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Marmorerpeton Histology
''Marmorerpeton'' is an extinct genus of prehistoric stem group- salamanders that lived in Britain during the Bathonian stage of the Middle Jurassic. They are among the oldest known salamanders. Two species were named when the genus was first described by Susan E. Evans et al. in 1988, ''M''. ''freemani'', and ''M''. ''kermacki'', from fragmentary remains found via screenwashing in the Forest Marble Formation of England. Due to the size of their osteocytic lacunae suggesting a large genome size and some morphological characters, like the presence of calcified cartilage in the medulla of its humerus, it was assumed that ''Marmorerpeton'' was neotenic. New more complete remains of a new species ''M. wakei'' were described in 2022 from the Kilmaluag Formation of the Isle of Skye, Scotland. These conclusively demonstrated that ''Marmorerpeton'' was neotenic, and was a member of the family Karauridae, with the other two members of the family, ''Karaurus'' and '' Kokartus'' bein ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Middle Jurassic
The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from about 174.1 to 163.5 million years ago. Fossils of land-dwelling animals, such as dinosaurs, from the Middle Jurassic are relatively rare, but geological formations containing land animal fossils include the Forest Marble Formation in England, the Kilmaluag Formation in Scotland,British Geological Survey. 2011Stratigraphic framework for the Middle Jurassic strata of Great Britain and the adjoining continental shelf: research report RR/11/06 British Geological Survey, Keyworth, Nottingham. the Daohugou Beds in China, the Itat Formation in Russia, and the Isalo III Formation of western Madagascar. Paleogeography During the Middle Jurassic Epoch, Pangaea began to separate into Laurasia and Gondwana, and the Atlantic Ocean formed. Eastern Laurasia was tectonically active as the Cimmerian plate continued to collide with Laurasia's southern coast, completely closing the Paleo-Tethys Ocean. A subduction zone ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kilmaluag Formation
The Kilmaluag Formation is a Middle Jurassic geologic formation in Scotland. It was formerly known as the Ostracod Limestone for the abundance of fossil freshwater ostracods within it. The Kilmaluag Formation is very fossiliferous, with ostracods, gastropods, bivalves, trace fossil burrows, and vertebrate fossil remains. Vertebrate fossils include fish, crocodylomorphs, mammals, small reptiles, amphibians and some large reptile remains including dinosaurs and pterosaurs.Panciroli E, RBJ Benson, S Walsh, RJ Butler, TA Castro, MEH Jones, SE. Evans. 2020Diverse vertebrate assemblage of the Kilmaluag Formation (Bathonian, Middle Jurassic) of Skye, Scotland Earth and Environmental Transactions of the Royal Society of Edinburgh nline1-22 Geology The Kilmaluag Formation is Bathonian, and dates to around 167 million years old. It is part of the Great Estuarine Group of the Hebrides Basin, a series of sediments laid down as the land rose and fell in the area running between what is now ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jurassic Amphibians Of Europe
The Jurassic ( ) is a geologic period and stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The Jurassic constitutes the middle period of the Mesozoic Era and is named after the Jura Mountains, where limestone strata from the period were first identified. The start of the Jurassic was marked by the major Triassic–Jurassic extinction event, associated with the eruption of the Central Atlantic Magmatic Province. The beginning of the Toarcian Stage started around 183 million years ago and is marked by an extinction event associated with widespread oceanic anoxia, ocean acidification, and elevated temperatures likely caused by the eruption of the Karoo-Ferrar large igneous provinces. The end of the Jurassic, however, has no clear boundary with the Cretaceous and is the only boundary between geological periods to remain formally undefined. By the beginning of the Jurassic, t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Marmorerpeton Histology
''Marmorerpeton'' is an extinct genus of prehistoric stem group- salamanders that lived in Britain during the Bathonian stage of the Middle Jurassic. They are among the oldest known salamanders. Two species were named when the genus was first described by Susan E. Evans et al. in 1988, ''M''. ''freemani'', and ''M''. ''kermacki'', from fragmentary remains found via screenwashing in the Forest Marble Formation of England. Due to the size of their osteocytic lacunae suggesting a large genome size and some morphological characters, like the presence of calcified cartilage in the medulla of its humerus, it was assumed that ''Marmorerpeton'' was neotenic. New more complete remains of a new species ''M. wakei'' were described in 2022 from the Kilmaluag Formation of the Isle of Skye, Scotland. These conclusively demonstrated that ''Marmorerpeton'' was neotenic, and was a member of the family Karauridae, with the other two members of the family, ''Karaurus'' and '' Kokartus'' bein ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pedicellate Teeth
Pedicellate teeth are a tooth morphology today unique to modern amphibians, but also seen in a variety of extinct labyrinthodonts. Pedicellate teeth consist of a tooth crown and a base (both composed of dentine) separated by a layer of uncalcified dentine. Further reading * * External links * http://palaeo.gly.bris.ac.uk/Palaeofiles/Fossilgroups/Amphibia/characters.html Amphibian anatomy {{amphibian-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kokartus
