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Psilichthys
''Psilichthys'' is an extinct genus of prehistoric bony fish from Eumeralla Formation, the Lower Cretaceous epoch of what is now Victoria, Australia, known from single species ''P. selwyni''. This is the first Mesozoic fossil vertebrate named from Victoria. Classification Due to the only known fossil of ''Psilichthys'' is incomplete holotype specimen, its classification is discussed for years. It was originally described as a possibly palaeoniscid or chondrosteid. It has also previously been referred to the family Birgeriidae. Waldman (1971) denied interpretation as chondrosteid, considering the character that lacked scales which used to classify it as acipenseriform, is misidentification and it preserved some of scales. Waldman suggested that is likely to be a palaeoniscid that belongs to Coccolepidae, although due to preservation it is tentative. It is not belong to birgeriid considering differences from '' Birgeria''.Waldman, M., 1971, A re-examination of ''Psilichthys ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Birgeriidae
''Birgeria'' is a genus of carnivorous marine ray-finned fish from the Triassic period. ''Birgeria'' had a global distribution. Fossils were found in Madagascar, Spitsbergen, Germany, Switzerland, Italy, Slovenia, China, Russia, Canada and Nevada, United States. The oldest fossils are from Griesbachian aged beds of the Wordie Creek Formation of East Greenland. The type species was first described as ''Saurichthys mougeoti''. Following a reinvestigation, Erik Stensiö concluded that this species cannot be ascribed to '' Saurichthys''. He thus erected a new genus, which he named after his colleague Birger Sjöström, who had joined him on an expedition to the Arctic island of Spitsbergen ( Svalbard) in 1915. Appearance The scale cover of ''Birgeria'' is reduced. Most of the body is devoid of scales. Scales are only developed on the upper lobe of the caudal fin and the hind portion of the caudal peduncle. The scales are small, rhombic and lack a ganoine layer. The heterocerc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Birgeria
''Birgeria'' is a genus of carnivorous marine ray-finned fish from the Triassic period. ''Birgeria'' had a global distribution. Fossils were found in Madagascar, Spitsbergen, Germany, Switzerland, Italy, Slovenia, China, Russia, Canada and Nevada, United States. The oldest fossils are from Griesbachian aged beds of the Wordie Creek Formation of East Greenland. The type species was first described as ''Saurichthys mougeoti''. Following a reinvestigation, Erik Stensiö concluded that this species cannot be ascribed to '' Saurichthys''. He thus erected a new genus, which he named after his colleague Birger Sjöström, who had joined him on an expedition to the Arctic island of Spitsbergen ( Svalbard) in 1915. Appearance The scale cover of ''Birgeria'' is reduced. Most of the body is devoid of scales. Scales are only developed on the upper lobe of the caudal fin and the hind portion of the caudal peduncle. The scales are small, rhombic and lack a ganoine layer. The heterocerc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palaeonisciformes
The Palaeonisciformes (Palaeoniscida) are an extinct order of early ray-finned fishes ( Actinopterygii). Palaeonisciformes ''sensu lato'' first appeared in the fossil record in the Late Silurian and last appeared in the Late Cretaceous. The name is derived from the Ancient Greek words παλαιός (''palaiós'', ancient) and ὀνίσκος (''oniskos'', 'cod-fish' or woodlouse), probably pertaining to the organization of the fishes' scales, similar to the exoskeletal plating of woodlice. In an early interpretation of the group, the Palaeonisciformes are divided in two suborders: Palaeoniscoidei (includes '' Palaeoniscum'' and fossil taxa with a broadly similar appearance) and Platysomoidei (includes '' Platysomus'' and other deep-bodied early actinopterygians). These groupings are considered paraphyletic today. In the cladistic sense, Palaeonisciformes '' sensu stricto'' should only refer to the Permian ''Palaeoniscum'', the name giving taxon, and all other taxa that fall ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lower Cretaceous
Lower may refer to: *Lower (surname) *Lower Township, New Jersey *Lower Receiver (firearms) *Lower Wick Lower Wick is a small hamlet located in the county of Gloucestershire, England. It is situated about five miles south west of Dursley, eighteen miles southwest of Gloucester and fifteen miles northeast of Bristol. Lower Wick is within the civil ... Gloucestershire, England See also * Nizhny {{Disambiguation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Australia
Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, smaller islands. With an area of , Australia is the largest country by area in Oceania and the world's List of countries and dependencies by area, sixth-largest country. Australia is the oldest, flattest, and driest inhabited continent, with the least fertile soils. It is a Megadiverse countries, megadiverse country, and its size gives it a wide variety of landscapes and climates, with Deserts of Australia, deserts in the centre, tropical Forests of Australia, rainforests in the north-east, and List of mountains in Australia, mountain ranges in the south-east. The ancestors of Aboriginal Australians began arriving from south east Asia approximately Early human migrations#Nearby Oceania, 65,000 years ago, during the Last Glacial Period, last i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prehistoric Fish
