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Stegotetrabelodontinae
Elephantidae is a family of large, herbivorous proboscidean mammals which includes the living elephants (belonging to the genera ''Elephas'' and '' Loxodonta''), as well as a number of extinct genera like ''Mammuthus'' (mammoths) and ''Palaeoloxodon''. They are large terrestrial mammals with a snout modified into a trunk and teeth modified into tusks. Most genera and species in the family are extinct. The family was first described by John Edward Gray in 1821, and later assigned to taxonomic ranks within the order Proboscidea. Elephantidae has been revised by various authors to include or exclude other extinct proboscidean genera. Description Elephantids are distinguished from more basal proboscideans like gomphotheres by their teeth, which have parallel lophs, formed from the merger of the cusps found in the teeth of more basal proboscideans, which are bound by cementum. In later elephantids, these lophs became narrow lamellae/plates, which are pockets of enamel filled wit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asian Elephant
The Asian elephant (''Elephas maximus''), also known as the Asiatic elephant, is the only living ''Elephas'' species. It is the largest living land animal in Asia and the second largest living Elephantidae, elephantid in the world. It is characterised by its long Elephant trunk, trunk with a single finger-like processing; large tusks in males; laterally folded large ears and wrinkled grey skin that is partly depigmented on the trunk, ears or neck. Adult males average in weight and females . It has a large and well developed neocortex of the brain, is highly intelligent and self-aware being able to display behaviours associated with grief, learning and greeting. Three subspecies are recognised—''Sri Lankan elephant, E. m. maximus'', Indian elephant, ''E. m. indicus'' and ''Sumatran elephant, E. m. sumatranus''. The Asian elephant is distributed in the Indian subcontinent and Southeast Asia, from India in the west to Borneo in the east, and Nepal in the north to Sumatra in th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tusk
Tusks are elongated, continuously growing front teeth that protrude well beyond the mouth of certain mammal species. They are most commonly canine tooth, canine teeth, as with Narwhal, narwhals, chevrotains, musk deer, water deer, muntjac, pigs, peccary, peccaries, hippopotamuses 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 Helix, helical tusk, which usually grows out from the left of the mouth, is an exception to the typical features of tusks describ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sexually Dimorphic
Sexual dimorphism is the condition where sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, dioecious species, which consist of most animals and some plants. Differences may include secondary sex characteristics, size, weight, color, markings, or behavioral or cognitive traits. Male-male reproductive competition has evolved a diverse array of sexually dimorphic traits. Aggressive utility traits such as "battle" teeth and blunt heads reinforced as battering rams are used as weapons in aggressive interactions between rivals. Passive displays such as ornamental feathering or song-calling have also evolved mainly through sexual selection. These differences may be subtle or exaggerated and may be subjected to sexual selection and natural selection. The opposite of dimorphism is ''monomorphism'', when both biological sexes are phenotype, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
African Bush Elephant
The African bush elephant (''Loxodonta africana''), also known as the African savanna elephant, is a species of elephant native to sub-Saharan Africa. It is one of three extant elephant species and, along with the African forest elephant, one of two extant species of African elephant. It is the largest living terrestrial animal, with fully grown bulls reaching an average shoulder height of and a body mass of ; the largest recorded specimen had a shoulder height of and an estimated body mass of . The African bush elephant is characterised by its long prehensile trunk with two finger-like processes; a convex back; large ears which help reduce body heat; and sturdy tusks that are noticeably curved. The skin is grey with scanty hairs, and bending cracks which support thermoregulation by retaining water. The African bush elephant inhabits a variety of habitats such as forests, grasslands, woodlands, wetlands and agricultural land. It is a mixed herbivore feeding mostly on grasse ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gomphothere
Gomphotheres are an extinct group of proboscideans related to modern elephants. First appearing in Africa during the Oligocene, they dispersed into Eurasia and North America during the Miocene and arrived in South America during the Pleistocene as part of the Great American Interchange. Gomphotheres are a paraphyletic group ancestral to Elephantidae, which contains modern elephants, as well as Stegodontidae. While most famous forms such as '' Gomphotherium'' had long lower jaws with tusks, the ancestral condition for the group, some later members developed shortened (brevirostrine) lower jaws with either vestigial or no lower tusks and outlasted the long-jawed gomphotheres. This change made them look very similar to modern elephants, an example of parallel evolution. During the Pliocene and Early Pleistocene, the diversity of gomphotheres declined, ultimately becoming extinct outside of the Americas. The last two genera, '' Cuvieronius'' ranging southern North America to weste ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetralophodon
''Tetralophodon'' ("four-ridged tooth") is an extinct genus of "tetralophodont gomphothere" belonging to the superfamily Elephantoidea, known from the Miocene of Afro-Eurasia. Taxonomy and evolution The genus ''Tetralophodon'' (meaning "four-ridged tooth") was named in the mid-19th century with the discovery of the specialized teeth. ''Tetralophodon'' is suggested to have descended from the "trilophodont gomphothere" ''Gomphotherium.'' "Tetralophodont gomphotheres" like ''Tetralophodon'' are thought to be ancestral to Elephantidae, elephantids and Stegodontidae, stegodontids,'''' with African species of ''Tetralophodon'' suggested to be the ancestor of elephantids. ''Tetralophodon'' is also suggested to be the ancestor of the fellow "tetralophodont gomphothere" ''Anancus''. Description A large individual of the European species ''T. longirostris'' is suggested to have been tall at the shoulder and up to 10 tonnes in weight. The first and second molar teeth are tetralophodont (b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypsodont
