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Zygomasseteric System
The zygomasseteric system (or zygomasseteric structure) refers to the anatomical arrangement of the masseter muscle and the zygomatic arch (cheek bone) in the skulls of Rodent, rodents. This system plays a crucial role in the diverse chewing mechanics observed across rodent species. The zygomatic arch is modified to accommodate the masseter muscle, a primary muscle responsible for jaw movement. The masseter muscle itself is often divided into superficial, lateral, and medial components, allowing for a wide range of jaw motion, particularly the anteroposterior or propalinal movement (front-to-back chewing motion) characteristic of rodents. Variations in the structure of the zygomatic arch and the masseter muscle's insertion points have led to the classification of rodents into four main zygomasseteric types: protrogomorphous, sciuromorphous, hystricomorphous, and myomorphous, reflecting adaptations to different dietary niches and chewing strategies. Protrogomorphy The members of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Masseter Muscle
In anatomy, the masseter is one of the muscles of mastication. Found only in mammals, it is particularly powerful in herbivores to facilitate chewing of plant matter. The most obvious muscle of mastication is the masseter muscle, since it is the most superficial and one of the strongest. Structure The masseter is a thick, somewhat quadrilateral muscle, consisting of three heads, superficial, deep and coronoid. The fibers of superficial and deep heads are continuous at their insertion. Superficial head The superficial head, the larger, arises by a thick, tendinous aponeurosis from the zygomatic process of the maxilla, the temporal process of the zygomatic bone and from the anterior two-thirds of the inferior border of the zygomatic arch. Its fibers pass inferior and posterior, to be inserted into the angle of the mandible and inferior half of the lateral surface of the ramus of the mandible. Deep head The deep head is much smaller, and more muscular in texture. It arises from t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Castoridae
Castoridae is a family of rodents that contains the two living species of beavers and their fossil relatives. A formerly diverse group, only a single genus is extant today, ''beaver, Castor.'' Two other genera of "giant beavers", ''Castoroides'' and ''Trogontherium,'' became extinct in the Late Pleistocene. Characteristics Castorids are medium-sized mammals, although large compared with most other rodents. They are semiaquatic, with sleek bodies and webbed hind feet, and are more agile in the water than on land. Their tails are flattened and scaly, adaptations that help them manoeuvre in the water. Castorids live in small family groups that each occupy a specific territory, based around a lodge and dam constructed from sticks and mud. They are herbivores, feeding on leaves and grasses in the summer, and woody plants such as willow in the winter. They have powerful incisors and the typical rodent dentition, dental formula: Evolution The earliest castorids belong to the ge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
George's Skull1
George may refer to: Names * George (given name) * George (surname) People * George (singer), American-Canadian singer George Nozuka, known by the mononym George * George Papagheorghe, also known as Jorge / GEØRGE * George, stage name of Giorgio Moroder * George, son of Andrew I of Hungary Places South Africa * George, South Africa, a city ** George Airport United States * George, Iowa, a city * George, Missouri, a ghost town * George, Washington, a city * George County, Mississippi * George Air Force Base, a former U.S. Air Force base located in California Computing * George (algebraic compiler) also known as 'Laning and Zierler system', an algebraic compiler by Laning and Zierler in 1952 * GEORGE (computer), early computer built by Argonne National Laboratory in 1957 * GEORGE (operating system), a range of operating systems (George 1–4) for the ICT 1900 range of computers in the 1960s * GEORGE (programming language), an autocode system invented by Charles Leonar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Graphiurus
The African dormice (genus ''Graphiurus'') are dormice that live throughout sub-Saharan Africa in a variety of habitats. They are very agile climbers and have bushy tails. They primarily eat invertebrates, with other components of their diet including small vertebrates Vertebrates () are animals with a vertebral column (backbone or spine), and a cranium, or skull. The vertebral column surrounds and protects the spinal cord, while the cranium protects the brain. The vertebrates make up the subphylum Vertebra ..., fruit, nuts and eggs. They represent the most diverse living genus of dormice, making up half of all living species. Species Genus ''Graphiurus'', African dormice * Angolan African dormouse, ''Graphiurus angolensis'' * Christy's dormouse, ''Graphiurus christyi'' * Jentink's dormouse, ''Graphiurus crassicaudatus'' * Johnston's African dormouse, ''Graphiurus johnstoni'' * Kellen's dormouse, ''Graphiurus kelleni'' * Lorrain dormouse, ''Graphiurus lorraineus'' * Small ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dormouse
