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Biseridens
''Biseridens'' ("two rows of teeth") is an extinct genus of anomodont therapsid, and one of the most basal anomodont genera known. Originally known from a partial skull misidentified as an eotitanosuchian in 1997, another well-preserved skull was found in the Qingtoushan Formation in the Qilian Mountains of Gansu, China, in 2009 that clarified its relationships to anomodonts, such as the dicynodonts. Among tetrapod taxa, the therapsid clade anomodontia in which ''Biseridens'' belong has one of the largest population sizes, highest levels of diversity, and longest stratigraphic range (Middle Permian to the Triassic, possibly into the Cretaceous), as well as being one of the only clades known from all the continents. Primarily understood from the recently discovered, most-well preserved specimen, ''Biseridens'' is most notably distinguishable as an anomodont due to its short snout, dorsally elevated zygomatic arch, and presence of a septomaxilla that distinctly lacks a facial ex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anomodont
Anomodontia is an extinct group of non-mammalian therapsids from the Permian and Triassic periods. By far the most speciose group are the dicynodonts, a clade of beaked, tusked herbivores.Chinsamy-Turan, A. (2011) ''Forerunners of Mammals: Radiation - Histology - Biology''p.39.Indiana University Press, . Retrieved May 2012 Anomodonts were very diverse during the Middle Permian, including primitive forms like ''Anomocephalus'' and ''Patranomodon'' and groups like Venyukovioidea and Dromasauria. Dicynodonts became the most successful and abundant of all herbivores in the Late Permian, filling ecological niches ranging from large browsers down to small burrowers. Few dicynodont families survived the Permian–Triassic extinction event, but one lineage (Kannemeyeriiformes) evolved into large, stocky forms that became dominant terrestrial herbivores right until the Late Triassic, when changing conditions caused them to decline, finally going extinct during the Triassic-Jurassic ext ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Qingtoushan Formation
The Qingtoushan Formation is a Middle Permian-age geologic formation in the Qilian Mountains of Gansu, China. It is known for its diverse tetrapod fauna known as the Dashankou fauna, which likely dates to the Roadian, and includes some of the oldest known therapsids. This formation was previously erroneously named as the Xidagou Formation, a name which applies to otherwise Triassic strata in the northern Qillian Mountains. The formation is over 300 metres thick, and primarily consists of purple-red coarse sandstones, with minor purple mudstone Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from '' shale'' by its lack of fissility (parallel layering).Blatt, H., and R.J. Tracy, 1996, ''Petrology. ....Liu J, Qinghua S, Keqin S, Lu L (2012The horizon of Dashankou Fauna and the Permo-Triassic strata in northern Qilian area, China Vertebr Palasiat 50(4):373–381 (In Chinese) Paleobiota Sy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dicynodont
Dicynodontia is an extinct clade of anomodonts, an extinct type of non-mammalian therapsid. Dicynodonts were herbivorous animals with a pair of tusks, hence their name, which means 'two dog tooth'. Members of the group possessed a horny, typically toothless beak, unique amongst all synapsids. Dicynodonts first appeared in Southern Pangaea during the mid-Permian, ca. 270–260 million years ago, and became globally distributed and the dominant herbivorous animals in the Late Permian, ca. 260–252 Mya. They were devastated by the end-Permian Extinction that wiped out most other therapsids ca. 252 Mya. They rebounded during the Triassic but died out towards the end of that period. They were the most successful and diverse of the non-mammalian therapsids, with over 70 genera known, varying from rat-sized burrowers to elephant-sized browsers. Characteristics The dicynodont skull is highly specialised, light but strong, with the synapsid temporal openings at the rear of the skull ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dicynodonts
Dicynodontia is an extinct clade of anomodonts, an extinct type of non-mammalian therapsid. Dicynodonts were Herbivore, herbivorous animals with a pair of tusks, hence their name, which means 'two dog tooth'. Members of the group possessed a horny, typically toothless beak, unique amongst all synapsids. Dicynodonts first appeared in Southern Pangaea during the Guadalupian, mid-Permian, ca. 270–260 million years ago, and became globally distributed and the dominant herbivorous animals in the Permian, Late Permian, ca. 260–252 Mya. They were devastated by the Permian–Triassic extinction event, end-Permian Extinction that wiped out most other therapsids ca. 252 Mya. They rebounded during the Triassic but died out towards the end of that period. They were the most successful and diverse of the non-mammalian therapsids, with over 70 genus, genera known, varying from rat-sized Fossorial, burrowers to elephant-sized Browsing (herbivory), browsers. Characteristics The dicynodont s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tabular Bone
The tabular bones are a pair of triangular flat bones along the rear edge of the skull which form pointed structures known as tabular horns in primitive Teleostomi Teleostomi is an obsolete clade of jawed vertebrates that supposedly includes the tetrapods, bony fish, and the wholly extinct acanthodian fish. Key characters of this group include an operculum and a single pair of respiratory openings, featu .... References Fish anatomy Amphibian anatomy {{vertebrate-anatomy-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heterodont
