of the Trans-European Suture Zone and west of the Ural Mountains. The thick core of Baltica, the East European Craton, i ...
and
Avalonia Avalonia was a microcontinent in the Paleozoic era. Crustal fragments of this former microcontinent are terranes in parts of the eastern coast of North America: Atlantic Canada, and parts of the East Coast of the United States, East Coast of the ...
during the Devonian. At the beginning of the Carboniferous, some models show it at the equator, while others place it further south. In either case, the continent drifted northwards, reaching low latitudes in the northern hemisphere by the end of the Period. The Central Pangean Mountain drew in moist air from the Paleo-Tethys Ocean resulting in heavy precipitation and a tropical wetland environment. Extensive coal deposits developed within the cyclothem sequences that dominated the Pennsylvanian
sedimentary basin Sedimentary basins are region-scale depressions of the Earth's crust where subsidence has occurred and a thick sequence of sediments have accumulated to form a large three-dimensional body of sedimentary rock They form when long-term subsidence ...
s associated with the growing orogenic belt. Subduction of the
Panthalassic Panthalassa, also known as the Panthalassic Ocean or Panthalassan Ocean (from Greek "all" and "sea"), was the vast superocean that encompassed planet Earth and surrounded the supercontinent Pangaea, the latest in a series of supercontinents ...
oceanic plate along its western margin resulted in the Antler orogeny in the Late Devonian to Early Mississippian. Further north along the margin, slab roll-back, beginning in the Early Mississippian, led to the rifting of the Yukon–Tanana terrane and the opening of the
Slide Mountain Ocean The Slide Mountain Ocean was an ancient ocean that existed between the Intermontane Islands and North America beginning around 245 million years ago in the Triassic The Triassic ( ; sometimes symbolized 🝈) is a geologic period and system ...
. Along the northern margin of Laurussia,
orogenic collapse In geology, orogenic collapse is the thinning and lateral spread of thickened crust. It is a broad term referring to processes which distribute material from regions of high gravitational potential energy to regions of low gravitational potential ...
of the Late Devonian to Early Mississippian
Innuitian orogeny The Innuitian orogeny, sometimes called the Ellesmere orogeny, was a major tectonic orogeny (mountain building episode) of the late Devonian to early Carboniferous, responsible for the formation of a series of mountain ranges in the Canadian Arcti ...
led to the development of the Sverdrup Basin.


Gondwana

Much of Gondwana lay in the southern polar region during the Carboniferous. As the plate moved, the South Pole drifted from southern Africa in the early Carboniferous to eastern Antarctica by the end of the period.
Glacial deposits image:Geschiebemergel.JPG, Closeup of glacial till. Note that the larger grains (pebbles and gravel) in the till are completely surrounded by the matrix of finer material (silt and sand), and this characteristic, known as ''matrix support'', is d ...
are widespread across Gondwana and indicate multiple ice centres and long-distance movement of ice. The northern to northeastern margin of Gondwana (northeast Africa, Arabia, India and northeastern West Australia) was a passive margin along the southern edge of the Paleo-Tethys with cyclothem deposition including, during more temperate intervals, coal swamps in Western Australia. The Mexican terranes along the northwestern Gondwana margin, were affected by the subduction of the Rheic Ocean. However, they lay to west of the Ouachita orogeny and were not impacted by continental collision but became part of the active margin of the Pacific. The Moroccan margin was affected by periods of widespread dextral strike-slip deformation, magmatism and metamorphism associated with the Variscan orogeny. Towards the end of the Carboniferous, extension and rifting across the northern margin of Gondwana led to the breaking away of the
Cimmerian terrane Cimmeria ( ) was an ancient continent, or, rather, a string of microcontinents or terranes, that rifted from Gondwana in the Southern Hemisphere and was accreted to Eurasia in the Northern Hemisphere. It consisted of parts of present-day Turke ...
during the early Permian and the opening of the Neo-Tethys Ocean. Along the southeastern and southern margin of Gondwana (eastern Australia and Antarctica), northward subduction of Panthalassa continued. Changes in the relative motion of the plates resulted in the early Carboniferous
Kanimblan Orogeny The Kanimblan orogeny was a mountain-building event in eastern Australia toward the end of Early Carboniferous time (about 318 million years ago). It was a terminal orogenic episode forming the Lachlan Fold Belt, which was also known as the Lach ...
.
Continental arc A continental arc is a type of volcanic arc occurring as an "arc-shape" topographic high region along a continental margin. The continental arc is formed at an active continental margin where two tectonic plates meet, and where one plate has conti ...
magmatism continued into the late Carboniferous and extended round to connect with the developing proto-Andean subduction zone along the western South American margin of Gondwana.


Siberia and Amuria

Shallow seas covered much of the Siberian craton in the early Carboniferous. These retreated as sea levels fell in the Pennsylvanian and as the continent drifted north into more temperate zones extensive coal deposits formed in the
Kuznetsk Basin The Kuznetsk Basin (, Кузбасс; often abbreviated as Kuzbass or Kuzbas) in southwestern Siberia, Russia, is one of the largest coal mining areas in Russia, covering an area of around . It lies in the Kuznetsk Depression between Tomsk and ...
. The northwest to eastern margins of Siberia were passive margins along the Mongol-Okhotsk Ocean on the far side of which lay Amuria. From the mid Carboniferous, subduction zones with associated magmatic arcs developed along both margins of the ocean. The southwestern margin of Siberia was the site of a long lasting and complex accretionary orogen. The Devonian to early Carboniferous Siberian and South Chinese Altai accretionary complexes developed above an east-dipping subduction zone, whilst further south, the Zharma-Saur arc formed along the northeastern margin of Kazakhstania. By the late Carboniferous, all these complexes had accreted to the Siberian craton as shown by the intrusion of post-orogenic granites across the region. As Kazakhstania had already accreted to Laurussia, Siberia was effectively part of Pangea by 310 Ma, although major strike-slip movements continued between it and Laurussia into the Permian.


Central and East Asia

The Kazakhstanian microcontinent is composed of a series of Devonian and older accretionary complexes. It was strongly deformed during the Carboniferous as its western margin collided with Laurussia during the Uralian orogen and its northeastern margin collided with Siberia. Continuing strike-slip motion between Laurussia and Siberia led the formerly elongate microcontinent to bend into an
orocline An orocline — from the Greek words for "mountain" and "to bend" — is a bend or curvature of an orogenic (mountain building) belt imposed after it was formed. The term was introduced by S. Warren Carey in 1955 in a paper setting forth how comp ...
. During the Carboniferous, the Tarim craton lay along the northwestern edge of North China. Subduction along the Kazakhstanian margin of the Turkestan Ocean resulted in collision between northern Tarim and Kazakhstania during the mid Carboniferous as the ocean closed. The South Tian Shan fold and thrust belt, which extends over 2,000 km from
Uzbekistan , image_flag = Flag of Uzbekistan.svg , image_coat = Emblem of Uzbekistan.svg , symbol_type = Emblem of Uzbekistan, Emblem , national_anthem = "State Anthem of Uzbekistan, State Anthem of the Republ ...
to northwest China, is the remains of this accretionary complex and forms the suture between Kazakhstania and Tarim. A continental magmatic arc above a south-dipping subduction zone lay along the northern North China margin, consuming the Paleoasian Ocean. Northward subduction of the Paleo-Tethys beneath the southern margins of North China and Tarim continued during the Carboniferous, with the South Qinling block accreted to North China during the mid to late Carboniferous. No sediments are preserved from the early Carboniferous in North China. However,
bauxite Bauxite () is a sedimentary rock with a relatively high aluminium content. It is the world's main source of aluminium and gallium. Bauxite consists mostly of the aluminium minerals gibbsite (), boehmite (γ-AlO(OH)), and diaspore (α-AlO(OH) ...
deposits immediately above the regional mid Carboniferous unconformity indicate warm tropical conditions and are overlain by cyclothems including extensive coals. South China and Annamia (Southeast Asia) rifted from Gondwana during the Devonian. During the Carboniferous, they were separated from each other and North China by the Paleoasian Ocean with the Paleo-Tethys to the southwest and Panthalassa to the northeast. Cyclothem sediments with coal and
evaporite An evaporite () is a water- soluble sedimentary mineral deposit that results from concentration and crystallization by evaporation from an aqueous solution. There are two types of evaporite deposits: marine, which can also be described as oce ...
s were deposited across the passive margins that surrounded both continents.


