首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
The fossil remains of the first flying vertebrates, the pterosaurs. have intrigued paleontologists for more than two centuries,
The fossil remains of the first flying vertebrates, the pterosaurs. have intrigued paleontologists for more than two centuries,
admin
2010-07-06
100
问题
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 eases as much as a piloted hang-glider 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 questions scientists have puzzled over.
Perhaps the least controversial assertion about the 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 wing like membrane. 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 ail fours, the three short fingers may have been employed for grasping. When a 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 hats in their overall structure and proportions. This is not surprising because the design of any flying vertebrate is subject to aerodynamic constraints. Both the pterosaurs and the birds have hollow bones, a feature that represents a savings in weight. In the birds, however, these bones are reinforced more massively by internal struts.
Although scales typically cover reptiles, the pterosaurs probably had hairy coats. T.H. Huxley reasoned that flying vertebrates must have been warm-blooded because flying implies a high rate of metabolism, which in turn implies a high internal temperature. 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 relatively thick hair—like fossil material was the first clear evidence that his reasoning was correct.
Efforts to explain how the pterosaurs became airborne have led to suggestions that they launched them- selves by jumping from cliffs, by dropping from trees or even by rising into light winds from the surfaces of waves Each hypothesis has its difficulties. The first wrongly assumes that the pterosaurs’ hind feet resembled a hat’s and could serve as hooks by which the animal could hang in preparation for flight. The second 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 control their flight once airborne.
The ideas attributed to T. H. Huxley in the passage suggest that he would most likely agree with which of the following statements?
选项
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 capabilities
C、Animals within a given family group are unlikely to change their appearance dramatically over a period of time.
D、The pterosaurs should be classified as birds, not reptiles.
答案
B
解析
分析推理题。对T.H.Huxley这个人物的理论说明见于第四段。该段第二、三句指出,他认为会飞行的脊椎动物是恒温动物,并且认为它们有羽毛防止体温散发、使身体呈流线型。这些论断都是根据动物所处的环境及功能来作出的,由此可推知他认为环境和功能会影响动物外形,B 最合这一逻辑。
转载请注明原文地址:https://kaotiyun.com/show/dYDd777K
本试题收录于:
公共英语四级笔试题库公共英语(PETS)分类
0
公共英语四级笔试
公共英语(PETS)
相关试题推荐
Itcanbeinferredfromthepassagethatscientistsnowgenerallyagreethatthe______.TheideasattributedtoT.H.Huxleyi
Peoplemayspendtimeinmakingdecisionsabout______.Routineplansoractionsserveausefulpurposebecausethey______.
【61】ShipbuildingindustryleaderSouthKoreasufferedaslumpinordersofnearly40percentinthefirsthalfofthisyeara
Whatdoesthephrase"fromvariouscomersofthiscountry"probablymean?WhattheChicagoPublicschoolspreferstoinlanguag
Surgeonswillsoonbeabletoentertheeyetocarryoutoperations--atleastinavirtualsense.Techniquesderivedfromvirtua
【B1】Swedenhasgotapopulationofonly8million,butitisalargecountrywithanareaof450,000squarekilometers.【B2】The
Predictionsofmanyrobotsinindustryhaveyetcometrue.Fortenyearsormore,manufacturersofbigrobotshaveexplainedhow
Allthewisdomoftheages,allthestoriesthathavedelightedmankindforcenturies,areeasilyandcheaply【21】______toal
Allthewisdomoftheages,allthestoriesthathavedelightedmankindforcenturies,areeasilyandcheaply【21】______toal
Allthewisdomoftheages,allthestoriesthathavedelightedmankindforcenturies,areeasilyandcheaply【21】______toal
随机试题
最能证明心动过速起源于心室的心电图表现是
气温低于()℃时,运输易冻的硝化甘油炸药,必须采取防冻措施。
塑料制220kV断路器外壳
将投资项目多项未来金额(比如现金流量)换算成一项当前金额(折现)的估值方法是()。
注册会计师应当根据审计结论给出审计意见,审计意见主要有()类型。
某企业为一般纳税人,增值税税率为17%,2013年7月发生下列业务:(1)购买材料一批,专用发票注明:价款300万元,增值税17万元,另外支付运费1万元,已入库,并付款;(2)销售产品一批,专用发票注明:价款500万元,增值税85万元,成本400万元,产
反映群体内部存在从众压力的光点实验是()于1935年做的。
(2017·江西)教育的根本任务是培养人,在一定社会中培养具有什么样政治方向、思想意识的人,是由()决定的。
编码与解码(暨南大学2011年研;北大2010年研;复旦大学2010年研)
党的十八大提出要全面提高开放型经济水平。下列说法正确的是()。
最新回复
(
0
)