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Cricodon
''Cricodon'' is an extinct genus of trirachodontid cynodonts that lived during the Early Triassic and Middle Triassic periods of Africa.Abdala, F., J. Neveling, and J. Welman. 2006. A new trirachodontid cynodont from the lower levels of the Burgersdorp Formation (Lower Triassic) of the Beaufort Group, South Africa and the cladistic relationships of Gondwanan gomphodonts. ''Zoological Journal of the Linnean Society'' 147:383–413. A. W. Crompton named ''Cricodon'' based on the ring-like arrangement of the cuspules on the crown of a typical postcanine tooth.Crompton, A. W. 1955. On some Triassic cynodonts from Tanganyika. ''Proceedings of the Zoological Society of London'' 125(3–4):617–669. The epithet of the type species, ''C. metabolus'', indicates the change in structure of certain postcanines resulting from replacement. Discovery ''Cricodon'' was first discovered in the Tanzanian Manda Beds of South Africa. Broili & Schröder (1936) were the first to describe ''Cricodon'', ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cynognathus Assemblage Zone
The ''Cynognathus'' Assemblage Zone is a tetrapod biozone utilized in the Karoo Basin of South Africa. It is equivalent to the Burgersdorp Formation, the youngest Lithostratigraphy, lithostratigraphic Geological formation, formation in the Beaufort Group, which is part of the fossiliferous and geologically important Karoo Supergroup. The ''Cynognathus'' Assemblage Zone is the youngest of the eight biozones found in the Beaufort Group, and is considered to be late Early Triassic (Olenekian) to early Middle Triassic (Anisian) in age (around 247 Ma). The name of the biozone refers to ''Cynognathus, Cynognathus crateronotus'', a large and carnivorous cynodont therapsid which occurs throughout the entire biozone. History The first fossils to be found in the Beaufort Group rocks that encompass the current eight biozones were discovered by Andrew Geddes Bain in 1856. However, it was not until 1892 that it was observed that the geological strata of the Beaufort Group could be different ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trirachodontid
Trirachodontidae is an extinct, possibly paraphyletic family of cynognathian cynodonts from the Triassic of China and southern Africa. Trirachodontids appeared during the Early Triassic soon after the Permian-Triassic extinction event and quickly spread over a wide geographic area in a comparatively brief amount of time from 250 to 237 million years ago. Trirachodontids have wide skulls and short, narrow snouts. Two large holes called temporal fenestrae run along the back of the head and have a uniformly large width. Trirachodontids also have two large canine teeth and smaller cusped postcanines. Most of the features that distinguish trirachodonts from other cynodonts are found in their dentition. Trirachodontids lived in semi-arid environments with seasonal rainfall. The bone structure of trirachodontids suggests that they grew quickly in seasons with high rainfall and slowly in less favorable seasons. One trirachodontid, ''Trirachodon'', has been found in association with comp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gomphodont
Gomphodontia is a clade of cynognathian cynodonts that includes the families Diademodontidae, Trirachodontidae, and Traversodontidae. Gomphodonts are distinguished by wide and closely spaced molar-like postcanine teeth, which are convergent with those of mammals. Other distinguishing characteristics of gomphodonts include deep zygomatic arches, upper postcanines with three or more cusps spanning their widths and lower postcanines with two cusps spanning their widths. They are thought to have been herbivorous or omnivorous. Gomphodonts first appeared in the Early Triassic and became extinct at the end of the Late Triassic. Fossils are known from southern Africa, Argentina and southern Brazil (Paleorrota geopark), eastern North America, Europe, China, and Antarctica. Gomphodontia was first named by paleontologist Harry Seeley in 1895. He considered it an order of wide-toothed therapsids (then called anomodonts) from South Africa, distinct from Cynodontia. By the 1930s Gomphodonti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cynodont
Cynodontia () is a clade of eutheriodont therapsids that first appeared in the Late Permian (approximately 260 Megaannum, mya), and extensively diversified after the Permian–Triassic extinction event. Mammals are cynodonts, as are their extinct ancestors and close relatives (Mammaliaformes), having evolved from advanced probainognathian cynodonts during the Late Triassic. Non-mammalian cynodonts occupied a variety of ecological niches, both as carnivores and as herbivores. Following the emergence of mammals, most other cynodont lines went extinct, with the last known non-mammaliaform cynodont group, the Tritylodontidae, having its youngest records in the Early Cretaceous. Description Early cynodonts have many of the skeletal characteristics of mammals. The teeth were fully differentiated and the braincase bulged at the back of the head. Outside of some Crown group, crown-group mammals (notably the therians), all cynodonts probably laid eggs. The temporal fenestrae#Fenestra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Manda Beds
The Manda Formation (also known as the Manda Beds) is a Middle Triassic (Anisian?) or possibly Late Triassic (Carnian?) geologic formation in Tanzania. It preserves fossils of many terrestrial vertebrates from the Triassic, including some of the earliest dinosauromorph archosaurs. The formation is often considered to be Anisian in age according to general tetrapod biochronology hypotheses and correlations to the ''Cynognathus'' Assemblage Zone of South Africa. However, some recent studies cast doubt to this age, suggesting that parts deposits may actually be younger (Carnian) in age. History of study One of the first to study rocks of the Manda Formation was British geologist G. M. Stockley. In 1932, Stockley explored the geology of the Ruhuhu Basin in Tanzania. He called a series of layers dating from the Late Carboniferous to the Middle Triassic the Songea Series and divided it into eight units labelled K1-K8. Stockley was also the first to describe fossils from these rocks, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maxillae