Climate

The Carboniferous climate was dominated by the Late Paleozoic Ice Age (LPIA), the most extensive and longest icehouse period of the Phanerozoic, which lasted from the Late Devonian to the Permian (365 Ma-253 Ma). Temperatures began to drop during the late Devonian with a short-lived glaciation in the late Famennian through Devonian–Carboniferous boundary, before the Early Tournaisian Warm Interval. Following this, a reduction in atmospheric CO2 levels, caused by the increased burial of organic matter and widespread ocean anoxia led to climate cooling and glaciation across the south polar region. During the Visean Warm Interval glaciers nearly vanished retreating to the proto-Andes in Bolivia and western Argentina and the Pan-African mountain ranges in southeastern Brazil and southwest Africa. The main phase of the LPIA (c. 335–290 Ma) began in the late Visean, as the climate cooled and atmospheric CO2 levels dropped. Its onset was accompanied by a global fall in sea level and widespread multimillion-year unconformities. This main phase consisted of a series of discrete several million-year-long glacial periods during which ice expanded out from up to 30 ice centres that stretched across mid- to high latitudes of Gondwana in eastern Australia, northwestern Argentina, southern Brazil, and central and Southern Africa. Isotope records indicate this drop in CO2 levels was triggered by tectonic factors with increased weathering of the growing Central Pangean Mountains and the influence of the mountains on precipitation and surface water flow. Closure of the oceanic gateway between the Rheic and Tethys oceans in the early Bashkirian also contributed to climate cooling by changing ocean circulation and heat flow patterns. Warmer periods with reduced ice volume within the Bashkirian, the late Moscovian and the latest Kasimovian to mid-Gzhelian are inferred from the disappearance of glacial sediments, the appearance of deglaciation deposits and rises in sea levels. In the early Kasimovian there was short-lived (<1 million years) intense period of glaciation, with atmospheric CO2 concentration levels dropping as low as 180 ppm. This ended suddenly as a rapid increase in CO2 concentrations to c. 600 ppm resulted in a warmer climate. This rapid rise in CO2 may have been due to a peak in pyroclastic volcanism and/or a reduction in burial of terrestrial organic matter. The LPIA peaked across the Carboniferous-Permian boundary. Widespread glacial deposits are found across South America, western and central Africa, Antarctica, Australia, Tasmania, the Arabian Peninsula, India, and the Cimmerian blocks, indicating trans-continental ice sheets across southern Gondwana that reached to sea-level. In response to the uplift and erosion of the more mafic basement rocks of the Central Pangea Mountains at this time, CO2 levels dropped as low as 175 ppm and remained under 400 ppm for 10 Ma.


Temperatures

Temperatures across the Carboniferous reflect the phases of the LPIA. At the extremes, during the Permo-Carboniferous Glacial Maximum (299–293 Ma) the global average temperature (GAT) was c. 13 °C (55 °F), the average temperature in the tropics c. 24 °C (75 °F) and in polar regions c. -23 °C (-10 °F), whilst during the Early Tournaisian Warm Interval (358–353 Ma) the GAT was c. 22 °C (72 °F), the tropics c. 30 °C (86 °F) and polar regions c. 1.5 °C (35 °F). Overall, for the Ice Age the GAT was c. 17 °C (62 °F), with tropical temperatures c. 26 °C and polar temperatures c. -9.0 °C (16 °F).


Atmospheric oxygen levels

There are a variety of methods for reconstructing past atmospheric oxygen levels, including the
charcoal Charcoal is a lightweight black carbon residue produced by strongly heating wood (or other animal and plant materials) in minimal oxygen to remove all water and volatile constituents. In the traditional version of this pyrolysis process, ca ...
record,
halite Halite ( ), commonly known as rock salt, is a type of salt, the mineral (natural) form of sodium chloride ( Na Cl). Halite forms isometric crystals. The mineral is typically colorless or white, but may also be light blue, dark blue, purple, pi ...
gas inclusions, burial rates of organic carbon and
pyrite The mineral pyrite ( ), or iron pyrite, also known as fool's gold, is an iron sulfide with the chemical formula Fe S2 (iron (II) disulfide). Pyrite is the most abundant sulfide mineral. Pyrite's metallic luster and pale brass-yellow hue ...
, carbon isotopes of organic material, isotope mass balance and forward modelling. Depending on the preservation of source material, some techniques represent moments in time (e.g. halite gas inclusions), whilst others have a wider time range (e.g. the charcoal record and pyrite). Results from these different methods for the Carboniferous vary. For example: the increasing occurrence of charcoal produced by wildfires from the Late Devonian into the Carboniferous indicates increasing oxygen levels, with calculations showing oxygen levels above 21% for most of the Carboniferous; halite gas inclusions from sediments dated 337–335 Ma give estimates for the Visean of c. 15.3%, although with large uncertainties; and, pyrite records suggest levels of c. 15% early in the Carboniferous, to over 25% during the Pennsylvanian, before dropping back below 20% towards the end. However, whilst exact numbers vary, all models show an overall increase in atmospheric oxygen levels from a low of between 15 and 20% at the beginning of the Carboniferous to highs of 25–30% during the Period. This was not a steady rise, but included peaks and troughs reflecting the dynamic climate conditions of the time. How the atmospheric oxygen concentrations influenced the large body size of arthropods and other fauna and flora during the Carboniferous is also a subject of ongoing debate.


Effects of climate on sedimentation

The changing climate was reflected in regional-scale changes in sedimentation patterns. In the relatively warm waters of the Early to Middle Mississippian, carbonate production occurred to depth across the gently dipping continental slopes of Laurussia and North and South China ( carbonate ramp architecture) and evaporites formed around the coastal regions of Laurussia, Kazakhstania, and northern Gondwana. From the late Visean, the cooling climate restricted carbonate production to depths of less than c. 10 m forming carbonate shelves with flat-tops and steep sides. By the Moscovian, the waxing and waning of the ice sheets led to cyclothem deposition with mixed carbonate-siliciclastic sequences deposited on continental platforms and shelves. Seasonal melting of glaciers resulted in near freezing waters around the margins of Gondwana. This is evidenced by the occurrence of glendonite (a pseudomorph of
ikaite Ikaite is the mineral name for the hexahydrate of calcium carbonate, . Ikaite tends to form very steep or spiky pyramidal crystals, often radially arranged, of varied sizes from thumbnail size aggregates to gigantic salient spurs. It is only fo ...
; a form of calcite deposited in glacial waters) in fine-grained, shallow marine sediments. The glacial grinding and erosion of siliciclastic rocks across Gondwana and the Central Pangaean Mountains produced vast amounts of silt-sized sediment. Redistributed by the wind, this formed widespread deposits of loess across equatorial Pangea.


Effects of climate on biodiversity

The main phase of the LPIA was considered a crisis for marine biodiversity with the loss of many genera, followed by low biodiversity. However, recent studies of marine life suggest the rapid climate and environmental changes that accompanied the onset of the main glacial phase resulted in an adaptive radiation with a rapid increase in the number of species. The oscillating climate conditions also led to repeated restructuring of Laurasian tropical forests between wetlands and seasonally dry ecosystems, and the appearance and diversification of tetrapods species. There was a major restructuring of wetland forests during the Kasimovian glacial interval, with the loss of arborescent (tree-like) lycopisids and other wetland groups, and a general decline in biodiversity. These events are attributed to the drop in CO2 levels below 400 ppm. Although referred to as the Carboniferous rainforest collapse, this was a complex replacement of one type of rainforest by another, not a complete disappearance of rainforest vegetation. Across the Carboniferous–Permian boundary interval, a rapid drop in CO2 levels and increasingly arid conditions at low-latitudes led to a permanent shift to seasonally dry woodland vegetation. Tetrapods acquired new terrestrial adaptations and there was a radiation of dryland-adapted
amniote Amniotes are tetrapod vertebrate animals belonging to the clade Amniota, a large group that comprises the vast majority of living terrestrial animal, terrestrial and semiaquatic vertebrates. Amniotes evolution, evolved from amphibious Stem tet ...
s.


