Tyrannosaurus Rex (T-REX)

Tyrannosaurus is a genus of theropod dinosaur. The species Tyrannosaurus rex, commonly abbreviated to T. rex, is one of the dinosaurs most often featured in popular culture around the world. It hails from what is now western North America. Some scientists consider Tarbosaurus bataar from Asia to represent a second species of Tyrannosaurus, while others maintain Tarbosaurus as a separate genus.
Like other tyrannosaurids, Tyrannosaurus was a bipedal carnivore with a massive skull balanced by a long, heavy tail. Relative to the large and powerful hindlimbs, Tyrannosaurus forelimbs were small and retained only two digits. Although other theropods rivaled or exceeded T. rex in size, it was the largest known tyrannosaurid and one of the largest known land predators, measuring over 13 metres (43 feet) in length and up to 6.8 metric tons (7.5 short tons) in weight.
Fossils of T. rex have been found in North American rock formations dating to the last three million years of the Cretaceous Period at the end of the Maastrichtian stage, approximately 68.5 to 65.5 million years ago; it was among the last dinosaurs to exist prior to the Cretaceous-Tertiary extinction event. More than 30 specimens of T. rex have been identified, some of which are nearly complete skeletons. Some researchers claim to have discovered soft tissue as well. The abundance of fossil material has allowed significant research into many aspects of its biology, including life history and biomechanics. The feeding habits, physiology and potential speed of T. rex are a few of the topics which remain controversial.

Description

Tyrannosaurus rex was one of the largest land carnivores of all time, measuring 12 to 13 meters (40 to 43.3 feet) long, and 4.5-5 m (14-16.6 ft) tall, when fully-grown. Mass estimates have varied widely over the years, from more than 7,200 kilograms (8 tons), to less than 4,500 kg (5 tons), with most modern estimates ranging between 5,400 and 6,800 kg (between 6 and 7.5 tons).The largest known T. rex skulls measure up to 1.5 m (5 ft) in length. Compared to other theropods, the skull was heavily modified. The skull was extremely wide posteriorly, with a narrow snout, allowing some degree of binocular vision. Some of the bones, such as the nasals, were fused, preventing movement between them. Large fenestrae (openings) in the skull reduced weight and provided areas for muscle attachment. The bones themselves were massive, as were the serrated teeth which, rather than being bladelike, were oval in cross-section. Like other tyrannosaurids, T. rex displayed marked heterodonty, with the premaxillary teeth at the front of the upper jaw closely-packed and D-shaped in cross-section. Large bite marks found on bones of other dinosaurs indicate that these teeth could penetrate solid bone. T. rex had the greatest bite force of any dinosaur and one of the strongest bite forces of any animal. Worn or broken teeth are often found, but unlike those of mammals, tyrannosaurid teeth were continually replaced throughout the life of the animal.The neck of T. rex formed a natural S-shaped curve like that of other theropods, but was short and muscular to support the massive head. The two-fingered forelimbs were very small relative to the size of the body, but heavily built. In contrast, the hindlimbs were among the longest in proportion to body size of any theropod. The tail was heavy and long, sometimes containing over forty vertebrae, in order to balance the massive head and torso. To compensate for the immense bulk of the animal, many bones throughout the skeleton were hollow. This reduced the weight of the skeleton while maintaining much of the strength of the bones.

Classification

Tyrannosaurus is the type genus of the superfamily Tyrannosauroidea, the family Tyrannosauridae, and the subfamily Tyrannosaurinae. Other members of the tyrannosaurine subfamily include the North American Daspletosaurus and the Asian Tarbosaurus, both of which have occasionally been synonymized with Tyrannosaurus. Tyrannosaurids were once commonly thought to be descendants of earlier large theropods such as megalosaurs and carnosaurs, although more recently they were reclassified with the generally smaller coelurosaurs.
In 1955, Soviet paleontologist Evgeny Maleev named a new species, Tyrannosaurus bataar, from Mongolia. By 1965, this species had been renamed Tarbosaurus bataar. Despite the renaming, many phylogenetic analyses have found Tarbosaurus bataar to be the sister taxon of Tyrannosaurus rex, and it has often been considered an Asian species of Tyrannosaurus. A recent redescription of the skull of Tarbosaurus bataar has shown that it was much narrower than that of Tyrannosaurus rex and that during a bite, the distribution of stress in the skull would have been very different, closer to that of Alioramus, another Asian tyrannosaur. A related cladistic analysis found that Alioramus, not Tyrannosaurus, was the sister taxon of Tarbosaurus, which, if true, would suggest that Tarbosaurus and Tyrannosaurus should remain separate.
Other tyrannosaurid fossils found in the same formations as T. rex were originally classified as separate taxa, including Aublysodon and Albertosaurus megagracilis, the latter being named Dinotyrannus megagracilis in 1995. However, these fossils are now universally considered to belong to juvenile T. rex. A small but nearly complete skull from Montana, 60 cm (2 ft) long, may be an exception. This skull was originally classified as a species of Gorgosaurus (G. lancensis) by Charles W. Gilmore in 1946, but was later referred to a new genus, Nanotyrannus. Opinions remain divided on the validity of N. lancensis. Many paleontologists consider the skull to belong to a juvenile T. rex. There are minor differences between the two species, including the higher number of teeth in N. lancensis, which lead some scientists to recommend keeping the two genera separate until further research or discoveries clarify the situation.

