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第一段
1 .Listen to part of a lecture in a zoology class.
听一段在动物学课堂上的演讲
第二段
1 .Your reading for today touched on dinosaur fossils from the Mesozoic era, which ended about 65 million years ago.
你今天的阅读接触到了大约在6500万年前毁灭的中生代的恐龙化石，
2 .Today we will be discussing the sauropods.
现在我们要讨论的是蜥脚类恐龙。
3 .I think our discussion of sauropods will illustrate what we can learn by comparing the fossil record to modern animals.
我想这些蜥脚类恐龙的讨论将会证明我们可以从化石记载和现代动物的比较中学到些什么。
4 .By fossils, we mean traces of prehistoric animals such as bones, which become mineralized, or impressions of bones or organs that are left in stone.
化石，意指史前动物的极少遗迹，如已矿化的骨头，或留在石头上的骨骼或器官痕迹
第三段
1 .Now sauropods were among the largest animals to exist ever!
蜥脚类恐龙是存在过的最大的动物之一！
2 .They were larger than blue whales, which are the largest animals alive today.
他们比现存最大的动物蓝鲸还要大。
3 .They weighed up to one hundred tons, twenty times as much as elephants.
蜥脚类恐龙重达百吨，是大象的二十倍有余。
4 .Also, they were an extremely successful kind of dinosaur.
此外，他们还是一类非常成功的恐龙。
5 .There's evidence of sauropods in the fossil record for an unusually long time, over one hundred million years.
化石记载中蜥脚类恐龙的证据已有一段不同寻常的悠久历史，超过了一亿年。
第四段
1 .So, why were sauropods so successful?
那么，为什么蜥脚类恐龙会如此成功呢？
2 .Biologically speaking, sauropods shouldn't have been successful.
从生理上来说，蜥脚类恐龙是不应该成功的。
3 .Large animals like elephants, say, they require much more food and energy and have fewer offspring than smaller animals.
也就是说，像大象类的大型动物，它们需要更多的食物和能量，但其后代比小型动物的后代要少。
4 .This makes maintaining a population harder.
这使得维持一定数量的种群更难。
5 .The largest animals today don't live on land.
当今最大的动物并不生活在陆地上。
6 .But in the ocean where food is easier to find: a blue whale, for instance, can eat up to 8,000 pounds of food a day.
但在易于找到食物的海洋中，一头蓝鲸，一天最多可以吃掉8000磅的食物。
7 .And they give birth only once every few years.
他们每隔几年才生育一次。
8 .We also know that body heat, that... well, large animals can't easily get rid of excess body heat.
我们也知道，身体的热量，那......好吧，大型动物不能轻易消耗掉体内多余的热量。
9 .But for an oceangoing whale, that's not a problem.
对于一个远洋鲸鱼来说，这根本不是个问题
10 .For a 100-ton land animal, it can be.
可对于一个100吨重的陆地动物，这可能是个问题。
第五段
1 .For years, we have assumed it was the abundant plant life of the Mesozoic that allowed these giants to thrive.
多年来，我们猜想是拥有着丰富的植物资源的中生代，让这些庞然大物茁壮成长。
2 .However, we now know that since oxygen levels were much lower in the Mesozoic than we assumed, there was much less plant life for sauropods to eat than we thought.
但是，现在我们知道，由于中生代时期的氧气水平远低于我们的假设，可供蜥脚类恐龙吃的植物比我们想象的还要少许多。
第六段
1 .So now, well, we are looking at other...
所以现在，好吧，我们正在寻找其他的.....
2 .We are, we are trying to understand the biology of sauropods, comparing their fossils to the anatomy of modern animals to get a better idea of how they lived.
我们，我们正试图了解有关蜥脚类恐龙的生物学，通过比较它们的化石和现代动物的解剖结构来更好地了解他们如何生活。
3 .What we've found is that sauropods were experts at conserving energy.
我们发现蜥脚类恐龙是节约能源方面的专家。
4 .They had enormous stomach capacity, the ability to digest food over a long period, converting it to energy at a slower pace, saving it for later.
他们有巨大的胃容量，以及长时间消化的食物的能力，以较慢的速度将其转换为能量，然后将能量保存供以后使用。
5 .For animals with small stomachs, it takes lots of energy to constantly look for food and then digest it.