Geochemistry

As the continents assembled to form Pangea, the growth of the Central Pangean Mountains led to increased
weathering Weathering is the deterioration of rocks, soils and minerals (as well as wood and artificial materials) through contact with water, atmospheric gases, sunlight, and biological organisms. It occurs '' in situ'' (on-site, with little or no move ...
and carbonate sedimentation on the ocean floor, whilst the distribution of continents across the paleo-tropics meant vast areas of land were available for the spread of tropical rainforests. Together these two factors significantly increased CO2 drawdown from the atmosphere, lowering global temperatures, increasing ocean pH and triggering the Late Paleozoic Ice Age. The growth of the supercontinent also changed
seafloor spreading Seafloor spreading, or seafloor spread, is a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge. History of study Earlier theories by Alfred Wegener ...
rates and led to a decrease in the length and volume of
mid-ocean ridge A mid-ocean ridge (MOR) is a undersea mountain range, seafloor mountain system formed by plate tectonics. It typically has a depth of about and rises about above the deepest portion of an ocean basin. This feature is where seafloor spreading ...
systems.


Magnesium/calcium isotope ratios in seawater

During the early Carboniferous, the Mg2+/Ca2+ ratio in seawater began to rise and by the Middle Mississippian
aragonite sea An aragonite sea contains aragonite and high-magnesium calcite as the primary inorganic calcium carbonate precipitates. The reason lies in the highly hydrated divalent ion, the second most abundant cation in seawater after , known to be a stron ...
s had replaced
calcite sea A calcite sea is a sea in which low-magnesium calcite is the primary inorganic marine calcium carbonate precipitate. An aragonite sea is the alternate seawater chemistry in which aragonite and high-magnesium calcite are the primary inorganic carb ...
s. The concentration of calcium in seawater is largely controlled by ocean pH, and as this increased the calcium concentration was reduced. At the same time, the increase in weathering, increased the amount of magnesium entering the marine environment. As magnesium is removed from seawater and calcium added along mid-ocean ridges where seawater reacts with the newly formed lithosphere, the reduction in length of mid-ocean ridge systems increased the Mg2+/Ca2+ ratio further. The Mg2+/Ca2+ ratio of the seas also affects the ability of organisms to
biomineralize Biomineralization, also written biomineralisation, is the process by which living organisms produce minerals, often resulting in hardened or stiffened '' mineralized tissues''. It is an extremely widespread phenomenon: all six taxonomic kingd ...
. The Carboniferous aragonite seas favoured those that secreted
aragonite Aragonite is a carbonate mineral and one of the three most common naturally occurring crystal forms of calcium carbonate (), the others being calcite and vaterite. It is formed by biological and physical processes, including precipitation fr ...
and the dominant reef builders of the time were aragonitic sponges and corals.


Strontium isotopic composition of seawater

The
strontium Strontium is a chemical element; it has symbol Sr and atomic number 38. An alkaline earth metal, it is a soft silver-white yellowish metallic element that is highly chemically reactive. The metal forms a dark oxide layer when it is exposed to ...
isotopic composition (87Sr/86Sr) of seawater represents a mix of strontium derived from continental weathering which is rich in 87Sr and from mantle sources e.g. mid-ocean ridges, which are relatively depleted in 87Sr. 87Sr/86Sr ratios above 0.7075 indicate continental weathering is the main source of 87Sr, whilst ratios below indicate mantle-derived sources are the principal contributor. 87Sr/86Sr values varied through the Carboniferous, although they remained above 0.775, indicating continental weathering dominated as the source of 87Sr throughout. The 87Sr/86Sr during the Tournaisian was c. 0.70840, it decreased through the Visean to 0.70771 before increasing during the Serpukhovian to the lowermost Gzhelian where it plateaued at 0.70827, before decreasing again to 0.70814 at the Carboniferous-Permian boundary. These variations reflect the changing influence of weathering and sediment supply to the oceans of the growing Central Pangean Mountains. By the Serpukhovian
basement A basement is any Storey, floor of a building that is not above the grade plane. Especially in residential buildings, it often is used as a utility space for a building, where such items as the Furnace (house heating), furnace, water heating, ...
rocks, such as
granite Granite ( ) is a coarse-grained (phanerite, phaneritic) intrusive rock, intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly coo ...
, had been uplifted and exposed to weathering. The decline towards the end of the Carboniferous is interpreted as a decrease in continental weathering due to the more arid conditions.


Oxygen and carbon isotope ratios in seawater

Unlike Mg2+/Ca2+ and 87Sr/86Sr isotope ratios, which are consistent across the world's oceans at any one time, δ18O and δ13C preserved in the fossil record can be affected by regional factors. Carboniferous δ18O and δ13C records show regional differences between the South China open-water setting and the epicontinental seas of Laurussia. These differences are due to variations in seawater salinity and evaporation between epicontinental seas relative to the more open waters. However, large scale trends can still be determined. δ13C rose rapidly from c. 0 to 1‰ (parts per thousand) to c. 5 to 7‰ in the Early Mississippian and remained high for the duration of the Late Paleozoic Ice Age (c. 3–6‰) into the early Permian. Similarly from the Early Mississippian there was a long-term increase in δ18O values as the climate cooled. Both δ13C and δ18O records show significant global isotope changes (known as excursions) during the Carboniferous. The mid-Tournaisian positive δ13C and δ18O excursions lasted between 6 and 10 million years and were also accompanied by c. 6‰ positive excursion in organic matter δ15N values, a negative excursion in carbonate δ 238U and a positive excursion in carbonate-associated sulphate δ34S. These changes in seawater geochemistry are interpreted as a decrease in atmospheric CO2 due to increased
organic matter Organic matter, organic material or natural organic matter is the large source of carbon-based compounds found within natural and engineered, terrestrial, and aquatic environments. It is matter composed of organic compounds that have come fro ...
burial and widespread ocean anoxia triggering climate cooling and onset of glaciation. The Mississippian-Pennsylvanian boundary positive δ18O excursion occurred at the same time as global sea level falls and widespread glacial deposits across southern Gondwana, indicating climate cooling and ice build-up. The rise in 87Sr/86Sr just before the δ18O excursion suggests climate cooling in this case was caused by increased continental weathering of the growing Central Pangean Mountains and the influence of the orogeny on precipitation and surface water flow rather than increased burial of organic matter. δ13C values show more regional variation, and it is unclear whether there is a positive δ13C excursion or a readjustment from previous lower values. During the early Kasimovian there was a short (<1myr), intense glacial period, which came to a sudden end as atmospheric CO2 concentrations rapidly rose. There was a steady increase in arid conditions across tropical regions and a major reduction in the extent of tropical rainforests, as shown by the widespread loss of coal deposits from this time. The resulting reduction in productivity and burial of organic matter led to increasing atmospheric CO2 levels, which were recorded by a negative δ13C excursion and an accompanying, but smaller decrease in δ18O values.


