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Skull Roof
The skull roof or the roofing bones of the skull are a set of bones covering the brain, eyes and nostrils in bony fishes, including land-living vertebrates. The bones are derived from dermal bone and are part of the dermatocranium. In comparative anatomy, the term is applied to the whole dermatocranium. Romer, A.S. & T.S. Parsons. 1977. ''The Vertebrate Body.'' 5th ed. Saunders, Philadelphia. (6th ed. 1985) In general anatomy, the roofing bones may refer specifically to the bones that form above and alongside the brain and neurocranium (i.e., excluding the marginal upper jaw bones such as the maxilla and premaxilla). In human anatomy, the skull roof often refers specifically to the skullcap. Origin Early armoured fish (such as jawless ostracoderms and jawed placoderms) did not have a skull in the common understanding of the word, but instead had a cartilaginous endocranium that was partially open from above. The loose cartilage was topped by dermal bones forming armo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xenotosuchus Skull Roof
''Xenotosuchus'' is an extinct genus of mastodonsaurid temnospondyl within the family Mastodonsauridae known from the Triassic of South Africa. The genus is based on a skull originally described as '' Parotosuchus'', an animal which it resembled in general build and habit. Description Like many mastodontosaurids, it was a large animal with a large head. Its amphibian life history meant that the distinct shape of the skull roof would change from a generalized tadpole-like skull type through to the distinct adult shape. The head bones are covered in large pits and grooves, indicating extensive dermal armour on the head. Both the upper and lower jaw had tusks, those of the upper jaw being situated on a 2nd row of teeth on the vomer and palatine bone. Contrary to related forms like '' Mastodonsaurus'', the tusks of the lower jaw were of moderate size and did not penetrate the premaxilla. See also * Prehistoric amphibian * List of prehistoric amphibians This list of prehistoric a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Armour (zoology)
Armor or armour in animals is a rigid cuticle or exoskeleton that provides exterior protection against attack by predators, formed as part of the body (rather than the behavioural utilization of external objects for protection) usually through the thickening and hardening of superficial tissues, outgrowths or skin secretions. It is often found in prey species that are too slow or clumsy to outrun predators, or those that would stand their ground and fight, thus needing to protect vital organs against claw, talon or bite injuries. Composition Armoured structures are usually composed of hardened mineral deposits, chitin, bone, or keratin. Species with armour Armour is evident in numerous animal species from both current and prehistoric times. Dinosaurs such as '' Ankylosaurus'', as well as other Thyreophora (armoured dinosaurs such as Ankylosauria and Stegosauria), grew thick plate-like armour on their bodies as well as offensive armour appendages such as the thagomizer or a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetrapodomorpha
Tetrapodomorpha (also known as Choanata) is a clade of vertebrates consisting of tetrapods (four-limbed vertebrates) and their closest sarcopterygian relatives that are more closely related to living tetrapods than to living lungfish. Advanced forms transitional between fish and the early labyrinthodonts, such as '' Tiktaalik'', have been referred to as "fishapods" by their discoverers, being half-fish, half-tetrapods, in appearance and limb morphology. The Tetrapodomorpha contains the crown group tetrapods (the last common ancestor of living tetrapods and all of its descendants) and several groups of early stem tetrapods, which includes several groups of related lobe-finned fishes, collectively known as the osteolepiforms. The Tetrapodomorpha minus the crown group Tetrapoda are the stem Tetrapoda, a paraphyletic unit encompassing the fish to tetrapod transition. Characteristics Among the characteristics defining tetrapodomorphs are modifications to the fins, notably a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cheliderpeton Skull2
''Cheliderpeton'' (often misspelled ''Chelyderpeton'') is an extinct genus of temnospondyl amphibian. It lived during the Early Permian in what is now Europe. Fossils have been found from the Ruprechtice horizon of the Intrasudetic Basin of Bohemia in the Czech Republic, as well as the Saar-Nahe Basin of southwestern Germany. ''Cheliderpeton'' had a 16 cm skull, and reached about 65 cm in length.http://www.angellis.net/Web/PDfiles/amphs.pdf The type species of ''Cheliderpeton'' is ''Chelidosaurus vranyi'', named in 1877 by the Czech (people), Czech paleontologist Antonin Fritsch and found from the Czech Republic. The preoccupied generic name, referring to the trunk armour of turtles, was first changed into ''Chelydosaurus'' in 1885 and finally into ''Cheliderpeton'' in 1887. A second species named ''C. latirostre'' was described in 1993 by J. A. Boy from Germany, after having been assigned to ''Archegosaurus''. It differs from the type in having a less extensive preor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Actinopterygii
