The position of Mid-ocean ridges Essay

The lithosphere consists of the crust and the upper mantle and is divided into several major plates. Plate tectonics provides the evidence that Australia was once part of an ancient super continent. Alfred Wagner proposed that the continents had once the continents had been united in one large land mass known as Pangaea. He suggested that Pangaea broke apart and the continents drifted apart into their present positions. For this reason his hypothesis was called the continental drift hypothesis.

Wagner however, was not the iris person to suggest the continents had once been Joined especially since many scientists noticed the maps of Africa and South America suggested the two continents were once Joined together. There was much opposition to Wager’s hypothesis but it was later hypothesized by Arthur Holmes that convention currents in the upper mantle moved the continents. However it was not until WI when scientists began to investigate the topography of the ocean floor that the theory of continental drift became prominent.

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Matching Continental Margins The continental margin is the zone between the ocean basin and the mass of the intent. The continental shelf is the area underwater from the shore to the continental margin. If the continental margins of the continents in the southern hemisphere are aligned like a Jigsaw, you can reconstruct the great southern landmass Goanna, which formed when Pangaea split around 1 50 may. Goanna consisted of the present day continents South America, Australia, Africa, India and Antarctica. When the continental margins are aligned, it is important that rock types and rock structures also align.

Position of Mid-ocean ridges + Spreading zones between continental plates Mid-ocean ridges are the sites where two crystal plates meet or move apart. The theory of continental drift suggests that as the continents drift apart magma wells up through the spreading floor and new crust is formed. There is scientific evidence using radiometric dating that the rocks towards the edges of these mid-ocean ridges are younger than those further in from the margins, supporting the idea that rock near the edges of spreading zones are newly laid down.

Mid-ocean ridges where plates collide are the sites where most volcanoes and earthquakes occur At subsection zones, where plates collide and fold, or one plate slides beneath the there, the formation of mountains and the continued movement of present-day continents provides evidence to support the theory of plate tectonics. The Himalayan mountain range is at a subsection point where India is sliding under the Asian plate. Evidence is provided by the fact that the Himalayan mountains are still slowly rising, supporting the theory of continental drift.

Australia is still moving northwards at a rate of approximately 7 CM per year. Common Fossils of Flora and Fauna A fossil is any trace or remains of past life. A study of the fossil evidence from the efferent continents that once made up Goanna shows great similarities that are hard to explain unless the continents were once connected. The Globetrotters are an order of plant that lived during the Permian period and were deciduous woody trees and shrubs They are hard to classify as most fossils are leaf impressions.

Fossils have been found in Australia, India, South America, Africa and Antarctica – all the continents that made up Goanna. The Globetrotters is a genus of seed ferns with several hundred species. Since the mature seeds were believed to be several millimeters in length, it is probable to include that the seeds were too big to be dispersed by wind across oceans. Hence the presence of the plant on the Southern Continents during the Permian is strong evidence to show that Goanna existed in that time frame. Signatories is a similar fern but has slightly different leaf structure but is also evidence for the existence of Goanna.

The distribution of mammals, especially the marsupials provides evidence for plate tectonics and the past existence of Goanna. When Australia and Antarctica separated from Africa around 1 50 million years ago, mammals were still primitive tit metronomes, marsupials and only a few placentas. Australia became isolated and the marsupials evolved and diverse species flourished. In the rest of the world, placental mammals flourished while metronomes became extinct and except for the South American possum, marsupials also became extinct.

When Australia crashed with Asia many placental mammals were able to island hop to Australia. The main point here is that the isolation of metronomes in Australia and marsupials in Australia and South Africa, provide information that Goanna existed and due to its separation isolated certain types. Present day Goanna organisms. Many present day plants and animals that are found on the continents of the Southern Hemisphere show Goanna Ancestry. 1 – Rattiest – The Flightless Birds The large flightless birds, the rattiest are found only on the Southern continents.

These include the Australian emus, the African Ostrich, New Zealand Kiwi and South American Rhea. Rattiest do not have a keel on their breastbone which is where the flight muscles are attached for birds that can fly. Thus they are called flat-cheated. It is believed that rattiest evolved in the Cretaceous period and then divergent evolution occurred when the groups were separated. 2 – Southern Beach Tree – Nuthouses This is found in Australia, New Guiana, New Zealand and South America and its presence on the southern continents led scientists to believe that these continents had once been Joined.

It evolved after Africa separated from Goanna and it formed large rainforest’s. Fossil pollen of Nuthouses from Ass has been dated at 80 may. As Ass became drier and hotter, the Eucalyptus evolved so that only certain species of Nuthouses remained. It is only present in Tasmania and Australia’s only deciduous tree. 3 – Protracted The Tamil Protracted includes many tamari Australian plants such as the Warpath and Banks. They have low dispersal ability but many are found on the southern continents showing the ancient landmass of Goanna once exited and enabled the spread of these plants.