Life


Plants

Early Carboniferous land plants, some of which were preserved in
coal ball A coal ball is a type of concretion, varying in shape from an imperfect sphere to a flat-lying, irregular slab. Coal balls were formed in Carboniferous Period swamps and mires, when peat was prevented from being turned into coal by the high am ...
s, were very similar to those of the preceding Late Devonian, but new groups also appeared at this time. The main early Carboniferous plants were the
Equisetales Equisetales is an order of subclass Equisetidae with only one living family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relation ...
(horse-tails),
Sphenophyllales Sphenophyllales is an extinct order of articulate land plants and a sister group to the present-day Equisetales ( horsetails). They are fossils dating from the Devonian to the Triassic. They were common during the Late Pennsylvanian to Early ...
(scrambling plants),
Lycopodiales The Lycopodiaceae (class Lycopodiopsida, order Lycopodiales) are an old family of vascular plants, including all of the core clubmosses and firmosses, comprising 17 accepted genera and about 500 known species. This family originated about 380 mi ...
(club mosses),
Lepidodendrales Lepidodendrales (from the Greek for "scale tree") or arborescent lycophytes are an extinct order of primitive, vascular, Heterospory, heterosporous, arborescent (tree-like) plants belonging to Lycopodiopsida. Members of Lepidodendrales are the bes ...
(scale trees),
Filicales The Polypodiidae, commonly called leptosporangiate ferns, formerly Leptosporangiatae, are one of four subclasses of ferns, the largest of these being the largest group of living ferns, including some 11,000 species worldwide. The group has also ...
(ferns),
Medullosales The Medullosales is an extinct order of pteridospermous seed plants characterised by large ovules with circular cross-section and a vascularised nucellus, complex pollen-organs, stems and rachides with a dissected stele, and frond-like leaves ...
(informally included in the "
seed ferns Pteridospermatophyta, also called pteridosperms or seed ferns, are a polyphyletic grouping of extinct Spermatophyte, seed-producing plants. The earliest fossil evidence for plants of this type are the Lyginopteridales, lyginopterids of late Devon ...
", an assemblage of a number of early
gymnosperm The gymnosperms ( ; ) are a group of woody, perennial Seed plant, seed-producing plants, typically lacking the protective outer covering which surrounds the seeds in flowering plants, that include Pinophyta, conifers, cycads, Ginkgo, and gnetoph ...
groups) and the
Cordaitales Cordaitales are an extinct order of gymnosperms, known from the early Carboniferous to the late Permian. Many Cordaitales had elongated strap-like leaves, resembling some modern-day conifers of the Araucariaceae and Podocarpaceae. They had co ...
. These continued to dominate throughout the period, but during the late Carboniferous, several other groups,
Cycadophyta Cycads are seed plants that typically have a stout and woody (ligneous) trunk with a crown of large, hard, stiff, evergreen and (usually) pinnate leaves. The species are dioecious, that is, individual plants of a species are either male or ...
(cycads), the
Callistophytales Callistophytales is an extinct order of spermatophytes (seed plants) which lived from the Pennsylvanian (Late Carboniferous) to Permian periods. They were mainly scrambling and lianescent (vine-like) plants found in the wetland "coal swamps" of E ...
(another group of "seed ferns"), and the
Voltziales Voltziales is an extinct order of conifers. The group contains the ancestral lineages from which modern conifer groups emerged. Voltzialean conifers are divided into two informal groups, the primitive "walchian conifers" like '' Walchia,'' where ...
, appeared. The Carboniferous lycophytes of the order Lepidodendrales, which are cousins (but not ancestors) of the tiny club-moss of today, were huge trees with trunks 30 meters high and up to 1.5 meters in diameter. These included ''
Lepidodendron ''Lepidodendron'' is an extinct genus of primitive lycopodian vascular plants belonging the order Lepidodendrales. It is well preserved and common in the fossil record. Like other Lepidodendrales, species of ''Lepidodendron'' grew as large-tree ...
'' (with its cone called Lepidostrobus), '' Anabathra'', '' Lepidophloios'' and ''
Sigillaria ''Sigillaria'' is a genus of extinct, spore-bearing, Lepidodendrales, arborescent lycophyte, known from the Carboniferous and Permian periods. It is related to the more famous ''Lepidodendron'', and more distantly to modern Isoetes, quillworts. ...
''. The roots of several of these forms are known as
Stigmaria ''Stigmaria'' is a form taxon for common fossils found in Carboniferous rocks. They represent the underground rooting structures of arborescent lycophytes such as ''Sigillaria'' and '' Lepidodendron'' under the order '' Lepidodendrales.'' Descr ...
. Unlike present-day trees, their
secondary growth In botany, secondary growth is the growth that results from cell division in the cambia or lateral meristems and that causes the stems and roots to thicken, while primary growth is growth that occurs as a result of cell division at the tips ...
took place in the
cortex Cortex or cortical may refer to: Biology * Cortex (anatomy), the outermost layer of an organ ** Cerebral cortex, the outer layer of the vertebrate cerebrum, part of which is the ''forebrain'' *** Motor cortex, the regions of the cerebral cortex i ...
, which also provided stability, instead of the
xylem Xylem is one of the two types of transport tissue (biology), tissue in vascular plants, the other being phloem; both of these are part of the vascular bundle. The basic function of the xylem is to transport water upward from the roots to parts o ...
. The Cladoxylopsids were large trees, that were ancestors of ferns, first arising in the Carboniferous. The fronds of some Carboniferous ferns are almost identical with those of living species. Probably many species were
epiphytic An epiphyte is a plant or plant-like organism that grows on the surface of another plant and derives its moisture and nutrients from the air, rain, water (in marine environments) or from debris accumulating around it. The plants on which epiphyt ...
. Fossil ferns and "seed ferns" include '' Pecopteris'', '' Cyclopteris'', ''
Neuropteris ''Neuropteris'' is an extinct seed fern that existed in the Carboniferous period, known only from fossils. Gallery File:Neuropteris flexuosa kz01.jpg, ''N. flexuosa'' File:Neuropteris flexuosa fossil plant (Mazon Creek Lagerstatte, Francis ...
'', '' Alethopteris'', and ''
Sphenopteris ''Sphenopteris'' is a genus of seed ferns containing the foliage of various extinct plants, ranging from the Devonian to Late Cretaceous. One species, ''S. höninghausi'', was transferred to the genus '' Crossotheca'' in 1911. Biology The fro ...
''; '' Megaphyton'' and '' Caulopteris'' were tree ferns. The Equisetales included the common giant form ''
Calamites ''Calamites'' is a genus of Extinction, extinct arborescent (tree-like) horsetails to which the modern horsetails (genus ''Equisetum'') are closely related. Unlike their Herbaceous plant, herbaceous modern cousins, these plants were medium-size ...
'', with a trunk diameter of 30 to and a height of up to . ''
Sphenophyllum ''Sphenophyllum'' is a genus in the order Sphenophyllales. It has been placed in the family Sphenophyllaceae. Species Species that have been described include: *†''Sphenophyllum angustifolium'' *†''Sphenophyllum biarmicum'' Zalessky (1937) ...
'' was a slender climbing plant with whorls of leaves, which was probably related both to the calamites and the lycopods. ''
Cordaites ''Cordaites'' is a genus of extinct gymnosperms, related to or actually representing the earliest conifers. These trees grew up to tall and stood in dry areas as well as wetlands. Brackish water mussels and crustacea are found frequently betwee ...
'', a tall plant (6 to over 30 meters) with strap-like leaves, was related to the cycads and conifers; the
catkin A catkin or ament is a slim, cylindrical flower cluster (a spike), with inconspicuous or no petals, usually wind- pollinated ( anemophilous) but sometimes insect-pollinated (as in '' Salix''). It contains many, usually unisexual flowers, arra ...
-like reproductive organs, which bore ovules/seeds, is called '' Cardiocarpus''. These plants were thought to live in swamps. True coniferous trees (''
Walchia ''Walchia'' is a primitive fossil conifer found in upper Pennsylvanian (geology), Pennsylvanian (Carboniferous) and lower Permian (about 310-290 Mya (unit), Mya) rocks of Europe and North America. A forest of In situ, in-situ Walchia tree-stumps ...
'', of the order Voltziales) appear later in the Carboniferous, and preferred higher drier ground.


