Flying squirrels are a tribe of 50 species of squirrels in the family Sciuridae. They are not capable of flight in the same way as birds or bats but are able to glide from one tree to another with the aid of a patagium, a furry, parachute-like membrane that stretches from wrist to ankle, their long tail provides stability in flight. Anatomically they are similar to other squirrels but have a number of adaptations to suit their life style. Flying squirrels are able to steer and exert control over their glide path with their limbs and tail. Molecular studies have shown that flying squirrels are monophyletic and originated some 18–20 million years ago. Most are nocturnal and omnivorous, eating fruit, buds, insects, spiders, bird's eggs and tree sap; the young are at first naked and helpless. They are cared for by their mother and by five weeks are able to practice gliding skills so that by ten weeks they are ready to leave the nest; some captive-bred southern flying squirrels have become domesticated as small household pets, a type of "pocket pet".
Flying squirrels are not capable of flight like bats. They are capable of obtaining lift within the course of these flights, with flights recorded to 90 metres; the direction and speed of the animal in midair are varied by changing the positions of its limbs controlled by small cartilaginous wrist bones. There is a cartilage projection from the wrist; this specialized cartilage is only present in flying squirrels and not other gliding mammals. Possible origins for the styliform cartilage have been explored, the data suggests that it is most homologous to the carpal structures that can be found in other squirrels; this cartilage along with the manus forms a wing tip to be used during gliding. After being extended, the wing tip may adjust to various angles; the wrist changes the tautness of the patagium, a furry parachute-like membrane that stretches from wrist to ankle. It has a fluffy tail; the tail acts as an adjunct airfoil. The colugos and Anomaluridae are gliding mammals which are similar to flying squirrels because of convergent evolution.
These mammals can glide through the trees, but they do not fly. They have a membrane of skin on either side of their body. Prior to the 21st century, the evolutionary history of the flying squirrel was debated; this debate was clarified as a result of two molecular studies. These studies found support that flying squirrels originated 18–20 million years ago, are monophyletic, have a sister relationship with tree squirrels. Due to their close ancestry, the morphological differences between flying squirrels and tree squirrels reveal insight into the formation of the gliding mechanism. Compared to squirrels of similar size, flying squirrels and southern flying squirrels show lengthening in bones of the lumbar vertebrae and forearm, whereas bones of the feet and distal vertebrae are reduced in length; such differences in body proportions reveal the flying squirrels’ adaptation to minimize wing loading and to increase more maneuverability while gliding. The consequence for these differences is that unlike regular squirrels, flying squirrels are not well adapted for quadrupedal locomotion and therefore must rely more on their gliding abilities.
Several hypotheses have attempted to explain the evolution of gliding in flying squirrels. One possible explanation is related to energy foraging. Gliding is an energetically efficient way to progress from one tree to another while foraging, as opposed to climbing down trees and maneuvering on the ground floor or executing dangerous leaps in the air. By gliding at high speeds, flying squirrels can rummage through a greater area of forest more than tree squirrels. Flying squirrels can glide long distances by increasing their aerial speed and increasing their lift. Other hypotheses state that the mechanism evolved to prevent injuries. If a dangerous situation arises on a specific tree, flying squirrels can glide to another, thereby escape the previous danger. Furthermore, take-off and landing procedures during leaps, implemented for safety purposes, may explain the gliding mechanism. While leaps at high speeds are important to escape danger, the high-force impact of landing on a new tree could be detrimental to a squirrel’s health.