对于小胃容量的动物来说，不断地寻找食物然后消化它需要消耗大量的能量，
6 .With larger stomachs and slower digestion, you don't need as much energy.
较大的胃加上较慢的消化速度，你并不需要那么多的能量。
7 .Joseph?
约瑟夫，你认为呢？
第七段
1 .Does... do scientists actually know about sauropods from looking at...
难道......难道科学家从看能真正了解蜥脚类恐龙...
2 .I mean, how much can we actually learn looking at some ancient bones compared to all we can learn from modern animals?
我的意思是，和我们从现代动物中学到的相比，我们在看一些古老的骨头的时候能真正学到些什么？
3 .And, comparisons between animals that lived millions of years apart? Well, it just seems... more like guessing.
而且，是部分存活数百万年的动物之间的比较？好吧，它似乎只是......更像是猜测。
第八段
1 .There's always some guesswork when studying extinct animals.
在研究灭绝的动物时，总有一些猜测。
2 .But that's exactly what leads to discoveries, a hypothesis, a type of guess is made.
但是，这正是一些发现的重要来源，一种假设，一种猜测被提出。
3 .We test the hypothesis by looking for evidence to support it.
我们通过寻找证据来支持自己提出的假设。
4 .Then some questions are answered, which may lead to new questions.
然后某些问题的回答，可能会导致新的问题的产生。
5 .For example, let's look at one of these comparisons.
例如，让我们来看看这些比较中的一个。
第九段
1 .We know sauropods couldn't chew food.
我们知道蜥脚类恐龙无法咀嚼食物。
2 .Their skulls show they had no chewing muscles.
他们的头骨表明他们没有咀嚼肌
3 .Lots of modern animals, like birds and reptiles, also can't chew food.
许多现代动物，如鸟类和爬行动物，也不能咀嚼食物。
4 .They need to swallow it whole.
他们需要吞下整个食物。
5 .But modern animals have an interesting aid for digesting food.
但现代动物有一个有趣的辅助消化食物的方法。
6 .They swallow stones, stones that are used to help grind up the food before it's actually digested in the stomach.
他们吞下石头，这些石头在未被消化之前用来帮助磨碎胃中的食物。
7 .These stones are called gastroliths.
它们被称为胃石。
8 .Gastroliths make food easier to digest, essentially smashing food up, just as we do when we chew.
胃石使食物更容易消化，从根本上粉碎食物，就像我们咀嚼时一样。
9 .Over time, gastroliths inside the animal are ground down and become smooth and rounded.
随着时间的推移，动物体内的胃石渐渐被消磨，变得光滑圆润。
第十段
1 .Now, sauropod fossils are commonly found with smooth stones.
现在，蜥脚类华师中常常发现光滑的石头
2 .For years we thought these were gastroliths. They look just like gastroliths and were found in the area of the sauropods' stomachs.
多年来，我们认为这些石头是胃石，他们看起来就像胃石，而且在蜥脚类化石的胃部被发现
3 .A recent study measured the gastroliths in modern animals, in ostriches.
最近的研究测量出胃石在现代的动物体内，鸵鸟体内
4 .And the study showed that ostriches need to ingest about one percent of their total body weight in gastroliths.
研究表明，鸵鸟需要咽下大约它体重1%的胃石
5 .But we have been able to determine that the stones found with sauropods totaled much less proportionally, less than a tenth of one percent of their body weight.
但我们已经能够确定，发现的蜥脚类恐龙的石头为更少的比例，低于百分之一的体重的十分之一。
第十一段
1 .So now we are not quite sure what these sauropods' stones were used for.
所以我们现在不是很确定这些蜥脚类的石头的用途
2 .It could be they were accidentally ingested as the sauropods foraged for food, that they served no real purpose.
可能是这些石头在觅食食物的蜥脚类恐龙进食时不小心摄入的，他们的存在没有什么实际意义。
3 .Other researchers speculate that sauropods ingested these stones as a source of some the minerals they needed, such as calcium.
其他研究人员推测，蜥脚类恐龙像摄入一些他们所需要的矿物质一样摄入这些石头，如钙物质。
第十二段
1 .So the original hypothesis that the stones found with sauropods were gastroliths, even though it hasn't been supported, has helped us to make new hypotheses, which may eventually lead to the answer.
所以原假设，即蜥脚类恐龙中发现的石头是胃石，尽管它并没有被支持，但却帮助我们做出新的假设，从而可能最终得出答案。