Marine invertebrates

In the oceans the
marine invertebrate Marine invertebrates are invertebrate animals that live in marine habitats, and make up most of the macroscopic life in the oceans. It is a polyphyletic blanket term that contains all marine animals except the marine vertebrates, including the ...
groups are the
Foraminifera Foraminifera ( ; Latin for "hole bearers"; informally called "forams") are unicellular organism, single-celled organisms, members of a phylum or class (biology), class of Rhizarian protists characterized by streaming granular Ectoplasm (cell bio ...
,
corals Corals are colonial marine invertebrates within the subphylum Anthozoa of the phylum Cnidaria. They typically form compact Colony (biology), colonies of many identical individual polyp (zoology), polyps. Coral species include the important Coral ...
,
Bryozoa Bryozoa (also known as the Polyzoa, Ectoprocta or commonly as moss animals) are a phylum of simple, aquatic animal, aquatic invertebrate animals, nearly all living in sedentary Colony (biology), colonies. Typically about long, they have a spe ...
,
Ostracoda Ostracods, or ostracodes, are a class of the Crustacea (class Ostracoda), sometimes known as seed shrimp. Some 33,000 species (only 13,000 of which are extant) have been identified,Brandão, S.N.; Antonietto, L.S; Nery, D.G.; Santos, S.G.; Karano ...
,
brachiopod Brachiopods (), phylum (biology), phylum Brachiopoda, are a phylum of animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear e ...
s,
ammonoids Ammonoids are extinct, (typically) coiled-shelled cephalopods comprising the subclass Ammonoidea. They are more closely related to living octopuses, squid, and cuttlefish (which comprise the clade Coleoidea) than they are to nautiluses (family N ...
, hederelloids, microconchids and
echinoderm An echinoderm () is any animal of the phylum Echinodermata (), which includes starfish, brittle stars, sea urchins, sand dollars and sea cucumbers, as well as the sessile sea lilies or "stone lilies". While bilaterally symmetrical as ...
s (especially
crinoid Crinoids are marine invertebrates that make up the class Crinoidea. Crinoids that remain attached to the sea floor by a stalk in their adult form are commonly called sea lilies, while the unstalked forms, called feather stars or comatulids, are ...
s). The diversity of brachiopods and fusilinid foraminiferans, surged beginning in the Visean, continuing through the end of the Carboniferous, although cephalopod and nektonic conodont diversity declined. This evolutionary radiation was known as the Carboniferous-Earliest Permian Biodiversification Event. For the first time foraminifera took a prominent part in the marine faunas. The large spindle-shaped genus Fusulina and its relatives were abundant in what is now Russia, China, Japan, North America; other important genera include ''Valvulina'', ''Endothyra'', ''Archaediscus'', and ''Saccammina'' (the latter common in Britain and Belgium). Some Carboniferous genera are still
extant Extant or Least-concern species, least concern is the opposite of the word extinct. It may refer to: * Extant hereditary titles * Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English * Exta ...
. The first true
priapulid Priapulida (priapulid worms, from Gr. πριάπος, ''priāpos'' 'Priapus' + Lat. ''-ul-'', diminutive), sometimes referred to as penis worms, is a phylum of unsegmented marine worms. The name of the phylum relates to the Greek god of fertility ...
s appeared during this period. The microscopic shells of
radiolaria The Radiolaria, also called Radiozoa, are unicellular eukaryotes of diameter 0.1–0.2 mm that produce intricate mineral skeletons, typically with a central capsule dividing the cell into the inner and outer portions of endoplasm and ect ...
ns are found in
chert Chert () is a hard, fine-grained sedimentary rock composed of microcrystalline or cryptocrystalline quartz, the mineral form of silicon dioxide (SiO2). Chert is characteristically of biological origin, but may also occur inorganically as a prec ...
s of this age in the Culm of
Devon Devon ( ; historically also known as Devonshire , ) is a ceremonial county in South West England. It is bordered by the Bristol Channel to the north, Somerset and Dorset to the east, the English Channel to the south, and Cornwall to the west ...
and
Cornwall Cornwall (; or ) is a Ceremonial counties of England, ceremonial county in South West England. It is also one of the Celtic nations and the homeland of the Cornish people. The county is bordered by the Atlantic Ocean to the north and west, ...
, and in Russia, Germany and elsewhere.
Sponges Sponges or sea sponges are primarily marine invertebrates of the animal phylum Porifera (; meaning 'pore bearer'), a basal clade and a sister taxon of the diploblasts. They are sessile filter feeders that are bound to the seabed, and ar ...
are known from
spicule Spicules are any of various small needle-like anatomical structures occurring in organisms Spicule may also refer to: *Spicule (sponge), small skeletal elements of sea sponges *Spicule (nematode), reproductive structures found in male nematodes ( ...
s and anchor ropes, and include various forms such as the Calcispongea ''Cotyliscus'' and ''Girtycoelia'', the
demosponge Demosponges or common sponges are sponges of the class Demospongiae (from + ), the most diverse group in the phylum Porifera which include greater than 90% of all extant sponges with nearly 8,800 species A species () is often de ...
''Chaetetes'', and the genus of unusual colonial
glass sponges Hexactinellid sponges are sponges with a skeleton made of four- and/or six-pointed siliceous spicules, often referred to as glass sponges. They are usually classified along with other sponges in the phylum Porifera, but some researchers consider ...
'' Titusvillia''. Both
reef A reef is a ridge or shoal of rock, coral, or similar relatively stable material lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic component, abiotic (non-living) processes such as deposition (geol ...
-building and solitary corals diversify and flourish; these include both
rugose Rugose means "wrinkled". It may refer to: * Rugosa, an extinct order of coral, whose rugose shape earned it the name * Rugose, adjectival form of rugae Species with "rugose" in their names * ''Idiosoma nigrum'', more commonly, a black rugose tra ...
(for example, '' Caninia'', ''Corwenia'', ''Neozaphrentis''), heterocorals, and
tabulate Tabulata, commonly known as tabulate corals, is a class of extinct corals. They are almost always colonial, forming colonies of individual hexagonal cells known as corallites defined by a skeleton of calcite, similar in appearance to a honeycomb. ...
(for example, ''Chladochonus'', ''Michelinia'') forms.
Conularids Conulariida are an extinct group of medusozoan cnidarians known from fossils spanning from the latest Ediacaran up until the Late Triassic. They are almost exclusively known from their hard external structures (alternatively referred to as a the ...
were well represented by ''Conularia''
Bryozoa Bryozoa (also known as the Polyzoa, Ectoprocta or commonly as moss animals) are a phylum of simple, aquatic animal, aquatic invertebrate animals, nearly all living in sedentary Colony (biology), colonies. Typically about long, they have a spe ...
are abundant in some regions; the fenestellids including ''Fenestella'', ''Polypora'', and ''
Archimedes Archimedes of Syracuse ( ; ) was an Ancient Greece, Ancient Greek Greek mathematics, mathematician, physicist, engineer, astronomer, and Invention, inventor from the ancient city of Syracuse, Sicily, Syracuse in History of Greek and Hellenis ...
'', so named because it is in the shape of an
Archimedean screw The Archimedes' screw, also known as the Archimedean screw, hydrodynamic screw, water screw or Egyptian screw, is one of the earliest documented hydraulic machines. It was so-named after the Greek mathematician Archimedes who first described it ...
.
Brachiopod Brachiopods (), phylum (biology), phylum Brachiopoda, are a phylum of animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear e ...
s are also abundant; they include productids, some of which reached very large for brachiopods size and had very thick shells (for example, the -wide '' Gigantoproductus''), while others like ''
Chonetes ''Chonetes'' is an extinct genus of brachiopods. It ranged from the Late Ordovician to the Middle Jurassic. Species The following species of ''Chonetes'' have been described: * ''C. (Paeckelmannia)'' * ''C. baragwanathi'' * ''C. billingsi' ...
'' were more conservative in form. Athyridids, spiriferids, rhynchonellids, and terebratulids are also very common. Inarticulate forms include ''
Discina DisCina was a French film production and film distribution, distribution company established in 1938 by Michel Safra and André Paulvé. It reached its peak during the 1940s and early 1950s, remaining active during the Occupation of France. It al ...
'' and '' Crania''. Some species and genera had a very wide distribution with only minor variations.
Annelid The annelids (), also known as the segmented worms, are animals that comprise the phylum Annelida (; ). The phylum contains over 22,000 extant species, including ragworms, earthworms, and leeches. The species exist in and have adapted to vario ...
s such as ''Serpulites'' are common fossils in some horizons. Among the mollusca, the
bivalve Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of aquatic animal, aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed b ...
s continue to increase in numbers and importance. Typical genera include '' Aviculopecten'', '' Posidonomya'', ''
Nucula ''Nucula'' is a genus of very small saltwater clams. They are part of the family Nuculidae. Fossil records This genus is very ancient. Fossils are known from the Arenig to the Quaternary (age range: from 478.6 to 0.0 million years ago). Fossils ...
'', '' Carbonicola'', ''Edmondia'', and ''Modiola''.
Gastropod Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...
s are also numerous, including the genera ''Murchisonia'', ''
Euomphalus ''Euomphalus'' is a genus of fossil marine gastropods known to have lived from the Silurian to the Middle Permian.J.B.Knight,et al 1960. Treatise on Invertebrate Paleontology, Part I, Mollusca 1, ch on systematic descriptions. Geol Soc of Ameri ...
'', ''Naticopsis''.
Nautiloid Nautiloids are a group of cephalopods (Mollusca) which originated in the Late Cambrian and are represented today by the living ''Nautilus'' and ''Allonautilus''. Fossil nautiloids are diverse and species rich, with over 2,500 recorded species. Th ...
cephalopod A cephalopod is any member of the molluscan Taxonomic rank, class Cephalopoda (Greek language, Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral symm ...
s are represented by tightly coiled nautilids, with straight-shelled and curved-shelled forms becoming increasingly rare.
Goniatite Goniatids, informally goniatites, are ammonoid cephalopods that form the order Goniatitida, derived from the more primitive Agoniatitida during the Middle Devonian some 390 million years ago (around Eifelian stage). Goniatites (goniatitids) su ...
ammonoids Ammonoids are extinct, (typically) coiled-shelled cephalopods comprising the subclass Ammonoidea. They are more closely related to living octopuses, squid, and cuttlefish (which comprise the clade Coleoidea) than they are to nautiluses (family N ...
such as Aenigmatoceras are common.
Trilobite Trilobites (; meaning "three-lobed entities") are extinction, extinct marine arthropods that form the class (biology), class Trilobita. One of the earliest groups of arthropods to appear in the fossil record, trilobites were among the most succ ...
s are rarer than in previous periods, on a steady trend towards extinction, represented only by the proetid group.
Ostracod Ostracods, or ostracodes, are a Class (biology), class of the crustacean, Crustacea (class Ostracoda), sometimes known as seed shrimp. Some 33,000 species (only 13,000 of which are extant taxon, extant) have been identified,Brandão, S.N.; Antoni ...
a, a class of
crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...
s, were abundant as representatives of the
meiobenthos Meiobenthos, also called meiofauna, are small benthic invertebrates that live in marine or freshwater environments, or both. The term ''meiofauna'' loosely defines a group of organisms by their sizelarger than microfauna but smaller than macr ...
; genera included ''Amphissites'', ''Bairdia'', ''Beyrichiopsis'', ''Cavellina'', ''Coryellina'', ''Cribroconcha'', ''Hollinella'', ''Kirkbya'', ''Knoxiella'', and ''Libumella''.
Crinoid Crinoids are marine invertebrates that make up the class Crinoidea. Crinoids that remain attached to the sea floor by a stalk in their adult form are commonly called sea lilies, while the unstalked forms, called feather stars or comatulids, are ...
s were highly numerous during the Carboniferous, though they suffered a gradual decline in diversity during the Middle Mississippian. Dense submarine thickets of long-stemmed crinoids appear to have flourished in shallow seas, and their remains were consolidated into thick beds of rock. Prominent genera include ''Cyathocrinus'', ''Woodocrinus'', and ''Actinocrinus''. Echinoids such as '' Archaeocidaris'' and ''Palaeechinus'' were also present. The
blastoid Blastoids (class Blastoidea) are an extinct type of stemmed echinoderm, often referred to as sea buds. They first appear, along with many other echinoderm classes, in the Ordovician period, and reached their greatest diversity in the Mississi ...
s, which included the Pentreinitidae and Codasteridae and superficially resembled crinoids in the possession of long stalks attached to the seabed, attain their maximum development at this time. File:Aviculopecten subcardiformis01.JPG, ''Aviculopecten subcardiformis''; a
bivalve Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of aquatic animal, aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed b ...
from the
Logan Formation The Logan Formation is the name given to a Lower Carboniferous (early Osagean) siltstone, sandstone and conglomeratic unit exposed in east-central Ohio and parts of western West Virginia, USA. Stratigraphy and paleoenvironment The Logan Format ...
(lower Carboniferous) of
Wooster, Ohio Wooster ( ) is a city in Wayne County, Ohio, United States, and its county seat. Located in northeastern Ohio, the city lies approximately south-southwest of Cleveland, southwest of Akron and west of Canton. The population was 27,232 at the ...
(external mold) File:LoganFauna011312.jpg, Bivalves (''Aviculopecten'') and brachiopods (''Syringothyris'') in the Logan Formation (lower Carboniferous) in Wooster, Ohio File:Syringothyris01.JPG, ''Syringothyris'' sp.; a spiriferid
brachiopod Brachiopods (), phylum (biology), phylum Brachiopoda, are a phylum of animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear e ...
from the Logan Formation (lower Carboniferous) of Wooster, Ohio (internal mold) File:Palaeophycus01.JPG, ''Palaeophycus'' ichnosp.; a
trace fossil A trace fossil, also called an ichnofossil (; ), is a fossil record of biological activity by lifeforms, but not the preserved remains of the organism itself. Trace fossils contrast with body fossils, which are the fossilized remains of part ...
from the Logan Formation (lower Carboniferous) of Wooster, Ohio File:PlatyceratidMississippian.JPG,
Crinoid Crinoids are marine invertebrates that make up the class Crinoidea. Crinoids that remain attached to the sea floor by a stalk in their adult form are commonly called sea lilies, while the unstalked forms, called feather stars or comatulids, are ...
calyx from the lower Carboniferous of Ohio with a conical platyceratid gastropod (''Palaeocapulus acutirostre'') attached File:Conulariid03.jpg, Conulariid from the lower Carboniferous of Indiana File:Syringoporid.jpg, Tabulate coral (a syringoporid); Boone Limestone (lower Carboniferous) near Hiwasse, Arkansas File:Typhloesus interpretation 2022.jpg, '' Typhloesus'' was a bizarre invertebrate that lived in Montana. It is possibly a mollusk related to gastropods. File:Essexella asherae.JPG, ''Essexella'' was a cnidarian that lived in Northern Illinois. It was long considered a scyphozoan, but is now regarded as a Sea anemone File:Concavicaris georgeorum.png, ''Concavicaris'' was a long lasting genus of thylacocephalan arthropod that lived from the Devonian to the Carboniferous. File:Triproetus bonbon cropped.jpg, ''Triproetus'' was a genus of proetid trilobite, which were the only order that survived the end-Devonian extinction File:Daidal.png, ''Daidal'' was a basal species of Mantis shrimp (stomatopoda) File:Jeletzkya douglassae.jpg, ''Jeletzkya'' was an early genus of Coleoidea, coleoid cephalopod from northern Illinois File:Syllipsimopodi bideni.webp, ''Syllipsimopodi'' was the earliest known Vampyropoda, vampyropod cephalopod, originating from Carboniferous rocks of Montana.


