Passage 4
　　The fossil remains¹ of the first flying vertebrates， the　pterosaurs， have intrigued² paleontologists for morethan two centuries. How such large creatures， which　weighed in some cases as much as a piloted hang-glider（5） and had wingspans from 8 to 12 meters， solved theproblems of powered flight， and exactly what thesecreatures were——reptiles³ or birds-are among the ques-tions scientists have puzzled over.
　　Perhaps the least controversial assertion about the（10） pterosaurs is that they were reptiles. Their skulls，pelvises， and hind⁴ feet are reptilian⁵. The anatomy⁶ oftheir wings suggests that they did not evolve into theclass of birds. In pterosaurs a greatly elongated⁷ fourthfinger of each forelimb supported a winglike membrane⁸.（15） The other fingers were short and reptilian， with sharpclaws. In birds the second finger is the principal strutof the wing， which consists primarily of feathers. If thepterosaurs walked on all fours， the three short fingersmay have been employed for grasping. When a（20） pterosaur walked or remained stationary¹⁰， the fourthfinger， and with it the wing， could only turn upward inan extended inverted¹¹ V-shape along each side of the animal‘s body.
　　The pterosaurs resembled both birds and bats in（25） their overall structure and proportions. This is not sur-prising because the design of any flying vertebrate issubject to aerodynamic constraints¹². Both the pterosaursand the birds have hollow bones， a feature that repre-sents a savings¹³ in weight. In the birds， however， these（30） bones are reinforced more massively by internal struts¹⁴.
　　Although scales typically cover reptiles， thepterosaurs probably had hairy coats. T.H. Huxley rea-soned that flying vertebrates must have been warm-blooded because flying implies a high rate of（35） metabolism¹⁵， which in turn implies a high internal tem-perature. Huxley speculated that a coat of hair wouldinsulate against loss of body heat and might streamlinethe body to reduce drag in flight. The recent discoveryof a pterosaur specimen¹⁶ covered in long， dense¹⁷， and（40） relatively¹⁸ thick hairlike fossil material was the first clearevidence that his reasoning was correct.
　　Efforts to explain how the pterosaurs became air-borne have led to suggestions that they launched them-selves by jumping from cliffs， by dropping from trees.（45） or even by rising into light winds from the crests¹⁹ ofwaves. Each hypothesis has its difficulties. The firstwrongly assumes that the pterosaurs‘ hind feet rese-mbled a bat’s and could serve as hooks by which theanimal could hang in preparation for flight. The second（50） hypothesis seems unlikely because large pterosaurscould not have landed in trees without damaging theirwings. The third calls for high waves to channelupdrafts. The wind that made such waves however，might have been too strong for the pterosaurs to（55） control their flight once airborne.

1. It can be inferred from the passage that scientists now　generally agree that the
　（A） enormous wingspan of the pterosaurs enabled　them to fly great distances　
　（B） structure of the skeleton of the pterosaurs suggests a　close evolutionary²⁰ relationship to bats
　（C） fossil remains of the pterosaurs reveal how they　solved the problem of powered flight
　（D） pterosaurs were reptiles
　（E） pterosaurs walked on all fours

2. The author views the idea that the pterosaurs became airborne by rising into light winds created by waves as
　（A） revolutionary
　（B） unlikely
　（C） unassailable
　（D） probable
　（E） outdated²¹

3. According to the passage， the skeleton of a　pterosaur can be distinguished²² 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 strut⁹
　（D） presence of hooklike projections²³ on its hind feet
　（E） location of the shoulder joint²⁴ joining the wing to its body

4. The ideas attributed to T.H. Huxley in the passage　suggest that he would most likely agree with which　of the following statements？
　（A） An animal‘s brain size has little bearing on its　ability to master complex behaviors.
　（B） An animal‘s appearance is often influenced by　environmental requirements and physical　capabilities²⁵.
　（C） Animals within a given family group are unlikely　to change their appearance dramatically over a　period of time.
　（D） The origin of flight in vertebrates was an　accidental development rather than the outcome　of specialization or adaptation.
　（E） The pterosaurs should be classified as birds， not reptiles.

5. It can be inferred from the passage that which of the　following is characteristic of the pterosaurs？
　（A） They were unable to fold their wings when not in　use.
　（B） They hung upside down from branches as bats do before flight.
　（C） They flew in order to capture prey²⁶.　
　（D） They were an early stage in the evolution of the　birds.
　（E） They lived primarily in a forestlike habitat.

6.Which of the following best describes the organization　of the last paragraph of the passage？
　（A） New evidence is introduced to support a traditional point of view.
　（B） Three explanations for a phenomenon are presented， and each is disputed 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 future study are projected
　（E） A summary of the material in the preceding paragraphs is presented， and conclusions are drawn²⁷.

7. It can be inferred from the passage that some　scientists believe that pterosaurs
　（A） lived near large bodies of water
　（B） had sharp teeth for tearing food
　（C） were attacked and eaten by larger reptiles
　（D） had longer tails than many birds　
　（E） consumed twice their weight daily to maintain　their body temperature