托福 托福 48 - Determining Dinosaur Diet
题目
1 2 3 4 5 6 7 8 9 10 11 12 13 14
9.What explanation is given in paragraph 7 to support the idea that coprolites are a good source of information about what dinosaurs ate?
  • A.They are likely to be preserved because of their resistance to decay.
  • B.They contain some parts of plants and animals that are unchanged by the digestive process.
  • C.They are usually found in close proximity to other dinosaur fossils.
  • D.They are produced by both carnivores and herbivores.
  • 正确答案:
    答案解析:
    答题统计
    答题统计

    登录 后才可以查看答案解析,还没有账号?

    还没有账号?马上 注册 >>

    阅读原文 中文译文

    Determining what extinct dinosaurs ate is difficult, but we can infer some aspects of their dietary preferences. Traditionally, this information has been derived from direct evidence, such as stomach contents, and indirect evidence, such as establishing a correlation between particular body characteristics and diets of living animals and then inferring habits for dinosaurs.

    Animals such as house cats and dogs have large, stabbing canine teeth at the front of the mouth and smaller, equally sharp teeth farther back in their jaws. Many of these animals are also armed with sharp claws. The advantage of teeth and claws as predatory tools is obvious. Now consider animals like cows, horses, rabbits, and mice. These animals have flat teeth at the back of the jaw that are analogous to and have the same function as grindstones. Unlike the meat-slicing and stabbing teeth of carnivores, the teeth of these animals grind and shred plant material before digestion.

    More clues exist in other parts of the skull. The jaw joint of carnivores such as dogs and cats has the mechanical advantage of being at the same level as the tooth row, allowing the jaws to close with tremendous speed and forcing the upper teeth to occlude against the lower teeth with great precision. In herbivorous animals, rapid jaw closure is less important. Because the flat teeth of herbivores work like grindstones, however, the jaws mush move both side to side and front to back. The jaw joints of many advanced herbivores, such as cows, lie at a different level than the tooth row, allowing transverse tearing, shredding, and compression of plant material. If we extend such observations to extinct dinosaurs, we can infer dietary preferences (such as carnivory and herbivory), even though we cannot determine the exact diet. The duck-billed dinosaurs known as hadrosaurs are a good example of a group whose jaw joint is below the level of the tooth row, which probably helped them grind up tough, fibrous vegetation.

    Paleontologists would like to be much more specific about a dinosaur's diet than simply differentiating carnivore from herbivore. This finer level of resolution requires direct fossil evidence of dinosaur meals. Stomach contents are only rarely preserved, but when present, allow us to determine exactly what these animals were eating.

    In the stomach contents of specimens of Coelophysis (a small, long-necked dinosaur) are bones from juvenile animals of the same species. At one time, these were thought to represent embryonic animals, suggesting that this small dinosaur gave birth to live young rather than laying eggs. Further research indicated that the small dinosaurs were too large and too well developed to be prehatchling young. In addition, the juveniles inside the body cavity were of different sizes. All the evidence points to the conclusion that these are the remains of prey items and that, as an adult, Coelophysis was at least in part a cannibal.

    Fossilized stomach contents are not restricted to carnivorous dinosaurs. In a few rare cases, most of them “mummies” (unusually well preserved specimens), fossilized plant remains have been found inside the body cavity of hadrosaurs. Some paleontologists have argued that these represent stream accumulations rather than final meals. The best known of these cases is the second Edmontosaurus mummy collected by the Sternbergs. In the chest cavity of this specimen, which is housed in the Senckenberg Museum in Germany, are the fossil remains of conifer needles, twigs, seeds, and fruits. Similar finds in Corythosaurus specimens from Alberta, Canada, have also been reported, indicating that at least two kinds of Late Cretaceous hadrosaurs fed on the sorts of tress that are common in today's boreal woodlands.

    A second form of direct evidence comes from coprolites (fossilized bodily waste). Several dinosaur fossil localities preserve coprolites. Coprolites yield unequivocal evidence about the dietary habits of dinosaurs. Many parts of plants and animals are extremely resistant to the digestive systems of animals and pass completely through the body with little or no alteration. Study of coprolites has indicated that the diets of some herbivorous dinosaurs were relatively diverse, while other dinosaurs appear to have been specialists, feeding on particular types of plants. The problem with inferring diets from coprolites is the difficulty in accurately associating a particular coprolite with a specific dinosaur.