Freshwater and lagoonal invertebrates

Freshwater Carboniferous invertebrates include various
bivalve Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of aquatic animal, aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed b ...
molluscs that lived in brackish or fresh water, such as ''Anthraconaia'', ''Naiadites'', and '' Carbonicola''; diverse
crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...
s such as ''Candona'', ''Carbonita (crustacean), Carbonita'', ''Darwinula'', ''Estheria (crustacean), Estheria'', ''Acanthocaris'', ''Dithyrocaris'', and ''Anthrapalaemon''. The eurypterids were also diverse, and are represented by such genera as ''Adelophthalmus'', ''Megarachne'' (originally misinterpreted as a giant spider, hence its name) and the specialised very large ''Hibbertopterus''. Many of these were amphibious. Frequently a temporary return of marine conditions resulted in marine or brackish water genera such as ''Lingula (genus), Lingula'', ''Orbiculoidea'', and ''Productus'' being found in the thin beds known as marine bands. File:20210116 Megarachne hypothetical reconstruction.png, ''Megarachne'' was a large freshwater eurypterid from South America that was originally misidentified as a spider File:Adelophthalmus irinae.png, ''Adelophthalmus'' was the only genus of Eurypterina, eurypterine eurypterid that survived past the Devonian File:Hibbertopterus scouleri.jpg, Due to its large and compact shell, ''Hibbertopterus'' was one of if not the heaviest eurypterid in the fossil record


