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Elpistostegidae
''Elpistostege'' is an extinct genus of finned tetrapodomorphs that lived during the late Givetian to early Frasnian ages of the Late Devonian epoch. Its only known species, ''E. watsoni'', was first described in 1938 by the British palaeontologist Thomas Stanley Westoll, based on a single partial skull roof discovered at the Escuminac Formation in Quebec, Canada. In 2010, a complete specimen was found in the same formation, which was described by Richard Cloutier and colleagues in 2020. It reveals that the paired fins of ''Elpistostege'' contained bones Homology (biology), homologous to the phalanges (digit bones) of modern tetrapods; it is the most basal (phylogenetics), basal tetrapodomorph known to possess these bones. At the same time, the fins were covered in scales and lepidotrichia (fin rays), which indicates that the origin of phalanges preceded the loss of fin rays, rather than the other way around. Relationships An analysis conducted by Swartz in 2012 found ''Elpistost ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetrapodomorph
The Tetrapodomorpha (also known as Choanata) are 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 forms transitional between fish and the early labyrinthodonts, such as ''Tiktaalik'', have been referred to as "fishapods" by their discoverers, being half-fish, half-tetrapods, in appearance and limb morphology. The Tetrapodomorpha contains the crown group tetrapods (the last common ancestor of living tetrapods and all of its descendants) and several groups of early stem tetrapods, which includes several groups of related lobe-finned fishes, collectively known as the osteolepiforms. The Tetrapodamorpha minus the crown group Tetrapoda are the Stem Tetrapoda, a paraphyletic unit encompassing the fish to tetrapod transition. Among the characteristics defining tetrapodomorphs are modifications to the fins, notably a humerus with convex h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elpistostegalia
Elpistostegalia or Panderichthyida is an order of prehistoric lobe-finned fishes which lived during the Middle Devonian to Late Devonian period (about 385 to 374 million years ago). They represent the advanced tetrapodomorph stock, the fishes more closely related to tetrapods than the osteolepiform fishes. The earliest elpistostegalians, combining fishlike and tetrapod-like characters, are sometimes called fishapods, a phrase coined for the advanced elpistostegalian ''Tiktaalik''. Through a strict cladistic view, the order includes the terrestrial tetrapods. Palaeobiology of the elpistostegalians A rise in global oxygen content allowed for the evolution of large, predatory fish that were able to exploit the shallow tidal areas and swamplands as top predators. Several groups evolved to fill these niches, the most successful were the elpistiostegalians. In such environments, they would have been challenged by periodic oxygen deficiency. In comparable modern aquatic environments ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thomas Stanley Westoll
Prof Thomas Stanley Westoll, FRS FRSE, FGS FLS LLD (3 July 1912 – 19 September 1995) was a British geologist, and the long-time head of the Department of Geology at Newcastle University. Education and career He was born in West Hartlepool the son of Horace Stanley Raine Westoll. He was educated at the West Hartlepool Grammar School. He then studied Sciences on a scholarship at Durham University, specialising in geology and palaeontology, graduating BSc in 1932. Continuing as a postgraduate he gained his first doctorate (PhD) in 1934 from research on Permian fishes. In 1937 he began lecturing in Geology and Mineralogy at Aberdeen University, his central interest being the study of fossil fish. In 1943 he was elected a Fellow of the Royal Society of Edinburgh. His proposers were Robert MacFarlane Neill, Thomas Phemister, Ernest Cruickshank, and James Robert Matthews. Aberdeen University awarded him his second doctorate (DSc). In 1948 he left Aberdeen to return to England as P ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stegocephalia
Stegocephali (often spelled Stegocephalia) is a group containing all four-limbed vertebrates. It is equivalent to a broad definition of Tetrapoda: under this broad definition, the term "tetrapod" applies to any animal descended from the first vertebrate with limbs and toes, rather than fins. This includes both the modern lineage of limbed vertebrates (the crown group, including modern amphibians, mammals, reptiles and birds) as well as a portion of the stem group, limbed vertebrates that evolved prior to the origin of the crown group. Members of the tetrapod stem group include the earliest limbed tetrapodomorphs such as '' Ichthyostega'' and '' Acanthostega,'' which evolved in the Devonian Period long before any modern form of tetrapod. Many paleontologists prefer a stricter definition of Tetrapoda which applies solely to the crown group, excluding earlier types of limbed tetrapodomorphs. Stegocephali was re-established to replace the broad definition of Tetrapoda, resolving th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pederpes22small
''Pederpes'' ("Peter's Foot") is an extinct genus of early Carboniferous tetrapod, dating from 348 to 347.6 Ma in the Tournaisian age (lower Mississippian). ''Pederpes'' contains one species, ''P. finneyae'', 1 m long. This most basal Carboniferous tetrapod had a large, somewhat triangular head, similar to that of later American sister-genus ''Whatcheeria'', from which it is distinguished by various skeletal features, such as a spike-like latissimus dorsi (an arm muscle) attachment on the humerus and several minor skull features. The feet had characteristics that distinguished it from the paddle-like feet of the Devonian Ichthyostegalia and resembled the feet of later, more terrestrially adapted Carboniferous forms. ''Pederpes'' is the earliest-known tetrapod to show the beginnings of terrestrial locomotion and despite the probable presence of a sixth digit on the forelimbs it was at least functionally pentadactyl. Discovery and classification ''Pederpes'' was discovered in 19 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Whatcheeriidae
Whatcheeriidae is an extinct family of tetrapods which lived in the Mississippian sub-period, a subdivision of the Carboniferous period. It contains the genera ''Pederpes'', '' Whatcheeria'', and possibly '' Ossinodus''. Fossils of a possible whatcheeriid have been found from the Red Hill locality of Pennsylvania. If these remains are from a whatcheeriid, they extend the range of the family into the Late Devonian and suggest that advanced tetrapods may have lived alongside primitive tetrapod ancestors like ''Hynerpeton'' and ''Densignathus''. They also imply that a very long ghost lineage of whatcheeriids lived through Romer's gap, a period during the Early Carboniferous conspicuously lacking in tetrapod remains. Classification Currently, using modern cladistic taxonomy, Whatcheeriidae is not placed in Amphibia Amphibians are tetrapod, four-limbed and ectothermic vertebrates of the Class (biology), class Amphibia. All living amphibians belong to the group Lissamphibi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ichthyostega BW
''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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ichthyostega
''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'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acanthostega BW
''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 ...
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Ventastega
''Ventastega'' (''Venta'' referring to the Venta River at the Ketleri Formation where ''Ventastega'' was discovered) is an extinct genus of stem tetrapod that lived during the Upper Fammenian of the Late Devonian, approximately 372.2 to 358.9 million years ago. Only one species is known that belongs in the genus, ''Ventastega curonica,'' which was described in 1996 after fossils were discovered in 1933 and mistakenly associated with a fish called ''Polyplocodus wenjukovi''. ‘Curonica’ in the species name refers to Curonia, the Latin name for Kurzeme, a region in western Latvia. ''Ventastega curonica'' was discovered in two localities in Latvia, and was the first stem tetrapod described in Latvia along with being only the 4th Devonian tetrapodomorph known at the time of description. Based on the morphology of both cranial and post-cranial elements discovered (see below), ''Ventastega'' is more primitive than other Devonian tetrapodomorphs including ''Acanthostega'' and ''Icht ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elginerpeton BW
''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 th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
