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Arctodus

Arctodus

Arctodus, also known as the Short-Faced Bear, is a genus of extinct bear. One species, the Giant Short-Faced Bear (Arctodus simus) was the biggest bear ever to have lived. Standing 1.5 metres at the shoulder (over 3 metres when standing on hind legs) and equipped with powerful jaws this bear would have been an intimidating sight. Arctodus seems to have been mainly a carnivore and was by far the most powerful land predator during the Ice Age in North America. It may have attacked bison, deer, and horses and other large herbivores, but probably partly lived, like many other large carnivores like lions, as a scavenger. Compared to modern brown bears it had much longer limbs and was generally more slender. It had a very short, broad muzzle which gives rise to its name, and which gave it a very powerful bite. Its long legs were adapted for a faster running-style than modern bears and enabled Arctodus to hunt and to range far and wide in search of prey and carrion and its powerful bite enabled it to crack open bones to reach rich marrow. The largest known skull of Arctodus was found by a Yukon gold miner. Another fossil from southern Saskatchewan indicates that Arctodus lived there more than 70,000 years ago. Arctodus simus, the largest species, ranged the high grasslands of western North America from Alaska to Mexico, while a lighter-built species (Arctodus pristinus) with smaller teeth inhabited the more heavily wooded Atlantic coastal region. The short-faced bear belongs to a group of bears known as the Tremarctine bears, which are of New World origin. The earliest member of the Tremarctinae is Plionarctos, which lived in Texas during the Pliocene Epoch (about 5-2 million years ago). It is likely that this genus is ancestral to the Spectacled Bear (Tremarctos) and the short-faced bear. Although the early history of Arctodus is poorly known, it evidently became widespread in North America by the Kansan age (about 800,000 years ago). The short-faced bear became extinct some 12,000 years ago, perhaps partly because some of its large prey died out earlier, and partly because of competition with the smaller, more herbivorous brown bears that entered North America from Eurasia. Since its demise coincides with the development of the Clovis technology and improved hunting techniques by humans in North America, hunting may also have contributed to its extinction both directly and due to the depletion of other large mammals on which it depended for food. Category:Prehistoric mammals Category:Pliocene mammals Category:Pleistocene mammals Category:Pleistocene extinctions Category:Bears

Bear


Ailuropoda
Ursus
Tremarctos
Arctodus (extinct) A bear is a large mammal of the order Carnivora, family Ursidae. The adjective, ursine, is used to describe things of bearlike nature.

Physical attributes

Common characteristics of bears include a short tail, excellent senses of smell and hearing, five un-retractable claws, and long, dense, shaggy fur. Bears have a large body with powerful limbs. They are capable of standing up on their hind legs. They have broad paws, long snouts, and round ears. Their teeth are used for defense and tools and depend on the diet of the bear. Their claws are used for ripping, digging, and catching.

Habitats

Bears live in a variety of habitats from the tropics to the Arctic and from forests to snowfields. They are mainly omnivorous, although some have a more specialised diet, such as polar bears. They eat lichens, roots, nuts, and berries. They can also go to a river or other body of water to capture fish. Bears will commonly travel far for food. Hunting times are usually in the dusk or the dawn except when humans are nearby. Some of the large species, such as the polar bear and the grizzly bear, are dangerous to humans, especially in areas where they have become used to people. For the most part, bears are shy and are easily frightened of humans. They will, however, defend their cubs ferociously.

Reproductive behaviour

The bear's courtship period is very brief. Bears reproduce seasonally, usually after hibernation. Cubs come out toothless, blind, and bald. The cubs, usually born in litters of 1–3, will stay with the mother for six months. They will be fed by milk at first and will start hunting with the mother in three months. Then, they are weaned. However, they will still remain nearby for three years. The cubs are more sexually mature at seven years. Normally, bears are very solitary and will not remain close together for long periods of time. solitary

Other

Many bears of northern regions are assumed to hibernate in the winter. In fact, they don't hibernate. Their body temperature sinks a moderate amount and they can be easily awakened. Laws have been passed in many areas of the world to protect bears from hunters or habitat destruction. Bears in captivity used to be trained to dance, box, or unicycle, but it is now controversial to use animals in this way. Bears have an average life expectancy of 25–40 years. A brown bear is Finland`s national animal. Kodiak bears are the largest type of bear (Polar bears are the heaviest though), indeed one of the largest extant carnivores. Sun bears are the smallest, only a bit smaller than the average woman.

Classification


- Family Ursidae
  - Subfamily Ailuropodinae
    - Giant Panda, Ailuropoda melanoleuca
    - Dwarf Panda, Ailuropoda minor (extinct)
  - Subfamily Tremarctinae
    - Spectacled Bear, Tremarctos ornatus
    - Florida Cave Bear, Tremarctos floridanus (extinct)
    - Giant Short-Faced Bear, Arctodus simus (extinct)
    - Short-Faced Bear, Arctodus pristinus (extinct)
    - Brazilian Short-Faced Bear, Arctotherium brasilense (extinct)
    - Argentine Short-Faced Bear, Arctotherium latidens (extinct)
  - Subfamily Ursinae
    - Brown Bear, Ursus arctos
      - Subspecies Syrian (Brown) Bear (Ursus arctos syriacus)
      - Subspecies Grizzly Bear, (Ursus arctos horribilis)
      - Subspecies Kodiak Bear, (Ursus arctos middendorffi)
    - American Black Bear, Ursus americanus
    - Polar Bear, Ursus maritimus
    - Asiatic black bear, Ursus thibetanus
      - Ursus thibetanus formosanus
      - Ursus thibetanus gedrosianus
      - Urus thibetanus japonica
      - Ursus thibetanus laniger
      - Ursus thibetanus mupinensis
      - Ursus thibetanus thibetanus
      - Ursus thibetanus ussuricu
    - Auvergne Bear, Ursus minimus (extinct)
    - Etruscan Bear, Ursus etruscus (extinct)
    - European Cave Bear, Ursus spelaeus (extinct)
    - Atlas Bear, Ursus crowtheri (extinct)
    - Sloth Bear, Melursus (Ursus) ursinus
      - Subspecies Sri Lankan sloth bear (Melursus (Ursus) ursinus inornatus)
      - Subspecies Indian sloth bear (Melursus (Ursus) ursinus ursinus)
    - Sun Bear, Helarctos malayanus
      - Subspecies Boreno sun bear (Helarctos (Ursus) malayanus euryspilus) The genera Melursus and Helarctos are included in the genus Ursus. The Asiatic black bear and the polar bear used to be placed in their own genera, Selenarctos and Thalarctos. A number of hybrids have been bred between black, brown and polar bears (see ursinae hybrids).

Evolutionary relationships

Bears are members of the Order Carnivora, Sub-Order Caniformia, and Family Ursidae. Other members of the Caniformia include wolves and other dog-like mammals (Family Canidae), weasels, skunks, and badgers (Family Mustelidae), raccoons (Family Procyonidae), and walruses (Family Odobenidae), seals (Family Phocidae), and sea lions (Family Otariidae). Although bears are often described as having evolved from a dog-like ancestor, their closest living relatives are the pinnipeds (walruses, seals, and sea lions). The origins of the bears can be traced back to the raccoon-sized, dog-like Cephalogale from the middle Oligocene and early Miocene (approximately 20-30 million years ago) of Europe. Cephalogale gave rise to a lineage of early bears, the genus Ursavus. This genus radiated in Asia and ultimately gave rise to the first true bears (genus Ursus) in Europe, 5 million years ago. Extinct bear genera includes Arctodus, Agriarctos, Agriotherium, Plionarctos and Indarctos. Although there has previously been much discussion as to whether the Giant Panda belongs to the bear family or the raccoon family, recent DNA analyses have shown that the Giant Panda is a member of the Family Ursidae and as such is more closely related to other bears. The status of the Red Panda remains uncertain, but many experts, including Wilson and Reeder, classify it as a member of the bear family. Others place it with the racoons in Procyonidae or in its own family, the Ailuridae. The many similarities between the two pandas are thought to represent convergent evolution for feeding primarily on bamboo. There is also evidence that, unlike their neighbors elsewhere, the brown bears of Alaska's ABC Islands are more closely related to polar bears than they are to other brown bears in the world. Researchers Gerald Shields and Sandra Talbot of the University of Alaska Fairbanks Institute of Arctic Biology studied the DNA of several samples of the species and found that their DNA is different from that of other brown bears. The researchers discovered that their DNA was unique compared to brown bears anywhere else in the world. The discovery has shown that while all other brown bears share a brown bear as their closest relative, those of Alaska's ABC Island's differ and share their closest relation with the polar bear.