In vertebrates, the maxilla (: maxillae ) 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. Anatomy Structure The maxilla is a paired bone - the two maxillae unite with each other at the intermaxillary suture. The maxilla consists of: * The body of the maxilla: pyramid-shaped; has an orbital, a nasal, an infratemporal, and a facial surface; contains the maxillary sinus. * Four processes: ** the zygomatic process ** the frontal process ** the alveolar process ** the palatine process It has three surfaces: * the anterior, posterior, medial Features of the maxilla include: * the infr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Occiput
The occipital bone () is a cranial dermal bone and the main bone of the occiput (back and lower part of the skull). It is trapezoidal in shape and curved on itself like a shallow dish. The occipital bone lies over the occipital lobes of the cerebrum. At the base of the skull in the occipital bone, there is a large oval opening called the foramen magnum, which allows the passage of the spinal cord. Like the other cranial bones, it is classed as a flat bone. Due to its many attachments and features, the occipital bone is described in terms of separate parts. From its front to the back is the basilar part, also called the basioccipital, at the sides of the foramen magnum are the lateral parts, also called the exoccipitals, and the back is named as the squamous part. The basilar part is a thick, somewhat quadrilateral piece in front of the foramen magnum and directed towards the pharynx. The squamous part is the curved, expanded plate behind the foramen magnum and is the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Upper Jaw
In vertebrates, the maxilla (: maxillae ) 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. Anatomy Structure The maxilla is a paired bone - the two maxillae unite with each other at the intermaxillary suture. The maxilla consists of: * The body of the maxilla: pyramid-shaped; has an orbital, a nasal, an infratemporal, and a facial surface; contains the maxillary sinus. * Four processes: ** the zygomatic process ** the frontal process ** the alveolar process ** the palatine process It has three surfaces: * the anterior, posterior, medial Features of the maxilla include: * the infr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Posterior (anatomy)
Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek language, Greek roots, describe something in its standard anatomical position. This position provides a definition of what is at the front ("anterior"), behind ("posterior") and so on. As part of defining and describing terms, the body is described through the use of anatomical planes and anatomical axes, axes. The meaning of terms that are used can change depending on whether a vertebrate is a biped or a quadruped, due to the difference in the neuraxis, or if an invertebrate is a non-bilaterian. A non-bilaterian has no anterior or posterior surface for example but can still have a descriptor used such as proximal or distal in relation to a body part that is nearest to, or furthest from its middle. International organisations have determined vocabularies that are often used as standards for subdisciplines of anatomy. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anterior
Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position provides a definition of what is at the front ("anterior"), behind ("posterior") and so on. As part of defining and describing terms, the body is described through the use of anatomical planes and axes. The meaning of terms that are used can change depending on whether a vertebrate is a biped or a quadruped, due to the difference in the neuraxis, or if an invertebrate is a non-bilaterian. A non-bilaterian has no anterior or posterior surface for example but can still have a descriptor used such as proximal or distal in relation to a body part that is nearest to, or furthest from its middle. International organisations have determined vocabularies that are often used as standards for subdisciplines of anatomy. For example, '' Termin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palate
The palate () is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but in most other tetrapods, the oral and nasal cavities are not truly separated. The palate is divided into two parts, the anterior, bony hard palate and the posterior, fleshy soft palate (or velum). Structure Innervation The maxillary nerve branch of the trigeminal nerve supplies sensory innervation to the palate. Development The hard palate forms before birth. Variation If the fusion is incomplete, a cleft palate results. Function in humans When functioning in conjunction with other parts of the mouth, the palate produces certain sounds, particularly velar, palatal, palatalized, postalveolar, alveolopalatal, and uvular consonants. History Etymology The English synonyms palate and palatum, and also the related adjective palatine (as in palatine bone), are all from the Latin ''palatum' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cusp (anatomy)
A cusp is a pointed, projecting, or elevated feature. In animals, it is usually used to refer to raised points on the crowns of teeth. The concept is also used with regard to the leaflets of the four heart valves. The mitral valve, which has two cusps, is also known as the bicuspid valve, and the tricuspid valve has three cusps. In humans A cusp is an occlusal or incisal eminence on a tooth. Canine teeth, otherwise known as cuspids, each possess a single cusp, while premolars, otherwise known as bicuspids, possess two each. Molars normally possess either four or five cusps. In certain populations the maxillary molars, especially first molars, will possess a fifth cusp situated on the mesiolingual cusp known as the Cusp of Carabelli. One other variation of the upper first premolar is the 'Uto-Aztecan' upper premolar. It is a bulge on the buccal cusp that is only found in Native American Indians, with highest frequencies of occurrence in Arizona. The name is not a d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