Yet the gliding mechanism of flying squirrels involves structures and techniques during flight that allow for great stability and control. If a leap is miscalculated, a flying squirrel may steer back onto the original course by using its gliding ability. A flying squirrel creates a large glide angle when approaching its target tree, decreasing its velocity due to an increase in air resistance and allowing all four limbs to absorb the impact of the target. In 2019 it was observed, by chance. Subsequent research by Paula Spaeth Anich, a biologist at Northland College in Northern Wisconsin, found that this is true for all three species of North American flying squirrels. At this time it is unknown. Non-flying squirrels do not fluoresce under UV light; the largest of the species is the woolly flying squirrel. The three species of the genus Glaucomys are native to North America, Central America, w
Sciuromorpha is a rodent clade that includes several different rodent families. It includes all members of the Sciuridae as well as the mountain beaver species. Traditionally, the term has been defined on the basis of the shape of the infraorbital canal. A sciuromorphous zygomasseteric system is characterized by attachment of the lateral masseter muscle along the side of the rostrum. Unlike hystricomorphous and myomorphous rodents, the medial masseter muscle does not pass through the infraorbital canal. Among extant rodents, only the families Sciuridae, Castoridae and Geomyidae are sciuromorphous; some authorities would exclude the Geomyidae and Heteromyidae from that list due to the attachment of the medial masseter directly behind the zygomatic arch. Carleton and Musser redefined the rodent suborders on molecular grounds, they defined the Sciuromorpha as including three families, Sciuridae and Gliridae. Of these, only the Sciuridae are sciuromorphous; the Aplodontiidae are protrogomorphous and the Gliridae are myomorphous.
The connection between Aplodontiidae and Sciuridae has been proposed numerous times in the past. The two families have been united into superfamily, it has long been suggested that dormice are not related to the Myomorpha, their zygomasseteric structure has been termed "pseudomyomorphy". The connection between squirrels and dormice has been exclusively suggested through genetic studies, to a lesser degree via the fossil rodent Reithroparamys; the suborder Sciuromorpha contains 307 living species in three families. At least three extinct families are recognised. †Allomyidae Aplodontiidae – mountain beaver †Mylagaulidae Sciuridae – squirrels, marmots, flying squirrels, etc. †Reithroparamyidae Gliridae – dormice Castoridae – beavers Geomyidae – pocket gophers Heteromyidae – kangaroo rats and mice Carleton, M. D. and G. G. Musser. 2005. Order Rodentia. Pp745–752 in Mammal Species of the World A Taxonomic and Geographic Reference. Baltimore, Johns Hopkins University Press
Hylopetes is a genus of flying squirrels. Particolored flying squirrel Hylopetes alboniger Bartel's flying squirrel Hylopetes bartelsi Chasen, 1939 Gray-cheeked flying squirrel Hylopetes lepidus Palawan flying squirrel Hylopetes nigripes Indochinese flying squirrel Hylopetes phayrei Jentink's flying squirrel Hylopetes platyurus Sipora flying squirrel Hylopetes sipora Chasen, 1940 Red-cheeked flying squirrel Hylopetes spadiceus Sumatran flying squirrel Hylopetes winstoni
Rodents 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 the most diversified mammalian order and live in a variety of terrestrial habitats, including human-made environments. Species can be fossorial, or semiaquatic. Well-known rodents include mice, squirrels, prairie dogs, chinchillas, beavers, guinea pigs, hamsters and capybaras. Other animals such as rabbits and pikas, whose incisors grow continually, were once included with them, but are now considered to be in a separate order, the Lagomorpha. Nonetheless and Lagomorpha are sister groups, sharing a most recent common ancestor and forming the clade of Glires. Most rodents are small animals with robust bodies, short limbs, long tails, they use their sharp incisors to gnaw food, excavate burrows, defend themselves. Most eat seeds or other plant material, they tend to be social animals and many species live in societies with complex ways of communicating with each other.
Mating among rodents can vary from monogamy, to polygyny, to promiscuity. Many have litters of altricial young, while others are precocial at birth; the rodent fossil record dates back to the Paleocene on the supercontinent of Laurasia. Rodents diversified in the Eocene, as they spread across continents, sometimes crossing oceans. Rodents reached both South America and Madagascar from Africa and were the only terrestrial placental mammals to reach and colonize Australia. Rodents have been used as food, for clothing, as pets, as laboratory animals in research; some species, in particular, the brown rat, the black rat, the house mouse, are serious pests and spoiling food stored by humans and spreading diseases. Accidentally introduced species of rodents are considered to be invasive and have caused the extinction of numerous species, such as island birds isolated from land-based predators; the distinguishing feature of the rodents is their pairs of continuously growing, razor-sharp, open-rooted incisors.
