2017英语专八阅读100篇高级篇附答案解析（69）

2017英语专八阅读100篇高级篇附答案解析（69）

　　The fossil remains of the first flying vertebrates, the pterosaurs, haveintrigued paleontologists for more than two centuries. How such largecreatures, which weighed in some cases as much as a piloted hang-glider and hadwingspans from 8 to 12 meters, solved the problems of powered flight, andexactly what these creatures were — reptiles or birds — are among the questionsscientists have puzzled over.

　　Perhaps the least controversial assertion about the pterosaurs is thatthey were reptiles. Their skulls, pelvises, and hind feet are reptilian. Theanatomy of their wings suggests that they did not evolve into the class ofbirds. In pterosaurs a greatly elongated fourth finger of each forelimbsupported a winglike membrane. The other fingers were short and reptilian, withsharpclaws. In birds the second finger is the principal strut of the wing,which consists primarily of feathers. If the pterosaurs walked on all fours,the three short fingers may have been employed for grasping. When a pterosaurwalked or remained stationary, the fourth finger, and with it the wing, couldonly turn upward in an extended inverted V shape along each side of the animal’s body.

　　The pterosaurs resembled both birds and bats in their overall structureand proportions. This is not surprising because the design of any flyingvertebrate is subject to aerodynamic constraints. Both the pterosaurs and thebirds have hollow bones, a feature that represents a savings in weight. In thebirds, however, these bones are reinforced more massively by internal struts.

　　Although scales typically cover reptiles, the pterosaurs probably hadhairy coats. T. H. Huxley reasoned that flying vertebrates must have beenwarm-blooded because flying implies a high rate of metabolism, which in turnimplies a high internal temperature. Huxley speculated that a coat of hairwould insulate against loss of body heat and might streamline the body toreduce drag in flight. The recent discovery of a pterosaur specimen covered inlong, dense, and relatively thick hairlike fossil material was the first clearevidence that his reasoning was correct.

　　Efforts to explain how the pterosaurs became airborne have led tosuggestions that they launched themselves by jumping from cliffs, by droppingfrom trees, or even by rising into light winds from the crests of waves. Eachhypothesis has its difficulties. The first wrongly assumes that the pterosaurs’ hind feet resembled a bat’s and could serve as hooks bywhich the animal could hang in preparation for flight. The second hypothesisseems unlikely because large pterosaurs could not have landed in trees withoutdamaging their wings. The third calls for high waves to channel updrafts. Thewind that made such waves however, might have been too strong for thepterosaurs to control their flight once airborne.

　　1. It can be inferred from the text that scientist now generally agreethat the

　　[A] enormous wingspan of the pterosaurs enabled them to fly greatdistances.

　　[B] structure of the skeleton of the pterosaurs suggests a closeevolutionary relationship to bats.

　　[C] fossil remains of the pterosaurs reveal how they solved the problemof powered flight.

　　[D] pterosaurs were reptiles.

　　2. The author views the idea that the pterosaurs became airborne byrising into light winds created by waves as

　　[A] revolutionary.

　　[B] unlikely.

　　[C] unassailable.

　　[D] probable.

　　3. According to the text, the skeleton of a pterosaur can bedistinguished from that of a bird by the

　　[A] size of its wingspan.

　　[B] presence of hollow spaces in its bones.

　　[C] anatomic origin of its wing strut.

　　[D] presence of hooklike projections on its hind feet.

　　4. The ideas attributed to T. H. Huxley in the text suggest that he wouldmost likely agree with which of the following statements?

　　[A] An animal’s brain size has little bearing on its ability to master complexbehaviors.

　　[B] An animal’s appearance is often influenced by environmental requirements andphysical capabilities.

　　[C] Animals within a given family group are unlikely to change theirappearance dramatically over a period of time.

　　[D] The origin of flight in vertebrates was an accidental developmentrather than the outcome of specialization or adaptation.

　　5. Which of the following best describes the organization of the lastparagraph of the text?

　　[A] New evidence is introduced to support a traditional point of view.

　　[B] Three explanations for a phenomenon are presented and each isdisputed by means of specific information.

　　[C] Three hypotheses are outlined and evidence supporting each is given.

　　[D] Recent discoveries are described and their implications for futurestudy are projected.

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