Bears in mythology

DNA, here incorporated in the arms of Pope Benedict XVI]] There is some evidence for prehistoric bear worship, see Arctic, Arcturus, Great Bear, Berserker, Kalevala. Anthropologists such as Joseph Campbell have regarded this as a common feature in most of the fishing and hunting-tribes. The prehistoric Finns, along with most fenno-ugric peoples, considered the bear as the spirit of one's forefathers. This is why the bear was a greatly respected animal, with several euphemistic names. There has been evidence about early bear worship in China and among the Ainu culture as well. In addition, the Proto-Indo-European word for bear,
- hr̥ktos (ancestral to the Greek arktos, Latin ursus, Welsh arth (c.f. Arthur), Sanskrit
- ṛkṣa, Hittite hartagga) seems to have been subject to taboo deformation or replacement (as was the word for wolf, wlkwos), resulting in the use of numerous unrelated words with meanings like "brown one" (English bruin) and "honey-eater" (Slavic medved). Thus four separate Indo-European language groups do not share the same PIE root. In the Finnish countryside, the word for "bear" remains taboo to this day. The theory of the bear taboo is taught to almost all beginning students of Indo-European and historical linguistics: the putative original PIE word for bear is itself descriptive, because a cognate word in Sanskrit is rakshas, meaning "harm, injury" [http://www.cloudline.org/LinguisticArchaeology.html]. Numerous cities around the world have adopted the bear as a symbol, notably the Swiss capital Bern, which takes its name from the German for bear, bär. The bear is also the name-emblem of Berlin. Bears are a common symbol of heraldry. In the arms of the bishopric of Freising (illustration, right) the bear is the dangerous totem animal tamed by Saint Corbinian and made to carry his civilized baggage over the mountains: the allegory of the civilizing influence of Christianity is inescapable. A bear also features prominently in the legend of Saint Romedius, who is also said to have tamed one of these animals and had the same bear carry him from his hermitage in the mountains to the city of Trento.

Bears in popular culture

Bears, usually anthropomorphized, appear frequently as characters in popular culture; see List of fictional bears. Some bears have been famous in their own right, like the bear that the U.S. president Theodore "Teddy" Roosevelt refused to shoot in Mississippi. That bear became the prototype for the Teddy bear, which is a stuffed animal toy; In the stock market, a bear market is a period of declining prices. Pessimistic forecasting or negative activity is said to be bearish (due to the stereotypical posture of bears looking downwards), and one who expresses bearish sentiment is a bear. Its opposite is a bull market, and bullish sentiment from bulls. Many cultures regard bears as possessing healing powers. The peoples of China, Japan and Korea use bears' body parts and secretions (notably their gall bladders and bile) as part of traditional Chinese medicine. This has had a major impact on populations of bears around the world. Thousands of bears are farmed for their bile in China, Vietnam and Korea. They are kept in appalling conditions and usually have bile drained from their gall bladders using catheters inserted into their abdomen or with hypodermic needles. There is no evidence to suggest that farming bears has reduced pressures on wild bear populations. Indeed the farming of bears in China has led to a huge increase in consumption of bear bile since the 1980's with many people prepared to pay very high prices for the 'superior' bile of a wild bear. The bear, the bruin, or specific types of bears are popular nicknames or mascots, e.g. for sports teams. The constellations Ursa Major and Ursa Minor represent bears. In CB slang, "bear" (or "smokey," in reference to Smokey Bear) is a nickname for law enforcement. In homosexual slang, the term "Bear" refers to male individuals who posess physical attributes much like a bear. Such as, a heavy build, abundant body hair, and commonly facial hair. Microsoft Bear is an unofficial mascot hidden in Windows 3.1 and Windows 95. The bear is the offical mascot of East Brunswick High School in New Jersey. Stephen Colbert frequently attacks bears as "godless killing machines" mobilized against humanity on The Colbert Report. Ross Harman is a prime example of an anthropomorphic bear.

Further reading


- Bears of the World, Terry Domico, Photographs by Terry Domico and Mark Newman, Facts on File, Inc, 1988, hardcover, ISBN 0816015368
- The Bear by William Faulkner

See also


- Animal
- List of mammals
- Mammal
- Mammal classification

External links


- [http://www.cloudline.org/LinguisticArchaeology.html Chuck Bigelow, note on PIE roots signifying "bear"]
- [http://www.iberianature.com/material/spainbearnews.htm Spanish bear news] regularly-updated news archive on Bears in Spain
- [http://www.gi.alaska.edu/ScienceForum/ASF13/1314.html The Brown Bear: Father of the Polar Bear?] Alaska Science Forum Article #1314 zh-min-nan:Hîm ko:곰 ms:Beruang ja:クマ simple:Bear th:หมี

Giant Short Faced Bear

Arctodus, also known as the Short-Faced Bear, is a genus of extinct bear. One species, the Giant Short-Faced Bear (Arctodus simus) was the biggest bear ever to have lived. Standing 1.5 metres at the shoulder (over 3 metres when standing on hind legs) and equipped with powerful jaws this bear would have been an intimidating sight. Arctodus seems to have been mainly a carnivore and was by far the most powerful land predator during the Ice Age in North America. It may have attacked bison, deer, and horses and other large herbivores, but probably partly lived, like many other large carnivores like lions, as a scavenger. Compared to modern brown bears it had much longer limbs and was generally more slender. It had a very short, broad muzzle which gives rise to its name, and which gave it a very powerful bite. Its long legs were adapted for a faster running-style than modern bears and enabled Arctodus to hunt and to range far and wide in search of prey and carrion and its powerful bite enabled it to crack open bones to reach rich marrow. The largest known skull of Arctodus was found by a Yukon gold miner. Another fossil from southern Saskatchewan indicates that Arctodus lived there more than 70,000 years ago. Arctodus simus, the largest species, ranged the high grasslands of western North America from Alaska to Mexico, while a lighter-built species (Arctodus pristinus) with smaller teeth inhabited the more heavily wooded Atlantic coastal region. The short-faced bear belongs to a group of bears known as the Tremarctine bears, which are of New World origin. The earliest member of the Tremarctinae is Plionarctos, which lived in Texas during the Pliocene Epoch (about 5-2 million years ago). It is likely that this genus is ancestral to the Spectacled Bear (Tremarctos) and the short-faced bear. Although the early history of Arctodus is poorly known, it evidently became widespread in North America by the Kansan age (about 800,000 years ago). The short-faced bear became extinct some 12,000 years ago, perhaps partly because some of its large prey died out earlier, and partly because of competition with the smaller, more herbivorous brown bears that entered North America from Eurasia. Since its demise coincides with the development of the Clovis technology and improved hunting techniques by humans in North America, hunting may also have contributed to its extinction both directly and due to the depletion of other large mammals on which it depended for food. Category:Prehistoric mammals Category:Pliocene mammals Category:Pleistocene mammals Category:Pleistocene extinctions Category:Bears

Carnivore

A carnivore is an animal that eats a diet consisting solely of meat, whether it comes from live animals or dead (scavenging). The word also refers to the mammals of the Order Carnivora, many (but not all) of which fit the first definition. Bears are an example of members of Carnivora that are not true carnivores. Carnivores that eat primarily (or only) insects are called insectivores.

Animals that are obligate carnivores

insectivore]] An obligate or true carnivore is an animal that subsists on a diet consisting only of meat. They may consume other products presented to them, especially animal products like cheese and bone marrow, or sweet sugary substances like honey and syrup, but, as these products are not essential, they do not need to consume these on a regular basis. True carnivores lack the physiology required for the digestion of vegetable matter. Domesticated carnivores are often recommended to have vegetable supplements (or such containing processed pet foods) as meats designed for human consumption may be lacking in vital nutrients.
- Felines, ranging from domestic cats to lions, tigers, and other large predators.
- Some canines, such the Grey wolf but not the Red wolf or coyote. Domestic dogs are broadly considered carnivorous but the classification is often debated.
- Hyenas
- Some mustelids
- Polar Bears
- Birds of prey, including hawks, eagles, falcons and owls
- Scavenger birds, like vultures
- Several species of waterfowl including gulls, penguins, pelicans and storks stork
- Anurans
- Snakes
- Crocodilians
- Sharks and many other species of fish
- Toothed whales
- Octopuses and squid
- Spiders
- Mantophasmatodea, Reduviidae and other insects There are also several species of carnivorous plants, though most are primarily insectivorous, some digest nematodes and other small invertebrates. Many dinosaurs were obligate carnivores, namely most –if not all– theropods, like Tyrannosaurus rex. Sauropods and ornithischians were herbivorous.