These incisors little enamel on the back. Because they do not stop growing, the animal must continue to wear them down so that they do not reach and pierce the skull; as the incisors grind against each other, the softer dentine on the rear of the teeth wears away, leaving the sharp enamel edge shaped like the blade of a chisel. Most species have up to 22 teeth with no canines or anterior premolars. A gap, or diastema, occurs between the cheek teeth in most species; this allows rodents to suck in their cheeks or lips to shield their mouth and throat from wood shavings and other inedible material, discarding this waste from the sides of their mouths. Chinchillas and guinea pigs have a high-fiber diet. In many species, the molars are large, intricately structured, cusped or ridged. Rodent molars are well equipped to grind food into small particles; the jaw musculature is strong. The lower jaw is pulled backwards during chewing. Rodent groups differ in the arrangement of the jaw muscles and associated skull structures, both from other mammals and amongst themselves.
The Sciuromorpha, such as the eastern grey squirrel, have a large deep masseter, making them efficient at biting with the incisors. The Myomorpha, such as the brown rat, have enlarged temporalis muscles, making them able to chew powerfully with their molars; the Hystricomorpha, such as the guinea pig, have larger superficial masseter muscles and smaller deep masseter muscles than rats or squirrels making them less efficient at biting with the incisors, but their enlarged internal pterygoid muscles may allow them to move the jaw further sideways when chewing. The cheek pouch is a specific morphological feature used for storing food and is evident in particular subgroups of rodents like kangaroo rats, hamsters and gophers which have two bags that may range from the mouth to the front of the shoulders. True mice and rats do not contain this structure but their cheeks are elastic due to a high degree of musculature and innervation in the region. While the largest species, the capybara, can weigh as much as 66 kg, most rodents weigh less than 100 g.
The smallest rodent is the Baluchistan pygmy jerboa, which averages only 4.4 cm in head and body length, with adult females weighing only 3.75 g. Rodents have wide-ranging morphologies, but have squat bodies and short limbs; the fore limbs have five digits, including an opposable thumb, while the hind limbs have three to five digits. The elbow gives the forearms great flexibility; the majority of species are plantigrade, walking on both the palms and soles of their feet, have claw-like nails. The nails of burrowing species tend to be long and strong, while arboreal rodents have shorter, sharper nails. Rodent species use a wide variety of methods of locomotion including quadrupedal walking, burrowing, bipedal hopping and gliding. Scaly-tailed squirrels and flying squirrels, although not related, can both glide from tree to tree using parachute-like membranes that stretch from the fore to the hind limbs; the agouti is antelope-like, being digitigrade and having hoof-like nails. The majority of rodents have tails, which can be of many shapes and siz
Jean Léopold Nicolas Frédéric, Baron Cuvier, known as Georges Cuvier, was a French naturalist and zoologist, sometimes referred to as the "founding father of paleontology". Cuvier was a major figure in natural sciences research in the early 19th century and was instrumental in establishing the fields of comparative anatomy and paleontology through his work in comparing living animals with fossils. Cuvier's work is considered the foundation of vertebrate paleontology, he expanded Linnaean taxonomy by grouping classes into phyla and incorporating both fossils and living species into the classification. Cuvier is known for establishing extinction as a fact—at the time, extinction was considered by many of Cuvier's contemporaries to be controversial speculation. In his Essay on the Theory of the Earth Cuvier proposed that now-extinct species had been wiped out by periodic catastrophic flooding events. In this way, Cuvier became the most influential proponent of catastrophism in geology in the early 19th century.
His study of the strata of the Paris basin with Alexandre Brongniart established the basic principles of biostratigraphy. Among his other accomplishments, Cuvier established that elephant-like bones found in the USA belonged to an extinct animal he would name as a mastodon, that a large skeleton dug up in Paraguay was of Megatherium, a giant, prehistoric ground sloth, he named the pterosaur Pterodactylus, described the aquatic reptile Mosasaurus, was one of the first people to suggest the earth had been dominated by reptiles, rather than mammals, in prehistoric times. Cuvier is remembered for opposing theories of evolution, which at the time were proposed by Jean-Baptiste de Lamarck and Geoffroy Saint-Hilaire. Cuvier believed there was no evidence for evolution, but rather evidence for cyclical creations and destructions of life forms by global extinction events such as deluges. In 1830, Cuvier and Geoffroy engaged in a famous debate, said to exemplify the two major deviations in biological thinking at the time – whether animal structure was due to function or morphology.
