|
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] |
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] |
Protaspididae
Protaspididae is an extinct family of pteraspidid heterostracan agnathans. Fossils of the various genera are found in early Devonian-aged marine strata. Protaspidids were once thought to represent a transitional form between the Pteraspididae and the Psammosteida, bearing the broad head shield shape of the latter, due to a more benthic (bottom-dwelling) existence, but recent phylogenical comparisons demonstrate that the protaspidids are actually highly derived pteraspidids,Pernegre, Vincent N., and David K. Elliott. "Phylogeny of the Pteraspidiformes (Heterostraci), Silurian–Devonian jawless vertebrates." Zoologica Scripta 37.4 (2008): 391-403. and that the anchipteraspidids, the most primitive of pteraspidids, are the sister-group of the Psammosteids. Genera Many genera are found in Lower Devonian marine deposits of the United States, especially of Utah and Wyoming. Others are found in Lower Devonian marine strata of Europe, especially of Svalbard, Norway, and Podolia, Ukrai ... [...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] |
Anchipteraspididae
Anchipteraspididae is an extinct family of heterostracan vertebrate Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, ...s restricted to Late Silurian and Early Devonian strata of Arctic Canada.Elliott, D. K. "A new subfamily of the Pteraspididae (Agnatha, Heterostraci) from the upper Silurian and lower Devonian of Arctic Canada." Palaeontology 27.1 (1984): 169-197 Anchipteraspidids superficially resemble the ancestral cyathaspidiformes, cyathaspidids, but, the articulation and growth patterns of the plates clearly define them as pteraspidids. References * On the recent discovery of Pteraspidian fish in the upper Silurian rocks of North America. Edward Waller Claypole, Quart. Journ. Geol. Soc. 1885, volume 41, pages 48–64, * Revised classification of Pteraspididae with descri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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] |
Pteraspis Dunensis
''Rhinopteraspis'' is an extinct genus of pteraspidid heterostracan agnathan Agnatha (, Ancient Greek 'without jaws') is an infraphylum of jawless fish in the phylum Chordata, subphylum Vertebrata, consisting of both present (cyclostomes) and extinct (conodonts and ostracoderms) species. Among recent animals, cyclostomes .... References Pteraspidiformes genera Devonian jawless fish Early Devonian fish Early Devonian fish of Europe {{Pteraspidomorphi-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lamiaspis
''Lamiaspis longiripa'' is an extinct pteraspid heterostracan agnathan vertebrate found in marine strata of Early Devonian Nevada Nevada ( ; ) is a U.S. state, state in the Western United States, Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. N ....uBio: Lamiaspis (accessed 13 February 2016)GBIF: Lamiaspis Ilyes & Elliott, 1994 (accessed 13 February 2016) The generic name translates as "shark shield", in reference to its shark-like hydrodynamic shape. References [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Psammosteida
Psammosteida also called as Psammosteoidei is a suborder of pteraspidid heterostracan agnathans. The psammosteids had broad, flattened bodies, suggesting a predominantly benthic habit. The earliest unequivocal psammosteid is '' Drepanaspis'' of Early Devonian Germany, which is either included in the family Psammosteidae, or placed within its own family, Drepanaspididae. If the late Silurian/Early Devonian '' Weigeltaspis'' is a psammosteid, as opposed to being a traquairaspid, then that genus, instead, would be the oldest psammosteid. However, its placement within Heterostraci remains a matter of debate. Other notable psammosteids include '' Psammosteus'', and '' Obruchevia'', two genera of enormous species with dorsal shields around one meter in diameter. The Psammosteids were the only heterostracans to survive to the end of the Devonian, where they finally perish during the Hangenberg event The Hangenberg event, also known as the Hangenberg crisis or end-Devonian extinct ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pteraspididae
Pteraspididae is an extinct family of heterostracan vertebrates. It is an Early Devonian-aged family that contains the stereotypical, torpedo-shaped pteraspidids, such as the type genus, ''Pteraspis'', and its close relatives ''Errivaspis'' and '' Rhinopteraspis'', that are popularly thought to have actively swam about in the water column. The elongated rostral plate is thought to help with their hydrodynamic ability. Various genera are found in various marine and estuarine strata of Early Devonian Europe and North America. Genera * †'' Althaspis'' * †''Blieckaspis'' * †'' Brachipteraspis'' * †''Errivaspis'' * †'' Escharaspis'' * †'' Grumantaspis'' * †'' Helaspis'' * †'' Larnovaspis'' * †'' Loricopteraspis'' * †'' Miltaspis'' * †'' Mitraspis'' * †'' Mylopteraspidella'' * †'' Mylopteraspis'' * †'' Podolaspis'' * †''Pteraspis ''Pteraspis'' (from el, πτερόν 'wing' or 'fin' and el, ἀσπίς 'shield') is an extinct genus of pteraspidid h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pineal Gland
The pineal gland, conarium, or epiphysis cerebri, is a small endocrine gland in the brain of most vertebrates. The pineal gland produces melatonin, a serotonin-derived hormone which modulates sleep, sleep patterns in both circadian rhythm, circadian and Season, seasonal cycles. The shape of the gland resembles a pine cone, which gives it its name. The pineal gland is located in the epithalamus, near the center of the brain, between the two cerebral hemisphere, hemispheres, tucked in a groove where the two halves of the thalamus join. The pineal gland is one of the neuroendocrinology, neuroendocrine Circumventricular organs, secretory circumventricular organs in which capillaries are mostly Vascular permeability, permeable to solutes in the blood. Nearly all vertebrate species possess a pineal gland. The most important exception is a primitive vertebrate, the hagfish. Even in the hagfish, however, there may be a "pineal equivalent" structure in the dorsal diencephalon. The lanc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rostrum (anatomy)
Rostrum (from Latin ', meaning ''beak'') is a term used in anatomy for a number of phylogenetically unrelated structures in different groups of animals. Invertebrates * In crustaceans, the rostrum is the forward extension of the carapace in front of the eyes. It is generally a rigid structure, but can be connected by a hinged joint, as seen in Leptostraca. * Among insects, the rostrum is the name for the piercing mouthparts of the order Hemiptera as well as those of the snow scorpionflies, among many others. The long snout of weevils is also called a rostrum. * Gastropod molluscs have a rostrum or proboscis. * Cephalopod molluscs have hard beak-like mouthparts referred to as the rostrum. File:Washington DC Zoo - Macrobrachium rosenbergii 6.jpg, Crustacean: the rostrum of the shrimp ''Macrobrachium rosenbergii'' is serrated along both edges. File:Gminatus australis with Beetle.jpg, Insect: assassin bug piercing its prey with its rostrum File:Architeuthis beak.jpg, Cephalopod: ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Order (biology)
Order ( la, wikt:ordo#Latin, ordo) is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between Family_(biology), family and Class_(biology), class. In biological classification, the order is a taxonomic rank used in the classification of organisms and recognized by the nomenclature codes. An immediately higher rank, superorder, is sometimes added directly above order, with suborder directly beneath order. An order can also be defined as a group of related families. What does and does not belong to each order is determined by a taxonomist, as is whether a particular order should be recognized at all. Often there is no exact agreement, with different taxonomists each taking a different position. There are no hard rules that a taxonomist needs to follow in describing or recognizing an order. Some taxa are accepted almost universally, while others are recognized only rarely. The name of an order is usually written with a capital letter. Fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.jpg "Click for more on -> Rostrum (anatomy)")