Manospondylus controversy

The first fossil specimen which can be attributed to Tyrannosaurus rex consists of two partial vertebrae (one of which has been lost) found by Edward Drinker Cope in 1892 and described as Manospondylus gigas. Osborn recognized the similarity between M. gigas and T. rex as early as 1917 but, due to the fragmentary nature of the Manospondylus vertebrae, he could not synonymize them conclusively.
Controversy erupted in June 2000 after the Black Hills Institute located the type locality of M. gigas in South Dakota and unearthed more tyrannosaur bones there. These were judged to represent further remains of the same individual, and to be identical to those of T. rex. According to the rules of the International Code of Zoological Nomenclature (ICZN), the system that governs the scientific naming of animals, Manospondylus gigas should therefore have priority over Tyrannosaurus rex, because it was named first. However, the Fourth Edition of the ICZN, which took effect on January 1, 2000, states that "the prevailing usage must be maintained" when "the senior synonym or homonym has not been used as a valid name after 1899" and "the junior synonym or homonym has been used for a particular taxon, as its presumed valid name, in at least 25 works, published by at least 10 authors in the immediately preceding 50 years..." Tyrannosaurus rex easily qualifies as the valid name under these conditions and would most likely be considered a nomen protectum ("protected name") under the ICZN if it was ever challenged, which it has not yet been. Manospondylus gigas would then be deemed a nomen oblitum ("forgotten name").

Life history

The identification of several specimens as juvenile Tyrannosaurus rex has allowed scientists to document ontogenetic changes in the species, estimate the lifespan, and determine how quickly the animals would have grown. The smallest known individual (LACM 28471, the "Jordan theropod") is estimated to have weighed only 29.9 kg (66 lb), while the largest, such as FMNH PR2081 ("Sue") most likely weighed over 5400 kg (6 short tons). Histologic analysis of T. rex bones showed LACM 28471 had aged only 2 years when it died, while "Sue" was 28 years old, an age which may have been close to the maximum for the species.
Histology has also allowed the age of other specimens to be determined. Growth curves can be developed when the ages of different specimens are plotted on a graph along with their mass. A T. rex growth curve is S-shaped, with juveniles remaining under 1800 kg (2 short tons) until approximately 14 years of age, when body size began to increase dramatically. During this rapid growth phase, a young T. rex would gain an average of 600 kg (1600 lb) a year for the next four years. At 18 years of age, the curve plateaus again, indicating that growth slowed dramatically. For example, only 600 kg (1,300 lb) separated the 28-year-old "Sue" from a 22-year-old Canadian specimen (RTMP 81.12.1). Another recent histological study performed by different workers corroborates these results, finding that rapid growth began to slow at around 16 years of age. This sudden change growth rate may indicate physical maturity, a hypothesis which is supported by the discovery of medullary tissue in the femur of a 16 to 20-year-old T. rex from Montana (MOR 1125, also known as "B-rex"). Medullary tissue is found only in female birds during ovulation, indicating that "B-rex" was of reproductive age. Other tyrannosaurids exhibit extremely similar growth curves, although with lower growth rates corresponding to their lower adult sizes.
Over half of the known T. rex specimens appear to have died within six years of reaching sexual maturity, a pattern which is also seen in other tyrannosaurs and in some large, long-lived birds and mammals today. These species are characterized by high infant mortality rates, followed by relatively low mortality among juveniles. Mortality increases again following sexual maturity, partly due to the stresses of reproduction. One study suggests that the rarity of juvenile T. rex fossils is due in part to low juvenile mortality rates; the animals were not dying in large numbers at these ages, and so were not often fossilized. However, this rarity may also be due to the incompleteness of the fossil record or to the bias of fossil collectors towards larger, more spectacular specimens.

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Mammoth

A mammoth is any of a number of an extinct genus of proboscidean (of which the elephant remains), often with long curved tusks and, in northern species, a covering of long hair. They lived from the Pliocene epoch from 4.8 million years ago to around 4,000 years ago. The word mammoth comes from the Russian мамонт mamont, probably in turn from the Khanty

Evolutionary history

Mammoth remains have been found in Europe, Africa, Asia, and North America. They are believed to have originally evolved in North Africa about 4.8 million years ago, during the Pliocene, where bones of Mammuthus africanavus have been found in Chad, Libya, Morocco and Tunisia. Mammuthus subplanifrons, found in South Africa and Kenya, is also believed to be one of the oldest species (about 4 million years ago).
Despite their African ancestry, they are in fact more closely related to the modern Asian Elephant than either of the two African elephants (as both Mammuthus and Elephas also originated in Africa). The common ancestor of both mammoths and Asian elephants split from the line of African elephants about 6 - 7.3 million years ago. The Asian elephants and mammoths diverged about half a million years later (5.5 - 6.3 million years ago).
In due course the African mammoth migrated north to Europe and gave rise to a new species, the southern mammoth (Mammuthus meridionalis). This eventually spread across Europe and Asia and crossed the now-submerged Bering Land Bridge into North America.
Around 700,000 years ago, the warm climate of the time deteriorated markedly and the savannah plains of Europe, Asia and North America gave way to colder and less fertile steppes. The southern mammoth consequently declined, being replaced across most of its territory by the cold-adapted steppe mammoth (Mammuthus trogontherii). This in turn gave rise to the woolly mammoth, Mammuthus primigenius) around 300,000 years ago. Woolly mammoths were better able to cope with the extreme cold of the Ice Ages.
The woollies were a spectacularly successful species; they ranged from Spain to North America and are thought to have existed in huge numbers. The Russian researcher Sergei Zimov estimates that during the last Ice Age, parts of Siberia may have had an average population density of sixty animals per hundred square kilometres - equivalent to African elephants today.

