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New World Flying Squirrel
The three species of New World flying squirrels, genus ''Glaucomys'', are the only species of flying squirrel found in North America.Walker EP, Paradiso JL. 1975. ''Mammals of the World''. Baltimore: Johns Hopkins University Press.Forsyth A. 1999. ''Mammals of North America: Temperate and Arctic Regions''. Willowdale: Firefly Books. They are distributed from Alaska to Honduras. They are similar in many ways to the Eurasian flying squirrels in the genus '' Pteromys''. Two species of New World flying squirrels can be easily distinguished on the basis of size and ventral pelage. Northern flying squirrels, ''Glaucomys sabrinus'' are larger and have belly hair that is dark at the base and white at the tip. Southern flying squirrels, ''Glaucomys volans'', are smaller and have belly hairs that are completely white. Humboldt's flying squirrel is more difficult to distinguish from the northern flying squirrel where their ranges overlap. In fact, they were once considered conspecific. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pleistocene
The Pleistocene ( , often referred to as the ''Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in 2009 by the International Union of Geological Sciences, the cutoff of the Pleistocene and the preceding Pliocene was regarded as being 1.806 million years Before Present (BP). Publications from earlier years may use either definition of the period. The end of the Pleistocene corresponds with the end of the last glacial period and also with the end of the Paleolithic age used in archaeology. The name is a combination of Ancient Greek grc, label=none, πλεῖστος, pleīstos, most and grc, label=none, καινός, kainós (latinized as ), 'new'. At the end of the preceding Pliocene, the previously isolated North and South American continents were joined by the Isthmus of Panama, causing a faunal interchange between the two reg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Southern Flying Squirrel
The southern flying squirrel or the assapan (''Glaucomys volans'') is one of three species of the genus '' Glaucomys'' and one of three flying squirrel species found in North America. It is found in deciduous and mixed woods in the eastern half of North America, from southeastern Canada to Florida. Disjunct populations of this species have been recorded in the highlands of Mexico, Guatemala, and Honduras. Description and ecology Southern flying squirrels have grey-brown fur on top with darker flanks and are a cream color underneath. They have large dark eyes and flattened tails. They have a furry membrane called a patagium that extends between the front and rear legs and is used to glide through the air. Total length (including tail) is . The tail can be . Southern flying squirrels are nocturnal. They feed on fruit and nuts from trees such as red and white oak, hickory, and beech. They store food, especially acorns, for winter consumption. They also dine on insects, buds, mus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Predator
Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill the host) and parasitoidism (which always does, eventually). It is distinct from scavenging on dead prey, though many predators also scavenge; it overlaps with herbivory, as seed predators and destructive frugivores are predators. Predators may actively search for or pursue prey or wait for it, often concealed. When prey is detected, the predator assesses whether to attack it. This may involve ambush or pursuit predation, sometimes after stalking the prey. If the attack is successful, the predator kills the prey, removes any inedible parts like the shell or spines, and eats it. Predators are adapted and often highly specialized for hunting, with acute senses such as vision, hearing, or smell. Many predatory animals, both vertebrate an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parachute
A parachute is a device used to slow the motion of an object through an atmosphere by creating drag or, in a ram-air parachute, aerodynamic lift. A major application is to support people, for recreation or as a safety device for aviators, who can exit from an aircraft at height and descend safely to earth. A parachute is usually made of a light, strong fabric. Early parachutes were made of silk. The most common fabric today is nylon. A parachute's canopy is typically dome-shaped, but some are rectangles, inverted domes, and other shapes. A variety of loads are attached to parachutes, including people, food, equipment, space capsules, and bombs. History Middle Ages In 852, in Córdoba, Spain, the Moorish man Armen Firman attempted unsuccessfully to fly by jumping from a tower while wearing a large cloak. It was recorded that "there was enough air in the folds of his cloak to prevent great injury when he reached the ground." Early Renaissance The earliest eviden ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Degree (angle)
A degree (in full, a degree of arc, arc degree, or arcdegree), usually denoted by ° (the degree symbol), is a measurement of a plane angle in which one full rotation is 360 degrees. It is not an SI unit—the SI unit of angular measure is the radian—but it is mentioned in the SI brochure as an accepted unit. Because a full rotation equals 2 radians, one degree is equivalent to radians. History The original motivation for choosing the degree as a unit of rotations and angles is unknown. One theory states that it is related to the fact that 360 is approximately the number of days in a year. Ancient astronomers noticed that the sun, which follows through the ecliptic path over the course of the year, seems to advance in its path by approximately one degree each day. Some ancient calendars, such as the Persian calendar and the Babylonian calendar, used 360 days for a year. The use of a calendar with 360 days may be related to the use of sexagesimal numbers. Another ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triangulation
