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第二十七篇 牙形石 题材： 文章类型： Conodonts,the spiky phosphatic remains (bones and teeth composed of calcium phosphate) of tiny marineanimals that probably appeared about 520 million years ago, were once among the most controversial of fossils. Both the nature of the organism to which the remainsbelonged and the function of the remains were unknown. However, since the 1981 discovery offossils preserving not just the phosphaticelements but alsoother remains of the tiny soft-bodied animals (also called conodonts) that borethem, scientists' reconstructions of the animals` anatomy have had important implications for hypothesesconcerning the development of the vertebrate skeleton. 月牙石是有争议性的化石。 对其性质和功能一无所知 然而，1981发现也发现了拥有他们的软体动物 这一发现对脊椎动物的发展假说有重要意义
The vertebrateskeleton had traditionally been regarded as a defensivedevelopment, champions of this view postulating that it was only with the much later evolution of jaws thatvertebrates became predators. The first vertebrates, which were soft bodied, would have been easy prey for numerous invertebratecarnivores, especially if these early vertebrates were sedentary suspensionfeeders. Thus, traditionalistsargued, these animals developed coverings of bony scales or plates, and teeth were secondary features, adaptedfrom the protective bony scales. Indeed, external skeletons of this type arecommon among the well-known fossils of ostracoderms, jawless vertebrates thatexisted from approximately 500 to 400 million years ago. However, otherpaleontologists argued that many of the definitive characteristics ofvertebrates, such as paired eyes and muscular and skeletal adaptations foractive life, would not have evolved unless thefirst vertebrates were predatory. Teeth weremore primitive than external armor according to this view, and the earliestvertebrates were predators.
传统上认为脊椎动物的发展过程很晚期下颚的进化让它们变成捕食者 第一个脊椎动物是软体动物很容易变成无脊椎食肉动物的猎物 因此，传统认为这种动物先进化bony scales和plates，最后进化出牙齿 而且，ostracoderns也证实了这一点 然而，其他学家认为其他一些特征不会拥有如果从一开始脊椎动物不是捕食者 牙齿要比外部的盔甲更早进化
The stiffeningnotochord along the back of the body, V-shaped muscle blocks along the sides,and posterior tail fins help to identifyconodonts as among the most primitive of vertebrates. The lack of anymineralized structures apart from the elements in the mouth indicates that conodonts were more primitive than thearmored jawless fishes such as the ostracoderms. （主旨句）It now appearsthat the hard parts that first evolved in the mouth of an animal improved itsefficiency as a predator, and that aggression rather than protection was the driving force behind the origin of thevertebrate skeleton.
Conodonts的一些特征 Conodont比Ost要早 证明了显示捕食者，现有的牙齿。
题目： According to thepassage, the anatomical evidence provided by the preserved soft bodies ofconodonts led scientists to conclude that · Aconodonts had actually been invertebrate carnivores · Bconodonts' teeth were adapted from protective bony scales · Cconodonts were primitive vertebrate suspension feeders · Dprimitivevertebrates with teeth appeared earlier than armored vertebrates · EScientists` original observations concerning thephosphatic remains of conodonts were essentially correct 难题：定位复杂 1. scientists' reconstructions of the animals` anatomy have had important implications for hypothesesconcerning the development of the vertebrate skeleton.
Traditionally（对应相反） However, other paleontologists arguedthat many of the definitive characteristics of vertebrates, such as paired eyesand muscular and skeletal adaptations for active life, wouldnot have evolved unless the first vertebrates were predatory. Teeth were more primitive than external armor according tothis view, and the earliest vertebrates were predators. 抓住主旨
The second paragraph in the passageserves primarily to（宏观题目：作者支持新观点） · Aoutline the significance of the 1981 discovery ofconodont remains to the debate concerning the development of the vertebrateskeleton · Bcontrast the traditional view of the development of thevertebrate skeleton with a view derived from the 1981 discovery of conodontremains · Ccontrast the characteristics of the ostracoderms with thecharacteristics of earlier soft-bodied vertebrates · Dexplain the importance of the development of teeth amongthe earliest vertebrate predators · Epresent thetwo sides of the debate concerning the development of the vertebrate skeleton 从however中不难看出第二段有两个观点。
It can beinferred（间接细节） that on the basis of the 1981 discoveryof conodontremains, paleontologists could draw which of the following conclusions? · AThe earliest vertebrates were sedentary suspensionfeeders.（错误） · BOstracoderms were not the earliest vertebrates.（直接推） · CDefensivearmor preceded jaws among vertebrates. · DPaired eyes and adaptations for activity are definitivecharacteristics of vertebrates.（次要信息） · EConodonts were unlikely to have been predators.（错误） 通过义群筛选信息： since the 1981 discovery of fossils preserving not just the phosphatic elements but also other remains of the tinysoft-bodied animals (also called conodonts) that bore them, scientists'reconstructions of the animals` anatomy have hadimportant implications for hypotheses concerning the development of thevertebrate skeleton. However, other paleontologists arguedthat many of the definitive characteristics of vertebrates, such as paired eyesand muscular and skeletal adaptations for active life, wouldnot have evolved unless the first vertebrates were predatory. Teeth were more primitive than external armor according tothis view, and the earliest vertebrates were predators. Thestiffening notochord along the back of the body, V-shaped muscle blocks alongthe sides, and posterior tail fins help to identifyconodonts as among the most primitive of vertebrates. The lack of anymineralized structures apart from the elements in the mouth indicates that conodonts were more primitive than thearmored jawless fishes such as the ostracoderms. （主旨句）It now appearsthat the hard parts that first evolved in the mouth of an animal improved itsefficiency as a predator, and that aggression rather than protection was the driving force behind the origin of thevertebrate skeleton.
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发表于 2020-9-7 18:59:56
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