Ichthyostegalia
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Ichthyostegalia
Ichthyostegalia is an order of extinct amphibians, representing the earliest landliving vertebrates. The group is thus an evolutionary grade rather than a clade. While the group are recognized as having feet rather than fins, most, if not all, had internal gills in adulthood and lived primarily as shallow water fish and spent minimal time on land. The group evolved from elpistostegalian fish in the late Devonian, or possibly in the middle Devonian. They continued to thrive as denizens of swampland and tidal channels throughout the period. They gave rise to the Temnospondyli and then disappeared during the transition to the Carboniferous. Classification *Ichthyostegalia ** Acanthostegidae ***''Acanthostega'' ** Crassigyrinidae ***''Crassigyrinus'' ** Densignathidae ***''Densignathus'' ** Elginerpetontidae ***'' Elginerpeton'' ***'' Obruchevichthys'' ** Ichthyostegidae ***'' Hynerpeton'' ***''Ichthyostega'' ** Jakubsonidae ***'' Jakubsonia'' ** Metaxygnathidae ***''Metaxygnathu ...
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Metaxygnathus
''Metaxygnathus'' is an extinct genus of ichthyostegalian found in Late Devonian deposits of New South Wales, Australia . It is known only from a lower jawbone. Previously thought to be a lobe-finned fish, it has now been reassigned to the earliest group of tetrapod Tetrapods (; ) are four-limbed vertebrate animals constituting the superclass Tetrapoda (). It includes extant and extinct amphibians, sauropsids ( reptiles, including dinosaurs and therefore birds) and synapsids ( pelycosaurs, extinct t ...s. References *Campbell, K.S.W. and M.W. Bell. 1977. "A primitive amphibian from the Late Devonian of New South Wales." Alcheringa 1: 369–382. External links ''Metaxygnathus denticulatus''at Devonian Times Ichthyostegalia Prehistoric amphibians of Australia Paleozoic vertebrates of Oceania Paleozoic animals of Australia Late Devonian animals Devonian Oceania Fossil taxa described in 1977 Prehistoric tetrapod genera Fauna of New South Wales { ...
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Carboniferous
The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carboniferous'' means "coal-bearing", from the Latin '' carbō'' ("coal") and '' ferō'' ("bear, carry"), and refers to the many coal beds formed globally during that time. The first of the modern 'system' names, it was coined by geologists William Conybeare and William Phillips in 1822, based on a study of the British rock succession. The Carboniferous is often treated in North America as two geological periods, the earlier Mississippian and the later Pennsylvanian. Terrestrial animal life was well established by the Carboniferous Period. Tetrapods (four limbed vertebrates), which had originated from lobe-finned fish during the preceding Devonian, became pentadactylous in and diversified during the Carboniferous, including early amphibian lin ...
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Genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus. :E.g. ''Panthera leo'' (lion) and ''Panthera onca'' (jaguar) are two species within the genus '' Panthera''. ''Panthera'' is a genus within the family Felidae. The composition of a genus is determined by taxonomists. The standards for genus classification are not strictly codified, so different authorities often produce different classifications for genera. There are some general practices used, however, including the idea that a newly defined genus should fulfill these three criteria to be descriptively useful: # monophyly – all descendants of an ancestral taxon are grouped together (i.e. phylogenetic analysis should clea ...
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Acanthostega
''Acanthostega'' (meaning "spiny roof") is an extinct genus of stem-tetrapod, among the first vertebrate animals to have recognizable limbs. It appeared in the late Devonian period (Famennian age) about 365 million years ago, and was anatomically intermediate between lobe-finned fishes and those that were fully capable of coming onto land.


Description

The ''Acanthostega'' Polydactyly in stem-tetrapods, had eight digits on each han ...
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Jakubsonia
''Jakubsonia'' is an extinct genus of early tetrapod from the Late Devonian of Russia. The type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specim ..., ''Jakubsonia livnensis'', was described and named in 2004. References Prehistoric tetrapod genera Devonian tetrapods Ichthyostegalia Prehistoric tetrapods of Asia Basal tetrapods of Europe Fossil taxa described in 2004 Extinct animals of Russia {{Devonian-animal-stub ...