    要确定已经灭绝的恐龙吃什么是一件很困难的事情,但是我们能推测出它们在饮食上的一些偏好。传统上,这些信息来自直接证据,如胃内食物,以及间接证据,如通过在恐龙的特定身体特征和现今存活的动物的饮食习惯之间建立关系来推断恐龙的饮食习惯。 像家养的猫和狗这类动物,嘴前部的牙齿又大又尖,后部的牙齿要小一些但是同样锋利。这些动物中有许多都有着锋利的爪子。牙齿和爪子作为捕食工具的优势非常明显。现在再看牛、马、兔子和老鼠这些动物。它们后部的牙齿比较扁平,功能类似于研磨的石头。不像食肉动物的牙齿是刺进肉里并把肉撕开,这些动物的牙齿会将植物磨成碎块再消化。 头骨的其他部分存在更多线索。狗和猫这类食肉动物的颌关节和牙齿在同一高度上,这种机械上的优势能使上下颌快速闭合,使得上下牙齿咬合严密。对草食动物来说,快速颌闭合并不重要。由于食草动物的扁平牙齿像磨刀石一般,上下颌必须前后左右移动。许多高等草食动物,如牛,颌关节和牙齿的高度并不一致,这样它们就能横向撕裂、切碎和挤压植物。如果我们把这种观察方法应用到灭绝的恐龙身上,我们可以推断出恐龙的饮食偏好(如肉食还是草食),虽然我们无法确定准确的食物。鸭嘴龙便是一个颌关节比牙齿低的例子,这种高度不一致可能会帮助它们把坚韧的纤维植物磨碎。 古生物学家不只是想要区分恐龙是食草还是吃肉,他们还想知道恐龙的具体饮食。这种更精细的研究决心需要直接的恐龙食物的化石证据。胃里的食物很少能保存,但如果有,就能让我们确定恐龙到底吃什么。 腔骨龙(一种体型较小、脖子较长的恐龙)的胃内食物样本是同类恐龙的幼崽骨头。科学家一度认为这些幼崽骨头属于腔骨龙的胚胎,认为这种小恐龙是胎生而非卵生。进一步的研究发现,这些幼崽体积太大,而且发育良好,不可能是孵化前的幼崽。另外,这些胃内的幼崽残骸大小也不一。所有的证据都表明,这些都是猎物的残骸,成年腔骨龙中至少有一部分是吃自己的同类的。 并非只有食肉恐龙才有胃内食物的化石。在一些罕见的情况下,鸭嘴龙的体内也发现有植物遗骸的化石或“木乃伊”(罕见的保存完好的标本)。一些古生物学家认为,这些食物是积累下来的食物而不是最后一餐。最著名的案例是施特恩伯格一家收集的第二具埃德蒙顿木乃伊。标本存放在德国森肯伯格博物馆内,在其胸腔内,是针叶、细枝、种子和果实的化石。加拿大阿尔伯塔的冠龙标本也报导了类似的发现,这表明至少有两种晚白垩纪的鸭嘴龙是以现在北半球森林中的常见树木为食的。 另一个直接的证据形式来自粪化石(身体排泄物的化石)。几个恐龙化石地点保存有粪化石。粪化石能明确说明恐龙的饮食习惯。很多植物和动物不容易被动物的消化系统消化,没有改变或者只有些许改变就排出体内了。对粪化石的研究表明,有些食草恐龙的饮食比较多样化,而另一些恐龙似乎专门吃某些特定的食物。从粪化石推断饮食偏好,困难在于如何准确知道哪种粪化石属于哪种特定的恐龙。

