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were introduced in this important and well-known time period. SUBDIVISIONS The Carboniferous is usually broken into Pennsylvanian (later) and Mississippian (earlier) Epochs. The Faunal Stage s from youngest to oldest, together with some of their subdivisions, are: Late Pennsylvanian Gzhelian (most recent)
Late Pennsylvanian Kasimovian
Middle Pennsylvanian Moscovian
Early Pennsylvanian Bashkirian/Morrowan
Late Mississippian Serpukhovian
Middle Mississippian Visean
Early Mississippian Tournaisian (oldest)
PALEOGEOGRAPHY The southern Continent s remained tied together in the Supercontinent Gondwana , which collided with North America-Europe ( Laurussia ) along the present line of eastern North America. In the same time frame, much of present eastern Eurasian Plate welded itself to Europe along the line of the Ural Mountains . Most of the Mesozoic supercontinent of Pangea was now assembled, although pieces of present east Asia still remained detached. ROCKS AND COAL Carboniferous rocks in Europe and eastern North America largely consist of a repeated sequence of Limestone , Sandstone , Shale and coal beds. In North America, the early Carboniferous is largely marine limestone, which accounts for the division of the Carboniferous into two periods in North American schemes. The Carboniferous coal beds provided much of the fuel for power generation during the Industrial Revolution and are still of great economic importance. The large coal deposits of the Carboniferous primarily owe their existence to two factors. The first of these is the appearance of Bark -bearing trees (and in particular the Evolution of the bark fiber Lignin ). The second is the lower sea levels that occurred during the Carboniferous as compared to the Devonian period. This allowed for the development of extensive lowland Swamp s and Forest s in North America and Europe. It has been hypothesized that large quantities of Wood were buried during this period because animals and decomposing Bacteria had not yet Evolved that could effectively digest the new lignin. It has also been observed that the extensive burial of organically produced Carbon led to a buildup of surplus Oxygen in the atmosphere resulting in concentrations up to 80% higher than today. The oxygen increase is implicated in increased Wildfire activity, as well as the expression of gigantism in certain Insect s and Amphibia ns, whose size is constrained by Respiratory systems that are limited in their ability to diffuse oxygen. In eastern North America, marine beds are more common in the older part of the period than the later part and are almost entirely absent by the late Carboniferous. More diverse geology existed elsewhere, of course. Marine life is especially rich in Crinoids and other Echinoderms . Brachiopods were abundant. Trilobites became quite uncommon. On land, large and diverse Plant populations existed. Land Vertebrates included large amphibians. LIFE Marine Invertebrates In the oceans the most important groups are the Foraminifera , Corals , Bryozoa , Brachiopod s, Ammonoid s, Echinoderm s (especially Crinoid s), and Chondrichthyes (sharks and their relatives). For the first time foraminifera take 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. The microscopic shells of Radiolaria are found in Chert s of this age in The Culm of Devonshire and Cornwall , and in Russia, Germany and elsewhere. Sponges are known from Spicule s and anchor ropes, and include various forms such as the Calcispongea '' Cotyliscus '' and '' Girtycoelia '', and the unusual colonial Glass Sponge '' Titusvillia ''. Both Reef -building and solitary corals diversify and flourish; these include both Rugose (e.g. '' Canina '', '' Corwenia '', '' Neozaphrentis ''), Heterocorals , and Tabulate (e.g. '' Chaetetes '', '' Chladochonus '', '' Michelinia '') forms. Conularids were well represented by '' Conularia '' Bryozoa are abundant in some regions; the Fenestellids including '' Fenestella '', '' Polypora '', and the remarkable '' Archimedes '', so named becasuse it is in the shape of an Archimedean Screw . Brachiopod s are also abundant; they include Productids , some of which (e.g. '' Gigantoproductus '') reached very large (for brachiopods) size and had very thick shells, while others like '' Chonetes '' were more conservative in form. Athyridids , Spiriferids , Rhynchonellids , are Terebratulids are also very common. Inarticulate forms include '' Discina '' and '' Crania ''. Some species and genera had a very wide distribution with only minor variations. Annelid s such as '' Spirorbis '' and '' Serpulites '' are common fossils in some horizons. Among the mollusca, the Bivalve s continue to increase in numbers and importance. Typical genera include '' Aviculopecten '', '' Posidonomya '', '' Nucula '', '' Carbonicola '', '' Edmondia '', and '' Modiola '' '' Conocardium '' is a common Rostoconch . Gastropod s are also numerous, including the genera '' Murchisonia '', '' Euomphalus '', '' Naticopsis ''. Nautiloid Cephalopod s are represented by tightly coiled Nautilids , with straight-shelled and curved-shelled forms becoming increasingly rare. Goniatite Ammonoids are common. Trilobite s are rare, represented only by the proetid group. Ostracod s such as '' Cythere '', '' Kirkbya '', and '' Beyrichia '' are abundant. Amongst the Echinoderm s, the Crinoid s were the most numerous. 