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Hynerpeton
''Hynerpeton'' ( ) is an extinct genus of early four-limbed vertebrate that lived in the rivers and ponds of Pennsylvania during the Late Devonian period, around 365 to 363 million years ago. The only known species of ''Hynerpeton'' is ''H. bassetti'', named after the describer's grandfather, city planner Edward Bassett. ''Hynerpeton'' is known for being the first Devonian four-limbed vertebrate discovered in the United States, as well as possibly being one of the first to have lost internal (fish-like) gills. This genus is known from few remains discovered at the Red Hill fossil site in Hyner, Pennsylvania. The most notable fossil is a large endochondral shoulder girdle consisting of the cleithrum, scapula, and coracoid (but not the interclavicle and clavicles), all connected into one shoulder bone. The inner surface of this shoulder bone possesses an array of depressions believed to have been attachment points for a unique set of powerful muscles around the chest. This may have ...
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Ichthyostegidae
''Ichthyostega'' (from el, ἰχθῦς , 'fish' and el, στέγη , 'roof') is an extinct genus of limbed tetrapodomorphs from the Late Devonian of Greenland. It was among the earliest four-limbed vertebrates in the fossil record, and was one of the first with weight-bearing adaptations for terrestrial locomotion. ''Ichthyostega'' possessed lungs and limbs that helped it navigate through shallow water in swamps. Although ''Ichthyostega'' is often labelled a 'tetrapod' due to the possession of limbs and fingers, it evolved long before true crown group tetrapods, and could more accurately be referred to as a stegocephalian or stem tetrapod. Likewise, while undoubtedly of amphibian build and habit, it is not considered a true member of the group in the narrow sense, as the first modern amphibians (members of the group Lissamphibia) appeared in the Triassic Period. Until finds of other early stegocephalians and closely related fishes in the late 20th century, ''Ichthyostega'' st ...
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Obruchevichthys
''Obruchevichthys'' is an extinct genus of tetrapod from Latvia during the Late Devonian. When the jawbone, the only known fossil of this creature, was uncovered in Latvia, it was mistaken as a lobe-fin fish. However, when it was analyzed, it proved to hold many similarities to ''Elginerpeton'', from Scotland. It was then declared belonging to the earliest group of tetrapod Tetrapods (; ) are four-limbed vertebrate animals constituting the superclass Tetrapoda (). It includes extant and extinct amphibians, sauropsids ( reptiles, including dinosaurs and therefore birds) and synapsids ( pelycosaurs, extinct t ...s. References External links ''Devonian Times'' article on ''Obruchevichthys gracilis'' Further reading * ''Gaining Ground: The Origin and Early Evolution of Tetrapods'' by Jennifer A. Clack * ''Origins of the Higher Groups of Tetrapods: Controversy and Consensus'' by Hans-Peter Schultze and Linda Trueb * ''Air-Breathing Fishes: Evolution, Diversity, and Ada ...
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Elginerpeton
''Elginerpeton'' is a genus of stegocephalian (stem-tetrapod), the fossils of which were recovered from Scat Craig, Morayshire in the UK, from rocks dating to the late Devonian Period (Early Famennian stage, 368 million years ago). The only known fossil has been given the name ''Elginerpeton pancheni''. ''Elginerpeton'' is known from skeletal fragments including a partial shoulder and hip, a femur, tibia (lower hind limb), and jaw fragments. The holotype is a lower jaw fragment estimated at 40 centimeters in total length. The total body is estimated to have measured about 1.5 m (5 ft) in length. Upon its description, ''Elginerpeton'' was allied with '' Obruchevichthys'' in the family Elginerpetontidae. A biomechanical analysis of stegocephalian jaws has indicated that ''Elginerpeton'' had an unusual feeding habit among tetrapod relatives. Its jaws were thin, and plotted as the most susceptible to high stresses among the sample group. However, the heavy sculpturing of ...
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Elginerpetontidae
Elginerpetontidae is an extinct family of basal stegocephalian tetrapodomorphs which lived in Europe during the Frasnian stage of the Late Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, wher ... epoch. It contains the genera '' Elginerpeton'', '' Obruchevichthys'' and '' Webererpeton''. References Stegocephalians Prehistoric vertebrate families {{Devonian-animal-stub ...
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