Cuvier rejected Lamarck's thinking. His most famous work is Le Règne Animal. In 1819, he was created a peer for life in honor of his scientific contributions. Thereafter, he was known as Baron Cuvier, he died in Paris during an epidemic of cholera. Some of Cuvier's most influential followers were Louis Agassiz on the continent and in the United States, Richard Owen in Britain, his name is one of the 72 names inscribed on the Eiffel Tower. Cuvier was born in Montbéliard, where his Protestant ancestors had lived since the time of the Reformation, his mother was Anne Clémence Chatel. At the time, the town, annexed to France on 10 October 1793, belonged to the Duchy of Württemberg, his mother, much younger than his father, tutored him diligently throughout his early years, so he surpassed the other children at school. During his gymnasium years, he had little trouble acquiring Latin and Greek, was always at the head of his class in mathematics and geography. According to Lee, "The history of mankind was, from the earliest period of his life, a subject of the most indefatigable application.
At the age of 10, soon after entering the gymnasium, he encountered a copy of Conrad Gessner's Historiae Animalium, the work that first sparked his interest in natural history. He began frequent visits to the home of a relative, where he could borrow volumes of the Comte de Buffon's massive Histoire Naturelle. All of these he read and reread, retaining so much of the information, that by the age of 12, "he was as familiar with quadrupeds and birds as a first-rate naturalist." He remained at the gymnasium for four years. Cuvier spent an additional four years at the Caroline Academy in Stuttgart, where he excelled in all of his coursework. Although he knew no German on his arrival, after only nine months of study, he managed to win the school prize for that language. Cuvier's German education exposed him to the work of the geologist Abraham Gottlob Werner, whose Neptunism and emphasis on the importance of rigorous, direct observation of three-dimensional, structural relationships of rock formations to geological understanding provided models for Cuvier's scientific theories and methods.
Upon graduation, he had no money on. So in July 1788, he took a job at Fiquainville chateau in Normandy as tutor to the only son of the Comte d'Héricy, a Protestant noble. There, during the early 1790s, he began his comparisons of fossils with extant forms. Cuvier attended meetings held at the nearby town of Valmont for the discussion of agricultural topics. There, he became acquainted with Henri Alexandre Tessier, he had been a physician and well-known agronomist, who had fled the Terror in Paris. After hearing Tessier speak on agricultural matters, Cuvier recognized him as the author of certain articles on agriculture in the Encyclopédie Méthodique and addressed him as M. Tessier. Tessier replied in dismay, "I am known and lost."—"Lost!" Replied M. Cuvier, "no, they soon became intimate and Tessier introduced Cuvier to his colleagues in Paris—"I have just found a pearl in the dungh
Afghan flying squirrel
The Afghan flying squirrel is a subspecies of rodent in the family Sciuridae. It is endemic to Afghanistan; the taxonomy of the Afghan flying squirrel is as follows: Kingdom - Animalia Phylum - Chordata Class - Mammalia Order - Rodentia Family - Sciuridae The Afghan flying squirrel is not considered to be threatened to become an endangered species because it is distributed, it has a large population, the population is not declining fast enough. The only threats that affect the Afghan flying squirrel are selective logging, hunting for the fur trade, it has a generation time of 4 to 5 years, it has up to two litters annually. It has 2 to 4 young; the Afghan flying squirrel is known to be found in montane coniferous forests. The Afghan flying squirrel is native to the following countries: Afghanistan India Pakistan Baillie, J. 1996. Hylopetes baberi. 2006 IUCN Red List of Threatened Species. Downloaded on 29 July 2007. Thorington, R. W. Jr. and R. S. Hoffman. 2005. Family Sciuridae. Pp. 754–818 in Mammal Species of the World a Taxonomic and Geographic Reference.
