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Cokotherium
''Cokotherium'' is an extinct genus of eutherian mammal from the Early Cretaceous of China. It includes a single species, ''Cokotherium jiufotangensis'', known from a single partial skeleton, missing a portion of the hindlimbs and tail. It was recovered from the Jiufotang Formation (120 Ma), the upper part of the fossiliferous Jehol Biota, Jehol biota. The generic name of ''Cokotherium'' honors the nickname of the late paleontologist Chuan-Kui Li, a specialist on the Jiufotang Formation. The specific name refers to the formation in question''. Cokotherium'' is one of the youngest and most well-preserved Early Cretaceous eutherians, illustrating an array of transitional conditions between Early Cretaceous and Late Cretaceous members of Eutheria. Description Dentition The incisors, though conical and Incisor procumbency, procumbent like other Early Cretaceous eutherians, are reduced in number; there are 4 in the upper jaw and 3 in the lower. Both the upper and lower Canine to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cokotherium Jaws And Teeth
''Cokotherium'' is an extinct genus of eutherian mammal from the Early Cretaceous of China. It includes a single species, ''Cokotherium jiufotangensis'', known from a single partial skeleton, missing a portion of the hindlimbs and tail. It was recovered from the Jiufotang Formation (120 Ma), the upper part of the fossiliferous Jehol Biota, Jehol biota. The generic name of ''Cokotherium'' honors the nickname of the late paleontologist Chuan-Kui Li, a specialist on the Jiufotang Formation. The specific name refers to the formation in question''. Cokotherium'' is one of the youngest and most well-preserved Early Cretaceous eutherians, illustrating an array of transitional conditions between Early Cretaceous and Late Cretaceous members of Eutheria. Description Dentition The incisors, though conical and Incisor procumbency, procumbent like other Early Cretaceous eutherians, are reduced in number; there are 4 in the upper jaw and 3 in the lower. Both the upper and lower Canine to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Early Cretaceous
The Early Cretaceous ( geochronological name) or the Lower Cretaceous (chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma. Geology Proposals for the exact age of the Barremian-Aptian boundary ranged from 126 to 117 Ma until recently (as of 2019), but based on drillholes in Svalbard the defining early Aptian Oceanic Anoxic Event 1a (OAE1a) was carbon isotope dated to 123.1±0.3 Ma, limiting the possible range for the boundary to c. 122–121 Ma. There is a possible link between this anoxic event and a series of Early Cretaceous large igneous provinces (LIP). The Ontong Java-Manihiki-Hikurangi large igneous province, emplaced in the South Pacific at c. 120 Ma, is by far the largest LIP in Earth's history. The Ontong Java Plateau today covers an area of 1,860,000 km2. In the Indian Ocean another LIP began to form at c. 120 Ma, the Kerguelen P ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Premolar
The premolars, also called premolar teeth, or bicuspids, are transitional teeth located between the canine and molar teeth. In humans, there are two premolars per quadrant in the permanent set of teeth, making eight premolars total in the mouth. They have at least two cusps. Premolars can be considered transitional teeth during chewing, or mastication. They have properties of both the canines, that lie anterior and molars that lie posterior, and so food can be transferred from the canines to the premolars and finally to the molars for grinding, instead of directly from the canines to the molars. Human anatomy The premolars in humans are the maxillary first premolar, maxillary second premolar, mandibular first premolar, and the mandibular second premolar. Premolar teeth by definition are permanent teeth distal to the canines, preceded by deciduous molars. Morphology There is always one large buccal cusp, especially so in the mandibular first premolar. The lower second ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deciduous Teeth
Deciduous teeth or primary teeth, also informally known as baby teeth, milk teeth, or temporary teeth,Illustrated Dental Embryology, Histology, and Anatomy, Bath-Balogh and Fehrenbach, Elsevier, 2011, page 255 are the first set of teeth in the growth and development of humans and other diphyodonts, which include most mammals but not elephants, kangaroos, or manatees which are polyphyodonts. Deciduous teeth develop during the embryonic stage of development and erupt (break through the gums and become visible in the mouth) during infancy. They are usually lost and replaced by permanent teeth, but in the absence of their permanent replacements, they can remain functional for many years into adulthood. Development Formation Primary teeth start to form during the embryonic phase of human life. The development of primary teeth starts at the sixth week of tooth development as the dental lamina. This process starts at the midline and then spreads back into the posterior region. B ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Entoconid