Extinction

Most mammoths died out at the end of the last Ice Age. A definitive explanation for their mass extinction is yet to be agreed upon. A small population survived on St. Paul Island, Alaska, up until 6000 BC , and the small mammoths of Wrangel Island became extinct only around 1700 to 1500 BC.
Whether the general mammoth population died out for climatic reasons or due to overhunting by humans is controversial. Another theory suggests that mammoths may have fallen victim to an infectious disease. A combination of climate change and hunting by humans is probably the most likely explanation for their extinction.
New data derived from studies done on living elephants and reported by the American Institute of Biological Sciences (BioScience, April 2006, Vol. 56 No. 4, pp. 292-298) suggests that though human hunting may not have been the primary cause toward the mammoth's final extinction, human hunting was likely a strong contributing factor. Homo erectus is known to have consumed mammoth meat as early as 1.8 million years ago (BioScience, April 2006, Vol. 56 No. 4, p. 295).
However, the American Institute of Biological Sciences also notes that bones of dead elephants, left on the ground and subsequently trampled by other elephants, tend to bear marks resembling butchery marks, which have previously been misinterpreted as such by archaeologists.
The survival of the dwarf mammoths on Russia's Wrangel Island was due to the fact that the island was very remote, and uninhabited in the early Holocene period. The actual island was not discovered by modern civilization until the 1820s by American whalers. A similar dwarfing occurred with Mammoths on the outer Channel Islands of California, but at an earlier period. Those animals were very likely killed by early Paleo-Native Americans, and habitat loss caused by a rising sea level that split the Santa Rosae into the outer Channel Islands.

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Tiger

Tigers (Panthera tigris) are mammals of the Felidae family, one of four "big cats" in the Panthera genus, and native to the mainland of southeastern Asia. They are apex predators and the largest feline species in the world, comparable in size to the biggest fossil felids. The Bengal Tiger is the most common subspecies of tiger, constituting approximately 80% of the entire tiger population, and is found in India, Bangladesh, Bhutan, Myanmar, and Nepal. An endangered species, the majority of the world's tigers now live in captivity.

Physical characteristics

Tigers are the heaviest cats found in the wild, but the subspecies differ strongly in size. Large male Siberian Tigers (Panthera tigris altaica) can reach a total length of 3,5 m and a weight of 300 kg. Usually they reach a head and body length of 190-220 cm and a weight of 250 kg. The heaviest Indian Tiger (P. t. tigris), which is confirmed through reliable sources weighed 258 kg (570 lb). Reports of tigers weighing far more than 300 kg are mentioned in literature, but none of these cases is confirmed[9]. Females are smaller those of the Siberian or Indian subspecies weigh only between 100 and 167 kg. Isle tigers like the sumatran subspecies (P. t. sumatrae) are much smaller than mainland tigers and weigh usually only 100-140 kg in males and 75-110 kg in females. The extinct bali tiger (P. t. balica) was even smaller with a weight of 90-100 kg in males and 65-80 kg in females.
Most tigers have orange coats, a fair (whitish) medial and ventral area and stripes that vary from brown or hay to pure black. The form and density of stripes differs between subspecies, but most tigers have in excess of 100 stripes. The pattern of stripes is unique to each animal, and thus could potentially be used to identify individuals, much in the same way as fingerprints are used to identify people. This is not, however, a preferred method of identification, due to the difficulty of recording the stripe pattern of a wild tiger. It seems likely that the function of stripes is camouflage, serving to hide these animals from their prey. The stripe pattern is found on a tiger's skin and if shaved, its distinctive camouflage pattern would be preserved.
Like most cats, tigers are believed to have some degree of colour vision.
There is a well-known mutation that produces the white tiger, an animal which is rare in the wild, but widely bred in zoos due to its popularity. The white tiger is not a separate sub-species, but only a colour variation. There are also unconfirmed reports of a "blue" or slate-coloured tiger, and largely or totally black tigers, and these are assumed, if real, to be intermittent mutations rather than distinct species. Similar to the lion, the tiger has the ability to roar.

Biology and ecology

Adult tigers are territorial and fiercely defensive. A tigress may have a territory of 20 km² while the territories of males are much larger, covering 60-100 km². Male territories may overlap those of many females, but males are intolerant of other males within their territory. Because of their aggressive nature, territorial disputes can be violent and may end in the death of one of the males, though deaths are uncommon. Most encounters between tigers end without physical incident. To identify his territory the male marks trees by spraying urine and anal gland secretions on trees as well as by marking trails with scat. Males show a behaviour called flehmen, a grimacing face, when identifying a female's reproductive condition by sniffing their urine markings.
A female is only receptive for a few days and mating is frequent during that time period. A pair will copulate frequently and noisily, like other cats. The gestation period is 103 days and 3–4 cubs of about 1 kg (2 lb) each are born. The females rear them alone. Wandering male tigers may kill cubs to make the female receptive. At 8 weeks, the cubs are ready to follow their mother out of the den. The cubs become independent around 18 months of age, but it is not until they are around 2–2½ years old that they leave their mother. The cubs reach sexual maturity by 3–4 years of age. The female tigers generally own territory near their mother, while males tend to wander in search of territory, which they acquire by fighting and eliminating another male. Over the course of her life, a female tiger will give birth to an approximately equal number of male and female cubs. Tigers breed well in captivity, and the captive population in the United States may rival the wild population of the world.
In the wild, tigers mostly feed on larger ungulates, but they also take smaller prey and tigers have been known to kill crocodiles on occasion, [11][12][13] although predation is rare and the predators typically avoid one another. Siberian tigers and brown bears are a serious threat to each other and both tend to avoid each other. Statistically though, the Siberian tiger has been the more successful in battles between the two animals because bears taken by tigers are often smaller sized bears; however, tigers can and do kill larger brown bears. Even female tigers, which are considerably smaller than male tigers, are capable of taking down and killing adult gaurs by themselves. Sambar, wild boar and gaur are the tiger's favoured prey in India. Young elephant and rhino calves are occasionally taken when they are left unprotected by their herds. A case where a tiger killed an adult female Indian rhino has been observed. [14]
Tigers prefer large prey such as sambar, gaur and wild water buffalo because they provide more meat and last for many days, avoiding the need for another hunt. In all of their range, tigers are the top predators and do not compete with other carnivores other than the dhole or Indian wild dog, which makes up for its relative lack of strength by numbers. They do not prey on large animals such as adult elephants and rhinos, although they will prey on their young whenever they have an opportunity. However, a desperate tiger will attack anything it regards as potential food, including humans.
Tigers have been studied in the wild using a variety of techniques. The populations of tigers were estimated in the past using plaster casts of their pugmarks. In recent times, camera trapping has been used instead. Newer techniques based on DNA from their scat are also being evaluated. Radio collaring has also been a popular approach to tracking them for study in the wild.