In anatomy, a heterodont (from Greek, meaning 'different teeth') is an animal which possesses more than a single tooth morphology. In vertebrates, heterodont pertains to animals where teeth are differentiated into different forms. For example, members of the Synapsida generally possess incisors, canines ("eyeteeth"), premolars, and molars. The presence of heterodont dentition is evidence of some degree of feeding and or hunting specialization in a species. In contrast, homodont or isodont dentition refers to a set of teeth that possess the same tooth morphology. In invertebrates, the term heterodont refers to a condition where teeth of differing sizes occur in the hinge plate, a part of the Bivalvia Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of w .... References See also * D ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Denticle (tooth Feature)
Denticles, also called serrations, are small bumps on a tooth that serve to give the tooth a serrated edge. In paleontology, denticle characteristics such as size and density (denticles per unit distance) are used to describe and classify fossilized teeth, especially those of dinosaurs. Denticles are also present on the teeth of varanoid lizards, sharks, and mammals. The term is also used to describe the analogous radular teeth of mollusks. Archived aPDF File:Dromaeosauridae tooth.TIF, Dromaeosauridae tooth with small denticles along the cutting edge. Scale bars are 1 mm. File:Ankylosaurus tooth.jpg, ''Ankylosaurus'' tooth with large denticles. File:Dentary teeth of Segnosaurus.png, ''Segnosaurus ''Segnosaurus'' is a genus of therizinosaurid dinosaur that lived in what is now southeastern Mongolia during the Late Cretaceous, about 102–86 million years ago. Multiple incomplete but well-preserved specimens were discovered in the Go ...'' dentition featuring a tripl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 a dee ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pterygoid Processes Of The Sphenoid
The pterygoid processes of the sphenoid (from Greek ''pteryx'', ''pterygos'', "wing"), one on either side, descend perpendicularly from the regions where the body and the greater wings of the sphenoid bone unite. Each process consists of a medial pterygoid plate and a lateral pterygoid plate, the latter of which serve as the origins of the medial and lateral pterygoid muscles. The medial pterygoid, along with the masseter allows the jaw to move in a vertical direction as it contracts and relaxes. The lateral pterygoid allows the jaw to move in a horizontal direction during mastication (chewing). Fracture of either plate are used in clinical medicine to distinguish the Le Fort fracture classification for high impact injuries to the sphenoid and maxillary bones. The superior portion of the pterygoid processes are fused anteriorly; a vertical groove, the pterygopalatine fossa, descends on the front of the line of fusion. The plates are separated below by an angular cleft, the pt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Middle Permian
The Guadalupian is the second and middle series/epoch of the Permian. The Guadalupian was preceded by the Cisuralian and followed by the Lopingian. It is named after the Guadalupe Mountains of New Mexico and Texas, and dates between 272.95 ± 0.5 – 259.1 ± 0.4 Mya. The series saw the rise of the therapsids, a minor extinction event called Olson's Extinction and a significant mass extinction called the end-Capitanian extinction event. The Guadalupian was previously known as the Middle Permian. Name and background The Guadalupian is the second and middle series or epoch of the Permian. Previously called Middle Permian, the name of this epoch is part of a revision of Permian stratigraphy for standard global correlation. The name "Guadalupian" was first proposed in the early 1900s, and approved by the International Subcommission on Permian Stratigraphy in 1996. References to the Middle Permian still exist. The Guadalupian was preceded by the Cisuralian and followed by the Lop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mandibular Foramen
The mandibular foramen is an opening on the internal surface of the ramus of the mandible. It allows for divisions of the mandibular nerve and blood vessels to pass through. Structure The mandibular foramen is an opening on the internal surface of the ramus of the mandible. It allows for divisions of the mandibular nerve and blood vessels to pass through. Variation There are two distinct anatomies to its rim. * In the common form the rim is “V” shaped, with a groove separating the anterior and posterior parts. * In the horizontal-oval form there is no groove, and the rim is horizontally oriented and oval in shape, the anterior and posterior parts connected. Rarely, a bifid inferior alveolar nerve may be present, in which case a second mandibular foramen, more inferiorly placed, exists and can be detected by noting a doubled mandibular canal on a radiograph. Function The mandibular nerve is one of three branches of the trigeminal nerve, and the only one having motor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nasal Bone
The nasal bones are two small oblong bones, varying in size and form in different individuals; they are placed side by side at the middle and upper part of the face and by their junction, form the bridge of the upper one third of the nose. Each has two surfaces and four borders. Structure The two nasal bones are joined at the midline internasal suture and make up the bridge of the nose. Surfaces The ''outer surface'' is concavo-convex from above downward, convex from side to side; it is covered by the procerus and nasalis muscles, and perforated about its center by a foramen, for the transmission of a small vein. The ''inner surface'' is concave from side to side, and is traversed from above downward, by a groove for the passage of a branch of the nasociliary nerve. Articulations The nasal articulates with four bones: two of the cranium, the frontal and ethmoid, and two of the face, the opposite nasal and the maxilla. Other animals In primitive bony fish and tetrapod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
