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OG20官方指南,建议同学们刷3遍。第一遍做题了解题型和考点,第二遍精刷,第三遍集中解决疑难问题。建议考生第一遍刷题采用官方正版纸质书籍,若遇到疑难问题,欢迎在此专区查阅解析,提供解析,参与题目讨论,与所有考生一起解决疑难问题。
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Conodonts, the spiky phosphatic remains (bones and teeth composed of calcium phosphate) of tiny marine animals that probably appeared about 520million years ago, were once among the most controversial of fossils. Both the nature of the organism to which the remains belonged and the function of there mains were unknown. However, since the 1981 discovery of fossils preserving not just the phosphatic elements but also other remains 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.

he 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-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 secondary features, adapted from the protective bony scales. Indeed, externa! 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.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 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 among the most primitive of vertebrates. The lack of any mineralized structures apart from the elements in the mouth indicates that conodonts were moreprimitive than the armored jawless fishes such as the ostracoderms. It now appears that the hard parts that 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.

【OG20-P451-582题】

It can be inferred that on the basis of the 1981 discovery of conodont remains, paleontologists could draw which of the following conclusions?

  • 分析A选项
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  • 分析B选项
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  • 分析C选项
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  • 分析D选项
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  • 分析E选项
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当前版本由 百香果蜂蜜茶 更新于2017-08-10 15:25:24 感谢由 百香果蜂蜜茶 对此题目的解答所做出的贡献。

A选项(错)第二段中说到一部分专家认为早期的vertebrate属于feeders,但1981的evidence却说 vertebrate是predator

B选项(对)定位第三段这一句话“they were more primitive than the ostracoderms”所以可以看出Os 并不是最早的

C选项(错)传统的专家认为“teeth were adapted from bony scales that provided defensive armor”而1981的evidence 后来证明 “Teeth were more primitive than external armor according to this view”

D选项(错)错在题目让我们基于原文的信息来推到结论,而该答案的内容属于原文重现

E选项(错)第三段已经明确表明conodonts 很有可能是predators


题目讨论 10条评论)

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    小熊维尼的蜜罐

    这篇真的整无语了....
    0 0 回复 2021-11-12 19:43:45
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    400473wdoj

    题干问的是 根据化石发现!
    0 0 回复 2021-10-16 16:33:43
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    358172hsa

    since the 1981 discovery of fossils preserving not just the phosphatic elements but also other remains of the tiny soft-bodied animals
    注意这里的soft bodied animals,就是证明,这个躯壳还是软的,但是却有phosphatic,就说明牙齿,骨骼开始有了,因此他们是有脊椎动物; 那Ostracoderms 后文提到说是最早的脊椎动物而且是有硬壳的, 那就说明Ostracoderms  是后来发展的, 因为最最最早的脊椎动物是软壳的
    0 0 回复 2021-02-08 04:28:36
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    Mariposa爱学习

    这道题可怕在题干无法定位,必须每个选项定位
    这就突出了逻辑图的重要性
    B 定位句“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.”和“Conodonts, the spiky phosphatic remains (bones and teeth composed of calcium phosphate) of tiny marine animals that probably appeared about 520million years ago” 比较两者存在时期
    2 0 回复 2020-11-14 18:16:15
    • 评论用户头像

      如果有时间的话我也能做对回复Mariposa爱学习

      问题故意挖坑让你去1981那段找,其实根本啥也没有。定位在最后结论这句话被我找到了“”……indicates that conodonts were more primitive than the armored jawless fishes such as the ostracoderms.牙形虫比装甲无颌鱼这种甲青鱼类更原始。 B Ostracoderms were not the earliest vertebrates.换句话说甲青鱼就不是最古早的软椎动物咯。

      0 0 回复 2021-08-02 00:02:13

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    175115uybpy

    绝了 B的“they were more primitive than the ostracoderms”就不算重复原文,D的就算……好无语
    0 0 回复 2020-11-07 18:44:19
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      315087kijf回复175115uybpy

      D跟1981年的研究无关,b是根据研究推断出来的

      0 0 回复 2021-05-16 21:53:51

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    Jayden8

    做个橡皮锤
    3 0 回复 2020-08-08 00:17:58
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    373961gg

    定位定错了,而且根本不认识primitive这个单词= =。。
    0 0 回复 2020-07-21 08:54:12
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    746860xgow

    这篇文章的难点在于,定位点是全文范围,所以一定要搞清楚文章的结论是什么
    2 0 回复 2020-05-22 06:53:53
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    园园爱吃肉

    1981代表的是一个大的观点而不是某个观点里的某个小时间点,所以定位的时候更需要从全文去提炼总结,或者通过选项定位
    0 0 回复 2019-12-07 17:53:32
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    245240abh

    直接定位到第一段1981去了……什么都没找到
    0 0 回复 2019-12-01 19:18:57
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