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The Antarctica

Antarctica is Earth's southernmost continent, overlying the South Pole. Situated in the southern hemisphere and largely south of the Antarctic Circle, Antarctica is surrounded by the Southern Ocean. At 14.4 million km², it is the fifth-largest continent in area after Asia, Africa, North America, and South America; in turn, Europe and Australia are smaller. Some 98% of Antarctica is covered by ice, which averages at least 1.6 km in thickness.
On average, Antarctica is the coldest, driest and windiest continent, and has the highest average elevation of all the continents. Since there is little precipitation, except at the coasts, the interior of the continent is technically the largest desert in the world. There are no permanent human residents and Antarctica has never had an indigenous population. Only cold-adapted plants and animals survive there, including penguins, fur seals, mosses, lichens, and many types of algae.
The name Antarctica comes from the Greek antarktikos (ανταρκτικός), meaning "opposite to the Arctic." Although myths and speculation about a Terra Australis ("Southern Land") date back to antiquity, the first confirmed sighting of the continent is commonly accepted to have occurred in 1820 by the Russian expedition of Mikhail Lazarev and Fabian Gottlieb von Bellingshausen. However, the continent remained largely neglected for the rest of the 19th century because of its hostile environment, lack of resources, and isolated location.
The Antarctic Treaty was signed in 1959 by twelve countries; to date, forty-five countries have signed the treaty. The treaty prohibits military activities and mineral mining, supports scientific research, and protects the continent's ecozone. Ongoing experiments are conducted by more than 4,000 scientists of many nationalities and with different research interests

History

Belief in the existence of a Terra Australis—a vast continent located in the far south of the globe to "balance" the northern lands of Europe, Asia and north Africa—had existed since the times of Ptolemy (first century CE), who suggested the idea in order to preserve the symmetry of all known landmasses in the world. Depictions of a large southern landmass were common in maps such as the early 16th century Turkish Piri Reis map. Even in the late 17th century, after explorers had found that South America and Australia were not part of the fabled "Antarctica," geographers believed that the continent was much larger than its actual size.

European maps continued to show this hypothetical land until Captain James Cook's ships, HMS Resolution and Adventure, crossed the Antarctic Circle on January 17, 1773, and once again in 1774. The first confirmed sighting of Antarctica can be narrowed down to the crews of ships captained by three individuals. According to various organizations (the National Science Foundation, NASA, the University of California, San Diego, and other sources), ships captained by three men sighted Antarctica in 1820: Fabian Gottlieb von Bellingshausen (a captain in the Russian Imperial Navy), Edward Bransfield (a captain in the British Navy), and Nathaniel Palmer (an American sealer out of Stonington, Connecticut). Von Bellingshausen supposedly saw Antarctica on January 27, 1820, three days before Bransfield sighted land, and ten months before Palmer did so in November 1820. On that day the two-ship expedition led by Von Bellingshausen and Mikhail Petrovich Lazarev reached a point within 32 km (20 miles) of the Antarctic mainland and saw ice fields there. The first documented landing on mainland Antarctica was by the American sealer John Davis in Western Antarctica on February 7, 1821, although some historians dispute this claim.
In December 1839, as part of the United States Exploring Expedition of 1838 – 1842 (conducted by the United States Navy) (sometimes called the "Ex. Ex.", or "the Wilkes Expedition"), the expedition sailed from Sydney, Australia into the Antarctic Ocean, as it was then known, and reported the discovery "of an Antarctic continent west of the Balleny Islands." That part of Antarctica was later named "Wilkes Land," a name it maintains to this day.
In 1841, explorer James Clark Ross passed through what is now known as the Ross Sea and discovered Ross Island (both of which were named for him). He sailed along a huge wall of ice that was later named the Ross Ice Shelf (also named for him). Mount Erebus and Mount Terror are named after two ships from his expedition: HMS Erebus and Terror. Mercator Cooper landed in Eastern Antarctica on January 26, 1853

During an expedition led by Ernest Shackleton in 1907, parties led by T. W. Edgeworth David became the first to climb Mount Erebus and to reach the South Magnetic Pole. In addition, Shackleton himself and three other members of his expedition made several firsts in December 1908 – February 1909: they were the first humans to traverse the Ross Ice Shelf, the first to traverse the Transantarctic Mountain Range (via the Beardmore Glacier), and the first to set foot on the South Polar Plateau. On December 14, 1911, a party led by Norwegian polar explorer Roald Amundsen from the ship Fram became the first to reach the geographic South Pole, using a route from the Bay of Whales and up the Axel Heiberg Glacier. One month later, the ill-fated Scott Expedition reached the pole.
Richard Evelyn Byrd led several voyages to the Antarctic by plane in the 1930s and 1940s. He is credited with implementing mechanized land transport on the continent and conducting extensive geological and biological research. However, it was not until October 31, 1956 that anyone set foot on the South Pole again; on that day a U.S. Navy group led by Rear Admiral George Dufek successfully landed an aircraft there.