Actinopterygii (; ), members of which are known as ray-finned fish or actinopterygians, is a class (biology), class of Osteichthyes, bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fish fin, fins made of webbings of skin supported by radially extended thin bony spine (zoology), spines called ''lepidotrichia'', as opposed to the bulkier, fleshy lobed fins of the sister taxon, sister clade Sarcopterygii (lobe-finned fish). Resembling folding fans, the actinopterygian fins can easily change shape and wetted area, providing superior thrust-to-weight ratios per movement compared to sarcopterygian and chondrichthyian fins. The fin rays attach directly to the proximal or basal skeletal elements, the radials, which represent the articulation (anatomy), articulation between these fins and the internal skeleton (e.g., pelvic and pectoral girdles). The vast majority of actinopterygians are teleosts. By species count, they domi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Robert L
The name Robert is an ancient Germanic given name, from Proto-Germanic "fame" and "bright" (''Hrōþiberhtaz''). Compare Old Dutch ''Robrecht'' and Old High German ''Hrodebert'' (a compound of '' Hruod'' () "fame, glory, honour, praise, renown, godlike" and ''berht'' "bright, light, shining"). It is the second most frequently used given name of ancient Germanic origin.Reaney & Wilson, 1997. ''Dictionary of English Surnames''. Oxford University Press. It is also in use as a surname. Another commonly used form of the name is Rupert. After becoming widely used in Continental Europe, the name entered England in its Old French form ''Robert'', where an Old English cognate form (''Hrēodbēorht'', ''Hrodberht'', ''Hrēodbēorð'', ''Hrœdbœrð'', ''Hrœdberð'', ''Hrōðberχtŕ'') had existed before the Norman Conquest. The feminine version is Roberta. The Italian, Portuguese, and Spanish form is Roberto. Robert is also a common name in many Germanic languages, including En ... [...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] |
Operculum (fish)
The operculum is a series of bones found in bony fish and chimaeras that serves as a facial support structure and a protective covering for the gills; it is also used for respiration and feeding. Anatomy The opercular series contains four bone segments known as the preoperculum, suboperculum, interoperculum and operculum. The preoperculum is a crescent-shaped structure that has a series of ridges directed posterodorsally to the organism’s canal pores. The preoperculum can be located through an exposed condyle that is present immediately under its ventral margin; it also borders the operculum, suboperculum, and interoperculum posteriorly. The suboperculum is rectangular in shape in most bony fish and is located ventral to the preoperculum and operculum components. It is the thinnest bone segment out of the opercular series and is located directly above the gills. The interoperculum is triangular shaped and borders the suboperculum posterodorsally and the preoperculum anterodo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sarcopterygii
Sarcopterygii (; )—sometimes considered synonymous with Crossopterygii ()—is a clade (traditionally a class (biology), class or subclass) of vertebrate animals which includes a group of bony fish commonly referred to as lobe-finned fish. These vertebrates are characterised by prominent muscular limb buds (lobes) within their fish fin, fins, which are supported by articulated appendicular skeletons. This is in contrast to the other clade of bony fish, the Actinopterygii, which have only skin-covered lepidotrichia, bony spines supporting the fins. The tetrapods, a mostly terrestrial animal, terrestrial clade of vertebrates, are now recognized as having evolved from sarcopterygian ancestors and are most closely related to lungfishes. Their paired pectoral fins, pectoral and pelvic fins evolved into limb (anatomy), limbs, and their lung bud, foregut diverticulum eventually evolved into air-breathing lungs. Cladistics, Cladistically, this would make the tetrapods a subgroup within ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Platycephalichthys
''Platycephalichthys'' is a genus of tristichopterid lobe-finned fish which lived during the Upper Devonian, Frasnian stage. Phylogeny Below is a cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ... from Swartz, 2012: See also * References Prehistoric lobe-finned fish genera Eotetrapodiformes Devonian bony fish {{paleo-lobefinned-fish-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cartilage
Cartilage is a resilient and smooth type of connective tissue. Semi-transparent and non-porous, it is usually covered by a tough and fibrous membrane called perichondrium. In tetrapods, it covers and protects the ends of long bones at the joints as articular cartilage, and is a structural component of many body parts including the rib cage, the neck and the bronchial tubes, and the intervertebral discs. In other taxa, such as chondrichthyans and cyclostomes, it constitutes a much greater proportion of the skeleton. It is not as hard and rigid as bone, but it is much stiffer and much less flexible than muscle. The matrix of cartilage is made up of glycosaminoglycans, proteoglycans, collagen fibers and, sometimes, elastin. It usually grows quicker than bone. Because of its rigidity, cartilage often serves the purpose of holding tubes open in the body. Examples include the rings of the trachea, such as the cricoid cartilage and carina. Cartilage is composed of specialized c ... [...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] |
