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Acanthodii
Acanthodii or acanthodians is an extinct class of gnathostomes (jawed fishes). They are currently considered to represent a paraphyletic grade of various fish lineages basal to extant Chondrichthyes, which includes living sharks, rays, and chimaeras. Acanthodians possess a mosaic of features shared with both osteichthyans (bony fish) and chondrichthyans (cartilaginous fish). In general body shape, they were similar to modern sharks, but their epidermis was covered with tiny rhomboid platelets like the scales of holosteians ( gars, bowfins). The popular name "spiny sharks" is because they were superficially shark-shaped, with a streamlined body, paired fins, a strongly upturned tail, and stout, largely immovable bony spines supporting all the fins except the tail—hence, "spiny sharks". However, acanthodians are not true sharks; their close relation to modern cartilaginous fish can lead them to be considered " stem-sharks". Acanthodians had a cartilaginous skeleton, bu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gyracanthides
''Gyracanthides'' is an extinct genus of Acanthodii, acanthodian gnathostome, known from Devonian to Mississippian (geology), Early Carboniferous. Description ''Gyracanthides'' is large Acanthodii, acanthodian, ''G. murrayi'' reached the length up to . The pectoral fin spines are large compared to its body, for specimen that have estimated to be had pectoral fin spines around long. A recent study suggested that ''Gyracanthides'' is closely related to Chondrichthyes, chondrichthyans (as currently delimited), and that Acanthodii, acanthodians are paraphyletic. References [...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] |
Climatiiformes
The Climatiiformes is a paraphyletic order of extinct fish belonging to the class Acanthodii. Like most other "spiny sharks", the Climatiiformes had sharp spines. These animals were often fairly small in size and lived from the Late Silurian to the Early Carboniferous period. The type genus is '' Climatius''. The order used to be subdivided into the suborder Order () is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and recognized ...s Climatiida and Diplacanthida, but subsequently Diplacanthida has been elevated to a separate order, the Diplacanthiformes. The Diplacanthiformes take their name from '' Diplacanthus'', first described by Agassiz in 1843. Family Gyracanthidae is sometimes rejected from this order. References Prehistoric cartilaginous fish Prehistoric cartilaginous fish orders Par ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gnathostomata
Gnathostomata (; from Ancient Greek: (') 'jaw' + (') 'mouth') are jawed vertebrates. Gnathostome diversity comprises roughly 60,000 species, which accounts for 99% of all extant vertebrates, including all living bony fishes (both ray-finned and lobe-finned, including their terrestrial tetrapod relatives) and cartilaginous fishes, as well as extinct prehistoric fish such as placoderms and acanthodians. Most gnathostomes have retained ancestral traits like true teeth, a stomach, and paired appendages ( pectoral and pelvic fins, limbs, wings, etc.). Other traits are elastin, horizontal semicircular canal of the inner ear, myelinated neurons, and an adaptive immune system which has discrete secondary lymphoid organs (spleen and thymus) and uses V(D)J recombination to create antigen recognition sites, rather than using genetic recombination in the variable lymphocyte receptor gene. It is now assumed that Gnathostomata evolved from ancestors that already possessed two pairs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gyracanthidae
Gyracanthidae is a family of extinct fish belonging to the class Acanthodii, known from early Devonian to late Carboniferous. Members are characterized by large, broad-based, paired fin spines with the pectoral fin spines having a distinct longitudinal curvature. Although it was originally classified in order Climatiiformes The Climatiiformes is a paraphyletic order of extinct fish belonging to the class Acanthodii. Like most other "spiny sharks", the Climatiiformes had sharp spines. These animals were often fairly small in size and lived from the Late Silurian to t ..., later research questioned this. References Prehistoric cartilaginous fish families {{Paleo-fish-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diplacanthidae
Diplacanthiformes (also known as Diplacanthida, Diplacanthoidei, or Diplacanthini) is an order of "acanthodian" stem- chondrichthyans which lived during the Devonian Period The Devonian ( ) is a geologic period and system of the Paleozoic era during the Phanerozoic eon, spanning 60.3 million years from the end of the preceding Silurian period at million years ago ( Ma), to the beginning of the succeeding C .... Subtaxa * ''incertae sedis'' ** Genus '' Bryantonchus'' ** Genus '' Culmacanthus'' ** Genus '' Devononchus'' ** Genus '' Striacanthus'' ** Genus '' Tetanopsyrus'' * Family Diplacanthidae ** Genus '' Diplacanthus'' ** Genus '' Milesacanthus'' ** Genus '' Ptychodictyon'' ** Genus '' Rhadinacanthus'' * Family Gladiobranchidae? ** Genus '' Gladiobranchus'' ** Genus '' Uraniacanthus''? References Prehistoric cartilaginous fish orders Devonian first appearances Devonian extinctions {{Acanthodii-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chondrichthyes