GeographyCentered asymmetrically around the South Pole and largely south of the Antarctic Circle, Antarctica is the southernmost continent and is surrounded by the Southern Ocean. (Alternatively, it may be considered to be surrounded by the southern Pacific, Atlantic, and Indian Oceans, or by the southern waters of the World Ocean.) It covers more than 14 million km², making it the fifth-largest continent, about 1.3 times larger than Europe. The coastline measures 17,968 km (11,160 miles) and is mostly characterized by ice formations, as the following shows:
Coastal types around Antarctica (Drewry, 1983) Type Frequency Ice shelf (floating ice front) 44% Ice walls (resting on ground) 38% Ice stream/outlet glacier (ice front or ice wall) 13% Rock 4% Total 100%
Antarctica is divided in two by the Transantarctic Mountains close to the neck between the Ross Sea and the Weddell Sea. The portion west of the Weddell Sea and east of the Ross Sea is called Western Antarctica and the remainder Eastern Antarctica, because they roughly correspond to the Western and Eastern Hemispheres relative to the Greenwich meridian.
About 98% of Antarctica is covered by the Antarctic ice sheet, a sheet of ice averaging at least 1.6 km (1.0 mi) thick. The continent has approximately 90% of the world's ice (and thereby approximately 70% of the world's fresh water). If all of this ice were melted, sea levels would rise about 61 m (200 feet). In most of the interior of the continent precipitation is very low, down to 20 mm/year; in a few "blue ice" areas precipitation is lower than mass loss by sublimation and so the local mass balance is negative. In the dry valleys the same effect occurs over a rock base, leading to a desiccated landscape.
Western Antarctica is covered by the West Antarctic Ice Sheet. The sheet has been of recent concern because of the real, if small, possibility of its collapse. If the sheet were to break down, ocean levels would rise by several meters in a relatively geologically short period of time, perhaps a matter of centuries. Several Antarctic ice streams, which account for about 10% of the ice sheet, flow to one of the many Antarctic ice shelves.

Vinson Massif, the highest peak in Antarctica at 4892 meters (16,050 feet), is located in the Ellsworth Mountains. Although Antarctica is home to many volcanoes, only Mount Erebus is known to be active. Located on Ross Island, Erebus is the southernmost active volcano. There is another famous volcano called Deception Island, which is famous for its giant eruption in 1970. Minor eruptions are frequent and lava flow has been observed in recent years. Other dormant volcanoes may potentially be active. In 2004, an underwater volcano was found in the Antarctic Peninsula by American and Canadian researchers. Recent evidence shows this unnamed volcano may be active.

Antarctica is home to more than 70 lakes that lie thousands of meters under the surface of the continental ice sheet. Lake Vostok, discovered beneath Russia's Vostok Station in 1996, is the largest of these subglacial lakes. It is believed that the lake has been sealed off for 25 million years. There is some evidence, in the form of ice cores drilled to about 400 m above the water line, that Vostok's waters may contain microbial life. The sealed, frozen surface of the lake shares similarities with Jupiter's moon Europa. If life is discovered in Lake Vostok, this would strengthen the argument for the possibility of life on Europa.

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The Amazon Jungle

There is just no way that you can really experience a rainforest without stepping into one. No photograph, film, movie, or book can truly do it justice. The power, majesty, energy, and feeling of a primeval rainforest is incredible yet indescribable. None of the pictures or videos I've taken in my jungle jaunts even come close to capturing it. I can only take solace in knowing that I am not alone in my frustration in trying to record its mystery and beauty for those that will never have the chance to experience it first hand.

The first thing that hits you when you step into the rainforest is the air. It's so heavy with oxygen and humidity that it is almost a tangible thing which just kind of envelops you. There is a heavy, rich stillness to it... because in the heart of a primary rainforest little to no wind really makes in down below the unbroken green canopy of trees above you. The clean oxygen-filled air and the sheer magnitude of living things all around you sort of energizes you somehow. The vibrancy of life you feel flowing around you and through you resonates. It's really hard to describe... but its like all of earth's core elements are there in an abundance that you've never experienced before that it can excite, overwhelm and energize you all at once. In some places, the air stays so heavy with moisture that there is an almost perpetual cloudy fog which envelopes and muffles everything around you and earns the name as a "Cloud Forest."

And yes, the jungle can be hot to some (but us Texans don't really think so!). It can be 100 degrees or a bit more above the canopy where the sun is shining... but 200 feet below, surrounded by dappled shades of every color of green you could possibly imagine, less than 10 percent of the sunlight filters down to the forest floor and it rarely rises above about 80 degrees.
The next thing that hits you is the sheer immensity of the trees and the incredible amount of different types of vegetation that surrounds you. It's an amazing display of Nature in her most flamboyant expression of life. Literally everything around you is in flux - in some state of living, breathing, growing, decaying and dying. You can actually watch some of the plants growing with a naked eye, and huge fallen trees that would take years to return to the earth in a temperate forest are reduced to compost in a month or two. Trees the size of skyscrapers, leaves the size of umbrellas and vines with incredible sizes and shapes seemingly knitting everything together... plants growing out vines which are growing up on trees covered with other plants.... it can be overwhelming to take it all in. Even if you've trekked a lot of forests, you are still caught off guard by the amazing diversity of different plants in a rainforest.
A really good diverse forest in the US has about 12-15 different species of trees in an acre. In the Amazon Rainforest, a single acre of jungle will have about 300 different species of trees and another 300 to 400 species of higher plants... every where you look - you see something new, different and amazing. I think the main problem in trying to capture this on film is perspective. What angle lense do you use to take a picture of a 12 story tree without losing definition, much less one that is surrounded by hundreds of other 12 story trees intermingled with literally hundreds of other species of trees, vines, shrubs and bushes? Even when you try to pan up with a video camera, you still lose the perspective... Not to even mention the lighting problems of shades, shadows and dappled darkness which mute the incredible hues of green!
I will continue to add to this page as time permits and focus more on what my trips into the Amazon are like. I am fortunate to be able to experience and explore the Amazon and its native cultures that the tourist never sees. Maybe I'll write a series of short stories about some of my more memorable adventures as everyone keeps telling me I should.