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 s, which included the Pentreinitidae and Codasteridae and superficially resembled crinoids in the possession of long stalks attached to the sea-bed, attain their maximum development at this time. Fish Many fish inhabited the Carboniferous seas; predominantly Elasmobranch s, sharks with crushing pavement-like teeth ('' Psammodus ''), adapted for grinding the shells of brachiopods, crustaceans, and other marine organisms. Other sharks had piercing teeth, such as the Symmoriida ; some, the Petalodont s, had peculiar cycloid cutting teeth. Most of the sharks were marine, but the Xenacanthida invaded fresh waters of the coal swamps. Among the Bony Fish , the Palaeonisciformes found in coastal waters also appear to have migrated to rivers. Sarcopterygia n fish were also prominent, and one group, the Rhizodont s, 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 fishes were abundant, and include the genera '' Ctenodus '', '' Uronemus '', '' Acanthodes '', '' Cheirodus '', and '' Gyracanthus ''. Plants Early Carboniferous land plants were very similar to those of the preceding Latest Devonian, but new groups also appeared at this time. The main Early Carboniferous plants were the Equisetales (Horse-tails), Sphenophyllales (vine-like plants), Lycopodiales (Club mosses), Lepidodendrales (scale trees), Filicales (Ferns), Medullosales (previously included in the " Seed Ferns ", an artificial assemblage of a number of early Gymnosperm groups) and the Cordaitales . These continued to dominate throughout the period, but during Late Carboniferous , several other groups, Cycadophyta (cycads), the Callistophytales (another group of "seed ferns"), and the Voltziales (related to and sometimes included under the Conifers ), 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 '' (with its fruit cone called '' Lepidostrobus ''), '' Halonia '', '' Lepidophloios '' and '' Sigillaria ''. The roots of several of these forms are known as '' Stigmaria ''. The fronds of some Carboniferous ferns are almost identical with those of living species. Probably many species were epiphytic. Fossil ferns and "seed ferns" include '' Pecopteris '', '' Cyclopteris '', '' Neuropteris '', '' Alethopteris '', and '' Sphenopteris ''; '' Megaphyton '' and '' Caulopteris '' were tree ferns. The Equisetales included the common giant form '' Calamites '', with a trunk diameter of 30 to 60 cm and a height of up to 20 meters. '' Sphenophyllum '' was a slender climbing plant with whorls of leaves, which was probably related both to the calamites and the lycopods. '' Cordaites '', a tall plant (6 to over 30 meters) with strap-like leaves, was related to the cycads and conifers; the Catkin -like inflorescence, which bore yew-like berries, is called '' Cardiocarpus ''. These plants were thought to live in swamps and mangroves. True coniferous trees ('' Waichia '', of the order Voltziales) appear later in the Carboniferous, and preferred higher drier ground.. Freshwater and Lagoonal Invertebrates Freshwater Carboniferous invertebrates include various Bivalve Mollusc s that lived in brackish or fresh water, such as '' Anthracomya '', '' Naiadiles '', and '' Carbonicola ''; diverse Crustacea such as '' Bairdia '', '' Carbonia '', '' Estheria '', '' Acanthocaris '', '' Dithyrocaris '', and '' Anthrapalaemon ''. The Eurypterid s were also diverse, and are represented by such genera as '' Eurypterus '', '' Glyptoscorpius '', '' Anthraconectes '', '' Megarachne '' (originally misinterpreted as a giant spider) amd 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 '', Orbiculoidea , and '' Productus '' being found in the thin beds known as marine bands. Terrestrial Invertebrates Fossil remains of air-breathing '', from the Derbyshire coalfield, had a spread of wing extending to more 35 cm; some specimens ('' Brodia '') still exhibit traces of brilliant wing colors. In the Nova Scotian tree trunks land snails ('' Archaeozonites '', '' Dendropupa '') have been found. Tetrapods Carboniferous Amphibian s were diverse and common by the middle of the period. They included a number of Basal tetrapod groups classified in early books under the Labyrinthodont ia. These had long bodies, a head covered with bony plates and 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 15 cm long. Some were aquatic and lived in rivers ('' Loxomma '', '' Eogyrinus '', '' Proterogyrinus ''); others may have been semi-aquatic ('' Ophiderpeton '', '' Amphibamus '') or terrestrial ('' Dendrerpeton '', '' Hyloplesion '', '' Tuditanus '', '' Anthracosaurus ''). One of the greatest evolutionary innovations of the Carboniferous was the Amniote egg, which allowed for the further exploitation of the land by certain Tetrapod s. These included the earliest Sauropsid reptiles ('' Hylonomus ''), and the earliest known Synapsida ('' Archaeothyris ''). These small lizard-like animals quickly gave rise to many descendants. The amniote egg allowed these ancestors of all later Bird s, Mammal s, and Reptile s to reproduce on land by preventing the desiccation, or drying-out, of the Embryo inside. SEE ALSO
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