    留言区中有很多我们对问题的解答喔, 登录后可以查看

    还没有账号?马上 注册 >>

    最新提问
    • wx_6697
      觉得B C 意思一样,不知道选哪个
    • wx_5576
      这道题C为什么对,E为什么不对?
    • wx_5576
      B为什么不能选啊?
    • wx_6697
      TPO30 passage 2 Q5我选的 D,不明白为啥不对?
    • wx_6697
      鑫哥,TPO6passage3Q5 答案是给错了吗?好多人都选A
    • wx_6697
      这题也很容易选错选成了D
    • wx_6697
      这道题A为什么错了
    • 芊儿
      为什么这道题不选c??a中的variety不是应该对应文中的differentiating 吗??求解!
    • wx_1000
      这道题不选E是因为太细节了吗
    • 王金阁
      这个题为什么不选C啊。。。
    • 芊儿
      这道题的D选项不是和文中的better able to reproduce in open settings相对应么??
    • 风荨火
      有大佬解释一下这个为啥选D嘛?
    • 以沫
      请问这个D 在哪里提现?为什么D错?
    • 芊儿
      第六题 的C选择为什么不对,感觉A是明显驳斥啊...
    • wx_6697
      鑫哥,这道题D是从哪里看出来的
    • wx_6697
      这题选的A,根据是Joly’s calculations clearly supported those geologists who insisted on an age for Earth far in excess of a few million years.想问鑫哥为啥不选A
    • wx_6697
      这题我选的是C依据是into a new habitat outside of its natural range, it may adapt to the new environment and leave its enemies behind.C为啥错了呢?鑫哥
    • wx_8861
      F选项的weather-related destruction在哪里体现了呢?原文最后一段的开头Among the costs里的costs是不是打错了?应该是coast?
    • wx_6697
      求问这道题B为啥不选,原文依据:viable seeds of pioneer species can be found in large numbers on some forest floors.
    • 与托福的斗争史
      与托福的斗争史 去解答 去解答
      这题为什么选C?
    • 小雨淅沥哗啦的下
      小雨淅沥哗啦的下 去解答 去解答
      B哪里错了
    • 小雨淅沥哗啦的下
      小雨淅沥哗啦的下 去解答 去解答
      B为啥不对
    • 李浩然
      B选项错误,是因为残缺么?
    • wx_100
      请问在做题的时候如何排除c呢。看了答案,感觉是该选a的,但是当时做题脑子一热,就特别钟爱c,也没看其他选项。。求敲醒。。
    • wx xxxxx
      请问鑫哥,这段开头有写As one pesticide replaces another为什么不是对应a new pesticide is developed?
    • wx_7695
      鑫哥,从哪里看出来这个masks 不是use呀,原文说了wear呀
    • haiyuqiao
      @鑫哥,这题the damage will continue 不应该对应前面的 the target species evolves resistance to it,然后As one pesticide replaces another,不应该是结束了time cycle 吗
    • wx_2065
      鑫哥,想知道E错在哪里?
    • wx_7695
      鑫哥,B选项 cannot extended to earlier geological periods. 原文说的意思是后来的进化无法估计吧
    • wx_2163
      B为什么不选
    • wx_7780
      鑫哥,这个哪里看不use了。BD是修饰错,C是无中生有,怎么能直接选出A?
    • 100
      看到第一句话,以为是中心句就选了A... 为什么不能选A呢
    • 100
      为什么选b?
    • gu33
      请问下 这里选D的原因是 因为 evolutionary approach 对应着 原文的 Rates of evolution 嘛? 这里我选了C。。不是很懂 插入句和 D的关系 求解答
    • 我是啦啦啦
      我是啦啦啦 去解答 去解答
      这个题A哪里错了?是因为主语不对吗?这个C比A多一步推理啊
    • haiyuqiao
      鑫哥,D选项里的19世纪出现了很多假设,原文中并没有提到啊
    • wx_7060
      为什么选a 呢。我觉得a是细节。F哪错了?
    • wx_1105
      我想问一下,这道题为什么不能选A呢?
    • wx_8122
      D为什么不选
    • wx_1655
      f选项哪里说了
    • chaulaw
      鑫哥,原文是below经济损害水平,D是一触发经济损害就用,这也对吗?
    • chaulaw
      interclan婚姻是对的吗?不是只在自己的family结婚扩大家族吗?
    • wx_6697
      鑫哥,这道题答案是不是错了,好多人选D 我也选的D求解答
    • wx_6697
      这道题应该是一道易错题,每个选项的都有,然而我选的A错了,求解
    • wx_6697
      鑫哥,这题的C是怎么得到的?B也没有找到啊?难道不是应该选B
    • wx_6697
      鑫哥,还有这个,好多人选A答案是不是错了
    • wx_6697
      求问D是从哪里得出来的,我选的B呀哎呀
    • wx_4185
      it is difficult to say how far they were intended to be portraits rather than generalized images 这句话怎么理解呢
    • 此楠楠
      请问下这个插入题怎么选的呢?
    • 此楠楠
      求鑫哥讲解下A选项。。。 Even though in error, Joly’s calculations clearly supported those geologists who insisted on an age for Earth far in excess of a few million years.