Words with same roots "eater of flesh" but different meaning


- Sarcophagus

See also


- Cannibalism
- Insectivore
- Sarcophagus
- Carnivorous plant

Compare and contrast


- Herbivore
- Omnivore Category:Eating behaviors ms:Maging ja:肉食動物 simple:Carnivore

Ice age

An ice age is a period of long-term downturn in the temperature of Earth's climate, resulting in an expansion of the continental ice sheets, polar ice sheets and mountain glaciers ("glaciation"). Glaciologically, ice age is often used to mean a period of ice sheets in the northern and southern hemispheres; by this definition we are still in an ice age (because the Greenland and Antarctic ice sheets still exist). More colloquially, when speaking of the last few million years, ice age is used to refer to colder periods with extensive ice sheets over the North American and European continents: in this sense, the last ice age ended about 10,000 years ago. This article will use the term ice age in the former, glaciological, sense; and use the term 'glacial periods' for colder periods during ice ages and 'interglacial' for the warmer periods. During the last few million years, there have been many glacial periods, occurring initially at 40,000-year frequency but more recently at 100,000-year frequencies. These are the best studied. There have been four major ice ages in the further past.

Origin of ice age theory

The idea that, in the past, glaciers had been far more extensive was folk knowledge in some alpine regions of Europe (Imbrie and Imbrie, p25, quote a woodcutter telling de Charpentier of the former extent of the Swiss Grimsel glacier). No single person invented the idea [http://academic.emporia.edu/aberjame/histgeol/agassiz/glacial.htm]. Between 1825 and 1833, Jean de Charpentier assembled evidence in support of this idea. In 1836 Charpentier convinced Louis Agassiz of the theory, and Agassiz published it in his book Étude sur les glaciers of 1840. At this early stage of knowledge, what were being studied were the glacial periods within the past few hundred thousand years, during the current ice age. The far earlier ice ages' very existence was unsuspected.

Major ice ages

There have been at least four major ice ages in the Earth's past. The earliest hypothesized ice age is believed to have occurred around 2.7 to 2.3 billion (109) years ago during the early Proterozoic Age. :Main article: Snowball Earth. The earliest well-documented ice age, and probably the most severe of the last 1 billion years, occurred from 800 to 600 million years ago (the Cryogenian period) and it has been suggested that it produced a Snowball Earth in which permanent sea ice extended to or very near the equator. It has been suggested that the end of this ice age was responsible for the subsequent Cambrian Explosion, though this theory is recent and controversial. A minor ice age occurred from 460 to 430 million years ago, during the Late Ordovician Period. There were extensive polar ice caps at intervals from 350 to 260 million years ago, during the Carboniferous and early Permian Periods. early Permian The present ice age began 40 million years ago with the growth of an ice sheet in Antarctica, but intensified during the Pleistocene (starting around 3 million years ago) with the spread of ice sheets in the Northern Hemisphere. Since then, the world has seen cycles of glaciation with ice sheets advancing and retreating on 40,000 and 100,000 year time scales. The last glacial period ended about 10,000 years ago. The timing of ice ages throughout geologic history is in part controlled by the position of the continental plates on the surface of the Earth. When landmasses are concentrated near the polar regions, there is an increased chance for snow and ice to accumulate. Small changes in solar energy can tip the balance between summers in which the winter snow mass completely melts and summers in which the winter snow persists until the following winter. Due to the positions of Greenland, Antarctica, and the northern portions of Europe, Asia, and North America in polar regions, the Earth today is considered prone to ice age glaciations. Evidence for ice ages comes in various forms, including rock scouring and scratching, glacial moraines, drumlins, valley cutting, and the deposition of till or tillites and glacial erratics. Successive glaciations tend to distort and erase the geological evidence, making it difficult to interpret. It took some time for the current theory to be worked out. Analyses of ice cores and ocean sediment cores unambiguously show the record of glacials and interglacials over the past few million years.

Interglacials

glacial erratic In between ice ages, there are multi-million year periods of more temperate climate, but also within the ice ages (or at least within the last one), temperate and severe periods occur. The colder periods are called 'glacial periods', the warmer periods 'interglacials', such as the Eemian interglacial era. We are in an interglacial period now, the last retreat ending about 10,000 years ago. There appears to be a folk wisdom that "the typical interglacial period lasts ~12,000 years" but this is hard to substantiate from the evidence of ice core records. For example, an article in Nature [http://www.nature.com/cgi-taf/DynaPage.taf?file=/nature/journal/v429/n6992/abs/nature02599_fs.html] argues that the current interglacial might be most analogous to a previous interglacial that lasted 28,000 years. Nonetheless, fear of a new glacial period starting soon does exist (See: global cooling). However, many now believe that anthropogenic (manmade) forcing from increased "greenhouse gases" would outweigh any Milankovitch (orbital) forcing; and some recent considerations of the orbital forcing have even argued that in the absence of human perturbations the present interglacial could potentially last 50,000 years.

Causes of ice ages

The cause of ice ages remains controversial for both the large-scale ice age periods and the smaller ebb and flow of glacial/interglacial periods within an ice age. The general consensus is that it is a combination of up to three different factors: atmospheric composition (particularly the fraction of CO2 and methane), changes in the Earth's orbit around the Sun known as Milankovitch cycles (and possibly the Sun's orbit around the galaxy), and the arrangement of the continents. The first of these three factors is probably responsible for much of the change, especially for the first ice age. The "Snowball Earth" hypothesis maintains that the severe freezing in the late Proterozoic was both caused and ended by changes in CO2 levels in the atmosphere. However, the other two factors do matter. An abundance of land within the Arctic and Antarctic Circles appears to be a necessity for an ice age, probably because the landmasses provide space on which snow and ice can accumulate during cooler times and thus trigger positive feedback processes like albedo changes. The Earth's orbit does not have a great effect on the long-term causation of ice ages, but does seem to dictate the pattern of multiple freezings and thawings that take place within the current ice age. The complex pattern of changes in Earth's orbit and the change of albedo may influence the occurrence of glacial and interglacial phases — this was first explained by the theory of Milutin Milankovic. The present ice ages are the most studied and best understood, particularly the last 400,000 years, since this is the period covered by ice cores that record atmospheric composition and proxies for temperature and ice volume. Within this period, the match of glacial/interglacial frequencies to the Milankovic orbital forcing periods is so good that orbital forcing is the generally accepted explanation. The combined effects of the changing distance to the sun, the precession of the Earth's axis, and the changing tilt of the Earth's axis can change and significantly redistribute the sunlight received by the Earth. Of particular importance are changes in the tilt of the Earth's axis, which impact the intensity of seasons. For example, the amount of solar influx in July at 65 degrees north latitude is calculated to vary by as much as 25% (from 400 W/m2 to 500 W/m2, see graph at [http://www.museum.state.il.us/exhibits/ice_ages/insolation_graph.html]). It is widely believed that ice sheets advance when summers become too mild to melt all of the accumulated snowfall from the previous winter. Some workers believe that the strength of the orbital forcing appears to be too small to trigger glaciations, but feedback mechanisms like CO2 may explain this mismatch. While Milankovic forcing predicts that cyclic changes in the Earth's orbital parameters can be expressed in the glaciation record, additional explanations are necessary to explain which cycles are observed to be most important in the timing of glacial/interglacial periods. In particular, during the last 800 thousand years, the dominant inter/glacial oscillation has been 100 thousand years, which corresponds to changes in Earth's eccentricity and orbital inclination, and yet is by far the weakest of the three frequencies predicted by Milankovic. During the period 3.0 — 0.8 million years ago, the dominant pattern of glaciation corresponded to the 41 thousand year period of changes in Earth's obliquity (tilt of the axis). The reasons for preferring one frequency to another are poorly understood and an active area of current research, but the answer probably relates to some form of resonance in the Earth's climate system. The "traditional" Milankovitch explanation struggles to explain the dominance of the 100,000-year cycle over the last 8 cycles. Richard A. Muller and Gordon J. MacDonald [http://www.pnas.org/cgi/content/full/94/16/8329] [http://muller.lbl.gov/pages/glacialmain.htm] [http://muller.lbl.gov/papers/sciencespectra.htm] and others have pointed out that those calculations are for a two-dimensional orbit of Earth but the three-dimensional orbit also has a 100 thousand year cycle of orbital inclination. They proposed that these variations in orbital inclination lead to variations in insolation, as the earth moves in and out of known dust bands in the solar system. Although this is a different mechanism to the traditional view, the "predicted" periods over the last 400,000 years are nearly the same. The Muller and MacDonald theory, in turn, has been challenged by Rial [http://pangea.stanford.edu/Oceans/GES290/Rial1999.pdf]. Another worker, Ruddiman has suggested a plausible model that explains the 100,000 cycle by the modulating effect of eccentricity (weak 100,000 year cycle) on precession (23,000 year cycle) combined with greenhouse gas feedbacks in the 41,000 and 23,000-year cycles. Yet another theory has been advanced by Peter Huybers who argued that the 41,000-year cycle has always been dominant, but that the Earth has entered a mode of climate behavior where only the 2nd or 3rd cycle triggers an ice age. This would imply that the 100,000-year periodicity is really an illusion created by averaging together cycles lasting 80 and 120 thousand years. This theory is consistent with the existing uncertainties in dating, but not widely accepted at present (Nature 434, 2005, [http://web.mit.edu/~phuybers/www/Doc/Obliquity_HuybersWunsch.pdf]).

