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Pteraspidoidei
Pteraspidoidei is an extinct suborder of heterostracan vertebrates. It contains the more derived taxa within Pteraspidiformes, such as ''Pteraspis'' and '' Errivaspis'', though, some protopteraspidids, such as '' Doryaspis'' and ''Panamintaspis ''Panamintaspis snowi'' is an extinct species of pteraspidid heterostracan agnathan which existed during the early Middle Devonian period of Death Valley, California.Elliott, David K., and Robert R. Ilyes. "New Early Devonian pteraspidids (Agnat ...'', share various features with these derived pteraspidids. References * Pernègre V., 2006. - Un nouveau pteraspidiforme (Vertebrata, Heterostraci) du Dévonien inférieur du Spitsberg: nouvelles données paléo-ontogéniques. Geodiversitas, fasc. 2, t. 28 Pteraspidiformes Fish suborders Devonian jawless fish Silurian jawless fish Prehistoric animal suborders Silurian first appearances Devonian extinctions {{Pteraspidomorphi-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pteraspidiformes
Pteraspidiformes is an extinct order of heterostracan agnathan vertebrates known from extensive fossil remains primarily from Early Devonian strata of Europe and North America, and from Upper Silurian Canada. Anatomy A pteraspidiform heterostracan has the cephalothorax enclosed in armor, formed from several plates, including dorsal, ventral, rostral, pineal plates, a dorsal spine derived from a scale, and a large, scale-covered tail. Many genera were benthic, others were apparently active swimming nekton.Botella, Hector, and Richard A. Farina. "Flow pattern around the rigid cephalic shield of the Devonian agnathan Errivaspis waynensis (Pteraspidiformes: Heterostraci)." Palaeontology 51.5 (2008): 1141-1150/ref> Delicate, finger-like components of the anterior end of the ventral plate forming the edges of the mouth suggest that pteraspidiform heterostracans were filter-feeding, filter-feeders that selectively filtered specific sized plankton from the water column.Purnell, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Panamintaspis
''Panamintaspis snowi'' is an extinct species of pteraspidid heterostracan agnathan which existed during the early Middle Devonian period of Death Valley, California.Elliott, David K., and Robert R. Ilyes. "New Early Devonian pteraspidids (Agnatha, Heterostraci) from Death Valley National Monument, southeastern California." Journal of Paleontology (1996): 152-161. Fossils are found in Late Emsian-aged marine strata of the Lost Burro Formation. ''P. snowi'' strongly resembles ''Pteraspis'', though while it was originally described as a member of the same family, Pteraspididae, a recent phylogenetic reassessment of the order Pteraspidiformes places ''P. snowi'' within the paraphyletic family "Protopeteraspidae," as the sister taxon of the suborder Pteraspidoidei (the super-taxon that contains Pteraspididae together with Protaspididae and '' Gigantaspis'').Pernegre, Vincent N., and David K. Elliott. "Phylogeny of the Pteraspidiformes (Heterostraci), Silurian–Devonian jawless v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palanasaspis
''Palanasaspis chekhivensis'' is an extinct species of pteraspidid heterostracan agnathan which existed during the Pragian epoch of the early Devonian period in what is now Podolia, Ukraine. It is known primarily from a wide rostral plate, which is referenced in the generic name, a compound word combining the Latin words ''pala'', "shovel," and ''nasus'', "nose," with the Greek suffix ''aspis,'' "a small shield." Although the rostral plate clearly marks the creature as a pteraspidoid heterostracan, that literally nothing else of its anatomy is known forces researchers to leave it as ''incertae sedis ' () or ''problematica'' is a term used for a taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertainty ...''. References Pteraspidiformes genera Devonian jawless fish Early Devonian fish Early Devonian fish of Europe Heterostrac ... [...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] |
Errivaspis
''Errivaspis'' is an extinct genus of pteraspid heterostracan agnathan vertebrate known from fossils at the Wayne Hereford Quarry, of Early Devonian England, and of Podolia, Early Devonian Ukraine. It was originally described by Dr. Errol Ivor White as one of five form-variants of ''Pteraspis rostrata'', i.e., "''Pteraspis rostrata var. waynesis''. In 1984, Alain Blieck moved ''var. waynesis'' into its own genus, ''Errivaspis'', which he named after Dr. White.Blieck, Alain. "Les Hétérostracés Ptéraspidiformes, Agnathes du Silurien-Dévonien du Continent nord-atlantique et des blocs avoisinants: révision systématique, phylogénie, biostratigraphie, biogéographie." (1984). Other later researchers would then mistakenly assume that Blieck synonymized the entire genus of ''Pteraspis'' into ''Errivaspis''. Description ''Errivaspis'' had large dorsal plates and ventral plates, the linking branchial plate, as well as a cornual plate at the side, an orbital plate around the eye ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prehistoric Animal Suborders
Prehistory, also known as pre-literary history, is the period of human history between the use of the first stone tools by hominins 3.3 million years ago and the beginning of recorded history with the invention of writing systems. The use of symbols, marks, and images appears very early among humans, but the earliest known writing systems appeared 5000 years ago. It took thousands of years for writing systems to be widely adopted, with writing spreading to almost all cultures by the 19th century. The end of prehistory therefore came at very different times in different places, and the term is less often used in discussing societies where prehistory ended relatively recently. In the early Bronze Age, Sumer in Mesopotamia, the Indus Valley Civilisation, and ancient Egypt were the first civilizations to develop their own scripts and to keep historical records, with their neighbors following. Most other civilizations reached the end of prehistory during the following Iron Age. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silurian Jawless Fish
