|
Dipnotetrapodomorph
Rhipidistia, also known as Dipnotetrapodomorpha, is a clade of lobe-finned fishes which includes the tetrapods and lungfishes. Rhipidistia formerly referred to a subgroup of Sarcopterygii consisting of the Porolepiformes and Osteolepiformes, a definition that is now obsolete. However, as cladistic understanding of the vertebrates has improved over the last few decades, a monophyletic Rhipidistia is now understood to include the whole of Tetrapoda and the lungfishes. Rhipidistia includes Porolepiformes and Dipnoi. Extensive fossilization of lungfishes has contributed to many evolutionary studies of this group. Evolution of autostylic jaw suspension, in which the palatoquadrate bone fuses to the cranium, and the lymph pumping "lymph heart" (later lost in mammals and flying birds), are unique to this group. Another feature shared by lungfish and tetrapods is the divided atrium. The precise time at which the choana of tetrapods evolved is debated, with some considering early rhipi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diabolepis
''Diabolepis'' is an extinct genus of very primitive marine lungfish which lived during the Early Devonian period. It contains a single species, ''D. speratus'' of Yunnan, China, from the mid-late Lochkovian of the Xitun Formation. It is one of the oldest known lungfish genera. It is the only member of the family Diabolepididae and the order Diabolepidiformes, although neither of these parent taxa have been officially described, despite their names being in scientific usage. Taxonomy ''Diabolepis'' was originally described as ''Diabolichthys'', but this name was found to be preoccupied by a now-outdated genus name given to the manta ray in the 19th century, thus necessitating a new genus name. It is generally considered the most basal known dipnoan, although some other studies instead find '' Youngolepis'' to be more basal. In addition, some studies do not find it to be a lungfish, but rather a more basal dipnotetrapodomorph. However, other studies have continued to recove ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lungfish
Lungfish are freshwater vertebrates belonging to the class Dipnoi. Lungfish are best known for retaining ancestral characteristics within the Osteichthyes, including the ability to breathe air, and ancestral structures within Sarcopterygii, including the presence of lobed fins with a well-developed internal skeleton. Lungfish represent the closest living relatives of the tetrapods (which includes living amphibians, reptiles, birds and mammals). The mouths of lungfish typically bear tooth plates, which are used to crush hard shelled organisms. Today there are only six known species of lungfish, living in Africa, South America, and Australia, though they were formerly globally distributed. The fossil record of the group extends into the Early Devonian, over 410 million years ago. The earliest known members of the group were marine, while almost all post-Carboniferous representatives inhabit freshwater environments. Etymology Dipnoi is Modern Latin derived from the Greek δίπν ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lymph
Lymph () is the fluid that flows through the lymphatic system, a system composed of lymph vessels (channels) and intervening lymph nodes whose function, like the venous system, is to return fluid from the tissues to be recirculated. At the origin of the fluid-return process, interstitial fluid—the fluid between the cells in all body tissues—enters the lymph capillaries. This lymphatic fluid is then transported via progressively larger lymphatic vessels through lymph nodes, where substances are removed by tissue lymphocytes and circulating lymphocytes are added to the fluid, before emptying ultimately into the right or the left subclavian vein, where it mixes with central venous blood. Because it is derived from interstitial fluid, with which blood and surrounding cells continually exchange substances, lymph undergoes continual change in composition. It is generally similar to blood plasma, which is the fluid component of blood. Lymph returns proteins and excess interstiti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dipnomorpha
Rhipidistia, also known as Dipnotetrapodomorpha, is a clade of lobe-finned fishes which includes the tetrapods and lungfishes. Rhipidistia formerly referred to a subgroup of Sarcopterygii consisting of the Porolepiformes and Osteolepiformes, a definition that is now obsolete. However, as cladistic understanding of the vertebrates has improved over the last few decades, a monophyletic Rhipidistia is now understood to include the whole of Tetrapoda and the lungfishes. Rhipidistia includes Porolepiformes and Dipnoi. Extensive fossilization of lungfishes has contributed to many evolutionary studies of this group. Evolution of autostylic jaw suspension, in which the palatoquadrate bone fuses to the cranium, and the lymph pumping " lymph heart" (later lost in mammals and flying birds), are unique to this group. Another feature shared by lungfish and tetrapods is the divided atrium. The precise time at which the choana of tetrapods evolved is debated, with some considering early ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Styloichthys
''Styloichthys'' (Greek: ''stylo'' "pillar" and ''ichthys'' "fish"; "Pillar fish") is a prehistoric sarcopterygian, lobe-finned fish which lived during the Early Devonian (Lochkovian) period of East Yunnan, South China. Because it is clear that the jaws and skull of ''Styloichthys'' share many derived features with coelacanthiformes it is placed as the oldest coelacanth. Description ''Styloichthys'' is characterized by large pores on the cosmine surface. These pores are often spoon-shaped and arranged in parallel grooves. There is a jagged margin between ethmosphenoid and otoccipital shields, an otoccipital with a wide flat surface carrying no vestibular fontanelle A fontanelle (or fontanel) (colloquially, soft spot) is an anatomical feature of the infant human skull comprising soft membranous gaps ( sutures) between the cranial bones that make up the calvaria of a fetus or an infant. Fontanelles allow .... The snout bends sharply downward and is slightly concave. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Actinistia