Recent glacial and interglacial phases

Richard A. Muller See Timeline of glaciation.

Glaciation in North America

The Wisconsinan glaciation has had a considerable effect on the landscape of the Northern Hemisphere. In North America, the Great Lakes and the Finger Lakes were carved by ice's deepening of old valleys. The old Teays River drainage system was radically altered and largely reshaped into the Ohio River drainage system. Other rivers were dammed and diverted to new channels, such as the Niagara, which formed a dramatic waterfall and gorge, when the waterflow encountered a limestone escarpment. Another similar waterfall near Syracuse, New York is now dry. Long Island was formed from glacial till, and the watersheds of Canada were so severely disrupted that they are still sorting themselves out — the plethora of lakes on the Canadian Shield in northern Canada can be almost entirely attributed to the action of the ice. As the ice retreated and the rock dust dried, winds carried the material hundreds of miles, forming beds of loess many dozens of feet thick in the Missouri Valley. Isostatic rebound continues to reshape the Great Lakes and other areas formerly under the weight of the ice sheets. The Driftless Zone, around the junction of Wisconsin, Minnesota, and Iowa, was not covered by glaciers.

Reference


- Imbrie, John and Katherine Palmer Imbrie. Ice ages: Solving the Mystery. Cambridge, Massachusetts: Harvard University Press, 1979, 1986 (reprint). ISBN 089490020X; ISBN 0894900153; ISBN 0674440757.

See also


- Geology
- Timeline of glaciation
- Cryogenian period
- Glacial erratic
- Glacial striations
- Glacier
- Little Ice Age
- Genesee River: Glacial Geology — Relief maps of some glacial landforms and drainage alterations in western NY.

External links


- [http://www.pbs.org/wgbh/nova/ice/ Cracking the Ice Age] from PBS
- http://www.globalchange.umich.edu/globalchange1/current/lectures/samson/climate_patterns/ Category:Glaciology Category:History of climate ms:Zaman air batu ja:氷河期

North America

North America is a continent in the northern hemisphere bordered on the north by the Arctic Ocean, on the east by the North Atlantic Ocean, on the south by the Caribbean Sea, and on the west by the North Pacific Ocean. It covers an area of 24,497,994 km² (9,458,728 sq mi), or about 4.8% of the Earth's surface. As of July 2002, its population was estimated at more than 514,600,000. It is the third largest continent in area, after Asia and Africa, and is fourth in population after Asia, Africa, and Europe. Both North and South America are named after Amerigo Vespucci, who was the first European to suggest that the Americas were not the East Indies, but a previously undiscovered (by Europeans) New World. North America occupies the northern portion of the landmass generally referred to as the New World, the Western Hemisphere, the Americas, or simply America. North America's only land connection is to South America at the narrow Isthmus of Panama. (For geopolitical reasons, all of Panama – including the segment east of the Panama Canal in the isthmus – is often considered a part of North America alone.) According to some authorities, North America begins not at the Isthmus of Panama but at the Isthmus of Tehuantepec, with the intervening region called Central America and resting on the Caribbean Plate. Most, however, tend to see Central America as a region of North America, considering it too small to be a continent on its own. Greenland, although a part of North America geographically, is not considered to be part of the continent politically.

Physical features

Greenland, plutonic, metamorphic rock types of North America. ]] Plate tectonics recognizes the vast majority of North America as being the surface of the North American Plate. Parts of California and western Mexico are known for being the edge of the Pacific Plate, with the two plates meeting along the San Andreas fault. The continent can be divided into four great regions (each of which contains many sub-regions): the Great Plains stretching from the Gulf of Mexico to the Canadian Arctic; the geologically young, mountainous west, including the Rocky Mountains, the Great Basin, California and Alaska; the raised but relatively flat plateau of the Canadian Shield in the northeast; and the varied eastern region, which includes the Appalachian Mountains, the coastal plain along the Atlantic seaboard, and the Florida peninsula. Mexico, with its long plateaus and cordilleras, falls largely in the western region, although the eastern coastal plain does extend south along the Gulf. The western mountains are split in the middle, into the main range of the Rockies and the coast ranges in California, Oregon, Washington, and British Columbia with the Great Basin – a lower area containing smaller ranges and low-lying deserts – in between. The highest peak is Denali in Alaska. Since 1931, Rugby, North Dakota, has officially been recognized as being at the geographic center of North America. The location is marked by a 4.5 metre (15 foot) field stone obelisk. Image:North america terrain 2003 map.jpg|North America bedrock and terrain. Image:North america basement rocks.png|North American cratons and basement rocks. Image:North America Tectonic Elements.jpg|Tectonic elements of North America Image:North america craton nps.gif|North American craton.

Territories and regions

craton On the main continent landmass, there are three large and relatively populous countries:
- Canada - many large islands off the shore of North America belong to Canada, including Vancouver Island and the Queen Charlotte Islands on the west, Prince Edward Island, Newfoundland and Cape Breton Island on the east, and the Canadian Arctic islands (including Ellesmere Island, Baffin Island, and Victoria Island) in the north
- Mexico - the Revillagigedo archipelago and numerous smaller islands off its coast belong to Mexico
- The United States - the 48 contiguous states and Alaska are part of North America, while the state of Hawaii in the Pacific Ocean is not; the Aleutian Islands south of Alaska also belong to the U.S. At the southern end of the continent, in a relatively small area known as Central America, are the countries of:
- Belize
- Costa Rica
- El Salvador
- Guatemala
- Honduras
- Nicaragua
- Panama 1 At the southeastern end of the continent lies a chain of islands territories called the Antilles, the Caribbean or the West Indies, which include the countries:
- Antigua and Barbuda
- Bahamas
- Barbados
- Cuba
- Dominica
- Dominican Republic
- Grenada
- Haiti
- Jamaica
- Saint Kitts and Nevis
- Saint Lucia
- Saint Vincent and the Grenadines
- Trinidad and Tobago 1 And the dependencies:
- Anguilla (British overseas territory)
- Aruba 2 (part of the Kingdom of the Netherlands)
- Cayman Islands (British overseas territory)
- Guadeloupe (French région d'outre-mer)
- Martinique (French région d'outre-mer)
- Montserrat (British overseas territory)
- Navassa Island (U.S. territory)
- Netherlands Antilles 1 (part of the Kingdom of the Netherlands)
- Puerto Rico (U.S. commonwealth)
- Turks and Caicos Islands (British overseas territory)
- British Virgin Islands (British overseas territory)
- U.S. Virgin Islands (territory of the USA) Lying in the Atlantic Ocean but considered part of the continent are the dependencies:
- Bermuda, a British overseas territory found about 1,072 km (670 mi.) southeast of New York City
- Greenland, the largest island in the world and a self-governing dependency of Denmark, which is located in the far north of the continent to the east of Nunavut.
- Saint Pierre and Miquelon, a French collectivité d'outre-mer off the south coast of Newfoundland, is the last of France's once vast possessions in America north of the Caribbean. 1 These states and dependencies have territory both in North and South America.
2 These dependencies lie in South America, but are considered North American because of cultural and historical reasons.
See here for details.

