1、精選優質文檔-傾情為你奉上TPO-44From Fish to Terrestrial VertebratesOne of the most significant evolutionary events that occurred on Earth was the transition of water-dwelling fish to terrestrial tetrapods (four-limbed organisms with backbones). Fish probably originated in the oceans, and our first records of th

2、em are in marine rocks. However, by the Devonian Period (408 million to 362 million years ago), they had radiated into almost all available aquatic habitats, including freshwater settings. One of the groups whose fossils are especially common in rocks deposited in fresh water is the lobe-finned fish

3、.The freshwater Devonian lobe-finned fish rhipidistian crossopterygian is of particular interest to biologists studying tetrapod evolution. These fish lived in river channels and lakes on large deltas. The delta rocks in which these fossils are found are commonly red due to oxidized iron minerals, i

4、ndicating that the deltas formed in a climate that had alternate wet and dry periods. If there were periods of drought, any adaptations allowing the fish to survive the dry conditions would have been advantageous. In these rhipidistians，several such adaptations existed. It is known that they had lun

5、gs as well as gills for breathing. Cross sections cut through some of the fossils reveal that the mud filling the interior of the carcass differed in consistency and texture depending on its location inside the fish. These differences suggest a sadlike cavity below the front end of the gut that can

6、only be interpreted as a lung. Gills were undoubtedly the main source of oxygen for these fish, but the lungs served as an auxiliary breathing device for gulping air when the water became oxygen depleted, such as during extended periods of drought. So, these fish had already evolved one of the prime

7、 requisites for living on land: the ability to use air as a source of oxygen.A second adaptation of these fish was in the structure of the lobe fins. The fins were thick, fleshy, and quite sturdy, with a median axis of bone down the center. They could have been used as feeble locomotor devices on la

8、nd, perhaps good enough to allow a fish to flop its way from one pool of water that was almost dry to an adjacent pond that had enough water and oxygen for survival. These fins eventually changed into short, stubby legs. The bones of the fins of a Devonian rhipidistian exactly match in number and po

9、sition the limb bones of the earliest known tetrapods, the amphibians. It should be emphasized that the evolution of lungs and limbs was in no sense an anticipation of future life on land. These adaptations developed because they helped fish to survive in their existing aquatic environment.What ecol

10、ogical pressures might have caused fishes to gradually abandon their watery habitat and become increasingly land-dwelling creatures? Changes in climate during the Devonian may have had something to do with this if freshwater areas became progressively more restricted. Another impetus may have been n

11、ew sources of food. The edges of ponds and streams surely had scattered dead fish and other water-dwelling creatures. In addition, plants had emerged into terrestrial habitats in areas near streams and ponds, and crabs and other arthropods were also members of this earliest terrestrial community. Th

12、us, by the Devonian the land habitat marginal to freshwater was probably a rich source of protein that could be exploited by an animal that could easily climb out of water. Evidence from teeth suggests that these earliest tetrapods did not utilize land plants as food; they were presumably carnivorou

13、s and had not developed the ability to feed on plants. How did the first tetrapods make the transition to a terrestrial habitat? Like early land plants such as rhyniophytes, they made only a partial transition; they were still quite tied to water. However, many problems that faced early land plants

14、were not applicable to the first tetrapods. The ancestors of these animals already had a circulation system, and they were mobile, so that they could move to water to drink. Furthermore, they already had lungs, which rhipidistians presumably used for auxiliary breathing. The principal changes for th

15、e earliest tetrapods were in the skeletal systemchanges in the bones of the fins, the vertebral column, pelvic girdle, and pectoral girdle.P1：One of the most significant evolutionary events that occurred on Earth was the transition of water-dwelling fish to terrestrial tetrapods (four-limbed organis

16、ms with backbones). Fish probably originated in the oceans, and our first records of them are in marine rocks. However, by the Devonian Period (408 million to 362 million years ago), they had radiated into almost all available aquatic habitats, including freshwater settings. One of the groups whose

17、fossils are especially common in rocks deposited in fresh water is the lobe-finned fish.1. Paragraph 1 supports which of the following statements about fish evolution?A. Lobe-finned fish were among the earliest types of fish to appear.B. Fish began living in freshwater habitats only after originatin