''Kokartus'' is an extinct genus of prehistoric stem-group salamander (Caudata) from the Middle Jurassic Balabansai Formation of Kyrgyzstan. The absence of clear lines of arrested growth and annuli in long bones suggests that the animals lived in an environment with stable local conditions. Like other members of Karauridae, it is thought to have been neotenic. ''Kokartus'' is thought to have fed using suction feeding via the enlargement of the buccal cavity on small fish and invertebrates, with the well developed palatal dentition (teeth on the roof of the mouth) and marginal teeth helping to grasp prey. See also * Prehistoric amphibian * List of prehistoric amphibians This list of prehistoric amphibians is an attempt to create a comprehensive listing of all genera from the fossil record that have ever been considered to be amphibians, excluding purely vernacular terms. The list includes all commonly accepted g ... References Prehistoric salamanders Middle Jurassic amp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Karaurus
''Karaurus'' (meaning ''head-tail'') is an extinct genus of stem-group salamander (Caudata) from the Middle to Late Jurassic (Callovian–Kimmeridgian) Karabastau Formation of Kazakhstan. It is one of the oldest salamanders known. ''Karaurus'' was large for a Jurassic salamander, about long, and very similar anatomically to modern salamanders. ''Karaurus'' is thought to have fed using suction feeding via the enlargement of the buccal cavity on small fish and invertebrates, with the well developed palatal dentition (teeth on the roof of the mouth) and marginal teeth helping to grasp prey. ''Karaurus'' is thought to form a clade with ''Kokartus'' from the Middle Jurassic (Bathonian) of Kyrgyzstan, and ''Marmorerpeton'' from the Bathonian of Britain, together forming the Karauridae, which are closely related to crown salamanders. Like other members of Karauridae, ''Karaurus'' is neotenic Neoteny (), also called juvenilization,Montagu, A. (1989). Growing Young. Bergin & Garvey: CT ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Karauridae
The Karauridae are a family of stem-group salamanders (Caudata) that are known from the Middle Jurassic to Late Jurassic in Central Asia (Kazakhstan and Kyrgyzstan) and Western Europe (United Kingdom). The family includes three members: ''Karaurus'' from the Middle-Late Jurassic Karabastau Formation of Kazakhstan, ''Kokartus'' from the Middle Jurassic Balabansai Formation of Kyrgyzstan, and ''Marmorerpeton'' from the Middle Jurassic Forest Marble Formation of England and Kilmaluag Formation of Scotland. The members are some of the oldest known salamanders. The family is united by several morphological characters, including sculptured skull roof bones. Like some modern salamanders, karaurids were neotenic. Members of the family likely fed via suction feeding Aquatic feeding mechanisms face a special difficulty as compared to feeding on land, because the density of water is about the same as that of the prey, so the prey tends to be pushed away when the mouth is closed. This probl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neoteny
Neoteny (), also called juvenilization,Montagu, A. (1989). Growing Young. Bergin & Garvey: CT. is the delaying or slowing of the physiological, or somatic, development of an organism, typically an animal. Neoteny is found in modern humans compared to other primates. In progenesis or paedogenesis, sexual development is accelerated. Both neoteny and progenesis result in paedomorphism (as having the form typical of children) or paedomorphosis (changing towards forms typical of children), a type of heterochrony. It is the retention in adults of traits previously seen only in the young. Such retention is important in evolutionary biology, domestication and evolutionary developmental biology. Some authors define paedomorphism as the retention of larval traits, as seen in salamanders.Schell, S. C. ''Handbook of Trematodes of North America North of Mexico'', 1985, pg. 22 History and etymology The origins of the concept of neoteny have been traced to the Bible (as argued by Ashley Monta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus comes above species and below family (taxonomy), 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 taxonomy (biology), 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Humerus
The humerus (; ) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of a rounded head, a narrow neck, and two short processes (tubercles, sometimes called tuberosities). The body is cylindrical in its upper portion, and more prismatic below. The lower extremity consists of 2 epicondyles, 2 processes (trochlea & capitulum), and 3 fossae (radial fossa, coronoid fossa, and olecranon fossa). As well as its true anatomical neck, the constriction below the greater and lesser tubercles of the humerus is referred to as its surgical neck due to its tendency to fracture, thus often becoming the focus of surgeons. Etymology The word "humerus" is derived from la, humerus, umerus meaning upper arm, shoulder, and is linguistically related to Gothic ''ams'' shoulder and Greek ''ōmos''. Structure Upper extremity The upper or pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Forest Marble Formation
The Forest Marble is a geological formation in England. Part of the Great Oolite Group, it dates to the late Bathonian stage of the Middle Jurassic.Weishampel, David B; et al. (2004). "Dinosaur distribution (Middle Jurassic, Europe)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 538–541. . Lithology The primary lithology of the formation typically consists of greenish grey variably calcareous silicate mudstone, with lenticular cross bedded limestone units deposited in a marine setting. Dinosaurian fauna Ornithischians Saurischians Microvertebrate fauna Despite the formation being nearly entirely marine, at several localities abundant remains of terrestrial microvertebrates are found, the primary locality being the Kirtlington Mammal Bed (designated 3p) in Kirtlington Quarry near Kirtlington, Oxfordshire. Another important locality is Watton Cliff near Eype in Dorset. Amp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
