研究生管理专业入学考试机考模拟阅读理解4(1)

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the fossil remains of the first flying vertebrates, the

　　pterosaurs, have intrigued paleontologists for more

than 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 the

problems of powered flight, and exactly what these

creatures were--reptiles 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 hind feet are reptilian. the anatomy of

their wings suggests that they did not evolve into the

class of birds. in pterosaurs a greatly elongated fourth

finger of each forelimb supported a winglike membrane.

(15) the other fingers were short and reptilian, with sharp

claws. 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

(20) pterosaur walked or remained stationary, the fourth

finger, and with it the wing, could only turn upward in

an extended inverted 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 is

subject to aerodynamic constraints. both the pterosaurs

and the birds have hollow bones, a feature that repre-

sents a savings in weight. in the birds, however, these

(30)bones are reinforced more massively by internal struts.

although scales typically cover reptiles, the

pterosaurs 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) metabolism, which in turn implies a high internal tem-

perature. huxley speculated that a coat of hair would

insulate against loss of body heat and might streamline

the body to reduce drag in flight. the recent discovery

of a pterosaur specimen covered in long, dense, and

(40) relatively thick hairlike fossil material was the first clear

evidence 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 crests of

waves. each hypothesis has its difficulties. the first

wrongly assumes that the pterosaurs hind feet rese-

mbled a bat s and could serve as hooks by which the

animal could hang in preparation for flight. the second

(50) hypothesis seems unlikely because large pterosaurs

could not have landed in trees without damaging their

wings. the third calls for high waves to channel

updrafts. 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 evolutionary 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) outdated

3. according to the passage, the skeleton of a

pterosaur can be distinguished from that of a bird by