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Stanocephalosaurus
''Stanocephalosaurus'' (stano from Greek stenos, meaning “narrow”, cephalo from Greek kephalē, meaning “head”) is an extinct genus of large-sized temnospondyl amphibians living through the early to mid Triassic. The etymology of its name most likely came from its long narrow skull when compared to other temnospondyls. ''Stanocephalosaurus'' lived an aquatic lifestyle, with some species even living in salt lakes. There are currently three recognized species and another that needs further material to establish its legitimacy. The three known species are ''Stanocephalosaurus pronus'' from the Middle Triassic in Tanzania, ''Stanocephalosaurus amenasensis'' from the Lower Triassic in Algeria, and ''Stanocephalosaurus birdi'', from the middle Triassic in Arizona. ''Stanocephalosaurus rajareddyi'' from the Middle Triassic in central India needs further evidence in order to establish its relationship among other Stanocephalosaurs. Like other temnospondyls, ''Stanocephalosaurus' ...
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Mastodonsauridae
Mastodonsauridae is a family of capitosauroid temnospondyls. Fossils belonging to this family have been found in North America, Greenland, Europe, Asia, and Australia. The family Capitosauridae is synonymous with Mastodonsauridae. Description Size Mastodonsaurids were generally large amphibians, with some length estimates ranging from 3 to 6 meters. Some genera, like ''Mastodonsaurus'' and ''Cyclotosaurus'' were specially large, reaching at least 4 meters or more. Other genera like ''Parotosuchus'' and '' Paracyclotosaurus'' only reached 2 meters or more in length, but it's still pretty large compared to modern-day amphibians. Distinguishing features Some mastodonsaurids including ''Parotosuchus'' were covered in a scaly skin, unlike the smooth skin of modern-day amphibians, and probably moved with an eel-like motion in the water. Another peculiar mastodonsaurid is ''Sclerothorax'', with unusual features including its elongated neural spines. The neural spines are tallest at ...
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Temnospondyli
Temnospondyli (from Greek τέμνειν, ''temnein'' 'to cut' and σπόνδυλος, ''spondylos'' 'vertebra') is a diverse order of small to giant tetrapods—often considered primitive amphibians—that flourished worldwide during the Carboniferous, Permian, and Triassic periods. A few species continued into the Jurassic and Cretaceous periods. Fossils have been found on every continent. During about 210 million years of evolutionary history, they adapted to a wide range of habitats, including freshwater, terrestrial, and even coastal marine environments. Their life history is well understood, with fossils known from the larval stage, metamorphosis, and maturity. Most temnospondyls were semiaquatic, although some were almost fully terrestrial, returning to the water only to breed. These temnospondyls were some of the first vertebrates fully adapted to life on land. Although temnospondyls are considered amphibians, many had characteristics, such as scales and armour-like bo ...
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Anisian
In the geologic timescale, the Anisian is the lower stage or earliest age of the Middle Triassic series or epoch and lasted from million years ago until million years ago. The Anisian Age succeeds the Olenekian Age (part of the Lower Triassic Epoch) and precedes the Ladinian Age. Stratigraphic definitions The stage and its name were established by Austrian geologists Wilhelm Heinrich Waagen and Carl Diener in 1895. The name comes from ''Anisus'', the Latin name of the river Enns. The original type locality is at Großreifling in the Austrian state of Styria. The base of the Anisian Stage (also the base of the Middle Triassic series) is sometimes laid at the first appearance of conodont species ''Chiosella timorensis'' in the stratigraphic record. Other stratigraphers prefer to use the base of magnetic chronozone MT1n. There is no accepted global reference profile for the base, but one ( GSSP or golden spike) was proposed at a flank of the mountain Deşli Caira in th ...
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Barnum Brown
Barnum Brown (February 12, 1873 – February 5, 1963), commonly referred to as Mr. Bones, was an American paleontologist. Named after the circus showman P. T. Barnum, he discovered the first documented remains of ''Tyrannosaurus'' during a career that made him one of the most famous fossil hunters working from the late Victorian era into the early 20th century. Fossil dinosaur expeditions Sponsored by the American Museum of Natural History (AMNH), Brown traversed the country bargaining and trading for fossils. His field was not limited to dinosaurs. He was known to collect or obtain anything of possible scientific value. Often, he simply sent money to have fossils shipped to the AMNH, and any new specimen of interest often resulted in a flurry of letters between the discoverer and Brown. After working a handful of years in Wyoming for AMNH in the late 1890s, Brown led an expedition to the Hell Creek Formation of southeastern Montana. There, in 1902, he discovered and excava ...
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Tetrapod
Tetrapods (; ) are four-limb (anatomy), limbed vertebrate animals constituting the superclass Tetrapoda (). It includes extant taxon, extant and extinct amphibians, sauropsids (reptiles, including dinosaurs and therefore birds) and synapsids (pelycosaurs, extinct therapsids and all extant mammals). Tetrapods evolved from a clade of primitive semiaquatic animals known as the Tetrapodomorpha which, in turn, evolved from ancient lobe-finned fish (sarcopterygians) around 390 million years ago in the Middle Devonian, Middle Devonian period; their forms were transitional between lobe-finned fishes and true four-limbed tetrapods. Limbed vertebrates (tetrapods in the broad sense of the word) are first known from Middle Devonian trackways, and body fossils became common near the end of the Late Devonian but these were all aquatic. The first crown group, crown-tetrapods (last common ancestors of extant tetrapods capable of terrestrial locomotion) appeared by the very early Mississippian ( ...