A dormouse is a rodent of the family Gliridae (this family is also variously called Myoxidae or Muscardinidae by different taxonomists). Dormice are nocturnal animals found in Africa, Asia, and Europe. They are named for their long, dormant hibernation period of six months or longer. There are 9 genera and 28 living species of dormice, with half of living species belonging to the African genus '' Graphiurus.'' Etymology The word dormouse comes from Middle English , of uncertain origin, possibly from a dialectal element ''*dor-'', from Old Norse and Middle English . The word is sometimes conjectured to come from an Anglo-Norman derivative of , with the second element mistaken for ''mouse'', but no such Anglo-Norman term is known to have existed. The Latin noun , which is the origin of the scientific name, descends from the Proto-Indo-European noun ''*gl̥h₁éys'' , and is related to Sanskrit () and Ancient Greek () . Characteristics Dormice are small rodents, with bod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Muroidea
The Muroidea are a large Taxonomic rank, superfamily of rodents, including mice, rats, voles, hamsters, lemmings, Gerbillinae, gerbils, and many other relatives. Although the Muroidea originated in Eurasia, they occupy a vast variety of habitat (ecology), habitats on every continent except Antarctica. Some authorities have placed all members of this group into a single family, Muridae, due to difficulties in determining how the subfamily, subfamilies are related to one another. Many of the families within the Muroidea superfamily have more variations between the families than between the different clades. A possible explanation for the variations in rodents is because of the location of these rodents; these changes could have been due to radiation or the overall environment they migrated to or originated in. The following Taxonomy (biology), taxonomy is based on recent well-supported molecular phylogeny, molecular phylogenies. The muroids are classified in six family (biology), f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dipodoidea
Dipodoidea is a Superfamily (biology), superfamily of Rodent, rodents, also known as dipodoids, found across the Northern Hemisphere. This superfamily includes over 50 species among the 16 genera in 3 families. They include the Jerboa, jerboas (family Dipodidae), Jumping mouse, jumping mice (family Zapodidae), and Birch mouse, birch mice (family Sminthidae). Different species are found in grassland, Desert, deserts, and Forest, forests. They are all capable of saltation (jumping while in a bipedal stance), a feature that is most highly evolved in the desert-dwelling jerboas. Taxonomy Formerly, Dipodoidea contained only a single large family, Dipodidae, which contained Jerboa, jerboas, Zapodidae, jumping mice, and Birch mouse, birch mice as subfamilies. However, phylogenetic evidence found all three to be distinct families from one another, and thus they were split into three different families within Dipodoidea. Characteristics Dipodoids are small to medium-sized rodents, ran ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Myomorpha
The suborder Myomorpha contains 1,524 species of mouse-like rodents, nearly a quarter of all mammal species. Included are mice, rats, gerbils, hamsters, lemmings, and voles. They are grouped according to the structure of their jaws and molar teeth. They are characterized by their myomorphous zygomasseteric system, which means that both their medial and lateral masseter muscles are displaced forward, making them adept at gnawing. As in the hystricognathous rodents, the medial masseter muscle goes through the eye socket, a feature unique among mammals. Myomorphs are found worldwide (apart from Antarctica) in almost all land habitats. They are usually nocturnal seed-eaters. Most myomorph species belong to the superfamily Muroidea: (hamsters, voles, lemmings, true mice, true rats, and gerbils). *Superfamily Muroidea **Family Platacanthomyidae ( spiny dormice and Chinese pygmy dormice) **Family Spalacidae ( blind mole-rats and bamboo rats) **Family Calomyscidae ( mouse-lik ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anomaluromorpha
Anomaluromorpha is a clade that unites the anomalures, springhares, and zenkerella. It has alternately been designated as either a suborder or infraorder. Most recently, recognized it as one of five suborders of rodents. Characteristics The suborder Anomaluromorpha was erected to unite sciurognathous rodents with a hystricomorphous zygomasseteric system restricted to sub-Saharan Africa. Many authors have suggested that the two extant families may be only distantly related, and that they belong to separate suborders or infraorders. For example, the Pedetidae are the only family of rodents with multiserial enamel except for the Hystricognathi. This characteristic, the hystricomorphous zygomatic region, and a common distribution in southern continents has led many researchers to suggest that the springhares (but not anomalures) may be allied with hystricognaths. generated some support for Anomaluromorpha in a molecular phylogeny using 12S rRNA and cytochrome b. Famili ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hystricomorpha
Hystricomorpha (from Greek ὕστριξ, ''hystrix'' 'porcupine' and Greek μορφή, ''morphē'' 'form') is a term referring to families and orders of rodents which has had many definitions throughout its history. In the broadest sense, it refers to any rodent (except dipodoids) with a hystricomorphous zygomasseteric system. This includes the Hystricognathi, Ctenodactylidae, Anomaluridae, and Pedetidae. Molecular and morphological results suggest the inclusion of the Anomaluridae and Pedetidae in Hystricomorpha may be suspect. Based on , these two families are discussed here as representing a distinct suborder Anomaluromorpha. Classification The modern definition of Hystricomorpha, also known as Entodacrya or Ctenohystrica, is a taxonomic hypothesis uniting the gundis with the hystricognath rodents. Considerable morphological and strong molecular support exists for this relationship. If true, this hypothesis renders the traditional view of Sciurognathi invalid, as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
