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Mesacanthidae
Mesacanthidae is a family of fish that existed during the Devonian in Northwestern Europe. It is part of the order Acanthodiformes Acanthodiformes (alternatively spelled Acanthodida) is an Order (biology), order of "Acanthodii, acanthodians" which lived from the Early Devonian to the Early Permian. Members of the order have been found Cosmopolitan distribution, worldwide in ..., and includes the genera of '' Mesacanthus'', '' Lodeacanthus'', '' Melanacanthus'', '' Teneracanthus'', and '' Promesacanthus''. References Taxa described in 1939 Acanthodiformes Prehistoric fish families {{Acanthodii-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acanthodiformes
Acanthodiformes (alternatively spelled Acanthodida) is an Order (biology), order of "Acanthodii, acanthodians" which lived from the Early Devonian to the Early Permian. Members of the order have been found Cosmopolitan distribution, worldwide in rocks preserving both Freshwater fish, freshwater and Saltwater fish, marine environments, and are distinguished from other acanthodians by the presence of only a single dorsal fin and dorsal fin spine, and in most members a lack of Tooth, teeth and well-developed Gill raker, gill rakers. Some acanthodiforms are presumed to have fed by Filter feeder, filter-feeding, and had large mouths and Branchial arch, gill arches. While they have been suggested to be close relatives of modern Osteichthyes, bony fish due to similarities in their skulls, recent research indicates that, like other acanthodians, they are more likely to be stem-group Chondrichthyes, cartilaginous fish. Classification The order was first established by Soviet Union, Sovie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 period at million years ago (Megaannum, Ma), to the beginning of the succeeding Carboniferous period at Ma. It is the fourth period of both the Paleozoic and the Phanerozoic. It is named after Devon, South West England, where rocks from this period were first studied. The first significant evolutionary radiation of history of life#Colonization of land, life on land occurred during the Devonian, as free-spore, sporing land plants (pteridophytes) began to spread across dry land, forming extensive coal forests which covered the continents. By the middle of the Devonian, several groups of vascular plants had evolved leaf, leaves and true roots, and by the end of the period the first seed-bearing plants (Pteridospermatophyta, pteridospermatophyt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesacanthus
''Mesacanthus'' ('middle spine') is an extinct genus of acanthodian fish from Devonian Scotland. It is among the more primitive of the Devonian acanthodians. Description ''Mesacanthus'' body fossils have pectoral, pelvic, anal and dorsal fin spines, as well as a pair of prepelvic spines, which are intermediate between the pectoral and pelvic fin spines. They also have small, unornamented, diamond shaped scales. According to Agassiz, the genus also has a distinct tail in which the upper lobe extends to a sharp point and the lower lobe forms a small triangle. Overall the genus is small (average length = 30mm) and fairly conservative, anatomically speaking, for acanthodians.Agassiz, L. (1833). Recherches sur les poissons fossiles.. (Vol. 1). chez l'auteur. Taxonomy The genus was erected by Ramsay Traquair in 1888 to accommodate certain species that had been previously assigned to ''Acanthodes'' by Louis Agassiz.Traquair, R. H. (1888). Old Red Sandstone fishes. These species incl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Taxa Described In 1939
In biology, a taxon (back-formation from ''taxonomy''; : taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and given a particular ranking, especially if and when it is accepted or becomes established. It is very common, however, for taxonomists to remain at odds over what belongs to a taxon and the criteria used for inclusion, especially in the context of rank-based (" Linnaean") nomenclature (much less so under phylogenetic nomenclature). If a taxon is given a formal scientific name, its use is then governed by one of the nomenclature codes specifying which scientific name is correct for a particular grouping. Initial attempts at classifying and ordering organisms (plants and animals) were presumably set forth in prehistoric times by hunter-gatherers, as suggested by the fairly sophisticated folk taxonomies. Much later, Aristotle, and later still ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
