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Loganellidae (fish)
Loganelliidae is an extinct family of thelodonts in the order Thelodontiformes. They are distinguished by the star or cross shaped ridges located on their head scales. Morphology The head scales possess cross shaped or star shaped ridges, transitional scales are rhomboidal, and trunk scales are horizontally elongated. The crown is notably posteriorly pointed, with the apex extending beyond the base. The main crown surface is flat and smooth, and can be inclined in either horizontal direction. The base of the crown possesses a short spine which points downwards and anteriorly. Classification The family contains the following genera: * '' Angaralepis'' * '' Illoganellia'' * '' Larolepis'' * ''Loganellia'' * '' Nunavutia'' * '' Sandivia'' * ''Stroinolepis ''Stroinolepis'' is an extinct genus of thelodontid that lived during the Middle Ordovician period in what is now the Severnaya Zemlya archipelago of Russia Russia (, , ), or the Russian Federation, is a List of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thelodont
Thelodonti (from Greek: "feeble teeth")Maisey, John G., Craig Chesek, and David Miller. Discovering fossil fishes. New York: Holt, 1996. is a class of extinct jawless fishes with distinctive scales instead of large plates of armor. There is much debate over whether the group of Palaeozoic fish known as the Thelodonti (formerly coelolepids) represent a monophyletic grouping, or disparate stem groups to the major lines of jawless and jawed fish. Thelodonts are united in possession of "thelodont scales". This defining character is not necessarily a result of shared ancestry, as it may have been evolved independently by different groups. Thus the thelodonts are generally thought to represent a polyphyletic group, although there is no firm agreement on this point. On the basis that they are monophyletic, they are reconstructed as being ancestrally marine and invading freshwater on multiple occasions. "Thelodonts" were morphologically very similar, and probably closely related ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thelodontiformes
Thelodontiformes is an extinct order of jawless fish of the Silurian.Kiaer, J., 1932: New coelolepids from the Upper Silurian on Oesel (Esthonia). Eesti Loodusteaduse Arhiiv, Seeria 1, 10: 167-176. Because the paucity of intact fossils, especially since some families are known entirely from scale fossils, taxonomy of thelodonts is based primarily on scale morphology. A recent assessment of thelodont taxonomy by Wilson and Märss in 2009 merges the orders Loganelliiformes, Katoporiida and Shieliiformes into Thelodontiformes, places families Lanarkiidae and Nikoliviidae into Furcacaudiformes (because of scale morphology) and establishes Archipelepidiformes as the basal-most order.Wilson, Mark VH, and Tiiu Märss. "Thelodont phylogeny revisited, with inclusion of key scale-based taxa." Estonian Journal of Earth Sciences 58.4 (2009): 297œ310/ref> References External links * Thelodonti Silurian jawless fish Prehistoric jawless fish orders Silurian first appeara ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Loganellia
''Loganellia'' is a genus of jawless fish which lived between 430 and 370 million years ago, during the Silurian and Devonian periods of the Paleozoic. ''Loganellia'' belonged to the Thelodonti class and like other Thelodonts possessed scales instead of plate armor. ''Loganellia'' are thought to be more closely related to the crown group of gnathostomes than conodonts. They are noted for their denticle whorls - oropharyngeal denticles that lined their branchial bars - which are thought to be homologous with other, later gnathostome teeth A tooth ( : teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, tear .... In this sense, ''Loganellia'' may possess the earliest known dental structures related to modern teeth, and would have evolved in the throat, rather than through dermal denticles or jaws. Refer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stroinolepis
''Stroinolepis'' is an extinct genus of thelodontid that lived during the Middle Ordovician period in what is now the Severnaya Zemlya archipelago of Russia Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the .... References Thelodonti genera Ordovician jawless fish Fossils of Russia {{ordovician-animal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thelodonti
Thelodonti (from Greek: "feeble teeth")Maisey, John G., Craig Chesek, and David Miller. Discovering fossil fishes. New York: Holt, 1996. is a class of extinct jawless fishes with distinctive scales instead of large plates of armor. There is much debate over whether the group of Palaeozoic fish known as the Thelodonti (formerly coelolepids) represent a monophyletic grouping, or disparate stem groups to the major lines of jawless and jawed fish. Thelodonts are united in possession of "thelodont scales". This defining character is not necessarily a result of shared ancestry, as it may have been evolved independently by different groups. Thus the thelodonts are generally thought to represent a polyphyletic group, although there is no firm agreement on this point. On the basis that they are monophyletic, they are reconstructed as being ancestrally marine and invading freshwater on multiple occasions. "Thelodonts" were morphologically very similar, and probably closely related, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
