IELTS Academic Reading Practice 57

 
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This reading practice simulates one part of the IELTS Academic Reading test. You should spend about twenty minutes on it. Read the passage and answer questions 28-40.

Questions 28-34

Complete each sentence with the correct ending A-M from the box below.

Write the correct letter A-M in boxes 28-34 on your answer sheet.

NB You may use any letter more than once.

28 The Genyornis was thought to have been
29 Contrary to what was believed the bird may not have been
30 These megafauna, prior to the animals’ demise were believed to have been
31 Carbon dating has been proved ineffective when it is found to have been
32 Zygomturus trilobus was the size of a bull and specimens have been
33 The remains of Zygomturus trilobus was
34 The Zygomaturus specimen

  1. wiped out in the manner that was originally though
  2. living alongside human beings
  3. made extinct due to dramatic changes in climate
  4. discovered in more than one location
  5. dated using a method called uranium series
  6. lacking in sufficient collagen
  7. made extinct because it was eaten by other animals and because of changes to its environment
  8. encased in its original sediments
  9. the reason that humans and megafauna were forced into contact
  10. destroyed by fire 50,000 years before human beings arrived
  11. found to have a great similarity to the megafauna of Africa
  12. shows that people and megafauna co-existed for less than 17,000 years
  13. died sometime around 33,000 years ago
Questions 35-39

Complete the sentences below.  

Choose NO MORE THAN THREE WORDS from the passage for each answer.
Write your answers in 35-39 on your answer sheet.

The evidence for firing of the landscape shows no record of plants going through as a result of significant firing events.

Age estimates on fossils using uranium series only represent .

Showing that megafauna died out just after the arrival of the first settlers would support a .

It is possible that climate change led to fewer sources of appearing around the Willandra Lakes.

Today we are able to forget the and look at the part changes in weather and population played in the extinction of megafauna.

Question 40

Answer the questions below.

Use NO MORE THAN THREE WORDS for each answer.

Write your answers in boxes 40-40 on your answer sheet.

40. Which method of dating provides the maximum age range of a specimen?


Answer Sheet
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2
3
4
5
6
7
8
9
10
11
12
13
14
N/A
15
N/A
16
N/A
17
N/A
18
N/A
19
N/A
20
N/A
21
N/A
22
N/A
23
N/A
24
N/A
25
N/A
26
N/A
27
N/A
28
N/A
29
N/A
30
N/A
31
N/A
32
N/A
33
N/A
34
N/A
35
N/A
36
N/A
37
N/A
38
N/A
39
N/A
40
N/A


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Extinction of Megafauna

Enormous reptiles, marsupials and birds, are known to have once roamed Australia. However, the way that these huge animals known as megafauna went extinct has been under debate throughout the course of the 19th century. Even with technological advances and improvements to the scientific techniques necessary to investigate the cause of their extinction, today there are still very few answers. In the 19th century, scientists asked the questions which we are still pondering today, “were humans responsible for their disappearance, or was it climate change?”

Recent research reveals that in Australia, early man coexisted for thousands of years with some of the megafauna prior to these animals’ extinction. Researchers investigating this issue once believed that the megafauna went extinct shortly following the time when the first Australians arrived. For instance, some argue that perhaps the introduction of fire to the environment drastically changed the ecology of ancient Australia. The giant flightless bird Genyornis newtoni was the subject of some research in this area, and the results demonstrated the creature was wiped out due to significant habitat changes and being targeted by predators.

Yet the critics of this hypothesis for Genyornis‘ extinction have been able to provide some evidence to the contrary. First, egg shells which were assumed to have been from Genyornis may actually have been from a much smaller megapode, according to some palaeontologists. The evidence for fires occurring around the landscape, seen by the genomes of fire sensitive plants, do not provide any proof of genetic bottlenecks in plants that would result from such fires. The population of aboriginal Australians may also have remained small until much later in prehistory. Current genomic research shows that no significant changes to demographics of the area took place until around 10,000 years ago. This genomic evidence indicates that for tens of thousands of years, Aboriginal populations remained relatively small.

More careful analysis of the genomic record can sometimes paint very different picture. Dating, and ideally, the application of multiple dating techniques can provide the best scientific explanation. If two different dating techniques result in similar dates, the age of a species can be fairly reliably predicted. Some critics suggest that valid dates for the extinction of megafauna are still extremely limited at this point. Some have also suggested that many of the approximately 45 megafauna species estimated to have gone extinct 50,000 years ago may actually have died out tens of thousands of years before humans arrived to Australia.