The Silurian ( ) is a geologic period and system spanning 24.6 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 shortest period of the Paleozoic Era. 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) became fully terrestrialized. A significant evolutionary milestone during th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Devonian Jawless Fish
The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, where rocks from this period were first studied. The first significant adaptive radiation of life on dry land occurred during the Devonian. Free-sporing vascular plants began to spread across dry land, forming extensive forests which covered the continents. By the middle of the Devonian, several groups of plants had evolved leaves and true roots, and by the end of the period the first seed-bearing plants appeared. The arthropod groups of myriapods, arachnids and hexapods also became well-established early in this period, after starting their expansion to land at least from the Ordovician period. Fish reached substantial diversity during this time, leading the Devonian to often be dubbed the Age of Fishes. The placoderms began dominating al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fish Suborders
Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of living fish species are ray-finned fish, belonging to the class Actinopterygii, with around 99% of those being teleosts. The earliest organisms that can be classified as fish were soft-bodied chordates that first appeared during the Cambrian period. Although they lacked a true spine, they possessed notochords which allowed them to be more agile than their invertebrate counterparts. Fish would continue to evolve through the Paleozoic era, diversifying into a wide variety of forms. Many fish of the Paleozoic developed external armor that protected them from predators. The first fish with jaws appeared in the Silurian period, after which many (such as sharks) became formidable marine predators rather than just the prey of arthropods. Most fis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pteraspis
''Pteraspis'' (from el, πτερόν 'wing' or 'fin' and el, ἀσπίς 'shield') is an extinct genus of pteraspidid heterostracan agnathan vertebrate that lived from the Lochkovian to Eifelian epochs of the Devonian period in what is now Brazil (Eifelian Maecuru Formation), Britain (Lochkovian Ditton Group), Ukraine (Lochkovian Ivane Suite, Pragian Babin Sandstone) and Belgium. Description Like other heterostracan fishes, ''Pteraspis'' had a protective armored plating covering the front of its body. Though lacking fins other than its lobed tail, it is thought to have been a good swimmer thanks to stiff, wing-like protrusions derived from the armoured plates over its gills. This, along with the horn-like rostrum, made ''Pteraspis'' very streamlined in shape; a perfect quality for a good swimmer. ''Pteraspis'' also had some stiff spikes on its back, possibly an additional form of protection against predators. It is thought to have fed from shoals of plankton P ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Doryaspis
''Doryaspis'' (from el, δόρῠ 'spear' and el, ἀσπίς 'shield') (also known by its synonym, "''Lyktaspis''") is an extinct genus of primitive jawless fish that lived in the Devonian period. Fossils have been discovered in Spitsbergen. The animals had canteen-shaped body armor and had large branchial plates that extended out and curved downward in a triangular shape, very similar to those of the pycnosteids. An element of the median oral plates (that would correspond to the lower lip or chin in gnathostomes) extends out in a long rod-shaped appendage, called the "pseudorostrum." The tail is long and slender and has large rows of thick scales. In the type species, ''D. nathorsti'', the lateral edges of the branchial plates and of the pseudorostrum are serrated. The second species, ''D. arctica'', is smaller, and lacks serrated edges. File:Doryaspis_arctica.JPG, Reconstruction of recently discovered species, ''D. arctica'' File:Doryaspis.jpg, Reconstruction of the ty ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protopteraspididae
Protopteraspididae is an extinct family of pteraspidid heterostracan agnathans. Fossils of the various genera are found in early Devonian-aged marine strata. Protopteraspidids were once thought to represent a taxon of basal pteraspidids (hence "proto") but recent evaluations demonstrate that Protopteraspididae is a paraphyletic group of various transitional forms representing a gradual transition between the more advanced Pteraspoidei (comprising Pteraspididae, '' Gigantaspis'' and Protaspididae),Pernegre, Vincent N., and David K. Elliott. "Phylogeny of the Pteraspidiformes (Heterostraci), Silurian–Devonian jawless vertebrates." Zoologica Scripta 37.4 (2008): 391-403. and the anchipteraspidids and the Psammosteids. Genera Protopteraspids are found in Lower Devonian marine strata of the Western United States, Northern Canada, England, France, Belgium, Svalbard, Norway, and Podolia, Ukraine.Blieck, Alain. "Les hétérostracés Ptéraspidiformes, agnathes du Silurien-Dévonien ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