D. E. Wilson and D. M. Reeder eds. Johns Hopkins University Press, Baltimore
The Korean Peninsula is located in East Asia. It extends southwards for about 1,100 km from continental Asia into the Pacific Ocean and is surrounded by the Sea of Japan to the east and the Yellow Sea to the west, the Korea Strait connecting the two bodies of water; the peninsula's names, in Korean and Japanese, all share the same origin, that being Joseon, the old name of Korea under the Joseon Dynasty and Gojoseon longer before that. In North Korea's standard language, the peninsula is called Chosŏn Pando, while in China, as well as in Singapore and Malaysia it is called Cháoxiǎn Bàndǎo. In Japan, it is either Chōsenhantō or Kanhantō. In Vietnam, it is called Bán đảo Triều Tiên. Meanwhile, in South Korea, it is called Hanbando, referring to the Samhan the Three Kingdoms of Korea, not the ancient confederacies in the southern Korean Peninsula, they both use "Korea" as part of their official English names, a name that comes from the Goryeo dynasty. Until the end of World War II, Korea was a single political entity whose territory coincided with the Korean Peninsula.
In August 1945, the Soviet Union declared war on Imperial Japan, as a result of an agreement with the United States, liberated Korea north of the 38th parallel. U. S. forces subsequently moved into the south. By 1948, as a product of the Cold War between the Soviet Union and the United States, Korea was divided into two regions, with separate governments. Both claimed to be the legitimate government of all of Korea, neither accepted the border as permanent; the conflict escalated into open warfare when North Korean forces—supported by the Soviet Union and China—moved into the south on 25 June 1950. Since the Armistice Agreement ended the Korean War in 1953, the northern section of the peninsula has been governed by the Democratic People's Republic of Korea, while the southern portion has been governed by the Republic of Korea; the northern boundaries for the Korean Peninsula are taken to coincide with today's political borders between North Korea and its northern neighbors and Russia. These borders are formed by the rivers Amnok and Duman.
Taking this definition, the Korean Peninsula has an area of 220,847 km2. The Korean Peninsula has a temperate climate with comparatively fewer typhoons than other countries in East Asia. Due to the peninsula's position, it has a unique climate influenced from Siberia in the north, the Pacific Ocean in the east and the rest of Eurasia in the west; the peninsula has four distinct seasons: spring, summer and winter. As influence from Siberia weakens, temperatures begin to increase while the high pressure begins to move away. If the weather is abnormally dry, Siberia will have more influence on the peninsula leading to wintry weather such as snow. During June at the start of the summer, there tends to be a lot of rain due to the cold and wet air from the Sea of Okhotsk and the hot and humid air from the Pacific Ocean combining; when these fronts combine, it leads to a so-called rainy season with cloudy days with rain, sometimes heavy. The hot and humid winds from the south west blow causing an increasing amount of humidity and this leads to the fronts moving towards Manchuria in China and thus there is less rain and this is known as midsummer.
High pressure is dominant during autumn leading to clear conditions. Furthermore, temperatures remain high but the humidity becomes low; the weather becomes dominated by Siberia during winter and the jet stream moves further south causing a drop in temperature. This season is dry with some snow falling at times. Temperatures can drop to -20 °C in the mountainous areas; the Korean Peninsula is located in East Asia. To the northwest, the Amnok River separates the peninsula from China and to the northeast, the Duman River separates it from China and Russia; the peninsula is surrounded by the Yellow Sea to the west, the East China Sea and Korea Strait to the south, the Sea of Japan to the east. Notable islands include Ulleung Island, Dokdo; the southern and western parts of the peninsula have well-developed plains, while the eastern and northern parts are mountainous. The highest mountain in Korea is Mount Paektu; the southern extension of Mount Paektu is a highland called Gaema Heights. This highland was raised during the Cenozoic orogeny and covered by volcanic matter.
To the south of Gaema Gowon, successive high mountains are located along the eastern coast of the peninsula. This mountain range is named Baekdudaegan; some significant mountains include Mount Sobaek or Sobaeksan, Mount Kumgang, Mount Seorak, Mount Taebaek, Mount Jiri. There are several lower, secondary mountain series whose direction is perpendicular to that of Baekdudaegan, they are developed along the tectonic line of Mesozoic orogeny and their directions are northwest. Unlike most ancient mountains on the mainland, many important islands in Korea were formed by volcanic activity in the Cenozoic orogeny. Jeju Island, situated off the southern coast, is a large volcanic island whose main mountain Mount Halla or Hallasan is the highest in South Korea. Ulleung Island is a volcanic island in the Sea of