18、g elsewhere.C. Lobe-finned fish radiated into almost all available aquatic habitats.D. During the Devonian, lobe-finned fish were more common in marine than in freshwater habitats.P2：The freshwater Devonian lobe-finned fish rhipidistian crossopterygian is of particular interest to biologists studyin

19、g tetrapod evolution. These fish lived in river channels and lakes on large deltas. The delta rocks in which these fossils are found are commonly red due to oxidized iron minerals, indicating that the deltas formed in a climate that had alternate wet and dry periods. If there were periods of drought

20、, any adaptations allowing the fish to survive the dry conditions would have been advantageous. In these rhipidistians，several such adaptations existed. It is known that they had lungs as well as gills for breathing. Cross sections cut through some of the fossils reveal that the mud filling the inte

21、rior of the carcass differed in consistency and texture depending on its location inside the fish. These differences suggest a sadlike cavity below the front end of the gut that can only be interpreted as a lung. Gills were undoubtedly the main source of oxygen for these fish, but the lungs served a

22、s an auxiliary breathing device for gulping air when the water became oxygen depleted, such as during extended periods of drought. So, these fish had already evolved one of the prime requisites for living on land: the ability to use air as a source of oxygen.2. According to paragraph 2, what do the

23、minerals in the delta rocks containing rhipidistian crossopterygian fossils reveal?A. These deltas formed in dry periods but gradually became wetter.B.These deltas contain different types of iron minerals than do the surrounding areas.C.Most rhipidistian crossopterygian fish died when the climate be

24、came dry.D.Rhipidistian crossopterygian fish lived in areas that experienced alternate dry and wet periods.3. The word "advantageous" in the passage is closest in meaning toA. beneficial B. necessary C. remarkableD. common4. In paragraph 2, why does the author include the information that

25、mud inside rhipidistian crossopterygian fossils differed in consistency and texture depending on where the mud was located?A. To provide evidence that rhipidistian crossopterygian lived in river channels and lakes on large deltas.B. To identify an effect of the oxidation of iron minerals on the evol

26、ution of rhipidistian crossopterygian.C. To help explain why scientists have concluded that rhipidistian crossopterygian probably had lungs.D. To explain why scientists decided to cut cross sections through some fossils of rhipidistian crossopterygian.5. Which of the sentences below best expresses t

27、he essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.A. Because the lungs of these fish were able to provide only a small amount of oxygen, these fish obtained most of their oxygen through their

28、 gills during periods of drought.B. During periods of extended drought, these fish used their lungs to increase their intake of oxygen beyond the levels absorbed by the gills in normal times.C. Although these fish primarily used their gills to obtain oxygen, they used their lungs to obtain oxygen fr

29、om the air when there was not enough in the water.D. During periods of extended drought, the gills became an auxiliary breathing device and the lungs became the main source of oxygen for these fish.6. Which of the sentences below best expresses the essential information in the highlighted sentence i

30、n the passage? Incorrect choices change the meaning in important ways or leave out essential information.A. Because the lungs of these fish were able to provide only a small amount of oxygen, these fish obtained most of their oxygen through their gills during periods of drought.B. During periods of

31、extended drought, these fish used their lungs to increase their intake of oxygen beyond the levels absorbed by the gills in normal times.C. Although these fish primarily used their gills to obtain oxygen, they used their lungs to obtain oxygen from the air when there was not enough in the water.D. D

32、uring periods of extended drought, the gills became an auxiliary breathing device and the lungs became the main source of oxygen for these fish.P3：A second adaptation of these fish was in the structure of the lobe fins. The fins were thick, fleshy, and quite sturdy, with a median axis of bone down t

33、he center. They could have been used as feeble locomotor devices on land, perhaps good enough to allow a fish to flop its way from one pool of water that was almost dry to an adjacent pond that had enough water and oxygen for survival. These fins eventually changed into short, stubby legs. The bones

34、 of the fins of a Devonian rhipidistian exactly match in number and position the limb bones of the earliest known tetrapods, the amphibians. It should be emphasized that the evolution of lungs and limbs was in no sense an anticipation of future life on land. These adaptations developed because they

35、helped fish to survive in their existing aquatic environment.Too many words you dont know? Look them up in新托福TPO閱讀詞匯速查速記! Wechat: geeqi08057. The word "adjacent" in the passage is closest in meaning to:A. nearby B. available C. temporary D. freshYou enjoy the convenience of having all voca