Chondrichthyes (; ) is a class of jawed fish that contains the cartilaginous fish or chondrichthyans, which all have skeletons primarily composed of cartilage. They can be contrasted with the Osteichthyes or ''bony fish'', which have skeletons primarily composed of bone tissue. Chondrichthyes are aquatic vertebrates with paired fins, paired nares, placoid scales, conus arteriosus in the heart, and a lack of opercula and swim bladders. Within the infraphylum Gnathostomata, cartilaginous fishes are distinct from all other jawed vertebrates. The class is divided into two subclasses: Elasmobranchii (sharks, rays, skates and sawfish) and Holocephali ( chimaeras, sometimes called ghost sharks, which are sometimes separated into their own class). Extant chondrichthyans range in size from the finless sleeper ray to the over whale shark. Anatomy Skeleton The skeleton is cartilaginous. The notochord is gradually replaced by a vertebral column during development, e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fish Fin
Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported only by muscles. Fish fins are distinctive anatomical features with varying structures among different clades: in ray-finned fish (Actinopterygii), fins are mainly composed of bony spines or rays covered by a thin stretch of scaleless skin; in lobe-finned fish ( Sarcopterygii) such as coelacanths and lungfish, fins are short rays based around a muscular central bud supported by jointed bones; in cartilaginous fish ( Chondrichthyes) and jawless fish ( Agnatha), fins are fleshy " flippers" supported by a cartilaginous skeleton. Fins at different locations of the fish body serve different purposes, and are divided into two groups: the midsagittal ''unpaired fins'' and the more laterally located ''paired fins''. Unpaired fins are p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silurian
The Silurian ( ) is a geologic period and system spanning 23.5 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the third and shortest period of the Paleozoic Era, and the third of twelve periods of the Phanerozoic Eon. As with other geologic periods, the rock beds that define the period's start and end are well identified, but the exact dates are uncertain by a few million years. The base of the Silurian is set at a series of major Ordovician–Silurian extinction events when up to 60% of marine genera were wiped out. One important event in this period was the initial establishment of terrestrial life in what is known as the Silurian-Devonian Terrestrial Revolution: vascular plants emerged from more primitive land plants, dikaryan fungi started expanding and diversifying along with glomeromycotan fungi, and three groups of arthropods ( myriapods, arachnids and hexapods) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diplacanthiformes
Diplacanthiformes (also known as Diplacanthida, Diplacanthoidei, or Diplacanthini) is an order of "acanthodian" stem- chondrichthyans which lived during the Devonian Period. Subtaxa * ''incertae sedis'' ** Genus '' Bryantonchus'' ** Genus '' Culmacanthus'' ** Genus '' Devononchus'' ** Genus '' Striacanthus'' ** Genus '' Tetanopsyrus'' * Family Diplacanthidae Diplacanthiformes (also known as Diplacanthida, Diplacanthoidei, or Diplacanthini) is an order of "acanthodian" stem- chondrichthyans which lived during the Devonian Period The Devonian ( ) is a geologic period and system of the Paleozoic e ... ** Genus '' Diplacanthus'' ** Genus '' Milesacanthus'' ** Genus '' Ptychodictyon'' ** Genus '' Rhadinacanthus'' * Family Gladiobranchidae? ** Genus '' Gladiobranchus'' ** Genus '' Uraniacanthus''? References Prehistoric cartilaginous fish orders Devonian first appearances Devonian extinctions {{Acanthodii-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ischnacanthiformes
Ischnacanthiformes is a prehistoric order of "acanthodian" stem- chondrichthyans found in Canada, Ukraine and United Kingdom. Members of this order were nektonic carnivores, eating animals that swim rather than plankton. They had slender builds, light armor, deeply inserted spines, shark-like teeth, and two dorsal fin A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...s. Some species were around 2 meters (6.56 feet) long. It was described by Berg in 1940. References Prehistoric cartilaginous fish orders {{Acanthodii-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fish
A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can be grouped into the more basal (phylogenetics), basal jawless fish and the more common jawed fish, the latter including all extant taxon, living cartilaginous fish, cartilaginous and bony fish, as well as the extinct placoderms and acanthodians. In a break to the long tradition of grouping all fish into a single Class (biology), class (Pisces), modern phylogenetics views fish as a paraphyletic group. Most fish are ectotherm, cold-blooded, their body temperature varying with the surrounding water, though some large nekton, active swimmers like white shark and tuna can hold a higher core temperature. Many fish can communication in aquatic animals#Acoustic, communicate acoustically with each other, such as during courtship displays. The stud ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
