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Now listen to a part of the lecture on the topic you just read about.
现在来听一段有关你刚刚所阅读到的话题的演讲
Many scientists have problems with the arguments you read in the passage.
许多科学家对你在文章中所读到的论点有问题。
They don't think those arguments prove that dinosaurs were endotherms.
他们认为那些论点不能能证明恐龙是恒温动物。
Take the polar dinosaur argument.
拿极地恐龙的论点来说 。
When dinosaurs lived, even the polar regions, where dinosaur fossils have been found, were much warmer than today,
在恐龙生活的年代，气温比现在暖和很多，即便是在恐龙化石被找到的极地区域，
warm enough during part of the year for animals that were not endotherms to live.
一年里的部分时间足够暖，所以那些不是恒温的动物也能生存下去。
And during the months when the polar regions were cold,
在极地地区很冷的几个月里，
the so-called polar dinosaurs could have migrated to warmer areas or hibernated like many modern reptiles do.
所谓的极地恐龙可以迁徙去暖和的地方或者像许多现代爬行动物一样冬眠。
So the presence of dinosaur fossils in polar regions doesn't prove the dinosaurs were endotherms.
所以，恐龙化石在极地地区出现不能证明恐龙是恒温动物。
Well, what about the fact that dinosaurs have their legs placed under their bodies, not out to the side like crocodiles.
那么，恐龙的腿是长在身体下面，并不像鳄鱼一样伸展到身体两侧的事实又是怎么回事呢？
That doesn't necessarily mean dinosaurs were high-energy endotherms built for running.
那也并不意味着恐龙是专为跑步的高能量恒温动物。
There is another explanation for having legs under the body.
对于腿长在身体下面有另一个解释。
This body structure supports more weight, so with the legs under their bodies, dinosaurs can grow to a very large size.
这种身体结构能承重更多，所以身下有腿，恐龙能长到很大的尺寸。
Being large had advantages for dinosaurs,
身形很大对恐龙来说是有好处的，
so we don't need the idea of endothermy and running to explain why dinosaurs evolved to have their legs under their bodies.
所以我们不需要用恒温动物和奔跑这个主意来解释为什么恐龙进化成在它们身体下面长出腿。
Ok, so how about bone structure?
好的，那么骨结构呢？
Many dinosaur bones do have Haversian canals, that's true.
许多恐龙的骨头确实有哈弗氏管，这是真的。
But dinosaur bones also have growth rings.
但是恐龙骨头也有生长环。
Growth rings are thickening of the bone that indicates periods of time when the dinosaurs weren't rapidly growing.
生长环是增厚的骨头，代表了一段恐龙没有快速生长的时期。
These growth rings are evidence that dinosaurs stopped growing or grew more slowly during cooler periods.
这些生长环是恐龙在较冷的时期里停止生长或者生长缓慢的证据。
This pattern of periodic growth, you know, rapid growth followed by no growth or slow growth,
这种周期性生长的模式，快速生长后跟随着没有生长或者缓慢生长，
and then rapid growth again, is characteristic of animals that are not endotherms.
然后又是快速生长，是非恒温动物的特点。
Animals that maintain a constant body temperature year-round as true endotherms do grow rapidly even when the environment becomes cool.
像真正的恒温动物一样一年四季有着恒定体温的动物，即使在环境变冷的时候也会快速生长。
Summarize the points made in the lecture, being sure to explain how they challenge the specific points made in the reading passage.
总结演讲中的观点，准确解释他们如何向阅读文章中的观点提出挑战。
