2019年1月5日托福阅读真题+题目+答案：Pleistocene Extinctions

2019年1月5日托福阅读真题+题目+答案：Pleistocene Extinctions

1. At the end of the Pleistocene (roughly 11,500 years ago), many large mammals became extinct. Large mammals in the Americas and Australia were particularly hard-hit. In Australia, 15 of the continent's 16 of large mammals died out; North America lost 33 of 45 genera of large mammals, and in South America 46 of 58 such genera went extinct. In contrast, Europe lost only 7 of 23 such genera, and in Africa south of the Sahara only 2 of 44 died out. What caused these extinctions Why did these extinctions eliminate mostly large mammals Why were the extinctions most severe in Australia and the Americas No completely satisfactory explanation exists, but two competing hypotheses are currently being debated. One holds that rapid climatic changes at the end of the Pleistocene caused extinctions, whereas another, called prehistoric overkill, holds that human hunters were responsible.

2. Rapid changes in climate and vegetation occurred over much of Earth's surface during the late Pleistocene, as glaciers began retreating. The North American and northern Eurasian open steppe tundras (treeless and permanently frozen land areas) were replaced by conifer and broadleaf forests as warmer and wetter conditions prevailed. The Arctic region changed from a productive herbaceous one that supported a variety of large mammals, to a relatively barren waterlogged tundra that supported a far sparser fauna. The southwestern United States region also changed from a moist area with numerous lakes, where saber-tooth cats, giant ground sloths, and mammoths roamed, to a semiarid environment unable to support a diverse fauna of large mammals.

3. Rapid changes in climate and vegetation can certainly affect animal populations, but the climate hypothesis presents several problems. First, why did the large mammals not migrate to more suitable habitats as the climate and vegetation changed After all, many other animal species did. For example, reindeer and the arctic fox lived in southern France during the last glaciation and migrated to the Arctic when the climate became warmer.

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托福阅读真题题目：

1..According to paragraph 1, which of the following groups of mammals experienced a high extinction rate at the end of the Pleistocene

A. Large mammals living in North America

B. Small mammals living in South America

C. Large mammals living in South Africa

D. Large mammals living in Europe

2..According to paragraph 1, researchers have been able to answer which of the following questions about late Pleistocene extinctions

A. Why did some parts of the world experience more extinctions than others

B. Which parts of the world experienced the greatest number of extinctions

C. Did the large mammals of the Americas or Australia become extinct first

D. How rapidly did the climate change during the extinctions

3..What can be inferred from paragraph 1 about the extinctions that occurred at the end of the Pleistocene

A. They were caused by a single factor.

B. They had relatively little impact on small mammals.

C. They wiped out nearly all of the world's large mammal species.

D. They occurred slowly over a period of thousands of years.

4..The word sparser in the passage is closest in meaning to

A. more thinly distributed

B. more threatened

C. less adapted

D. less mobile

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