Terrestrial invertebrates

Fossil remains of air-breathing insects, Myriapoda, myriapods, and
arachnid Arachnids are arthropods in the Class (biology), class Arachnida () of the subphylum Chelicerata. Arachnida includes, among others, spiders, scorpions, ticks, mites, pseudoscorpions, opiliones, harvestmen, Solifugae, camel spiders, Amblypygi, wh ...
s are known from the Carboniferous. Their diversity when they do appear, however, shows that these arthropods were both well-developed and numerous. Some arthropods grew to large sizes with the up to millipede-like ''
Arthropleura ''Arthropleura'', from Ancient Greek ἄρθρον (''árthron''), meaning "joint", and πλευρά (''pleurá''), meaning "rib", is an extinct genus of massive myriapoda, myriapod that lived in what is now Europe and North America around 344 t ...
'' being the largest-known land invertebrate of all time. In the mid-Mississippian the oldest known Pterygota, winged insects appears, followed by the huge predatory Meganisoptera, Protodonata (griffinflies), which includes ''Meganeura'', a giant dragonfly-like insect and with a wingspan of ca. —the largest flying insect ever to roam the planet. Further groups are the Syntonopterodea (relatives of present-day Ephemeroptera, mayflies), the abundant and often large sap-sucking Palaeodictyopteroidea, the diverse herbivorous Protorthoptera, and numerous Basal (phylogenetics), basal Dictyoptera (ancestors of cockroaches). Many insects have been obtained from the coalfields of Saarbrücken and Commentry, and from the hollow trunks of fossil trees in Nova Scotia. Some British coalfields have yielded good specimens: ''Archaeoptilus'', from the Derbyshire coalfield, had a large wing with preserved part, and some specimens (''Brodia'') still exhibit traces of brilliant wing colors. In the Nova Scotian tree trunks land snails (''Archaeozonites'', ''Dendropupa'') have been found. File:Meganeura.png, The late Carboniferous giant dragonfly-like insect ''Meganeura'' grew to wingspans over . File:20210116 Pulmonoscorpius kirktonensis.png, The gigantic ''
Pulmonoscorpius ''Pulmonoscorpius'' is an extinct genus of scorpion from the Mississippian (Early Carboniferous) of Scotland. It contains a single named species, ''Pulmonoscorpius kirktonensis''. It was one of the largest scorpions to have ever lived, with the ...
'' from the early Carboniferous reached a length of up to . File:Arthropleura Reconstruction.jpg, ''
Arthropleura ''Arthropleura'', from Ancient Greek ἄρθρον (''árthron''), meaning "joint", and πλευρά (''pleurá''), meaning "rib", is an extinct genus of massive myriapoda, myriapod that lived in what is now Europe and North America around 344 t ...
'' was a giant millipede that fed on the Carboniferous plants. At long, it was the largest terrestrial arthropod that ever lived. File:Homaloneura ligeia.jpg, ''Homaloneura'', a palaeodictyopteran insect which have two winglets on thorax in addition to four wings. File:Helenodora inopinata.jpg, Helenodora, ''Helenodora inopinata'', a stem-group onychophoran known from Illinois File:Blattoidae - Fossil.JPG, A roachoid insect found in Carboniferous rocks of France File:20201202 Maiocercus celticus.png, ''Maiocercus'' was a Trigonotarbida, trigonotarbid arachnid that lived in the United Kingdom around 310 million years ago.


Fish

Many fish inhabited the Carboniferous seas; predominantly Elasmobranchs (sharks and their relatives). These included some, like ''Psammodus'', with crushing pavement-like teeth adapted for grinding the shells of brachiopods, crustaceans, and other marine organisms. Other groups of elasmobranchs, like the ctenacanthiformes grew to large sizes, with some genera like ''Saivodus'' reaching around . Other fish had piercing teeth, such as the Symmoriida; some, the petalodonts, had peculiar cycloid cutting teeth. Most of the other cartilaginous fish were marine, but others like the Xenacanthida, and several genera like ''Bandringa'' invaded fresh waters of the coal swamps. Among the Osteichthyes, bony fish, the Palaeonisciformes found in coastal waters also appear to have migrated to rivers. Sarcopterygii, Sarcopterygian fish were also prominent, and one group, the Rhizodonts, reached very large size. Most species of Carboniferous marine fish have been described largely from teeth, fin spines and dermal ossicles, with smaller freshwater fish preserved whole. Freshwater fish were abundant, and include the genera ''Ctenodus'', ''Uronemus'', ''Acanthodes'', ''Cheirodus'', and ''Gyracanthus''. Chondrichthyes (especially Holocephali, holocephalans like the Stethacanthidae, Stethacanthids) underwent a major
evolutionary radiation An evolutionary radiation is an increase in taxonomic diversity that is caused by elevated rates of speciation, that may or may not be associated with an increase in morphological disparity. A significantly large and diverse radiation within ...
during the Carboniferous. It is believed that this evolutionary radiation occurred because the decline of the Placodermi, placoderms at the end of the Devonian caused many Niche (ecology), environmental niches to become unoccupied and allowed new organisms to evolve and fill these niches. As a result of the evolutionary radiation Carboniferous holocephalans assumed a wide variety of bizarre shapes including ''Stethacanthus'' which possessed a flat brush-like dorsal fin with a patch of Dermal denticle, denticles on its top. ''Stethacanthus'' unusual fin may have been used in mating rituals. Other groups like the Eugeneodontida, eugeneodonts filled in the niches left by large predatory placoderms. These fish were unique as they only possessed one, at most two, rows of teeth in either their upper or lower jaws in the form of elaborate tooth whorls. The first members of the helicoprionidae, a family eugeneodonts that were characterized by the presence of one circular tooth whorl in the lower jaw, appeared during the early Carboniferous. Perhaps the most bizarre radiation of holocephalans at this time was that of the iniopterygiformes, an order of holocephalans that greatly resembled modern day flying fish that could have also "flown" in the water with their massive, elongated pectoral fins. They were further characterized by their large eye sockets, club-like structures on their tails, and spines on the tips of their fins. File:Stethacanthus BW.jpg, ''Akmonistion'' of the Holocephali order Symmoriida roamed the oceans of the early Carboniferous. File:Falcatus.jpg, ''Falcatus'' was a Carboniferous holocephalan, with a high degree of sexual dimorphism. File:Dracopristis hoffmanorum.png, ''Dracopristis'' was a Ctenacanthiformes, Ctenacanthiform Elasmobranchii, elasmobranch from the late Carboniferous of New Mexico. File:Ornithoprion.png, ''Ornithoprion'' was a small-sized Eugeneodontida, Eugeneodont holocephalan that had an elongated lower jaw. File:Allenypterus montanus (Restoration) (cropped).jpg, ''Allenypterus'' was a Coelacanth fish known from the Bear Gulch Limestone in Montana. File:†Phanerosteon phonax Carboniferous Bear Gulch.jpg, ''Phanerosteon'' was a Osteichthyes, Bony fish belonging to the extinct order Palaeonisciformes. File:Edestus recon.png, ''Edestus'' was a large Eugeneodontida, eugeneodontid fish that possessed two tooth whorls in its mouth File:Rhizodus.jpg, ''Rhizodus'' was a large freshwater Rhizodontida, Rhizodont Sarcopterygii, sarcopterygian from Europe and North America. File:Squatinactis NT small.jpg, ''Squatinactis'', a genus of elasmobranch fish from Montana that possessed enlarged pectoral fins similar to modern Angelshark, angel sharks File:Bandringa SW.png, ''Bandringa'' is a bizarre elasmobranch fish that lived in Illinois, Ohio and Pennsylvania during the
Moscovian Moscovian may refer to: *An inhabitant of Moscow, the capital of Russia *Something of, from, or related to Moscow *Moscovian (Carboniferous) The Moscovian is in the International Commission on Stratigraphy, ICS geologic timescale a stage (strat ...
stage. It superficially resembled a paddlefish, with an elongated upper Rostrum (anatomy), rostrum. File:Iniopteryx sp.png, ''Iniopteryx'' was a holocephalan that lived in North America. This fish belonged to a group called the Iniopterygiformes, that possibly lived like flying fish. File:Strigilodus tollesonae-novataxa 2023-Hodnett Toomey Olson.jpg, Restoration of ''Strigilodus tollesonae, Strigilodus'', a Petalodontiformes, petalodont holocephalan from the upper Carboniferous of Kentucky.