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Indonesia's Mount Merapi spews hot lava

Mount Merapi

Hot gas and molten lava from Mount Merapi has forced the evacuation of thousands of people this week, officials said Wednesday, warning that a large eruption at Indonesia's most dangerous volcano was still possible.
"It has the potential to spew bigger hot clouds," said Subandriyo, a vulcanologist monitoring Merapi's peak, adding that scorching ash and debris shot nearly two miles down the mountain's flank on nine separate occasions Wednesday.
The volcano's lava dome has swelled in recent weeks, raising concerns that it could suddenly collapse and send scalding clouds of gas and debris into populated areas.
Some scientists say a powerful May 27 earthquake that killed more than 5,700

people in area only 25 miles south of Merapi may have contributed to the increased activity at the volcano.
Subandriyo said the mountain appeared a little calmer than on Monday and Tuesday, but that it was still in a state of flux.
Puji Pujiono, leader of the United Nations disaster assessment and coordination team at the site, said 3,500 people living near the base were evacuated this week, many taken in trucks and cars to temporary shelters. Thousands living nearer to the peak had already been relocated.
Pujiono said a U.N. helicopter was to fly over the 9,800 foot peak later Wednesday, and that a status report would be filed later in the evening, but he did not think the mountain was any more dangerous than it was three weeks ago.
Merapi's last deadly eruption was in 1994, when it sent out a searing gas cloud that burned 60 people to death.
About 1,300 people were killed when it erupted in 1930.

Indonesia is located on the so-called Pacific "Ring of Fire," a string of volcanoes and fault lines that encircle the Pacific Basin. It has 76 volcanoes, the largest number of any nation.
In southern Japan, meanwhile, Mount Sakurajima erupted Wednesday and sent a plume of smoke about 3,300 feet into the air, the country's Weather Agency said, but there were no immediate reports of damage or injuries.
The eruption registered as moderate on the agency's scale for both the sound and the strength of the tremors it caused.
There was no other significant change in volcanic activity, the bulletin said. "We do not believe that a large-scale eruption is imminent," said agency official Akira Otani.
Authorities in the area have received no immediate reports of damage or injuries, according to police official Shoichi Araki in Kagoshima, across the bay from the volcano. Ash has been falling in the city for several days, he added.
The 3,686-foot Sakurajima is one of the most active of Japan's 108 volcanoes. It sits in Kagoshima Bay, about 590 miles southwest of Tokyo.

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Huge Variety of Marine Life Found in Deep Antarctic Waters

Carnivorous sponges, blind creepy-crawlies adorned with hairy antennae and ribbed worms are just some of the new characters recently found to inhabit the dark abysses of the Southern Ocean, an alien abode once thought devoid of such life.
Recent expeditions have uncloaked this polar region, finding nearly 600 organisms never described before and challenging some assumptions that deep-sea biodiversity is depressed.
The findings also suggest that all of Earth's marine life originated in Antarctic waters.

Carnivorous sponges, blind creepy-crawlies adorned with hairy antennae and ribbed worms are just some of the new characters recently found to inhabit the dark abysses of the Southern Ocean, an alien abode once thought devoid of such life.
Recent expeditions have uncloaked this polar region, finding nearly 600 organisms never described before and challenging some assumptions that deep-sea biodiversity is depressed.
The findings also suggest that all of Earth's marine life originated in Antarctic waters.
Scientists had assumed that the deep sea of the South Pole would follow similar trends in biodiversity documented for the Arctic.
"There are less species in the Arctic than around the equator," said one of the study scientists, Brigitte Ebbe, a taxonomist at the German Center for Marine Biodiversity Research. "People assumed that it would be the same if you went from the equator south, but it didn't prove to be true at all."
The findings, reported this week in the journal Nature, provide a more accurate picture of creatures in the southern deep sea and shed light on the evolution of biodiversity in the deep ocean, including ancient colonization dating back 65 million years
"The Antarctic deep sea is potentially the cradle of life of the global marine species," said lead author Angelika Brandt of the Zoological Institute and Zoological Museum at the University of Hamburg.

Deep dwellers
Between 2002 and 2005, an international team of scientists completed three research expeditions to the Weddell Sea aboard the German vessel Polarstern.
Part of the Southern Ocean, the Weddell Sea is bounded by an Antarctic bulge called Coats Land and the Antarctic Peninsula.
Ernest Shackleton's ship Endurance was trapped and crushed by ice in this sea in 1915. Shackleton and his entire crew survived. Shackleton died in 1922 of a heart attack on a different Antarctic expedition.
Part of the ANDEEP (Antarctic benthic deep-sea biodiversity) project, the team collected biological samples from regions between about 2,000 and 21,000 feet below the surface of the Weddell Sea and nearby areas.
In addition to cataloging biodiversity, the scientists aimed to determine how species intermingled within and between the deep and shallower waters and whether continental-shelf organisms colonized the deep ocean or vice versa.
The Weddell Sea is part of a vast ocean current and a critical source of deep water and possibly a mode of transport to the rest of the Southern Ocean.
Some of the scientists' findings indicate species originating in a single water domain did migrate to the Southern Ocean, and some even trekked across the globe and now inhabit the Arctic waters.
Many of the organisms have relatives in both the nearby shallower waters and even in other ocean basins.
Species finds included 674 species of isopods, an order of crustaceans, 80 percent of which were new to science.
Some of the isopods and marine worms spotted on the continental shelf sported vestiges of their deep-water past.
"On the shelf, the animals have eyes because they can see. There's light in the water. In the deep sea you don't really need them, so many animals get rid of their eyes," Ebbe told LiveScience.
"There were some [species] that are very closely related to eyeless isopods, and they are now living on the shelf. So that's an indication they have moved upward," Ebbe said.