Usage

The United States, Canada, and the other English-speaking nations of the Americas (Belize, Guyana, and the Anglophone Caribbean) are sometimes grouped under the term Anglo-America, while the remaining nations of North and South America are grouped under the term Latin America. Alternatively, Northern America is used to refer to Canada and the U.S. together (plus Greenland and Bermuda), while Central America is mainland North America south of the United States. The West Indies generally include all islands in the Caribbean Sea. In this respect, Latin America generally includes Central America and South America and, sometimes, the West Indies. The term Middle America is sometimes used to refer to Mexico, Central America, and the Caribbean collectively. The term "North America" may mean different things to different people. The term in common usage is often taken to mean "the United States and Canada, only" by some people of the United States and Canada, excluding Mexico and the countries of Central America, unless the context makes it clear that they are to be included (such as with specific reference to Mexico, when talking about NAFTA). For example, guides to wild flora and fauna published by the National Audubon Society for "North America" frequently include only species found in Canada and the U.S. This may be attributed to the fact that culturally and economically, the U.S. and Canada are more alike to each other than they are to the rest of North America. Mexicans, however, are acutely aware that Mexico is a part of North America and object to this usage. Central Americans, however, are generally content to be called Central Americans – largely because of their shared history, which includes several attempts at supranational integration in the region and in which Mexico, their much larger northern neighbor, was never involved.

Political divisions and regions

Notes:
1 Continental regions as per UN categorisations/map.
2 Depending on definitions, Aruba, Netherlands Antilles, Panama, and Trinidad and Tobago have territory in one or both of North and South America.
3 Due to ongoing activity of the Soufriere Hills volcano beginning 1995, much of Plymouth, Montserrat's de jure capital, was destroyed and government offices relocated to Brades.

See also


- Discoverer of the Americas
- Economy of North America
- European colonization of the Americas
- History of North America
- Birds of North America

External links


- http://www.america-norte.com/america-norte-mapa.htm Category:Continents Category:North America zh-min-nan:Pak Bí-chiu ko:북아메리카 ja:北アメリカ simple:North America th:ทวีปอเมริกาเหนือ

Deer

:Stag redirects here. For other senses of that word, see stag (disambiguation).
Capreolinae
Cervinae
Hydropotinae
Muntiacinae A deer is a ruminant mammal belonging to the family Cervidae. A number of broadly similar animals, from related families within the order Artiodactyla, are often also called deer. Artiodactyla Depending on the species, male deer are called stags, harts, bucks or bulls, and females are called hinds, does or cows. Young deer are called calves or fawns (not to be confused with fauns, a kind of nature spirit). Hart is an expression for a stag, particularly a Red Deer stag past its fifth year. It is not commonly used, but an example is in Shakespeare's "Romeo and Juliet" when Tybalt refers to the brawling Montagues and Capulets as hartless hinds. "The White Hart" and "The Red Hart" are common English pub names. Deer are widely distributed, with representatives in all continents except Australia, Antarctica, and Africa. Australia does have six introduced species of deer that have established sustainable wild populations from Acclimatisation Society releases in the 19th Century. These are Fallow Deer, Red Deer, Sambar Deer, Hog Deer, Rusa deer, and Chital Deer[http://rubens.anu.edu.au/student.projects/rabbits/wildanim.html]. Although exotic to the continent, environmental factors restrict their ranges to habitable patches, thereby preventing any one species from becoming a serious pest. Red Deer introduced into New Zealand in early 1900s (a gift from United States President Theodore Roosevelt) have been largely domesticated in deer farms since the late 1960s and are common farm animals there now. Deer differ from other ruminants in that they have antlers instead of horns. Antlers are bony growths that develop each year (usually in summer) and, in general, it is only male deer that develop them (although there are exceptions). A young buck's first pair of antlers grow from two tiny bumps on their head that they have had from birth. The antlers grow wrapped in a thick layer of velvet and remain that way for one month, until the bone inside is hard; later the velvet is shed. During the mating season, bucks use their antlers to fight one another for mates. The two bucks circle each other, bend back their legs, lower their heads, and charge. A doe usually has one or two fawns at a time. Most fawns are born with their fur covered with white spots, though they lose their spots once they get older (excluding the Fallow Deer who keeps its spots for life). In the first twenty minutes of a fawn's life, the fawn begins to take its first steps. Its mother licks it clean until it is almost free of scent, so predators will not find it. Its mother leaves often, and the fawn does not like to be left behind. Sometimes its mother must gently push it down with her foot. The fawn stays hidden in the grass for one week until it is strong enough to walk with its mother. After two days, a fawn is able to walk, and by three weeks it can run and jump. The fawn and its mother stay together for about one year. They then go their seperate ways. A male usually never sees his mother again, but females sometimes come back with their own fawns and form small herds. horn horn There are about 34 species of deer worldwide, divided into two broad groups: the old world group includes the subfamilies Muntiacinae and Cervinae; the new world deer the subfamilies Hydropotinae and Capreolinae. Note that the terms indicate the origin of the groups, not their modern distribution: the Water Deer, for example, is a new world species but is found only in China and Korea. It is thought that the new world group evolved about 5 million years ago in the forests of North America and Siberia, the old world deer in Asia. The family Cervidae is organized as follows:
- Subfamily Hydropotinae
  - Chinese Water Deer (Hydroptes inermis)
- Subfamily Muntiacinae (mostly Muntjacs)
  - Bornean Yellow Muntjac (Muntiacus atherodes)
  - Black Muntjac (Muntiacus crinifrons)
  - Fea's Muntjac (Muntiacus feae)
  - Gongshan Muntjac (Muntiacus gongshanensis)
  - Indian Muntjac (Muntiacus muntjac)
  - Leaf Muntjac (Muntiacus putaoensis)
  - Reeves' Muntjac (Muntiacus reevesi)
  - Truong Son Muntjac (Muntiacus trungsonensis)
  - Giant Muntjac (Muntiacus vuquangensis)
  - Tufted Deer (Elaphodus cephalophus)
- Subfamily Cervinae
  - White-lipped Deer or Thorold's Deer (Cervus albirostris)
  - Philippine Spotted Deer or Visayan Spotted Deer (Cervus alfredi)
  - Barasingha (Cervus duvaucelii)
  - Red Deer (Cervus elaphus) -- called elk or wapiti in America
  - Thamin (Cervus eldii)
  - Philippine Sambar or Philippine Brown Deer (Cervus mariannus)
  - Sika Deer (Cervus nippon)
  - Sunda Sambar or Rusa deer (Cervus timorensis)
  - Sambar Deer (Cervus unicolor)
  - Chital (Axis axis)
  - Calamian Deer (Axis calamianensis)
  - Bawean Deer (Axis kuhlii)
  - Hog Deer (Axis porcinus)
  - Père David's Deer (Elaphurus davidianus)
  - Fallow Deer (Dama dama)
  - Persian Fallow Deer (Dama mesopotamica)
- Subfamily Odocoilinae
  - Roe Deer (Capreolus capreolus)
  - Moose (Alces alces)
  - Mule Deer (Odocoileus hemionus)
  - White-tailed Deer (Odocoileus virginianus)
  - Pampas Deer (Ozotoceros bezoarticus)
  - Red Brocket (Mazama americana)
  - Merioa Brocket (Mazama bricenii)
  - Dwarf Brocket (Mazama chunyi)
  - Grey Brocket (Mazama gouazoupira)
  - Pygmy Brocket (Mazama nana)
  - Yucatan Brown Brocket (Mazama pandora)
  - Little Red Brocket (Mazama rufina)
  - Northern Pudu (Pudu mephistophiles)
  - Southern Pudu (Pudu pudu)
  - Marsh Deer (Blastocerus dichotomus)
  - Peruvian Guemal or North Andean Deer (Hippocamelus antisensis)
  - Chilean Huemul or South Andean Deer (Hippocamelus bisulcus)
  - Caribou/Reindeer (Rangifer tarandus) Deer are selective feeders. They feed on leaves. They have small, unspecialised stomachs by herbivore standards, and high nutrition requirements: ingesting sufficient minerals to grow a new pair of antlers every year is a significant task. Rather than attempt to digest vast quantities of low-grade, fibrous food as, for example, sheep and cattle do, deer select easily digestible shoots, young leaves, fresh grasses, soft twigs, fruit, fungi, and lichens. Deer have long had economic significance to humans. While they are generally not as easily domesticated as sheep, goats, pigs, and even cattle, the association between people and deer is very old. Deer meat, for which they are hunted and farmed, is called venison. venison