The evolution of fish began about 530 million years ago during the Cambrian explosion. It was during this time that the early chordates developed the skull and the vertebral column, leading to the first craniates and vertebrates. The first fish lineages belong to the Agnatha, or jawless fish. Early examples include ''Haikouichthys''. During the late Cambrian, eel-like jawless fish called the conodonts, and small mostly armoured fish known as ostracoderms, first appeared. Most jawless fish are now extinct; but the extant lampreys may approximate ancient pre-jawed fish. Lampreys belong to the Cyclostomata, which includes the extant hagfish, and this group may have split early on from other agnathans. The earliest jawed vertebrates probably developed during the late Ordovician period. They are first represented in the fossil record from the Silurian by two groups of fish: the armoured fish known as placoderms, which evolved from the ostracoderms; and the Acanthodii (or spin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acipenseriformes
Acipenseriformes is an order of basal ray-finned fishes that includes living and fossil sturgeons and paddlefishes (Acipenseroidei), as well as the extinct families Chondrosteidae and Peipiaosteidae. They are the second earliest diverging group of living ray-finned fish after the bichirs. Despite being early diverging, they are highly derived, having only weakly ossified skeletons that are mostly made of cartilage, and in modern representatives highly modified skulls. Description The axial skeleton of Acipenseriformes is only partially ossified, with the majority of the bones being replaced with cartilage. The notochord, usually only found in fish embryos, is unconstricted and retained throughout life. The premaxilla The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammal has ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Family (taxonomy)
Family ( la, familia, plural ') is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between order and genus. A family may be divided into subfamilies, which are intermediate ranks between the ranks of family and genus. The official family names are Latin in origin; however, popular names are often used: for example, walnut trees and hickory trees belong to the family Juglandaceae, but that family is commonly referred to as the "walnut family". What belongs to a family—or if a described family should be recognized at all—are proposed and determined by practicing taxonomists. There are no hard rules for describing or recognizing a family, but in plants, they can be characterized on the basis of both vegetative and reproductive features of plant species. Taxonomists often take different positions about descriptions, and there may be no broad consensus across the scientific community for some time. The publishing of new data and opini ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chondrosteidae
Chondrosteidae is a family of extinct marine actinopterygian fishes in the order Acipenseriformes. Three genera are known from the Early Jurassic of Europe, ''Chondrosteus'', '' Gyrosteus'', and '' Strongylosteus''. Included species were of large size, with body lengths ranging from up to . Their skeleton was largely made up of bones (unlike living chondrosteans), but ossification was reduced compared to other ray-fins. Evolutionary relationships Chondrosteidae are related with the Late Jurassic to Early Cretaceous Asian family Peipiaosteidae, and with living sturgeon and paddlefish (Acipenseroidei). The Early Triassic '' Eochondrosteus'' from China is more basal than all other aforementioned acipenseriforms. See also * Prehistoric fish The evolution of fish began about 530 million years ago during the Cambrian explosion. It was during this time that the early chordates developed the skull and the vertebral column, leading to the first craniates and vertebrates. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesozoic
The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceous Periods. It is characterized by the dominance of archosaurian reptiles, like the dinosaurs; an abundance of conifers and ferns; a hot greenhouse climate; and the tectonic break-up of Pangaea. The Mesozoic is the middle of the three eras since complex life evolved: the Paleozoic, the Mesozoic, and the Cenozoic. The era began in the wake of the Permian–Triassic extinction event, the largest well-documented mass extinction in Earth's history, and ended with the Cretaceous–Paleogene extinction event, another mass extinction whose victims included the non-avian dinosaurs, pterosaurs, mosasaurs, and plesiosaurs. The Mesozoic was a time of significant tectonic, climatic, and evolutionary activity. The era witnessed the gradual ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Victoria (state)
Victoria is a state in southeastern Australia. It is the second-smallest state with a land area of , the second most populated state (after New South Wales) with a population of over 6.5 million, and the most densely populated state in Australia (28 per km2). Victoria is bordered by New South Wales to the north and South Australia to the west, and is bounded by the Bass Strait to the south (with the exception of a small land border with Tasmania located along Boundary Islet), the Great Australian Bight portion of the Southern Ocean to the southwest, and the Tasman Sea (a marginal sea of the South Pacific Ocean) to the southeast. The state encompasses a range of climates and geographical features from its temperate coastal and central regions to the Victorian Alps in the northeast and the semi-arid north-west. The majority of the Victorian population is concentrated in the central-south area surrounding Port Phillip Bay, and in particular within the metropolitan ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