One method used to test individual models that have been proposed to explain an extinction is to search for megafauna in landscapes that Aboriginals inhabited continuously over the past 50,000 years. In addition to aboriginals, these landscapes are best if they also exhibit conditions which would better preserve fossil bones. Very few locations like this exist, however there is one in in New South Wales, Australia known as Willandra Lakes World Heritage Area.

If it’s possible to demonstrate that megafauna died out shortly following the time that the first Australians arrived, this would support a rapid extinction model. If, however, evidence emerges that megafauna and people lived alongside each other over a long period of time, this would instead negate the rapid extinction model. Although this seems rather simple on its surface, there are still other factors which further complicate the ability to draw either conclusion.

Even though numerous megafauna fossils have been found in the Willandra area, erosion has taken many of these out of the original contexts in which they were buried. Age estimates are possible for these fossils by use of uranium series (U-series) dating, but only minimum age estimates can be reached. Fossils which are still encased within their original sediments could allow researchers to date the age of the sand grains with a technique known as optically stimulated luminescence dating (OSL for short). By dating the sand grains that a fossil is found in we arrive at the maximum age range, while U-series dating can only provide a minimum age range. Unfortunately, carbon dating is not particularly effective for megafauna fossils found in  Willandra, as most bones found lack the necessary collagen to obtain a carbon date. After a lengthy period of field work, very few fossils were found. Although there were numerous specimens uncovered, the bones were often found sitting on eroded surfaces, isolated. In spite of the difficulties, there was one specimen found a few decades before the search began which presented an excellent dating opportunity.

Zygomaturus trilobus was a large marsupial which appeared similar to a wombat, but the size of a very large bull. Little is known about its ecology, and it remains unclear how the animal became extinct. Two specimens of this extraordinary marsupial were excavated separately in the 1980s. Zoologist Jeanette Hope found the first, and archaeologists Harvey Johnston and Peter Clarke discovered the second specimen. Researchers sent the animal’s upper jaw (maxilla) to the Australian Museum in Sydney, who then encased it within its original sediments. The lower jaw is on display at Mungo National Park. Taking sediment samples for OSL dating and dating the fossil directly with U-series allowed researchers to determine that the specimen went extinct approximately 33,000 years ago.

Aboriginal people first came to the Willandra about 50,000 years ago, and the possibility remains that evidence for the First Australians’ arrival in that landscape prior to this time may later be uncovered. The Zygomaturus specimen provides evidence for the claim that humans and megafauna inhabited the same area for at least 17,000 years. The species certainly appears to have been around up to the beginning of dramatic climate changes. These changes are known as the last glacial cycle before the Last Glacial Maximum. The estimated date of 33,000 years ago does not necessarily reflect the exact date of the extinction date of Zygomaturus, just the most recent dated remains of that particular species.

Perhaps it was worsening climatic conditions around the Willandra Lakes which led to it becoming a refuge for both megafauna and humans, because the plains around the area would have held less water. This condition may have been what forced species such as Zygomaturus and humans to come into contact more often. This individual fossil allowed the megafauna extinction debate to continue evolving. It is now possible to put the overkill hypothesis to rest, and begin work on solving the puzzle on the influences of climate change, or changes in the Aboriginal population levels on the ecology of the megafauna.

It’s worth trying to understand more about the ways these animals interacted with the overall ecology of ancient Australia. For example, could they have been a key part of managing certain habitats, similarly to the megafauna of Africa are today? Today, hardly anything is known of the ecology of the majority of these species. More work needs to be done, as the possibilities for the role of Australia’s ancient megafauna seem to remain endless.

Reading Passage Vocabulary
Extinction of Megafauna

Enormous reptiles, marsupials and birds, are known to have once roamed Australia. However, the way that these huge animals known as megafauna went extinct has been under debate throughout the course of the 19th century. Even with technological advances and improvements to the scientific techniques necessary to investigate the cause of their extinction, today there are still very few answers. In the 19th century, scientists asked the questions which we are still pondering today, “were humans responsible for their disappearance, or was it climate change?”

Recent research reveals that in Australia, early man coexisted for thousands of years with some of the megafauna prior to these animals’ extinction. Researchers investigating this issue once believed that the megafauna went extinct shortly following the time when the first Australians arrived. For instance, some argue that perhaps the introduction of fire to the environment drastically changed the ecology of ancient Australia. The giant flightless bird Genyornis newtoni was the subject of some research in this area, and the results demonstrated the creature was wiped out due to significant habitat changes and being targeted by predators.