The drying of Ass has led to a division between the east coast species and west coast species and current research is being done with DNA sequences to trace evolutionary paths of the family. Discuss current research into the evolutionary relationships between extinct species, including Managua and extant Australian species The geological history of Australia shows that the land area we identify as ‘Australia’ has experienced a vast variety of conditions and has been in many geographical locations from the equator to the south pole. Many species evolved and have become extinct.

For example, Globetrotters appears in the fossil record of the Permian period but became extinct 245 may. Extant species have living representatives. For example the Nuthouses is still distributed in Tasmania but appeared during the Cretaceous era. The Managua are animals which are similar to present day organisms but are much bigger. For example the Australian Managua included large kangaroos, wombats, the huge Deposition, giant running birds and a giant python. Current Research into the evolutionary relationships between extinct and extant species revolves around the search for fossil evidence.

Many sites are being excavated in search of these fossils. Once the fossils are found, similarities and differences with other known species, both living and extinct can be made so that relationships can be deduced. Radiometric dating provides dates for when these animals died and the study of a range of these animals gives clues about the climatic ND environmental conditions of the time. Ancient temperatures can be calculated by studying fossil plants and by the oxygen isotope in fossil marine shells. Windward was a primitive marsupial that was a cross between a wombat and a kangaroo.

It is one of the oldest fossil marsupials with a preserved skeleton and is believed to be the ancestor of Australia’s living deprivation marsupials. By about 20000 years ago most of the Managua had become extinct. Some species survived egg. The large red and grey kangaroo, however their ancestors had been significantly larger. Some fossils found show these ancestors to be double the size of present day organisms. • Illustrate the changing ideas tot scientists in the last 200 years about individual species such as the platypus as new information and technologies became available.

The Platypus: Ornithology’s Initials The platypus is quite an unusual species that baffled scientist for many years, until new information and technologies became available. The platypus was firstly described in 1799 along with the koala, kangaroo, wombat and the MME which were all curious creates to the scientific community of that era. There was significant debate on the classification by the platypus as little information about it was available and the technology of the time was unable to retrieve that information.

The platypus is one of the primitive mammals that are present on Australia, and it displays characteristics which make it unique when compared with other mammals. For example: some of these characteristics include the fact that it lays eggs, there is an absence of true teeth, there is also no mammary glands but despite this, it has special glands that are able to secrete milk. Additionally, it has fur like most other mammals, but it also has a horny beak similar to a bill of a duck. Unusually, it has webbed feet and a short tail like a beaver.

Dried platypus skin was sent to England in 1798, a year after the discovery of the unusual species, but the sample was rejected, with many claiming that the skin was a fake. For more than 80 years, there was uncertainty about how the platypus reproduced. Thus showing how lack of information and technology shaped the views of the scientists of that time, however, in 1884, as technology improved, scientists were able to unravel the mystery by capturing female eggs. This again altered the sews of scientist as with new information, they needed to again re-understand the characteristics of this species.

Furthermore, now with technology supremely advanced to what it was 200 years ago, scientists are able to use modern technologies such as fiber optics to enable to them to televise and view female platypuses feeding and caring for their young. Around 1904, as increasing information became available, a scientific Journal was able to publish the fact that many mammals do not posses teeth when they are adults. This was a striking discovery as the platypus was one of these mammals but it was commonly belie hat it was a rare kind.

For the next seventy-odd years, due to lack of technology and scientific information there was much uncertainty about how the platypus was able to regulate its body temperature like other mammals do. Only through recent research and advanced technology has it been discovered, how this operation works. Scientists have now understood how it regulates body temperature, but they believe that the mechanism is primitive or underdeveloped. New fossils have helped scientists understand the evolution of the platypus, further showing how increasing information can shift the views of scientists.

For example, omen of the fossil findings as well as research based on the sequence of amino acid have led to changes in the scientific community in the way they interpret the origin and evolution of mammals and in particular the platypus. Some of the important fossil finds that shaped the views that scientists currently hold on the evolution of the platypus include: – 120 – 170 million year old fossil of an ancestor of metronomes (as the platypus is classified as a Monterey) were found in Australia and Madagascar. – 100 million year old fossils of platypus ancestors were discovered in Lightning Ridge, New South Wales, Australia.

Scientific name of the ancestor: Stropped Galvanic). – Relatively recent (50 million years ago) fossils were discovered of platypus-like creatures from Southern South-America. As the number and type of fossils were found, the knowledge depth of the scientists increased vastly, thus allowing for a more accurate evolutionary path of the platypus to be determined. Furthermore, increasing information, in the form of fossils, arrived from both hemispheres of the Earth showed evidence of certain molar teeth that were designed both to grind down food as well as slice through meat.