Tetrapods

Carboniferous
amphibian Amphibians are ectothermic, anamniote, anamniotic, tetrapod, four-limbed vertebrate animals that constitute the class (biology), class Amphibia. In its broadest sense, it is a paraphyletic group encompassing all Tetrapod, tetrapods, but excl ...
s were diverse and common by the middle of the period, more so than they are today; some were as long as 6 meters, and those fully terrestrial as adults had scaly skin. They included basal tetrapod groups classified in early books under the Labyrinthodontia. These had a long body, a head covered with bony plates, and generally weak or undeveloped limbs. The largest were over 2 meters long. They were accompanied by an assemblage of smaller amphibians included under the Lepospondyli, often only about long. Some Carboniferous amphibians were aquatic and lived in rivers (''Loxomma'', ''Eogyrinus'', ''Proterogyrinus''); others may have been semi-aquatic (''Ophiderpeton'', ''Amphibamus'', ''Hyloplesion'') or terrestrial (''Dendrerpeton'', ''Tuditanus'', ''Anthracosaurus''). The Carboniferous rainforest collapse slowed the evolution of amphibians who could not survive as well in the cooler, drier conditions. Amniotes, however, prospered because of specific key adaptations. One of the greatest evolutionary innovations of the Carboniferous was the amniote egg, which allowed the laying of eggs in a dry environment, as well as keratinized scales and claws, allowing for the further exploitation of the land by certain
tetrapod A tetrapod (; from Ancient Greek :wiktionary:τετρα-#Ancient Greek, τετρα- ''(tetra-)'' 'four' and :wiktionary:πούς#Ancient Greek, πούς ''(poús)'' 'foot') is any four-Limb (anatomy), limbed vertebrate animal of the clade Tetr ...
s. These included the earliest Sauropsida, sauropsid reptiles (''Hylonomus''), and the earliest known
synapsid Synapsida is a diverse group of tetrapod vertebrates that includes all mammals and their extinct relatives. It is one of the two major clades of the group Amniota, the other being the more diverse group Sauropsida (which includes all extant rept ...
(''Archaeothyris''). Synapsids quickly became huge and diversified in the Permian, only for their dominance to stop during the Mesozoic. Sauropsids (reptiles, and also, later, birds) also diversified but remained small until the Mesozoic, during which they dominated the land, as well as the water and sky, only for their dominance to stop during the Cenozoic. Reptiles underwent a major evolutionary radiation in response to the drier climate that preceded the rainforest collapse. By the end of the Carboniferous amniotes had already diversified into a number of groups, including several families of synapsid pelycosaurs, Protorothyrididae, protorothyridids, captorhinidae, captorhinids, saurians and Araeoscelidia, araeoscelids. File:Pederpes2223DB.jpg, The
amphibian Amphibians are ectothermic, anamniote, anamniotic, tetrapod, four-limbed vertebrate animals that constitute the class (biology), class Amphibia. In its broadest sense, it is a paraphyletic group encompassing all Tetrapod, tetrapods, but excl ...
-like ''Pederpes'', the most primitive tetrapod found in the Mississippian age, Mississippian, and known from Scotland. File:Hylonomus BW.jpg, ''Hylonomus'', the earliest sauropsid reptile, appeared in the
Pennsylvanian Pennsylvanian may refer to: * A person or thing from Pennsylvania * Pennsylvanian (geology) The Pennsylvanian ( , also known as Upper Carboniferous or Late Carboniferous) is, on the International Commission on Stratigraphy, ICS geologic timesc ...
, and is known from the Joggins Formation in Nova Scotia, and possibly New Brunswick. File:Petrolacosaurus BW.jpg, ''Petrolacosaurus'', the earliest known diapsid reptile, lived during the late Carboniferous. File:Archaeothyris BW.jpg, ''Archaeothyris'' is the oldest known
synapsid Synapsida is a diverse group of tetrapod vertebrates that includes all mammals and their extinct relatives. It is one of the two major clades of the group Amniota, the other being the more diverse group Sauropsida (which includes all extant rept ...
, and is found in rocks from Nova Scotia. File:Coloraderpeton.jpg, ''Coloraderpeton'' was a snake-like aïstopod Tetrapodomorpha, tetrapodomorph from the late Carboniferous of Colorado. File:Crassigyrinus BW.jpg, ''Crassigyrinus'' was a carnivorous stem-tetrapod from the Viséan, early Carboniferous of Scotland. File:Microbrachis pelikani.png, ''Microbrachis'' was a Lepospondyli, lepospondyl amphibian known from the Czech Republic. File:Amphibamus BW.jpg, ''Amphibamus'' was a Dissorophoidea, dissorophoid Temnospondyli, temnospondyl from the late Carboniferous of Illinois.


Fungi

As plants and animals were growing in size and abundance in this time, land fungi diversified further. Marine fungi still occupied the oceans. All modern classes of fungi were present in the late Carboniferous.


Extinction events


Romer's gap

The first 15 million years of the Carboniferous had very limited terrestrial fossils. While it has long been debated whether the gap is a result of fossilisation or relates to an actual event, recent work indicates there was a drop in atmospheric oxygen levels, indicating some sort of ecological collapse. The gap saw the demise of the Devonian fish-like ichthyostegalian labyrinthodonts and the rise of the more advanced
temnospondyl Temnospondyli (from Greek language, Greek τέμνειν, ''temnein'' 'to cut' and σπόνδυλος, ''spondylos'' 'vertebra') or temnospondyls is a diverse ancient order (biology), order of small to giant tetrapods—often considered Labyrinth ...
ian and reptiliomorphan
amphibian Amphibians are ectothermic, anamniote, anamniotic, tetrapod, four-limbed vertebrate animals that constitute the class (biology), class Amphibia. In its broadest sense, it is a paraphyletic group encompassing all Tetrapod, tetrapods, but excl ...
s that so typify the Carboniferous terrestrial vertebrate fauna.


Carboniferous rainforest collapse

Before the end of the Carboniferous, an extinction event occurred. On land this event is referred to as the Carboniferous rainforest collapse. Vast tropical rainforests collapsed suddenly as the climate changed from hot and humid to cool and arid. This was likely caused by intense glaciation and a drop in sea levels. The new climatic conditions were not favorable to the growth of rainforest and the animals within them. Rainforests shrank into isolated islands, surrounded by seasonally dry habitats. Towering lycopsid forests with a heterogeneous mixture of vegetation were replaced by much less diverse tree fern dominated flora. Amphibians, the dominant vertebrates at the time, fared poorly through this event with large losses in biodiversity; reptiles continued to diversify through key adaptations that let them survive in the drier habitat, specifically the hard-shelled egg and scales, both of which retain water better than their amphibian counterparts.


See also

* List of Carboniferous tetrapods * Important Carboniferous Lagerstätten ** Granton Shrimp Bed; 359 mya; Edinburgh, Scotland ** East Kirkton Quarry; c. 350 mya; Bathgate, Scotland ** Bear Gulch Limestone; 324 mya; Montana, US ** Mazon Creek; 309 mya; Illinois, US ** Hamilton Quarry; 300 mya; Kansas, US * List of fossil sites


References


Sources

* * * * * * * * * * * * * * * * * * * * * * * * * * *Rainer Zangerl and Gerard Ramon Case: ''Iniopterygia: a new order of Chondrichthyan fishes from the Pennsylvanian of North America.'' Fieldiana Geology Memoirs, v. 6, Field Museum of Natural History, 197
Biodiversity Heritage Library
(Volltext, engl.) * * * * * *


External links

*
60+ images of Carboniferous Foraminifera
{{Authority control Carboniferous, Geological periods