Yet the critics of this hypothesis for Genyornis‘ extinction have been able to provide some evidence to the contrary. First, egg shells which were assumed to have been from Genyornis may actually have been from a much smaller megapode, according to some palaeontologists. The evidence for fires occurring around the landscape, seen by the genomes of fire sensitive plants, do not provide any proof of genetic bottlenecks in plants that would result from such fires. The population of aboriginal Australians may also have remained small until much later in prehistory. Current genomic research shows that no significant changes to demographics of the area took place until around 10,000 years ago. This genomic evidence indicates that for tens of thousands of years, Aboriginal populations remained relatively small.

More careful analysis of the genomic record can sometimes paint very different picture. Dating, and ideally, the application of multiple dating techniques can provide the best scientific explanation. If two different dating techniques result in similar dates, the age of a species can be fairly reliably predicted. Some critics suggest that valid dates for the extinction of megafauna are still extremely limited at this point. Some have also suggested that many of the approximately 45 megafauna species estimated to have gone extinct 50,000 years ago may actually have died out tens of thousands of years before humans arrived to Australia.

One method used to test individual models that have been proposed to explain an extinction is to search for megafauna in landscapes that Aboriginals inhabited continuously over the past 50,000 years. In addition to aboriginals, these landscapes are best if they also exhibit conditions which would better preserve fossil bones. Very few locations like this exist, however there is one in in New South Wales, Australia known as Willandra Lakes World Heritage Area.

If it’s possible to demonstrate that megafauna died out shortly following the time that the first Australians arrived, this would support a rapid extinction model. If, however, evidence emerges that megafauna and people lived alongside each other over a long period of time, this would instead negate the rapid extinction model. Although this seems rather simple on its surface, there are still other factors which further complicate the ability to draw either conclusion.

Even though numerous megafauna fossils have been found in the Willandra area, erosion has taken many of these out of the original contexts in which they were buried. Age estimates are possible for these fossils by use of uranium series (U-series) dating, but only minimum age estimates can be reached. Fossils which are still encased within their original sediments could allow researchers to date the age of the sand grains with a technique known as optically stimulated luminescence dating (OSL for short). By dating the sand grains that a fossil is found in we arrive at the maximum age range, while U-series dating can only provide a minimum age range. Unfortunately, carbon dating is not particularly effective for megafauna fossils found in  Willandra, as most bones found lack the necessary collagen to obtain a carbon date. After a lengthy period of field work, very few fossils were found. Although there were numerous specimens uncovered, the bones were often found sitting on eroded surfaces, isolated. In spite of the difficulties, there was one specimen found a few decades before the search began which presented an excellent dating opportunity.

Zygomaturus trilobus was a large marsupial which appeared similar to a wombat, but the size of a very large bull. Little is known about its ecology, and it remains unclear how the animal became extinct. Two specimens of this extraordinary marsupial were excavated separately in the 1980s. Zoologist Jeanette Hope found the first, and archaeologists Harvey Johnston and Peter Clarke discovered the second specimen. Researchers sent the animal’s upper jaw (maxilla) to the Australian Museum in Sydney, who then encased it within its original sediments. The lower jaw is on display at Mungo National Park. Taking sediment samples for OSL dating and dating the fossil directly with U-series allowed researchers to determine that the specimen went extinct approximately 33,000 years ago.

Aboriginal people first came to the Willandra about 50,000 years ago, and the possibility remains that evidence for the First Australians’ arrival in that landscape prior to this time may later be uncovered. The Zygomaturus specimen provides evidence for the claim that humans and megafauna inhabited the same area for at least 17,000 years. The species certainly appears to have been around up to the beginning of dramatic climate changes. These changes are known as the last glacial cycle before the Last Glacial Maximum. The estimated date of 33,000 years ago does not necessarily reflect the exact date of the extinction date of Zygomaturus, just the most recent dated remains of that particular species.

Perhaps it was worsening climatic conditions around the Willandra Lakes which led to it becoming a refuge for both megafauna and humans, because the plains around the area would have held less water. This condition may have been what forced species such as Zygomaturus and humans to come into contact more often. This individual fossil allowed the megafauna extinction debate to continue evolving. It is now possible to put the overkill hypothesis to rest, and begin work on solving the puzzle on the influences of climate change, or changes in the Aboriginal population levels on the ecology of the megafauna.

It’s worth trying to understand more about the ways these animals interacted with the overall ecology of ancient Australia. For example, could they have been a key part of managing certain habitats, similarly to the megafauna of Africa are today? Today, hardly anything is known of the ecology of the majority of these species. More work needs to be done, as the possibilities for the role of Australia’s ancient megafauna seem to remain endless.

 
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