This new information led scientists to the hypothesis that mammals (such as the platypus), might have had dual origins, thus further showing how scientists views have changed as increasing information became available due to the advancements in technology. In recent years, the contribution tot Australian scientists to this puzzle NAS been through the research of amino-acids. With advancing technology and faster machinery, scientist were able to observe trends between amino acid sequences of placentas and marsupials.

This has changed the views of scientists who now understand that the two species are more closely related than what they were lived to be initially. Currently, scientists believe the metronomes diverged between 160 and 180 million years ago. Note: A Monterey is a mammal, instead of giving birth to live young, lays eggs. So simply put, it is an egg laying mammal. Evolution of the Platypus: The platypus shows no obvious signs of evolution, its only change seems to be the loss of teeth and a distinct shrink in size. Thus, most evolutionary scientists are baffled about the unknown ancestry of this unique creature.

The only significant information available to current day scientists a few fossils scattered all over Australia. However, in 1984, a 110 year old fossil was found in NEWS (Lightning Ridge as mentioned above). This increased knowledge depth, shifted the views of scientists as they had no record of any mammals present on Australia before about 20 million years ago. However, the evolutionary mystery still remained a puzzle as the fossil that had been discovered showed a skull that was significantly bigger than current-day platypuses.

This only showed the obvious degeneration in present day platypuses but this information was already inferred due to previous mega-fauna degeneration knowledge. This shows how lack of knowledge can shape the views of scientists spite the fact that there is more advanced technology. Food Collecting: Scientists were yet to unravel this puzzle until recently. Many scientists believed that the primitive (or dumb) platypus had not evolved to enough of an extent that it was able to be a food collector.

Scientists believed that it simply swam along eating any food that came along. However with increasing technology such as acute magnetic detectors as well as fiber optical vision and fast computers scientists have bee able to determine that the platypus has a highly tuned receptor that is able to pick up the weak electric fields of shrimps and worms. This sense is so acute that it is able to detect prey under mud and rocks. It has also been discovered that platypuses don’t stay under water for long periods of time to collect food.

Thus due to increasing technology, scientists nave been able to discover much more information about the platypus. This has changed the way that they perceive the animal and their views have shifted as the depth of knowledge that they posses increases. Thus showing how the ideas of scientists changed in the last 200 years about individual species such as the platypus as new information and technologies became available. 2. The changes in Australian flora and fauna over millions of years have happened through evolution.

Discuss examples of variations between members of a species A species is a group of organisms that can interbreed and produce fertile offspring. Within a species there is variations – I. E. Differences between individuals. Variations occur due to genetic mutations or environmental adaptations. Examples tot Variations: – In humans – eye color, skin color, height, build, etc are all variations that make each individual different from another – In dogs (Canes familiars), the are great differences in size, color, hair length etc.

The Papacies Impress is the ‘common heath’. It has flowers that are tubular or bell- shaped. It is only found in Australia and belongs the family Peacekeeper. It is found in the dry chlorophyll forest and coastal heaths of Tasmania, and the East coast. It is a very polymorphic species. Those that are found in Victoria are most distinguishable with large flowers and grayish leaves covered in hairs. The soils in this region are more fertile compared to ‘normal’ land in Australia.

The ‘Began’ from of the heath as bright red flowers and some can have white flowers and may be located n the same population. Identify the relationship between variation within a species and the chances of survival of that species when environmental change occurs Variations in a species are important in a changing environment. A particular adaptation may provide an advantage (egg as protection against a predator or too find food or attract a mate). The variation in the gene pool of a population is important in determining the chances of survival of that population.

If there is a sudden change in the environment, those individuals in the population that randomly possess a variation hat is of advantage are more likely to survive the changed conditions. Individuals that do not possess that variation may be unable to compete and survive. Those that survive are more likely to reach an age where they can reproduce and pass their favorable characteristic on to their offspring. Individuals with less favorable variations will eventually be eliminated from the population as they are out- competed.

If individuals within the population become so different that they can no longer interbreed with individuals from the original population to produce fertile offspring, hen the population is considered to be a new species. Therefore variation in a population is extremely important, because it gives the population a better chance of surviving a sudden environmental change. Variation can arise is several ways. In both sexually and asexually reproducing organisms mutations can change the genetic code and hence change the characteristics of the individual.

A mutation that occurs in the body cell of a multicultural organism will be lost when that individual dies. A mutation that occurs in a sex cell (such as sperm) it will be passed on to the next generation. In sexually reproducing organisms variation is also caused by random segregation of chromosomes during meiosis, crossing over during meiosis and the fact that sexual reproduction involves the union of two gametes which means half the characteristics come from one parent and the other half from the other and thus the offspring is not identical to either parent.

Heredity is the transfer of similar characteristics from parents to offspring. Heredity and variation are both essential for evolution to occur. Darwin Wallace Theory of Natural Selection: In 1858, based on their independent studies and observation of flora and fauna over any years, both Charles Darwin and Alfred Wallace proposed the same mechanism for evolution


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