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Geomyoidea
Geomyoidea is a superfamily of rodent that contains the pocket gophers ( Geomyidae), the kangaroo rats and mice ( Heteromyidae), and their fossil relatives. Characteristics Although dissimilar in overall appearance, gophers have been united with kangaroo rats into a common superfamily for a considerable time. The superfamily Geomyoidea is among the few superfamilial relationships in rodents that is not subject to much controversy. Overall morphology, the fossil record, molecular analyses, and biogeography all support this relationship. Geomyoids are most noticeably characterized by the position of the infraorbital canal. Unlike all other rodents who have the opening of the infraorbital canal facing forward, geomyoids have an infraorbital canal that faces to the side. Instead of passing through the zygoma, the infraorbital canal of geomyoids has moved to the side of the snout. This condition is so pronounced and the snout so narrow in heteromyids that the infraorbital can ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heliscomyidae
Heliscomyidae is a family of extinct rodents from the mid-Tertiary of North America related to pocket gophers (family Geomyidae) and kangaroo rats and their relatives (family Heteromyidae). The family contains four genera, '' Apletotomeus'', '' Heliscomys'', '' Passaliscomys'', and '' Tylionomys'' (Korth et al., 1991; Korth and Eaton, 2004; Korth and Branciforte, 2007). McKenna and Bell (1997) placed the first two genera in synonymy, with ''Heliscomys'' the senior synonym. Characteristics Heliscomyids are distinguished from other geomyoid rodents by several characteristics of the skull including fusion of three cranial foramina, elongation of the incisive foramina, and an unusual position of the mental foramen The mental foramen is one of two foramina (openings) located on the anterior surface of the mandible. It is part of the mandibular canal. It transmits the terminal branches of the inferior alveolar nerve and the mental vessels. Structure The ... (Korth et al., ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rodent
Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are native to all major land masses except for New Zealand, Antarctica, and several oceanic islands, though they have subsequently been introduced to most of these land masses by human activity. Rodents are extremely diverse in their ecology and lifestyles and can be found in almost every terrestrial habitat, including human-made environments. Species can be arboreal, fossorial (burrowing), saltatorial/richochetal (leaping on their hind legs), or semiaquatic. However, all rodents share several morphological features, including having only a single upper and lower pair of ever-growing incisors. Well-known rodents include mice, rats, squirrels, prairie dogs, porcupines, beavers, guinea pigs, and hamsters. Rabbits, hares, and pikas, wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sciuromorphous
The zygomasseteric system (or zygomasseteric structure) in rodents is the anatomical arrangement of the masseter muscle of the jaw and the zygomatic arch of the skull. The anteroposterior or propalinal (front-to-back) motion of the rodent jaw is enabled by an extension of the zygomatic arch and the division of the masseter into a superficial, lateral and medial muscle. The four main types are described as protrogomorphous, sciuromorphous, hystricomorphous, and myomorphous.{* Protrogomorphy The members of this grade include nearly all of the pre-Oligocene rodents of North America and Asia and some of those of Europe. Several lineages survive into the Oligocene or early Miocene, with only one species still alive today, the mountain beaver ('' Aplodontia rufa''). The molerats (family Bathyergidae) are considered secondarily protrogomorphous since their zygomatic condition is clearly derived from a hystricomorphous ancestor. The rostrum of protrogomorph rodents is unmodified an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Myomorphous
The zygomasseteric system (or zygomasseteric structure) in rodents is the anatomical arrangement of the masseter muscle of the jaw and the zygomatic arch of the skull. The anteroposterior or propalinal (front-to-back) motion of the rodent jaw is enabled by an extension of the zygomatic arch and the division of the masseter into a superficial, lateral and medial muscle. The four main types are described as protrogomorphous, sciuromorphous, hystricomorphous, and myomorphous.{* Protrogomorphy The members of this grade include nearly all of the pre-Oligocene rodents of North America and Asia and some of those of Europe. Several lineages survive into the Oligocene or early Miocene, with only one species still alive today, the mountain beaver ('' Aplodontia rufa''). The molerats (family Bathyergidae) are considered secondarily protrogomorphous since their zygomatic condition is clearly derived from a hystricomorphous ancestor. The rostrum of protrogomorph rodents is unmodified an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Florentiamyidae
Florentiamyidae is a family of extinct rodents from North America. They are part of the Superfamily Geomyoidea according to R. L. Carroll 1988. They are known to have existed 33.3 to 15.97 mya. They are known from the Miocene of United States, Harrisonian of United States, Arikareean of United States, and Oligocene of Canada. Four fossil specimens from the Arikareean were obtained at the John Day Fossil Beds in Oregon Oregon () is a state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington, while the Snake River delineates much of its eastern boundary with Idaho. T .... References Geomyoid rodents Eocene rodents Eocene odd-toed ungulates Eocene mammals of North America Paleogene geology of Oregon Prehistoric rodent families John Day Fossil Beds National Monument Extinct rodents Extinct mammals of North America Eocene first appearances Eocene extinctions Rupe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beaver
