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Now listen to a part of the lecture on the topic you just read about.
現在來聽一段有關你剛剛所閱讀到的話題的演講
Many scientists have problems with the arguments you read in the passage.
許多科學家對你在文章中所讀到的論點有問題。
They don't think those arguments prove that dinosaurs were endotherms.
他們認為那些論點不能能證明恐龍是恒溫動物。
Take the polar dinosaur argument.
拿極地恐龍的論點來說 。
When dinosaurs lived, even the polar regions, where dinosaur fossils have been found, were much warmer than today,
在恐龍生活的年代，氣溫比現在暖和很多，即便是在恐龍化石被找到的極地區域，
warm enough during part of the year for animals that were not endotherms to live.
一年里的部分時間足夠暖，所以那些不是恒溫的動物也能生存下去。
And during the months when the polar regions were cold,
在極地地區很冷的幾個月里，
the so-called polar dinosaurs could have migrated to warmer areas or hibernated like many modern reptiles do.
所謂的極地恐龍可以遷徙去暖和的地方或者像許多現代爬行動物一樣冬眠。
So the presence of dinosaur fossils in polar regions doesn't prove the dinosaurs were endotherms.
所以，恐龍化石在極地地區出現不能證明恐龍是恒溫動物。
Well, what about the fact that dinosaurs have their legs placed under their bodies, not out to the side like crocodiles.
那么，恐龍的腿是長在身體下面，并不像鱷魚一樣伸展到身體兩側的事實又是怎么回事呢？
That doesn't necessarily mean dinosaurs were high-energy endotherms built for running.
那也并不意味著恐龍是專為跑步的高能量恒溫動物。
There is another explanation for having legs under the body.
對于腿長在身體下面有另一個解釋。
This body structure supports more weight, so with the legs under their bodies, dinosaurs can grow to a very large size.
這種身體結構能承重更多，所以身下有腿，恐龍能長到很大的尺寸。
Being large had advantages for dinosaurs,
身形很大對恐龍來說是有好處的，
so we don't need the idea of endothermy and running to explain why dinosaurs evolved to have their legs under their bodies.
所以我們不需要用恒溫動物和奔跑這個主意來解釋為什么恐龍進化成在它們身體下面長出腿。
Ok, so how about bone structure?
好的，那么骨結構呢？
Many dinosaur bones do have Haversian canals, that's true.
許多恐龍的骨頭確實有哈弗氏管，這是真的。
But dinosaur bones also have growth rings.
但是恐龍骨頭也有生長環。
Growth rings are thickening of the bone that indicates periods of time when the dinosaurs weren't rapidly growing.
生長環是增厚的骨頭，代表了一段恐龍沒有快速生長的時期。
These growth rings are evidence that dinosaurs stopped growing or grew more slowly during cooler periods.
這些生長環是恐龍在較冷的時期里停止生長或者生長緩慢的證據。
This pattern of periodic growth, you know, rapid growth followed by no growth or slow growth,
這種周期性生長的模式，快速生長后跟隨著沒有生長或者緩慢生長，
and then rapid growth again, is characteristic of animals that are not endotherms.
然后又是快速生長，是非恒溫動物的特點。
Animals that maintain a constant body temperature year-round as true endotherms do grow rapidly even when the environment becomes cool.
像真正的恒溫動物一樣一年四季有著恒定體溫的動物，即使在環境變冷的時候也會快速生長。
Summarize the points made in the lecture, being sure to explain how they challenge the specific points made in the reading passage.
總結演講中的觀點，準確解釋他們如何向閱讀文章中的觀點提出挑戰。
