Reading Comprehension
试题详情
文章：
| Line | Conodonts, the spiky phosphatic remains (bones |
| and teeth composed of calcium phosphate) of | |
| tiny marine animals that probably appeared about | |
| 520 million years ago, were once among the most | |
| (5) | controversial of fossils. Both the nature of the |
| organism to which the remains belonged and the | |
| function of the remains were unknown. However, | |
| since the 1981 discovery of fossils preserving not | |
| just the phosphatic elements but also other remains | |
| (10) | of the tiny soft-bodied animals (also called conodonts) |
| that bore them, scientists’ reconstructions of the | |
| animals’ anatomy have had important implications | |
| for hypotheses concerning the development of the | |
| vertebrate skeleton. | |
| (15) | The vertebrate skeleton had traditionally been |
| regarded as a defensive development, champions of | |
| this view postulating that it was only with the much | |
| later evolution of jaws that vertebrates became | |
| predators. The first vertebrates, which were soft- | |
| (20) | bodied, would have been easy prey for numerous |
| invertebrate carnivores, especially if these early | |
| vertebrates were sedentary suspension feeders. | |
| Thus, traditionalists argued, these animals developed | |
| coverings of bony scales or plates, and teeth were | |
| (25) | secondary features, adapted from the protective |
| bony scales. Indeed, external skeletons of this | |
| type are common among the well-known fossils of | |
| ostracoderms, jawless vertebrates that existed from | |
| approximately 500 to 400 million years ago. | |
| (30) | However, other paleontologists argued that many of |
| the definitive characteristics of vertebrates, such as | |
| paired eyes and muscular and skeletal adaptations | |
| for active life, would not have evolved unless the | |
| first vertebrates were predatory. Teeth were more | |
| (35) | primitive than external armor according to this view, |
| and the earliest vertebrates were predators. | |
| The stiffening notochord along the back of the | |
| body, V-shaped muscle blocks along the sides, | |
| and posterior tail fins help to identify conodonts as | |
| (40) | among the most primitive of vertebrates. The lack of |
| any mineralized structures apart from the elements | |
| in the mouth indicates that conodonts were more | |
| primitive than the armored jawless fishes such as the | |
| ostracoderms. It now appears that the hard parts that | |
| (45) | first evolved in the mouth of an animal improved its |
| efficiency as a predator, and that aggression rather | |
| than protection was the driving force behind the origin | |
| of the vertebrate skeleton. |
题目：
The second paragraph in the passage serves primarily to
选项:
A、outline the significance of the 1981 discovery of conodont remains to the debate concerning the development of the vertebrate skeleton
B、contrast the traditional view of the development of the vertebrate skeleton with a view derived from the 1981 discovery of conodont remains
C、contrast the characteristics of the ostracoderms with the characteristics of earlier soft-bodied vertebrates
D、explain the importance of the development of teeth among the earliest vertebrate predators
E、present the two sides of the debate concerning the development of the vertebrate skeleton
答案:
E