Hypsodont is a pattern of dentition characterized by with high crowns, providing extra material for wear and tear. Some examples of animals with hypsodont dentition are cows and horses; all animals that feed on gritty, fibrous material. The opposite condition is called brachydont. Evolution Since the morphology of the hypsodont tooth is suited to a more abrasive diet, hypsodonty was thought to have evolved concurrently with the spread of grasslands. Grass contains phytoliths, silica-rich granules, which wear away dental tissue more quickly. Analysis has shown, however, that the development of this morphology is out of sync with the spread and flourishing of grasslands. Instead, the ingestion of grit and soil is hypothesized to be the primary driver of hypsodonty, a hypothesis termed the grit, not grass hypothesis. Morphology Hypsodont dentition is characterized by: * high-crowned teeth * A rough, flattish occlusal surface adapted for crushing and grinding * Cementum both ab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Concertina
A concertina is a free-reed musical instrument, like the various accordions and the harmonica. It consists of expanding and contracting bellows, with buttons (or keys) usually on both ends, unlike accordion buttons, which are on the front. The concertina was developed independently in both England and Germany. The English version was invented in 1829 by Sir Charles Wheatstone, while Carl Friedrich Uhlig introduced the German version five years later, in 1834. Various forms of concertina are used for classical music, for the traditional music of Ireland, England, and South Africa, and for tango and polka music. The concertina has historically been a favorite instrument among people who travel often (due to its small and compact size), leading it to be a common instrument among soldiers, sailors, and cowboys. One was even brought aboard Robert Peary's 1891 expedition of the Greenland Arctic. Despite the pop-culture association of the concertina with the Golden Age of Piracy, t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dentin
Dentin ( ) (American English) or dentine ( or ) (British English) () is a calcified tissue (biology), tissue of the body and, along with tooth enamel, enamel, cementum, and pulp (tooth), pulp, is one of the four major components of teeth. It is usually covered by enamel on the crown and cementum on the root and surrounds the entire pulp. By volume, 45% of dentin consists of the mineral hydroxyapatite, 33% is organic material, and 22% is water. Yellow in appearance, it greatly affects the color of a tooth due to the translucency of enamel. Dentin, which is less mineralized and less brittle than enamel, is necessary for the support of enamel. Dentin rates approximately 3 on the Mohs scale of mineral hardness. There are two main characteristics which distinguish dentin from enamel: firstly, dentin forms throughout life; secondly, dentin is sensitive and can become hypersensitive to changes in temperature due to the sensory function of odontoblasts, especially when enamel recedes an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tooth Enamel
Tooth enamel is one of the four major Tissue (biology), tissues that make up the tooth in humans and many animals, including some species of fish. It makes up the normally visible part of the tooth, covering the Crown (tooth), crown. The other major tissues are dentin, cementum, and Pulp (tooth), dental pulp. It is a very hard, white to off-white, highly mineralised substance that acts as a barrier to protect the tooth but can become susceptible to degradation, especially by acids from food and drink. In rare circumstances enamel fails to form, leaving the underlying dentin exposed on the surface. Features Enamel is the hardest substance in the human body and contains the highest percentage of minerals (at 96%),Ross ''et al.'', p. 485 with water and organic material composing the rest.Ten Cate's Oral Histology, Nancy, Elsevier, pp. 70–94 The primary mineral is hydroxyapatite, which is a crystalline calcium phosphate. Enamel is formed on the tooth while the tooth develops wit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cementum
Cementum is a specialized calcified substance covering the root of a tooth. The cementum is the part of the periodontium that attaches the teeth to the alveolar bone by anchoring the periodontal ligament. Structure The cells of cementum are the entrapped cementoblasts, the cementocytes. Each cementocyte lies in its lacuna, similar to the pattern noted in bone. These lacunae also have canaliculi or canals. Unlike those in bone, however, these canals in cementum do not contain nerves, nor do they radiate outward. Instead, the canals are oriented toward the periodontal ligament and contain cementocytic processes that exist to diffuse nutrients from the ligament because it is vascularized. After the apposition of cementum in layers, the cementoblasts that do not become entrapped in cementum line up along the cemental surface along the length of the outer covering of the periodontal ligament. These cementoblasts can form subsequent layers of cementum if the tooth is injured. Sh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gomphotheres
Gomphotheres are an extinct group of proboscideans related to modern Elephant, elephants. First appearing in Africa during the Oligocene, they dispersed into Eurasia and North America during the Miocene and arrived in South America during the Pleistocene as part of the Great American Interchange. Gomphotheres are a Paraphyly, paraphyletic group ancestral to Elephantidae, which contains modern elephants, as well as Stegodontidae. While most famous forms such as ''Gomphotherium'' had long lower jaws with tusks, the Plesiomorphy and symplesiomorphy, ancestral condition for the group, some later members developed shortened (brevirostrine) lower jaws with either vestigial or no lower tusks and outlasted the long-jawed gomphotheres. This change made them look very similar to modern elephants, an example of parallel evolution. During the Pliocene and Early Pleistocene, the diversity of gomphotheres declined, ultimately becoming extinct outside of the Americas. The last two genera, ''Cuv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