In trigonometry and geometry, triangulation is the process of determining the location of a point by forming triangles to the point from known points. Applications In surveying Specifically in surveying, triangulation involves only angle measurements at known points, rather than measuring distances to the point directly as in trilateration; the use of both angles and distance measurements is referred to as triangulateration. In computer vision Computer stereo vision and optical 3D measuring systems use this principle to determine the spatial dimensions and the geometry of an item. Basically, the configuration consists of two sensors observing the item. One of the sensors is typically a digital camera device, and the other one can also be a camera or a light projector. The projection centers of the sensors and the considered point on the object's surface define a (spatial) triangle. Within this triangle, the distance between the sensors is the base ''b'' and must be kno ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Patagium
The patagium (plural: patagia) is a membranous body part that assists an animal in obtaining lift when gliding or flight. The structure is found in extant and extinct groups of flying and gliding animals including bats, birds, some dromaeosaurs, pterosaurs, gliding mammals, some flying lizards, and flying frogs. The patagium that stretches between an animal's hind limbs is called the uropatagium (especially in bats) or the interfemoral membrane. Bats In bats, the skin forming the surface of the wing is an extension of the skin of the abdomen that runs to the tip of each digit, uniting the forelimb with the body. The patagium of a bat has four distinct parts: #Propatagium: the patagium present from the neck to the first digit. #Dactylopatagium: the portion found within the digits. #Plagiopatagium: the portion found between the last digit and the hindlimbs. #Uropatagium: the posterior portion of the flap between the two hindlimbs. Pterosaurs In the flying pterosaurs, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Northern Flying Squirrel
The northern flying squirrel (''Glaucomys sabrinus'') is one of three species of the genus '' Glaucomys'', the only flying squirrels found in North America.Walker EP, Paradiso JL. 1975. ''Mammals of the World''. Baltimore: Johns Hopkins University Press.Forsyth A. 1999. ''Mammals of North America: Temperate and Arctic Regions''. Willowdale: Firefly Books. They are found in coniferous and mixed coniferous forests across much of Canada, from Alaska to Nova Scotia, and south to the mountains of North Carolina and west to Utah in the United States. They are light brown with pale underparts and grow to a length of . They are proficient gliders but uncoordinated walkers on the ground. They feed on a variety of plant material as well as tree sap, fungi, insects, carrion, bird eggs and nestlings. They mostly breed once a year in a cavity lined with lichen or other soft material. Except when they have young, they change nests frequently, and in winter a number of individuals may huddle tog ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cryptic Species
In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each other, further blurring any distinctions. Terms that are sometimes used synonymously but have more precise meanings are cryptic species for two or more species hidden under one species name, sibling species for two (or more) species that are each other's closest relative, and species flock for a group of closely related species that live in the same habitat. As informal taxonomic ranks, species group, species aggregate, macrospecies, and superspecies are also in use. Two or more taxa that were once considered conspecific (of the same species) may later be subdivided into infraspecific taxa (taxa within a species, such as bacterial strains or plant varieties), that is complex but it is not a species complex. A species complex is in most ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Humboldt's Flying Squirrel
Humboldt's flying squirrel (''Glaucomys oregonensis'') is one of three species of the genus '' Glaucomys'', the only flying squirrels found in North America. The squirrel was named after the naturalist Alexander von Humboldt and California's Humboldt County, which is one of the areas inhabited by the squirrel. Taxonomy Using genetic analyses, Arbogast et al. (2017) showed that Humboldt's flying squirrel, previously thought to be conspecific with the northern flying squirrel, was actually a distinct species. The San Bernardino flying squirrel subspecies (''G. o. californicus'') is considered a ''Critically Imperiled Subspecies'' by NatureServe. Description They do not actually fly but glide from tree to tree. They are similar in appearance to the northern flying squirrel, however, they are generally smaller and have darker pelage. They are good gliders but clumsy walkers on the ground. Fluorescence Under ultraviolet light, females and males of all 3 species of ''Glaucomys ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Northern Flying Squirrel
The northern flying squirrel (''Glaucomys sabrinus'') is one of three species of the genus '' Glaucomys'', the only flying squirrels found in North America.Walker EP, Paradiso JL. 1975. ''Mammals of the World''. Baltimore: Johns Hopkins University Press.Forsyth A. 1999. ''Mammals of North America: Temperate and Arctic Regions''. Willowdale: Firefly Books. They are found in coniferous and mixed coniferous forests across much of Canada, from Alaska to Nova Scotia, and south to the mountains of North Carolina and west to Utah in the United States. They are light brown with pale underparts and grow to a length of . They are proficient gliders but uncoordinated walkers on the ground. They feed on a variety of plant material as well as tree sap, fungi, insects, carrion, bird eggs and nestlings. They mostly breed once a year in a cavity lined with lichen or other soft material. Except when they have young, they change nests frequently, and in winter a number of individuals may huddle tog ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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