36、bulary questions listed as a separate part in新托福TPO閱讀詞匯速查速記.P4：What ecological pressures might have caused fishes to gradually abandon their watery habitat and become increasingly land-dwelling creatures? Changes in climate during the Devonian may have had something to do with this if freshwater are

37、as became progressively more restricted. Another impetus may have been new sources of food. The edges of ponds and streams surely had scattered dead fish and other water-dwelling creatures. In addition, plants had emerged into terrestrial habitats in areas near streams and ponds, and crabs and other

38、 arthropods were also members of this earliest terrestrial community. Thus, by the Devonian the land habitat marginal to freshwater was probably a rich source of protein that could be exploited by an animal that could easily climb out of water. Evidence from teeth suggests that these earliest tetrap

39、ods did not utilize land plants as food; they were presumably carnivorous and had not developed the ability to feed on plants. 8. The word “progressively” in the passage is closest in meaning to:A. increasinglyB. noticeablyC. occasionallyD. rapidly9. In paragraph 4, why does the author point out tha

40、t crabs and other arthropods were already living on land when the ancestors of the first tetrapods began living there?A. To account for the presence of dead fish along the edges of ponds and streams during the Devonian.B. To support the claim that climate change caused freshwater habitats to become

41、more restricted during the Devonian.C. To identify a consequence of the emergence of plants into terrestrial habitats near ponds and streams.D. To identify a possible reason for why certain fish gradually became terrestrial organisms.10. According to paragraph 4，teeth of the earliest tetrapods sugge

42、st that these tetrapods A. competed with other animals for protein B. were probably carnivores C. could easily climb out of water D. were able to eat plantsP5：How did the first tetrapods make the transition to a terrestrial habitat? Like early land plants such as rhyniophytes, they made only a parti

43、al transition; they were still quite tied to water. However, many problems that faced early land plants were not applicable to the first tetrapods. The ancestors of these animals already had a circulation system, and they were mobile, so that they could move to water to drink. Furthermore, they alre

44、ady had lungs, which rhipidistians presumably used for auxiliary breathing. The principal changes for the earliest tetrapods were in the skeletal systemchanges in the bones of the fins, the vertebral column, pelvic girdle, and pectoral girdle.11. According to paragraph 5, which of the following was

45、true of the first tetrapods? A. They became dependent for food on organisms already living on land.B. They needed to develop new mechanisms for obtaining nutrients.C. They continued to live in close association with aquatic environments.D. They were evolutionarily far removed from their rhipidistian

46、 ancestors.12. According to paragraph 5, what was the main way that the earliest tetrapods differed from their immediate fish ancestors?A. The tetrapods had a different skeletal structure.B. The tetrapods had more sources of food availableC. The tetrapods had a circulation system.D. The tetrapods co

47、uld move to new pools of water.P4：What ecological pressures might have caused fishes to gradually abandon their watery habitat and become increasingly land-dwelling creatures? Changes in climate during the Devonian may have had something to do with this if freshwater areas became progressively more

48、restricted. Another impetus may have been new sources of food. The edges of ponds and streams surely had scattered dead fish and other water-dwelling creatures. In addition, plants had emerged into terrestrial habitats in areas near streams and ponds, and crabs and other arthropods were also members

49、 of this earliest terrestrial community. Thus, by the Devonian the land habitat marginal to freshwater was probably a rich source of protein that could be exploited by an animal that could easily climb out of water. Evidence from teeth suggests that these earliest tetrapods did not utilize land plan

50、ts as food; they were presumably carnivorous and had not developed the ability to feed on plants. 13. Look at the four squares that indicate where the following sentence could be added to the passage.These would have been deposited by the receding waters of droughts, during which many aquatic animal

51、s must have died.Where would the sentence best fit? Click on a square to add the sentence to the passage14. Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in t

52、he passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.Freshwater lobe-finned fish may be the direct ancestors of terrestrial tetrapods.Answer ChoicesA. Rhipidistian c

53、rossopterygian had features such as primitive lungs and thick fins that could have helped it survive dry periods.B. During the Devonian, the number of bones increased in the fins of rtiipidistians, improving such animals ability to swim and move over landC. Shortly after the earliest tetrapods devel

