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Cyathaspidiformes
Cyathaspidiformes is an extinct order of heterostracan vertebrates known from extensive fossil remains primarily from Silurian to Early Devonian strata of Europe, and North America, and from Early Devonian marine strata of Siberia. Anatomy Like their descendants, the pteraspidids, all cyathaspidiform heterostracans had the cephalothorax enclosed in armor, formed from several plates, including dorsal, ventral, a dorsal spine derived from a scale, and a large, scale-covered tail. Thus, the living animals would have resembled tadpoles encased in massive armor. The majority of taxa have the rostral and pineal plates fused or merged with the dorsal plate, and in the amphiaspidids, all the plates of the cephalothorax were fused together into a single "muff-like" unit. Unlike the pteraspidids, all cyathaspidiforms are thought to be almost uniformly benthic in lifestyle, though only the amphiaspids and the ctenaspids are thought to be burrowers. Taxonomy The taxonomy of Cyathaspidifo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heterostraci
Heterostraci (Ancient Greek, ἕτερος+ὄστρακον "those itha different shell" i is pl. of -us is an extinct subclass of pteraspidomorph jawless vertebrate that lived primarily in marine and estuary environments. Heterostraci existed from the mid-Ordovician to the conclusion of the Devonian. Description and anatomy The Heterostracans differed from other Paleozoic agnathan taxa both in the arrangement and histology of their scales. Most heterostracans had two plates which form a large dorsal shield and a large ventral shield, and had series of scales arranged in various patterns on the sides of their bodies, the exact pattern differing from one group to another. In a few primitive forms, such as '' Lepidaspis'', the dorsal and ventral shields are composed of a mosaic of tiny scales. In most other known forms, though, these tiny scales have fused together to form the shield-plates. The scales of heterostracans are histologically distinct from other vertebrate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amphiaspidida
Amphiaspidida is a taxon of extinct cyathaspidid heterostracan agnathans whose fossils are restricted to Lower Devonian marine strata of Siberia near the Taimyr Peninsula. Some authorities treat it as a suborder of Cyathaspidiformes,Lundgren, Mette, and Henning Blom. "Phylogenetic relationships of the cyathaspidids (Heterostraci)." GFF 135.1 (2013): 74-84. while others treat it as an order in its own right as "Amphiaspidiformes."Novitskaya, Larisse. Les amphiaspides (Heterostraci) du Devonien de la Siberie. Éditions du Centre national de la recherche scientifique, 1971. In life, they are thought to be benthic animals that lived most of their lives mostly buried in the sediment of a series of hypersaline lagoons. Amphiaspids are easily distinguished from other heterostracans in that all of the plates of the cephalothorax armor are fused into a single, muff-like unit, so that the forebody of the living animal would have looked like a potpie or a hot waterbottle with a pair ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heterostraci
Heterostraci (Ancient Greek, ἕτερος+ὄστρακον "those itha different shell" i is pl. of -us is an extinct subclass of pteraspidomorph jawless vertebrate that lived primarily in marine and estuary environments. Heterostraci existed from the mid-Ordovician to the conclusion of the Devonian. Description and anatomy The Heterostracans differed from other Paleozoic agnathan taxa both in the arrangement and histology of their scales. Most heterostracans had two plates which form a large dorsal shield and a large ventral shield, and had series of scales arranged in various patterns on the sides of their bodies, the exact pattern differing from one group to another. In a few primitive forms, such as '' Lepidaspis'', the dorsal and ventral shields are composed of a mosaic of tiny scales. In most other known forms, though, these tiny scales have fused together to form the shield-plates. The scales of heterostracans are histologically distinct from other vertebrate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyathaspis
''Cyathaspis'' is the type genus of the heterostracan order Cyathaspidiformes. Fossils are found in late Silurian strata in the Cunningham Creek Formation, New Brunswick, Canada and Europe, especially in the Downton Castle Sandstone of Great Britain and Gotland, Sweden. The living animal would have looked superficially like a tadpole, albeit covered in bony plates composed of the tissue aspidine, which is unique to heterostracan armor. ''Cyathaspis ludensis'' is the earliest British vertebrate fossil. It was found in rocks at Leintwardine Leintwardine ( ) is a small to mid-size village and civil parish in north Herefordshire, England, close to the border with Shropshire. History Roman A popular misconception is that the Romans called the village ''Branogenium''. Branogenium in f ... in Herefordshire, a noted fossil locality. References Cyathaspidida Cyathaspidiformes genera Wenlock first appearances Ludlow life Silurian extinctions Silurian jawless fish Silur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hibernaspis
''Hibernaspis'' is a genus of extinct amphiaspidid heterostracan agnathans whose fossils are restricted to Lower Devonian marine strata of Siberia Siberia ( ; rus, Сибирь, r=Sibir', p=sʲɪˈbʲirʲ, a=Ru-Сибирь.ogg) is an extensive geographical region, constituting all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has been a part of ... near the Taimyr Peninsula. In life, species of ''Hibernaspis'' were thought to be benthic animals that lived most of their lives mostly buried in the sediment of a series of hypersaline lagoons. All amphiaspids are easily distinguished from other heterostracans in that all of the plates of the cephalothorax armor are fused into a single, muff-like unit, so that, in the case of ''Hibernaspis'', the forebody of the living animal would have looked like a large guitar pic with serrated edges, with a pair of tiny, degenerated eyes, a pair of branchial openings for exhaling, and a simpl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ctenaspididae
Ctenaspidae is a family of extinct cyathaspidiform heterostracan agnathans in the suborder Cyathaspidida. If Amphiaspidida can be ignored as a daughter-taxon, the family Ctenaspidae contains ''Ctenaspis'' and its various sister-taxa originally contained within both Ctenaspididae and Ctenaspididae, including '' Allocryptaspis'', ''Alainaspis ''Alainaspis platyrhina'' is an extinct cyathaspidid heterostracan agnathan vertebrate which existed in a marine environment in what is now the Northwest Territories of Canada, during the upper Silurian period. It was first named by David Ellio ...'', '' Zaphoctenaspis'', '' Arctictenaspis'', and '' Boothiaspis'', which was first described as a "Canadian amphiaspid."Lundgren, Mette, and Henning Blom. "Phylogenetic relationships of the cyathaspidids (Heterostraci)." GFF 135.1 (2013): 74-84. References Cyathaspidida Prehistoric jawless fish families {{Devonian-jawless-fish-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyathaspidida
Cyathaspidida is a taxon of extinct cyathaspidiform heterostracan agnathans whose fossils are found in Silurian to Lower Devonian marine strata of Europe and North America.Lundgren, Mette, and Henning Blom. "Phylogenetic relationships of the cyathaspidids (Heterostraci)." GFF 135.1 (2013): 74-84. In life, they are thought to be benthic animals that lived most of their lives either mostly buried in or resting directly on top of the substrate. Taxonomy The cyathaspidids of Cyathaspidida were tadpole-like animals with drum-shaped, cigar-shaped or wedge-shaped cephalothoraxes, and were anatomically similar to several other heterostracan groups. However, with some groups, such as the traquairaspids, cardiopeltids, and corvaspidids, this similarity appears to be superficial. With other groups, namely the tolypelepidids, the similarity suggests a close relationship. The type genus of the tolypelepidids, '' Tolypelepis'', in particular, was determined to be the sister-taxon of Cya ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ariaspidae
Ariaspidae is a family of extinct cyathaspidiform heterostracan agnathans in the suborder Cyathaspidida. Family Ariaspidae contains ''Ariaspis'', and its sister-taxa originally contained within Anglaspididae/Anglaspidinae, including ''Anglaspis ''Anglaspis'' is an extinct genus of cyathaspidiform heterostracan agnathan. Fossils are found in marine strata of Europe, from the late Silurian period until the genus' extinction during the Early Devonian. As with other cyathaspidiforms, i ...'', '' Listraspis'', '' Liliaspis'', and '' Paraliliaspis''.Lundgren, Mette, and Henning Blom. "Phylogenetic relationships of the cyathaspidids (Heterostraci)." GFF 135.1 (2013): 74-84. References * Phylogenetic patterns in the heterostracan families Cyathaspidae, Ariaspidae and Ctenaspidae. Lundgren Mette and Blom Henning, The 2nd Wiman meeting : Carl Wiman's Legacy: 100 years of Swedish Palaeontology : Uppsala 17–18 November 2011, 16-17 p. Cyathaspidida Prehistoric jawless fish ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pteraspidomorphi