Water travel
Many species living in the deep abyss of the Weddell Sea showed strong links with other oceans, particularly organisms that can disperse their larvae over long distances.
Poor dispersers — including some isopods, nematode worms and seed shrimps — stayed close to home in the Southern Ocean.
One particularly cosmopolitan group included the foraminifera, or tiny single-celled organisms covered with relatively decorative shells.
Genetic analyses showed that three foraminifera species (Epistominella exigua, Cibicidoides wuellerstorfi and Oridorsalis umbonatus) found in both the Weddell Sea and the Arctic Ocean were nearly identical.
"They literally found some of [the foraminifera] from pole to pole, which is really amazing," Ebbe said.
Time to diversify
In terms of the soaring biodiversity, the scientists suggest organisms in the Antarctic have been around for a long time, giving them time to diversify.
"The Southern Ocean has been like it is pretty much for the last 40 million years, and it has been isolated," Ebbe said. "So the communities have had a long, long time to evolve. In the Arctic, it is much different."
In the geologic past, Antarctica belonged to a giant land mass called Gondwana that straddled the equator.
This land mass, which also included Africa, Australia, India and the tip of South America, started breaking apart more than 100 million years ago.
About 60 million years ago, Antarctica had drifted close to the South Pole, and oceans filled the gaps between Antarctica and Africa and India.
By 40 million years ago, the continent had become completely encircled by water, now called the Southern Ocean.

source of http://www.foxnews.com/ by

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Bone-Crushing Wolves Roamed Alaska During Ice Age

Gray wolves that roamed Alaska during the last ice age were built to tackle prey much larger than themselves and devour them completely—bones and all—a new study says.
The ancient wolves had short snouts, strong jaws, and massive canine teeth unlike those on any wolves today.
But these Alaskan wolves died out along with mastodons, saber-toothed cats, and other big animals at the end of the Pleistocene epoch, about 10,000 years ago.
The finding is based on an analysis of skull and tooth bones collected decades ago from the permafrost and stored today at museums in the U.S. and Canada.
The wolves were specially adapted to a highly competitive life on the vast, icy Alaskan expanses, according to the study, which examined bone shape and DNA and chemical signatures in the bones.
"Certainly, competition would favor those adaptations," said study co-author Blaire Van Valkenburgh, a professor of ecology and evolutionary biology at the University of California, Los Angeles.
She noted that the ancient wolves in Alaska didn't have to compete with larger relatives called dire wolves. This allowed the Alaskan gray wolves to fill a niche unavailable to gray wolf populations farther south.
"If there are advantages, as there generally are, to being stronger, then evolution will proceed in that direction," she said.
The study was published online today in the journal Current Biology.

Big Biters
The ancient Alaskan wolves' short snouts, broad skulls, and large teeth "indicate a specialization for big bite forces," Van Valkenburgh added.
Many of the teeth were also worn down and fractured. This shows that the wolves were eating a lot of bones for nutrition as the animals competed for access to limited prey.
Ice Age carnivores from a cave in Mexico and tar pits in Peru and California also have high rates of tooth wear and fracture, according to the researchers.
"If you killed something, you were likely to have someone come and try to steal it, and so it would behoove you to eat very rapidly and to consume as much of what you killed as possible," Van Valkenburgh said.
Chemical signatures in the wolf bones suggested the animals ate a varied diet of mammoth, musk ox, bison, and horse.
The ancient Alaskan wolves were also genetically distinct from any wolves living today, the authors add.
"If this animal were alive today, it would be classified as a distinct subspecies," Van Valkenburgh said.
Kathleen Lyons is a biologist at Old Dominion University in Norfolk, Virginia, who studies late Pleistocene mammals to understand how current climate change might affect species diversity.
She was not involved in the new research. But she said it is a "great example of how using different lines of evidence can give you a full picture of an extinct animal."
Ice Age Extinction
Like much of their prey and contemporary carnivores, the specialized Alaskan wolves disappeared at the end of the Ice Age.
Scientists have long debated the causes of these extinctions. Some studies link the demise to overhunting by humans. Other studies suggest a warming climate doomed the animals.
And a recent controversial theory says a comet or meteor exploded over northern North America and triggered the die-off.
Study co-author Van Valkenburgh said her study fails to shed light on the cause of the extinction. But "it's most likely that the carnivores went extinct as a result of their prey going extinct."
This kind of effect on Ice Age carnivores highlights a problem for conservation efforts that target a single predator species as the Earth warms and alters landscapes, noted Lyons, of Old Dominion University.
"If you don't preserve the species' habitat and the species' prey species," she said, "then your efforts to try and preserve a species are going to be problematic at best."

source of http://www.nationalgeographic.com/

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The Volcano's

A volcano is an opening, or rupture, in the Earth's surface or crust, which allows hot, molten rock, ash and gases to escape from deep below the surface. Volcanic activity involving the extrusion of rock tends to form mountains or features like mountains over a period of time.

Volcanoes are generally found where tectonic plates pull apart or are coming together. A mid-oceanic ridge, like the Mid-Atlantic Ridge, has examples of volcanoes caused by "divergent tectonic plates" pulling apart; the Pacific Ring of Fire has examples of volcanoes caused by "convergent tectonic plates" coming together. By contrast, volcanoes are usually not created where two tectonic plates slide past one another. Volcanoes can also form where there is stretching of the Earth's crust and where the crust grows thin (called "non-hotspot intraplate volcanism"), such as in the African Rift Valley, the European Rhine Graben with its Eifel volcanoes, the Wells Gray-Clearwater Volcanic Field and the Rio Grande Rift in North America.

Finally, volcanoes can be caused by "mantle plumes", so-called "hotspots"; these hotspots can occur far from plate boundaries, such as the Hawaiian Islands. Interestingly, hotspot volcanoes are also found elsewhere in the solar system, especially on rocky planets and moons.

Divergent plate boundaries

At the mid-oceanic ridges, two tectonic plates diverge from one another. New oceanic crust is being formed by hot molten rock slowly cooling down and solidifying. In these places, the crust is very thin due to the pull of the tectonic plates. The release of pressure due to the thinning of the crust leads to adiabatic expansion, and the partial melting of the mantle. This melt causes the volcanism and make the new oceanic crust. The main part of the mid-oceanic ridges are at the bottom of the ocean, and most volcanic activity is submarine. Black smokers are a typical example of this kind of volcanic activity. Where the mid-oceanic ridge comes above sea-level, volcanoes like the Hekla on Iceland are formed. Divergent plate boundaries create new seafloor and volcanic islands.