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Stapes
The ''stapes'' or stirrup is a bone in the middle ear of humans and other animals which is involved in the conduction of sound vibrations to the inner ear. This bone is connected to the oval window by its annular ligament, which allows the footplate to transmit sound energy through the oval window into the inner ear. The ''stapes'' is the smallest and lightest bone in the human body, and is so-called because of its resemblance to a stirrup ( la, Stapes). Structure The ''stapes'' is the third bone of the three ossicles in the middle ear and the smallest in the human body. It measures roughly , greater along the head-base span. It rests on the oval window, to which it is connected by an annular ligament and articulates with the '' incus'', or anvil through the incudostapedial joint. They are connected by anterior and posterior limbs ( la, crura). Development The ''stapes'' develops from the second pharyngeal arch during the sixth to eighth week of embryological life. Th ...
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X-ray Microtomography
X-ray microtomography, like tomography and X-ray computed tomography, uses X-rays to create cross-sections of a physical object that can be used to recreate a virtual model ( 3D model) without destroying the original object. The prefix ''micro-'' (symbol: µ) is used to indicate that the pixel sizes of the cross-sections are in the micrometre range. These pixel sizes have also resulted in the terms high-resolution X-ray tomography, micro–computed tomography (micro-CT or µCT), and similar terms. Sometimes the terms high-resolution CT (HRCT) and micro-CT are differentiated, but in other cases the term high-resolution micro-CT is used. Virtually all tomography today is computed tomography. Micro-CT has applications both in medical imaging and in industrial computed tomography. In general, there are two types of scanner setups. In one setup, the X-ray source and detector are typically stationary during the scan while the sample/animal rotates. The second setup, much more like a ...
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Maxilla
The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The two maxillary bones are fused at the intermaxillary suture, forming the anterior nasal spine. This is similar to the mandible (lower jaw), which is also a fusion of two mandibular bones at the mandibular symphysis. The mandible is the movable part of the jaw. Structure In humans, the maxilla consists of: * The body of the maxilla * Four processes ** the zygomatic process ** the frontal process of maxilla ** the alveolar process ** the palatine process * three surfaces – anterior, posterior, medial * the Infraorbital foramen * the maxillary sinus * the incisive foramen Articulations Each maxilla articulates with nine bones: * two of the cranium: the frontal and ethmoid * seven of the face: the nasal, zygomatic, lacrimal, ...
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Premaxilla
The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammal has been usually termed as the incisive bone. Other terms used for this structure include premaxillary bone or ''os premaxillare'', intermaxillary bone or ''os intermaxillare'', and Goethe's bone. Human anatomy In human anatomy, the premaxilla is referred to as the incisive bone (') and is the part of the maxilla which bears the incisor teeth, and encompasses the anterior nasal spine and alar region. In the nasal cavity, the premaxillary element projects higher than the maxillary element behind. The palatal portion of the premaxilla is a bony plate with a generally transverse orientation. The incisive foramen is bound anteriorly and laterally by the premaxilla and posteriorly by the palatine process of the maxilla. It is formed from ...
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Palatine Bone
In anatomy, the palatine bones () are two irregular bones of the facial skeleton in many animal species, located above the uvula in the throat. Together with the maxillae, they comprise the hard palate. (''Palate'' is derived from the Latin ''palatum''.) Structure The palatine bones are situated at the back of the nasal cavity between the maxilla and the pterygoid process of the sphenoid bone. They contribute to the walls of three cavities: the floor and lateral walls of the nasal cavity, the roof of the mouth, and the floor of the orbits. They help to form the pterygopalatine and pterygoid fossae, and the inferior orbital fissures. Each palatine bone somewhat resembles the letter L, and consists of a horizontal plate, a perpendicular plate, and three projecting processes—the pyramidal process, which is directed backward and lateral from the junction of the two parts, and the orbital and sphenoidal processes, which surmount the vertical part, and are separated by ...
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Vomer
The vomer (; lat, vomer, lit=ploughshare) is one of the unpaired facial bones of the skull. It is located in the midsagittal line, and articulates with the sphenoid, the ethmoid, the left and right palatine bones, and the left and right maxillary bones. The vomer forms the inferior part of the nasal septum in humans, with the superior part formed by the perpendicular plate of the ethmoid bone. The name is derived from the Latin word for a ploughshare and the shape of the bone. In humans The vomer is situated in the median plane, but its anterior portion is frequently bent to one side. It is thin, somewhat quadrilateral in shape, and forms the hinder and lower part of the nasal septum; it has two surfaces and four borders. The surfaces are marked by small furrows for blood vessels, and on each is the nasopalatine groove, which runs obliquely downward and forward, and lodges the nasopalatine nerve and vessels. Borders The ''superior border'', the thickest, presents a d ...
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Tusk
Tusks are elongated, continuously growing front teeth that protrude well beyond the mouth of certain mammal species. They are most commonly canine teeth, as with pigs and walruses, or, in the case of elephants, elongated incisors. Tusks share common features such as extra-oral position, growth pattern, composition and structure, and lack of contribution to ingestion. Tusks are thought to have adapted to the extra-oral environments, like dry or aquatic or arctic. In most tusked species both the males and the females have tusks although the males' are larger. Most mammals with tusks have a pair of them growing out from either side of the mouth. Tusks are generally curved and have a smooth, continuous surface. The male narwhal's straight single helical tusk, which usually grows out from the left of the mouth, is an exception to the typical features of tusks described above. Continuous growth of tusks is enabled by formative tissues in the apical openings of the roots of the teeth ...
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