Hybrid deer

In Origin of Species (1859) Charles Darwin wrote "Although I do not know of any thoroughly well-authenticated cases of perfectly fertile hybrid animals, I have some reason to believe that the hybrids from Cervulus vaginalis and Reevesii [...] are perfectly fertile." These two varieties of muntjac are currently considered the same species. A number of deer hybrids are bred to improve meat yield in farmed deer. Once considered separate species because of the great differences between them, American Elk (or Wapiti) and Red Deer from the Old World can produce fertile offspring, and are now considered one species. (The European Elk is a different species and is known as Moose in the USA.) The hybrids are about 30% more efficient in producing antler by comparing velvet to body weight. Wapiti have been introduced into some European Red Deer herds to improve the Red Deer type, but not always with the intended improvement. In New Zealand, where deer are introduced species, there are hybrid zones between Red Deer and North American Wapiti populations and also between Red Deer and Sika Deer populations. In New Zealand Red Deer have been artificially hybridized with Pere David Deer in order to create a farmed deer which gives birth in spring. The initial hybrids were created by artificial insemination and back-crossed to Red Deer. In Canada, the farming of European Red Deer and Red Deer hybrids is considered a threat to native Wapiti. In Britain, the introduced Sika Deer is considered a threat to native Red Deer. Initial Sika Deer/Red Deer hybrids occur when young Sika stags expand their range into established red deer areas and have no Sika hinds to mate with. They mate instead with young Red hinds and produce fertile hybrids. These hybrids mate with either Sika or Red Deer (depending which species is prevalent in the area), resulting in mongrelization. Many of the Sika Deer which escaped from British parks were probably already hybrids for this reason. In captivity, Mule Deer have been mated to White-tail Deer. Both male Mule Deer/female White-tail and male White-tail/female Mule deer matings have produced hybrids. Less than 50% of the hybrid fawns survived their first few months. Hybrids have been reported in the wild but are disadvantaged because they don't properly inherit survival strategies. Mule Deer bound (all 4 hooves hit the ground at once, called "stotting") to escape predators. Stotting is so specialized that only 100% genetically pure Mule Deer seem able to do it. In captive hybrids, even a one-eighth White-tail/seven-eighths Mule Deer hybrid has an erratic escape behaviour and would be unlikely to survive to breeding age. Hybrids do survive on game ranches where both species are kept and where predators are controlled by man.

Fictional deer

Moose Moose]
- For role of deer in mythology, see deer in mythology.
- In Christmas lore (such as in the narrative poem "A Visit from St. Nicholas"), reindeer are believed to pull the sleigh of Santa Claus.
- One famous fictional deer is Bambi. Contrary to what most people believe, in the Disney movie Bambi, he is a white-tailed deer, while in Felix Salten's original book Bambi, A Life in the Woods, he is a roe deer.
- In The Lion, the Witch and the Wardrobe, a white stag, said to grant one wish to the one who catches him, misleads the Pevensie children in the forest. Lost, they stumble back through the wardrobe to return to our world, ending their adventure.
- Saint Hubertus saw a stag with a crucifix between its antlers while hunting on Good Friday and was converted to Christianity by the vision.
- In Harry Potter and the Prisoner of Azkaban, the Patronus Charm that Harry Potter conjures up to scare away the Dementors is a silver stag. James Potter, Harry's father, had an Animagus form as a stag.
- On the television series Angel, one episode depicts the hart as the last of three animals symbolically representing the evil law firm of Wolfram & Hart.
- In one of the stories of Baron Munchhausen, the baron encounters a stag while eating cherries and without ammunition. He fires the cherry-pits at the stag with his musket, but it escapes. The next year, the baron encounters a stag with a cherry tree growing from its head; presumably this is the animal he had shot at the previous year.
- A Samurai warrior named Honda Tadakatsu famously adorned deer antlers on his helmet.
- Deer has been a subject in Chinese painting numerous times as a tranquility symbol. Category:Even-toed ungulates Category:Deer ko:사슴 ms:Rusa sambar ja:シカ th:กวาง

Horses


The Horse (Equus caballus) is a sizeable ungulate mammal, one of the seven modern species of the genus Equus. It has long played an important role in transport, whether ridden or used for pulling vehicles. They are also used for food. Though horses may have been domesticated in one isolated locale in 4500 BC, the unequivocal date of (1) domestication and (2) use as a means of transport dates to no earlier than circa 2000 BC, evidenced by the Sintashta chariot burials (see Domestication of the horse). Nevertheless, a close cousin of the horse, the donkey, was likely domesticated and used for transport circa 3000 BC (see discussions at Donkey and [http://nefertiti.iwebland.com/timelines/topics/means_of_transportation.htm]). Until the mid 20th century, armies used horses extensively in warfare: soldiers still call the groups of machines that now take the place of the horse on the battlefield "cavalry" units, sometimes keeping traditional names (Lord Strathcona's Horse, et cetera).

Domestication of the horse and surviving wild species

The earliest evidence for the domestication of the horse comes from Central Asia and dates to about 4,000 BCE. Competing theories exist about the time and place of domestication. However, wild species continued into historic times, including the Forest Horse, Equus caballus silvaticus (also called the Diluvial Horse); it is thought to have evolved into Equus caballus germanicus, and may have contributed to the development of the heavy horses of northern Europe, such as the Ardennais. The Tarpan, Equus caballus gmelini, became extinct in 1880. Its genetic line is lost, but a substitute has been recreated by "breeding back", crossing living domesticated horses that had features selected as primitive, thanks to the efforts of the brothers Lutz Heck (director of the Berlin zoo) and Heinz Heck (director of Tierpark Munich Hellabrunn). The resulting animal is more properly called the Wild Polish Horse or Konik. Konik] Only one true wild-horse species survives: Przewalski's Horse, Equus caballus przewalskii, a rare Asian species. Mongolians know it as the taki, while the Kirghiz people call it a kirtag. Wild populations exist in Mongolia; see: http://www.treemail.nl/takh/.

Wild vs. feral horses

One can distinguish between wild animals, whose ancestors have never undergone domestication, and feral animals, who had domesticated ancestors but who now live in the wild. Several populations of feral horses exist, including those in the West of the United States and Canada (often called "mustangs") and in parts of Australia (called brumbies) and in New Zealand (called "Kaimanawa horses"). These feral horses may provide useful insights into the behavior of their ancestral wild horses. The Icelandic horse (pony-sized but called a horse) provides an opportunity to compare contemporary and historical breed appearances and behaviour. Introduced by the Vikings into Iceland, Icelandic horses did not subsequently undergo the intensive selective breeding that took place in the rest of Europe from the middle ages onwards, and so they consequently bear a closer resemblance to pre-medieval breeds. The Icelandic horse has a four-beat gait called the "tölt", which equates to the rack exhibited by several American gaited breeds.

Other equids

Other members of the horse family include zebras, donkeys, and hemionids. The Donkey, Burro or Domestic Ass, Equus asinus, like the horse, has many breeds. A mule is a hybrid of a male ass and a mare and is infertile. A hinny is the less common hybrid of a female ass and a stallion. Recently breeders have begun crossing various species of zebra with mares or female asses to produce "zebra mules"—zorses and zonkeys (also called zedonks). This will probably remain a novelty hybrid as these individuals tend to inherit some of the nervous, difficult nature of their zebra parent. Full species list:
- Domesticated Horse (Equus caballus)
- Tarpan (Equus caballus gmelini)
- Przewalski's Horse (Equus caballus przewalskii)
- Donkey (Equus asinus)
- Onager (Equus hemionus)
- Kiang (Equus kiang)
- Mountain Zebra (Equus zebra)
- Plains Zebra (Equus quagga)
- Grevy's Zebra (Equus grevyi)

Evolution

All equids are part of the family Equidae, which dates back more than 50 million years. One of the first species was the tiny Hyracotherium. In the course of the million years, the horses evolved from leaf-eating forest-dwellers into grass-eating fast-running inhabitants of the open plains. The Evolution of the Horse lead to a reduction of the number of toes: from 5 per foot, to 3 per foot, to only 1 toe per foot. The genus Equus, to which all living equids belong, evolved a few million years ago. Examples of extinct horse genera include: Propalaeotherium, Mesohippus, Miohippus, Orohippus, Pliohippus, Anchitherium, Merychippus, Parahippus, Hipparion and Hippidion.