Convergent plate boundaries

Subduction zones, as they are called, are places where two plates, usually an oceanic plate and a continental plate, collide. In this case, the oceanic plate subducts, or submerges under the continental plate forming a deep ocean trench just offshore. The crust is then melted by the heat from the mantle and becomes magma. This is due to the water content lowering the melting temperature. The magma created here tends to be very viscous due to its high silica content, so often does not reach the surface and cools at depth. When it does reach the surface, a volcano is formed. Typical examples for this kind of volcano are the volcanoes in the Pacific Ring of Fire, Mount Etna.

Hotspots

Hotspots are not located on the ridges of tectonic plates, but on top of mantle plumes, where the convection of Earth's mantle creates a column of hot material that rises until it reaches the crust, which tends to be thinner than in other areas of the Earth. The temperature of the plume causes the crust to melt and form pipes, which can vent magma. Because the tectonic plates move whereas the mantle plume remains in the same place, each volcano becomes dormant after a while and a new volcano is then formed as the plate shifts over the hotspot. The Hawaiian Islands are thought to be formed in such a manner, as well as the Snake River Plain, with the Yellowstone Caldera being the current part of the North American plate over the hotspot.

Volcanic features

The most common perception of a volcano is of a conical mountain, spewing lava and poisonous gases from a crater in its top. This describes just one of many types of volcano, and the features of volcanoes are much more complicated. The structure and behavior of volcanoes depends on a number of factors. Some volcanoes have rugged peaks formed by lava domes rather than a summit crater, whereas others present landscape features such as massive plateaus. Vents that issue volcanic material (lava, which is what magma is called once it has broken the surface, and ash) and gases (mainly steam and magmatic gases) can be located anywhere on the landform. Many of these vents give rise to smaller cones such as Puʻu ʻŌʻō on a flank of Hawaii's KīlaueaOther types of volcanoes include cryovolcanos (or ice volcanoes), particularly on some moons of Jupiter, Saturn and Neptune; and mud volcanoes, which are formations often not associated with known magmatic activity. Active mud volcanoes tend to involve temperatures much lower than those of igneous volcanoes, except when a mud volcano is actually a vent of an igneous volcano

Shield volcanoes

Hawaii and Iceland are examples of places where volcanoes extrude huge quantities of basaltic lava that gradually build a wide mountain with a shield-like profile. Their lava flows are generally very hot and very fluid, contributing to long flows. The largest lava shield on Earth, Mauna Loa, rises over 9,000 m from the ocean floor, is 120 km in diameter and forms part of the Big Island of Hawaii, along with other shield volcanoes such as Mauna Kea and Kīlauea. Olympus Mons is the largest shield volcano on Mars, and is the tallest known mountain in the solar system. Smaller versions of shield volcanoes include lava cones, and lava mounds.Quiet eruptions spread out basaltic lava in flat layers. The buildup of these layers form a broad volcano with gently sloping sides called a shield volcano. Examples of shield volcanoes are the Hawaiian Islands.

Cinder cones

Volcanic cones or cinder cones result from eruptions that throw out mostly small pieces of scoria and pyroclastics (both resemble cinders, hence the name of this volcano type) that build up around the vent. These can be relatively short-lived eruptions that produce a cone-shaped hill perhaps 30 to 400 m high. Most cinder cones erupt only once. Cinder cones may form as flank vents on larger volcanoes, or occur on their own. Parícutin in Mexico and Sunset Crater in Arizona are examples of cinder cones.

Stratovolcanoes

Stratovolcanoes are tall conical mountains composed of lava flows and other ejecta in alternate layers, the strata that give rise to the name. Stratovolcanoes are also known as composite volcanoes. Classic examples include Mt. Fuji in Japan, Mount Mayon in the Philippines, and Mount Vesuvius and Stromboli in Italy.

Super volcanoes

A supervolcano is the popular term for a large volcano that usually has a large caldera and can potentially produce devastation on an enormous, sometimes continental, scale. Such eruptions would be able to cause severe cooling of global temperatures for many years afterwards because of the huge volumes of sulfur and ash erupted. They can be the most dangerous type of volcano. Examples include Yellowstone Caldera in Yellowstone National Park, Lake Taupo in New Zealand and Lake Toba in Sumatra, Indonesia. Supervolcanoes are hard to identify centuries later, given the enormous areas they cover. Large igneous provinces are also considered supervolcanoes because of the vast amount of basalt lava erupted.

Submarine volcanoes

Submarine volcanoes are common features on the ocean floor. Some are active and, in shallow water, disclose their presence by blasting steam and rocky debris high above the surface of the sea. Many others lie at such great depths that the tremendous weight of the water above them prevents the explosive release of steam and gases, although they can be detected by hydrophones and discoloration of water because of volcanic gases. Even large submarine eruptions may not disturb the ocean surface. Because of the rapid cooling effect of water as compared to air, and increased buoyancy, submarine volcanoes often form rather steep pillars over their volcanic vents as compared to above-surface volcanos. In due time, they may break the ocean surface as new islands. Pillow lava is a common eruptive product of submarine volcanoes.

Subglacial volcanoes

Subglacial volcanoes develop underneath icecaps. They are made up of flat lava flows atop extensive pillow lavas and palagonite. When the icecap melts, the lavas on the top collapse leaving a flat-topped mountain. Then, the pillow lavas also collapse, giving an angle of 37.5 degrees. These volcanoes are also called table mountains, tuyas or (uncommonly) mobergs. Very good examples of this type of volcano can be seen in Iceland, however, there are also tuyas in British Columbia. The origin of the term comes from Tuya Butte, which is one of the several tuyas in the area of the Tuya River and Tuya Range in northern British Columbia. Tuya Butte was the first such landform analyzed and so its name has entered the geological literature for this kind of volcanic formation. The Tuya Mountains Provincial Park was recently established to protect this unusual landscape, which lies north of Tuya Lake and south of the Jennings River near the boundary with the Yukon Territory.

source of http://www.wikipedia.org/

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