Beavers are large, semiaquatic rodents in the genus ''Castor'' native to the temperate Northern Hemisphere. There are two extant species: the North American beaver (''Castor canadensis'') and the Eurasian beaver (''C. fiber''). Beavers are the second-largest living rodents after the capybaras. They have stout bodies with large heads, long chisel-like incisors, brown or gray fur, hand-like front feet, webbed back feet and flat, scaly tails. The two species differ in the shape of the skull and tail and fur color. Beavers can be found in a number of freshwater habitats, such as rivers, streams, lakes and ponds. They are herbivorous, consuming tree bark, aquatic plants, grasses and sedges. Beavers build dams and lodges using tree branches, vegetation, rocks and mud; they chew down trees for building material. Dams impound water and lodges serve as shelters. Their infrastructure creates wetlands used by many other species, and because of their effect on other organisms in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mountain Beaver
The mountain beaver (''Aplodontia rufa'')Other names include mountain boomer, ground bear, giant mole, gehalis, lesser sasquatch, sewellel, suwellel, showhurll, showtl, and showte, as well as a number of Chinookan and other Native American terms; "mountain boomer" is a misnomer, and the animal does not make the characteristic tail slapping sound of the true beaver species. See Carraway and Verts, 1993. Lewis and Clark originally called the animal "sewellel", a misunderstanding of the Chinook word "she-wal-lal", the name for garments made from the skin of the creature. See Borrecco and Anderson, 1980. is a North American rodent. It is the only living member of its genus, ''Aplodontia'', and family, Aplodontiidae. It should not be confused with true North American and Eurasian beavers, to which it is not closely related, being more closely related to squirrels. There are 7 subspecies of mountain beavers, 6 of which are found in California and 3 of which are endemic to the state. S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Masseter Muscle
In human 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 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 the posterior third of the low ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Squirrel
Squirrels are members of the family Sciuridae, a family that includes small or medium-size rodents. The squirrel family includes tree squirrels, ground squirrels (including chipmunks and prairie dogs, among others), and flying squirrels. Squirrels are indigenous to the Americas, Eurasia, and Africa, and were introduced by humans to Australia. The earliest known fossilized squirrels date from the Eocene epoch, and among other living rodent families, the squirrels are most closely related to the mountain beaver and to the dormice. Etymology The word ''squirrel'', first attested in 1327, comes from the Anglo-Norman which is from the Old French , the reflex of a Latin word , which was taken from the Ancient Greek word (; from ) 'shadow-tailed', referring to the long bushy tail which many of its members have. The native Old English word for the squirrel, , survived only into Middle English (as ) before being replaced. The Old English word is of Common Germanic origin, c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eocene
The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', " dawn") and (''kainós'', "new") and refers to the "dawn" of modern ('new') fauna that appeared during the epoch. The Eocene spans the time from the end of the Paleocene Epoch to the beginning of the Oligocene Epoch. The start of the Eocene is marked by a brief period in which the concentration of the carbon isotope 13C in the atmosphere was exceptionally low in comparison with the more common isotope 12C. The end is set at a major extinction event called the ''Grande Coupure'' (the "Great Break" in continuity) or the Eocene–Oligocene extinction event, which may be related to the impact of one or more large bolides in Siberia and in what is now Chesapeake Bay. As with other geologic periods, the strata that define the start and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Muroidea
The Muroidea are a large superfamily of rodents, including mice, rats, voles, hamsters, lemmings, gerbils, and many other relatives. Although the Muroidea originated in Eurasia, they occupy a vast variety of 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 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 is based on recent well-supported molecular phylogenies. The muroids are classified in six families, 19 subfamilies, around 280 genera, and at least 1,750 species. Taxonomy *Family Platacanthomyidae ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Great American Interchange
The Great American Biotic Interchange (commonly abbreviated as GABI), also known as the Great American Interchange and the Great American Faunal Interchange, was an important late Cenozoic paleozoogeographic biotic interchange event in which land and freshwater fauna migrated from North America via Central America to South America and vice versa, as the volcanic Isthmus of Panama rose up from the sea floor and bridged the formerly separated continents. Although earlier dispersals had occurred, probably over water, the migration accelerated dramatically about 2.7 million years ( Ma) ago during the Piacenzian age. It resulted in the joining of the Neotropic (roughly South American) and Nearctic (roughly North American) biogeographic realms definitively to form the Americas. The interchange is visible from observation of both biostratigraphy and nature ( neontology). Its most dramatic effect is on the zoogeography of mammals, but it also gave an opportunity for reptiles, amphibians ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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