Many different terms have been proposed for features of the tooth crown in mammals. The structures within the molars receive different names according to their position and morphology. This nomenclature was developed by Henry Fairfield Osborn in 1907 and is, although with many variations, the one that continues today. * The suffix "-cones /-conids" (upper molar/lower molar) is added to the main cusps: Paraconus, Metaconus, Protoconus and Hypoconus on the upper molar, and Paraconid, Metaconid, Protoconid, Hypoconid and Entoconid on the lower molar. This name is used for both bunodont and selenodont molars, that is, as many for "buno" pillar-like cusps as for "selenes" crescent-like cusps. * The suffix "-conule /-conulid" (upper molar/lower molar) is added to the secondary cusps. For example, Metaconule, Hypoconulid. * The suffix "-style/-stylid" (upper molar/lower molar) is added to the peripheral cusps that are found in the cornices or cingulus of the tooth. These cusps are tra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Talonid
The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone tooth", from ''mola'', millstone and ''dens'', tooth. Molars show a great deal of diversity in size and shape across mammal groups. The third molar of humans is sometimes vestigial. Human anatomy In humans, the molar teeth have either four or five cusps. Adult humans have 12 molars, in four groups of three at the back of the mouth. The third, rearmost molar in each group is called a wisdom tooth. It is the last tooth to appear, breaking through the front of the gum at about the age of 20, although this varies from individual to individual. Race can also affect the age at which this occurs, with statistical variations between groups. In some cases, it may not even erupt at all. The human mouth contains upper (maxillary) and lower (mandibul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metaconid
Many different terms have been proposed for features of the tooth crown in mammals. The structures within the molars receive different names according to their position and morphology. This nomenclature was developed by Henry Fairfield Osborn in 1907 and is, although with many variations, the one that continues today. * The suffix "-cones /-conids" (upper molar/lower molar) is added to the main cusps: Paraconus, Metaconus, Protoconus and Hypoconus on the upper molar, and Paraconid, Metaconid, Protoconid, Hypoconid and Entoconid on the lower molar. This name is used for both bunodont and selenodont molars, that is, as many for "buno" pillar-like cusps as for "selenes" crescent-like cusps. * The suffix "-conule /-conulid" (upper molar/lower molar) is added to the secondary cusps. For example, Metaconule, Hypoconulid. * The suffix "-style/-stylid" (upper molar/lower molar) is added to the peripheral cusps that are found in the cornices or cingulus of the tooth. These cusps are tr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protoconid
Many different terms have been proposed for features of the tooth crown in mammals. The structures within the molars receive different names according to their position and morphology. This nomenclature was developed by Henry Fairfield Osborn in 1907 and is, although with many variations, the one that continues today. * The suffix "-cones /-conids" (upper molar/lower molar) is added to the main cusps: Paraconus, Metaconus, Protoconus and Hypoconus on the upper molar, and Paraconid, Metaconid, Protoconid, Hypoconid and Entoconid on the lower molar. This name is used for both bunodont and selenodont molars, that is, as many for "buno" pillar-like cusps as for "selenes" crescent-like cusps. * The suffix "-conule /-conulid" (upper molar/lower molar) is added to the secondary cusps. For example, Metaconule, Hypoconulid. * The suffix "-style/-stylid" (upper molar/lower molar) is added to the peripheral cusps that are found in the cornices or cingulus of the tooth. These cusps are tra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trigonid
The molars or molar teeth are large, flat tooth, teeth at the back of the mouth. They are more developed in mammal, mammals. They are used primarily to comminution, grind food during mastication, chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone tooth", from ''mola'', millstone and ''dens'', tooth. Molars show a great deal of diversity in size and shape across mammal groups. The third molar of humans is sometimes vestigial. Human anatomy In humans, the molar teeth have either four or five cusp (dentistry), cusps. Adult humans have 12 molars, in four groups of three at the back of the mouth. The third, rearmost molar in each group is called a Third molar, wisdom tooth. It is the last tooth to appear, breaking through the front of the gum at about the age of 20, although this varies from individual to individual. Race can also affect the age at which this occurs, with statistical variations between groups. In some cases, it may not even erupt a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metacone
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. Buccal Cusp- 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 no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