Pteraspidomorphi is an extinct class of early jawless fish. They have long been regarded as closely related or even ancestral to jawed vertebrates, but the few characteristics they share with the latter are now considered as basal traits for all vertebrates. Characteristics Pteraspidomorphs are characterized by their massive dermal head armour having large, median, ventral and dorsal plates or shields. Janvier, Philippe (1997Pteraspidomorphi''The Tree of Life Web Project''. The fossils show extensive shielding of the head. Many had hypocercal tails in order to generate lift to increase ease of movement through the water for their armoured bodies, which were covered in dermal bone. They also had sucking mouth parts and some species may have lived in fresh water. Most pteraspidomorphs were marine, but lived very near to the shore, in lagoons and deltas. Some groups are thought to have been fresh water-dwelling. They were certainly bottom-dwellers, as shown by traces of abrasi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eglonaspididae
Eglonaspididae is a family of extinct amphiaspidid heterostracan agnathans whose fossils are restricted to Lower Devonian marine strata of Siberia near the Taimyr Peninsula. In life, all of the amphiaspidids are thought to be benthic animals that lived most of their lives mostly buried in the sediment of a series of hypersaline lagoons. Amphiaspids are easily distinguished from other heterostracans in that all of the plates of the cephalothoracic armor are fused into a single, muff-like unit, so that the forebody of the living animal would have looked, in the case of elgonaspidids, very much like a hot water bottle with or without a pair of small, degenerated eyes and a simple, slit-like mouth positioned at the anteriormost portion of the cephalothoracic armor. Taxonomy ''Eglonaspis'' ''Eglonaspis'' has a flattened, triangular-shaped cephalothoracic shield with large, crenulated fringes at the posteriolateral ends, and an elongated, tube-like head. Unlike most of its clos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyathaspidae
Cyathaspididae is an extinct family in the heterostracan order Cyathaspidiformes.The Classification and Evolution of the Heterostraci. L. Beverly Tarlo, Acta Palaeontologica Polonica, 1962 Cyathaspididae contains most of the genera originally contained within Cyathaspididae, as well as those genera contained within Irregularaspididae, and Poraspididae. In addition to the type genus, †''Cyathaspis'', Cyathaspididae contains the following genera: †'' Americaspis'', †'' Archegonaspis'', †'' Capitaspis'', †'' Dikenaspis'', †'' Dinaspidella'', †'' Homaspidella'', †'' Irregulareaspis'', †'' Nahanniaspis'', †'' Pionaspis'', †''Poraspis ''Poraspis'' is an extinct genus of heterostracan. Fossils are found in Late Silurian and Early Devonian marine strata of Norway, Canada and the United States The United States of America (U.S.A. or USA), commonly known as the United ...'', †'' Ptomaspis'', †'' Seretaspis'', †'' Steinaspis'', †'' Torpedaspis'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amphiaspidoidei
Amphiaspidoidei is a taxon of extinct amphiaspidid heterostracan agnathans whose fossils are restricted to Lower Devonian marine strata of Siberia Siberia ( ; rus, Сибирь, r=Sibir', p=sʲɪˈbʲirʲ, a=Ru-Сибирь.ogg) is an extensive geographical region, constituting all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has been a part of ... near the Taimyr Peninsula. In life, the amphiaspidids of Amphiaspidoidei are thought to be benthic animals that lived most of their lives mostly buried in the sediment of a series of hypersaline lagoons. Amphiaspids are easily distinguished from other heterostracans in that all of the plates of the cephalothorax armor are fused into a single, muff-like unit, so that the forebody of the living animal would have looked like a potpie or a hot waterbottle with a pair of small, or degenerated eyes flanked by preorbital openings, a pair of branchial openings for exhaling, and a simple, s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