Natural History of the horse

Hippidion] In nature, horses function as prey animals. They have a natural tendency to flee from danger, though they will fight if cornered. Their eyes lie to the side of the head, giving them a wide view while grazing (slightly less than 180 degrees to each side, overlapped in front and leaving a blind spot in the rear). Even domesticated horses startle easily and must, for the safety of riders, undergo careful introductions to strange objects and situations. Horses live in family groups in primarily grassland habitats. These normally consist of a mature stallion, his harem of about one to ten mares, and the mares' offspring. Once young males reach breeding age and begin to attempt to breed with mares or to challenge the herd stallion, the latter drives them out of the herd to form "bachelor bands" with other young stallions. Usually not until a stallion reaches 7 or 8 years old does he stand a real chance of acquiring mares, eventually becoming, if successful in the attempt, a "band stallion", i.e. having a harem of his own, having separated female equids from another stallion's band. harem An alpha mare dictates the direction in which a family herd travels, while the stallion brings up the rear, "herding" his family. Recently, researchers have observed that a form of democracy appears to exist among horses. For instance, if the majority of the herd wants to stop and eat, the whole herd follows suit and stops.

Specialized vocabulary

The English-speaking world measures the height of horses in hands. One hand is defined in British law as 101.6 mm and is derived from a previous definition of 4 inches. Adult horses can range in size from 5 hands (0.5 m) (a very small miniature horse or falabella) to over 19 hands (1.8 m). By convention, 15.2 hh means 15 hands, 2 inches (1.57 m) in height, measured at the highest point of the withers. Usually, size alone marks the difference between horses and ponies. The threshold is 14.2 hh (1.47 m) for an adult. Below the threshold it is a pony, above the threshold it is a horse. Thus normal variations can mean that a horse stallion and horse mare can become the parents of an adult pony. However, a distinct set of characteristic pony traits, developed in northwest Europe and further evolved in the British Isles, muddies the issue of whether we use the word "pony" to describe a size or a type. Many people consider the Shetland pony as the archetypical pony, with its proportions very different from horses. Several small breeds appear as "horses" or "ponies" interchangeably, including the Icelandic, Fjord, and Caspian. Breeders of miniature horses favor that name because they strive to reproduce horse-like conformation in a very small size, even though their animals undeniably descend from ponies.

Words for gaits

All horses move naturally in four basic gaits, the walk, trot, canter/lope ("canter" in English riding, "lope" in Western), and the gallop.
- the walk - a "four beat" lateral gait in which a horse must have three feet on the ground and only one foot in the air at any time. The walking horse will lift first a hind leg, then the foreleg on the same side, then the remaining hind leg, then the foreleg on the same side. To get a horse into walk from halt, one must gently squeeze the sides of the horse and release the pressure on the reins. To get a horse to walk from trot, one must take sitting trot and gently apply pressure on the reins.
- the trot/jog - a "two beat" diagonal gait in which a foreleg and opposite hindleg (often called "diagonals") touch the ground at the same time. In this gait, each leg bears weight separately, making it ideal to check for lameness or for stiffness in the joints. To get a horse to trot fom walk you must soften your reins and apply more pressure with the leg. There are two types of trot a rider can do. Rising trot, where the rider stands up slightly in the saddle each time the horses outside front leg goes forward, and sitting trot, where the rider sits in the saddle and goes with the horse's movement.
- the canter/lope - A "three beat" gait in which a foreleg and opposite hindleg strike the ground together, and the other two legs strike separately. A cantering horse will first stride off with the outside hind leg, then then inside hind and outside fore together, then the inside front leg, and finally a period of suspension in which all four legs are off the ground. the rhythm should be 1-2-3, 1-2-3, etc. When cantering in a straight line, it does not usually matter which foreleg (or leading leg) goes first, but both leads should receive equal practice time, as otherwise the horse may become "one-sided" or develop a reluctance to canter on a specific lead. In the arena, the horse should canter on the inside lead. In making a fairly tight turn, the inside leg (the one nearest to the center of the turn) should lead, as this prevents the horse from "falling in". to get a horse to canter on the correct leg from trot, one must go into sitting trot, place their outside leg slightly behind the girth and squeeze with the inside leg. To get a horse to canter from gallop, one must alter the position of the body slightly back in the saddle, then you must place the outside leg behind the girth to allow the horse to canter on the correct leg, and apply pressure on the reins. Also called "lope" when riding in a Western show class. The canter is not a natural gait, but a restrained form of a gallop. Shetland pony
- the gallop - Another "four beat" gait which follows a similar progression to the canter, except the two paired legs land separately, the hind leg landing slightly before the foreleg. The gallop also involves having a leading leg. In turning at a very rapid rate, it is even more important that the horse use the appropriate lead, leading with the left leg if making a left turn, and the right leg if making a right turn, since the faster the turn the more the horse needs to lean into the turn. Horses that usually are galloped in a straight line need to be caused to alternate leads so that they do not suffer a muscular imbalance and subsequent difficulty making turns in one direction or the other. To get a horse into gallop, the rider must alter their position so they are slightly more forward in the saddle, then they should allow the horse to head and gently kick the horse's sides. The gallop is usually used in races or fox hunting. However, one would not gallop a horse during training in a ring or enclosed area, due to the fact that the horse may slip in attempting to gallop in such an area. Although a race track is an enclosed area, it is designed for a horse to gallop around, without being too enclosed which may cause the horse to slip while turning. Some horses have other gaits other than the most common three above. These horses are called Gaited Horses.
- tölt or tolt is a four beat running walk and can be ridden at any speed, from slow dancing steps to the speed of a galloping horse. This beat is natural to the Icelandic breed.
- pace is a lateral two-beat gait more commonly used in racing. In the pace, the legs move in lateral pairs, in a two beat gait, similar to the trot (however, in a trot, the legs move in diagonal pairs). In most countries pacers are raced in front of a sulky, an open mouthed two-wheeled vehicle drawn by one horse. These horses are commonly called "pacers" because of their unique gait.
- corto, largo, fino are the smooth four-beat gaits performed by Paso Finos. Similar natural four-beat gaits are found in breeds such as the Peruvian Paso. The corto occurs naturally, and is similar to the trot in speed. The largo is extended and high-speed, and the fino is very collected. This is the gait emphasized in high-level competition. Trainers have developed various artificial gaits for reasons such as appearance, and to improve the riding or driving quality. For details, see Horse gaits. Cited: Sly, Debbie. "The Practical Rider's Handbook". London: Lorenz Books, 1997.

Words relating to horses

You can view an entire equine dictionary at: [http://ultimatehorsesite.com/dictionary/dictionary.html The Horse Dictionary]
- Bronco - a wild, untamed horse, typically used in reference to the American mustang.
- Brumby - a wild or untrained Australian horse
- Charger - a medieval war horse
- cob - any horse of a short-legged, stout variety, with short legs, and a compact body, neck and back
- colt - an unaltered male horse from birth till the age of 4.
- destrier - a heavy, strong medieval war horse
- draught horse - heavy, muscular beast of burden
- filly - female horse from birth till the age of 4.
- foal - infant horse of either sex
- garron - small and disdained horse
- gelding - a castrated male horse of any age
- God dog - how the Apaches referred to horses
- green - a term used to describe an inexperienced horse
- hack - (noun) a horse for hire, or adapted to general work, used for driving or riding. Although the word sometimes means an old, worn out horse, it is also used to signify an extremely elegant horse used for riding on social occasions ("park hack", "hunter hack" etc.) (verb)- to ride a horse for pleasure, not as training
- hackney - a specific breed of flashy, elegant driving pony
- Hand - a unit of measuring used frequently to measure a horses height. One hand is equal to 4 inches (appox. 10 cm)
- horse - adult equine of either sex over 14.2 hh (58 inches, 1.47 m)
- jennet - a small horse, particularly a Spanish one
- mare - adult female horse
- mustang - a feral horse found in the western plains of North America
- nag - small horse or pony used for riding (uncomplimentary term)
- palfrey - a smooth gaited type, a riding horse, a woman's horse
- pony - equine 14.2 hh or less (58 inches, 1.47 metres)
- School Horse/Pony- A horse owned by a riding academy
- shelt or shelty - a Shetland pony
- stallion - adult, male horse that is able to produce offspring
- weanling - a young horse that has just been weaned from their mother (usually 6 months or a little older)
- yearling - male or female horse two years old In horse racing the definitions of colt, filly, mare, and horse differ from those given above. Thoroughbred racing defines a colt as a male horse less than five years old and a filly as a female horse less than five years old; harness racing defines colts and fillies as less than four years old. Horses older than colts and fillies become known as horses and mares respectively.