54、oped lungs, plants and other animals began to flourish on land.D. By the Devonian period, lobe-finned fish preferred freshwater habitats to life in the ocean.E. A drier climate and new sources of food on land may have encouraged the lobe-finned fishs move to a terrestrial existence.F. Early tetrapod

55、s remained closely connected to water, but several of their body structures were adapted for life on land.參考答案：1-5.BDACC 6-10.DAADB 11-13.CAA 14.AEFIf you have any questions concerning the texts or answers, feel free to contact Wechat: geeqi0805.If you are tired of looking up TPO words in a dictiona

56、ry, try新托福TPO閱讀詞匯速查速記! 參考譯文：從魚類到陸生脊椎動物水中棲息的魚類進化為陸地四足動物（有脊椎的四肢生物）是地球上發生過的重大進化事件之一。魚類很可能起源于海洋，有關魚類的最早記錄是在海洋巖石中。然而，到了泥盆紀（4.08億至3.62億年前），魚類的棲息地已經擴展到幾乎所有可能的水生環境，包括淡水水域。淡水沉積巖石中十分常見的是一種葉狀鰭魚化石。研究四足動物進化的生物學家對泥盆紀時期生活在淡水水域的總鰭魚綱、扇鰭魚目葉狀鰭魚尤其感興趣。這種魚生活在大型三角洲的河道和湖泊里。它們的化石常見于三角洲巖石中，這類巖石因為含有氧化鐵礦物，故而呈紅色，這也表明三角洲形成時已經有干濕

57、季節的交替。如果有干旱期存在，任何有助于魚類度過干旱的進化都會是有利的。這些扇鰭魚身上也出現了幾處這樣的進化。我們知道扇鰭魚的呼吸器官除了鰓還有肺。一些化石的橫截面顯示，扇鰭魚尸體內的泥的稠度和質地根據其在體內位置的不同而不同。這些差異表明在魚腸前端下面像腔一樣的東西只可能是肺。鰓無疑是這些魚的主要氧氣來源，但當水中含氧量大幅減少時，比如在長期干旱的情況下，肺就會作為輔助呼吸系統來吸氣。可見，這些魚已經進化出陸地生存的必備條件之一：將空氣作為氧氣來源的能力。這些魚的另一個適應是在葉狀的鰭。這些鰭很厚、很有肉質感、而且十分結實，內有一條軸心骨。在陸地上魚鰭從一定程度上可以作為運動的裝置，或許能使

58、魚為了生存從幾近干涸的池塘挪動到相鄰的有足夠水和氧氣的池塘。這些鰭最終進化成了短而健壯的腿。泥盆紀扇鰭魚的鰭骨在數量和位置上與已知的最早的四足動物的肢骨完全匹配。應該強調的是，肺和四肢的進化并不是因為它們預料到未來要在陸地上生活。這些適應是為了幫助它們在當時的水生環境中存活下來。新托福TPO閱讀詞匯速查速記，配合TPO使用，帶你高效做題背單詞。Wechat: geeqi0805是什么樣的生態壓力導致魚類逐漸放棄在水中的棲息地，逐漸成為陸生生物呢？如果淡水區域逐步縮減，泥盆紀的氣候變化可能與此相關。另一個動力可能是新的食物來源。池塘和溪流的邊緣無疑會散落有死掉的魚和其他水棲生物。此外，溪流與池塘

59、附近的陸地開始有植物出現，蟹和其他節肢動物也加入了這一最早的陸地群落。因此，在泥盆紀時期，對于能夠輕易爬出水面的生物，淡水邊緣的陸地很可能是豐富的蛋白質食物來源。對四足動物的牙齒的研究表明，最早的四足動物并不食用陸生植物；它們可能是食肉動物，而且也尚未形成食用植物的能力。第一批四足動物是怎樣向陸地環境過渡的呢？就像早期的陸生植物萊尼蕨類一樣，這些四足動物只是產生了部分變化，這個階段，它們仍然很依賴于水。不過，早期陸生植物面臨的許多問題并不會困擾到它們。這些動物從祖先起就已經有了一個流通系統，它們可以移動，所以可以挪到水邊飲水。另外，它們已經有肺了，當時扇鰭魚可能都已經將其用于輔助呼吸了。最早期的四足動物主要