Coelacanths ( ) are an ancient group of lobe-finned fish (Sarcopterygii) in the class Actinistia. As sarcopterygians, they are more closely related to lungfish and tetrapods (the terrestrial vertebrates including living amphibians, reptiles, birds and mammals) than to ray-finned fish. The name coelacanth originates from the Permian genus '' Coelacanthus'', which was the first scientifically named genus of coelacanths (in 1839), becoming the type genus of Coelacanthiformes as other species were discovered and named. Well-represented in freshwater and marine deposits from as early as the Devonian period (more than 410million years ago), they were thought to have become extinct in the Late Cretaceous, around 66million years ago. The first living species, ''Latimeria chalumnae'', the West Indian Ocean coelacanth, was described from specimens fished off the coast of South Africa from 1938 onward; they are now also known to inhabit the seas around the Comoro Islands off the eas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Combining Form
Neoclassical compounds are compound words composed from combining forms (which act as affixes or stems) derived from classical languages (classical Latin or ancient Greek) roots. Neo-Latin comprises many such words and is a substantial component of the technical and scientific lexicon of English and other languages, via international scientific vocabulary (ISV). For example, Greek '' bio-'' combines with ''-graphy'' to form ''biography'' ("life" + "writing/recording"). Source of international technical vocabulary Neoclassical compounds represent a significant source of Neo-Latin vocabulary. Moreover, since these words are composed from classical languages whose prestige is or was respected throughout the Western European culture, these words typically appear in many different languages. Their widespread use makes technical writing generally accessible to readers who may only have a smattering of the language in which it appears. Not all European languages have been equally re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bellows
A bellows or pair of bellows is a device constructed to furnish a strong blast of air. The simplest type consists of a flexible bag comprising a pair of rigid boards with handles joined by flexible leather sides enclosing an approximately airtight cavity which can be expanded and contracted by operating the handles, and fitted with a valve allowing air to fill the cavity when expanded, and with a tube through which the air is forced out in a stream when the cavity is compressed. It has many applications, in particular blowing on a fire to supply it with air. The term "bellows" is used by extension for a flexible bag whose volume can be changed by compression or expansion, but not used to deliver air. For example, the light-tight (but not airtight) bag allowing the distance between the lens and film of a folding photographic camera to be varied is called a bellows. Etymology "Bellows" is only used in plural. The Old English name for "bellows" was , 'blast-bag', 'blowing-ba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Convergent Evolution
Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last common ancestor of those groups. The cladistic term for the same phenomenon is Cladogram#Homoplasies, homoplasy. The recurrent evolution of flight is a classic example, as flying pterygota, insects, birds, pterosaurs, and bats have independently evolved the useful capacity of flight. Functionally similar features that have arisen through convergent evolution are ''analogous'', whereas ''homology (biology), homologous'' structures or traits have a common origin but can have dissimilar functions. Bird, bat, and pterosaur wings are analogous structures, but their forelimbs are homologous, sharing an ancestral state despite serving different functions. The opposite of convergence is divergent evolution, where related species evolve different trai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Choana
The choanae (: choana), posterior nasal apertures or internal nostrils are two openings found at the back of the nasal passage between the nasal cavity and the pharynx, in humans and other mammals (as well as crocodilians and most skinks). They are considered one of the most important synapomorphies of tetrapodomorphs, that allowed the passage from water to land. In animals with secondary palates, they allow breathing when the mouth is closed. Janvier, Philippe (2004) "Wandering nostrils". ''Nature'', 432 (7013): 23–24. In tetrapods without secondary palates their function relates primarily to olfaction (sense of smell). The choanae are separated in two by the vomer. Boundaries A choana is the opening between the nasal cavity and the nasopharynx. It is therefore not a structure but a space bounded as follows: * anteriorly and inferiorly by the horizontal plate of palatine bone, * superiorly and posteriorly by the sphenoid bone * laterally by the medial pterygoid pla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atrium (heart)
The atrium (; : atria) is one of the two Heart#Chambers, upper chambers in the heart that receives blood from the circulatory system. The blood in the atria is pumped into the Ventricle (heart), heart ventricles through the atrioventricular valve, atrioventricular mitral valve, mitral and tricuspid valve, tricuspid heart valves. There are two atria in the human heart – the left atrium receives blood from the pulmonary circulation, and the right atrium receives blood from the venae cavae of the systemic circulation. During the cardiac cycle, the atria receive blood while relaxed in diastole, then contract in systole to move blood to the ventricles. Each atrium is roughly cube-shaped except for an ear-shaped projection called an atrial appendage, previously known as an auricle. All animals with a closed circulatory system have at least one atrium. The atrium was formerly called the 'auricle'. That term is still used to describe this chamber in some other animals, such as the ''Mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