Words relating to horse anatomy

harness racing ; withers: the highest point of the shoulder seen best with horse standing square and head slightly lowered. The tops of the two shoulder blades and the space between them define the withers. ; mane and forelock: long and relatively coarse hair growing from the dorsal ridge of the neck, lying on either the left or right side of the neck, and the continuation of that hair on the top of the head, where it generally hangs forward. (See illustration.) ; Dock: the point where the tail connects to the rear of the horse. ; Flank: Where the hind legs and the stomach of the horse meet. ; Pastern: The connection between the coronet and the fetlock. ; Fetlock: Resembles the ankle of the horse. ; Coronet: The part of the hoof that connects the hoof to the pastern. ; Cannon: Resembles the shin of the horse. ; Muzzle: the chin, mouth, and nostrils make up the muzzle on the horse's face. ; Crest: the point on the neck where the mane grows out of. ; Poll: the portion of the horse's neck right behind the ears. ; Hock: Hindlimb equivalent to the Heel, the main joint on the hind leg. ; Stifle: corresponds to the elbow of a horse, except on the hind limb. ; Gaskin: also known as the "second thigh," the large muscle on the hind leg, just above the hock, below the stifle. ; Jowl: the cheek bone under the horses ear on both sides Chestnut: on the inside of every leg

Horse coat colors and markings

withers Horses exhibit a diverse array of coat colors and distinctive markings, and a specialized vocabulary has evolved to describe them. In fact, one will often refer to a horse in the field by his or her coat color rather than by breed or by gender. Coat colors include:
- Appaloosa - a breed of horse with spots, any color mixed with white. There are different patterns: blanket- white blanket that typically starts around or behind withers with dark spots mostly over the hips, snowflake - solid with white spots over hips, and leopard - which is white with dark spots over all the coat. A true Appaloosa is actually a breed, not a color.
- Bay- From light brown to very dark brown with black mane and tail with black points. Three types - Dark bay, blood bay, light bay and just bay.
- Black- There are two types of black, fading black and jet black. Ordinary black horses will fade to a rusty brownish color if the horse is exposed to sunlight on a regular basis. Jet black is a blue-black shade that is fadeproof. Black foals are usually born a mousy grey color. As their foal coat begins to shed out, their black color will show through,but jet black foals are born jet black. Usually for a horse to be considered black it must be completely black with no brown at all, only white markings.
- Brown - A bay without any black points.
- Buckskin- A bay horse with a gene that 'dilutes' the coat colour to a yellow, cream, or gold while keeping the black points (mane, tail, ears, legs).
- Chestnut- A reddish body color with no black.
- Cremello - A chestnut horse with two dilute genes that washes out almost all colour. Often called pseudo albinos, they have blue eyes. There are no true albino horses.
- Dun - Yellowish brown with a dorsal stripe along the back and occasionally zebra stripings on the legs.
- Fleabitten - refers to usually red hairs flecked in the coat of a gray horse.
- Gray - A horse with black skin and clear hairs. Gray horses can be born any color, and eventually most will turn gray or white with age. If you would define the horse as white it is still grey unless it is albino. Some gray horses that are very light must wear sunscreen.
- Grulla- A black horse with a dun gene. It is often a grayish/silver colored horse with dark dun factors.
- Pinto - a multi-colored horse with large patches of brown, white, and/or black and white. Piebald is black and white, while Skewbald is white and brown. Specific patterns such as tobiano, overo, and tovero refer to the orientation of white on the body.
- Paint - In 1962, the American Paint Horse Association began to recognize pinto horses with known Quarter Horse and/or Thoroughbred bloodlines as a separate breed. Today, Paint horses are the world's fifth most popular breed. Also palomino paint - palomino with white.
- Palomino-chesnut horse that has one cream dilute gene that turns the horse to a golden, yellow, or tan shade with a flaxen (white) mane and tail. Often cited as being a color "within three shades of a newly minted coin", palominos actually come in all shades from extremely light, to deep chocolate.
- Perlino - Exactly like a cremello but a bay horse with two dilute genes.
- Roan - a color pattern that causes white hairs to be sprinkled over the horse's body color. Red roans are chesnut and white hairs, blue roans are black/bay with white hairs. Roan can happen on any body color; for example, there are palomino roans and dun roans. Roans are distinguishable from greys because roans typically do not change colour in their lifetimes, unlike gray that gradually gets lighter as a horse ages. Roans also have solid colored heads that do not lighten.
- Splash - a genetically controlled horse coat variation.
- Tobiano - a genetic trait among horses which produces a characteristic white pattern in the coat.
- White - Any non-albino white horse is called a gray, even though they appear white. All white, may be the result of overlapping pinto, appaloosa, or sabino markings. Rarely there are true white horses born and are documented to have a dominant white gene (see Gray (horse) for a discussion of these). These horses have normal eye colour, and they stay white for life. Markings include: On the face:
- Star
- Snip
- Stripe
- Blaze
- White Face (sometimes called Bald Face) On the legs:
- Coronet
- Pastern
- Sock
- Stocking Elsewhere:
- Cowlicks (hair whorls)--can occur on any part of the animal, but are mainly seen on the forehead and neck. For horse color and marking genetics see Equine coat color genetics. Another good resource for horse color is: [http://ultimatehorsesite.com/colors/index.html Horse color, markings, and genetics]. Another that has numerous photographs of various colors and markings is [http://equinecolor.com/ Equine color].

The origin of modern horse breeds

Equine coat color genetics]] Horses come in various sizes and shapes. The draft breeds can top 20 hands (80 inches, 2 metres) while the smallest miniature horses can stand as low as 5.2 hands (22 inches, 0.56 metres). The Patagonian Fallabella, usually considered the smallest horse in the world, compares in size to a German Shepherd Dog. Several schools of thought exist to explain how this range of size and shape came about. These schools grew up reasoning from the type of dentition and from the horses' outward appearance. One school, which we can call the "Four Foundations", suggests that the modern horse evolved from two types of early domesticated pony and two types of early domesticated horse; the differences between these types account for the differences in type of the modern breeds. A second school -- the "Single Foundation" -- holds only one breed of horse underwent domestication, and it diverged in form after domestication through human selective breeding (or in the case of feral horses, through ecological pressures). Finally, certain geneticists have started evaluating the DNA and mitochondrial DNA to construct family trees. See: Domestication of the horse

Breeds, studbooks, purebreds and landraces

Domestication of the horse The idea of a "purebred" animal gained importance in Europe during the 19th century but selective breeding has occurred almost everywhere man has kept horses. The Arabs had a reputation for breeding their prize mares to only the most worthy stallions, and kept extensive pedigrees of their "asil" (purebred) horses. During the late middle ages the Carthusian monks of southern Spain, themselves forbidden to ride, bred horses which nobles throughout Europe prized; the lineage survives to this day in the Andalusian horse or caballo de pura raza español. The modern landscape of breed designation presents a complicated picture. Some breeds have closed studbooks; a registered Thoroughbred, Arabian, or Quarter Horse must have two registered parents of the same breed, and no other criteria for registration apply. Other breeds tolerate limited infusions from other breeds—the modern Appaloosa for instance must have at least one Appaloosa parent but may also have a Quarter Horse, Thoroughbred, or Arabian parent and must also exhibit spotted coloration to gain full registration. Still other breeds, such as most of the warmblood sporthorses, require individual judging of an individual animal's quality before registration or breeding approval. Breed registries also differ as to their acceptance or rejection of breeding technology. For example, all Thoroughbred registries require that a registered Thoroughbred be a product of a natural mating. A foal born of two Thoroughbred parents, but by means of