科学美国人60秒 SSS 解开古老谜题:鸟类是如何飞行的?(2)（在线收听）

But compare the majestic eagle with a frantically flapping duck…

但是，把雄鹰与一只疯狂拍打翅膀的鸭子作对比……

Birds with a deep sternal keel fly more slowly, those with long sternums are associated with running birds.

胸骨较深的鸟飞得较慢，胸骨较长的鸟与擅长奔跑的鸟有关。

Merri also looked at foot-propelled, underwater diving birds.

梅里还研究了用脚推进的潜鸟。

These are species like the cormorant, the loon and the grebe.

这些鸟类包括鸬鹚、潜鸟和鸊鷉。

They have this streamlined sternum with lower sternal keels.

它们拥有流线型的胸骨，龙骨突较低。

Everything is kind of compact and flattened, but you actually see something really similar in birds that are wing propelled divers.

所有的胸骨都是小型而扁平的，但实际上你可以在鸟类身上看到类似的东西，它们是用翅膀推进的潜鸟。

Those wing-propelled divers include small birds you might find on the ocean - puffins, common murres and penguins.

这些用翅膀推进的潜鸟包括你可能在海洋上看到的小鸟——海鹦、普通海鸦和企鹅。

Merri says whether wing or foot-propelled, the sternums of these birds are similar in shape.

梅里表示，无论是用翅膀推进还是用脚推进，这些鸟的胸骨在形状上是相似的。

All other sorts of factors are possibly most likely contributing to the shape of the sternum, not just locomotion, things like birds that dance to attract a mate or how big their egg is relative to their body size.

所有其他的因素都有可能影响到胸骨的形状，而不仅仅是运动，比如鸟类通过跳舞来吸引配偶，或者它们的蛋相对于它们身体的大小。

We've just, you know, scratched the surface, looked at one aspect of variation, but there's so much more.

我们只是触及了表面，研究了变化的一个方面，但还有很多没有涉及。

Merri believes that the shape and structure of the sternum impacts how different species of birds breathe.

梅里认为，胸骨的形状和结构影响着不同鸟类的呼吸方式。

She also says different methods of flight mean different resource demands for individual species.

她还表示，不同的飞行方式意味着不同物种对资源的需求。

Diving deep into how birds fly today can tell scientists a lot about how they evolved over millions of years.

深入研究今天的鸟类如何飞行可以让科学家了解鸟类在数百万年里是如何进化的。

So, birds evolved from dinosaurs… and we don't know exactly which fossil birds and which dinosaurs were capable of flight.

鸟类是从恐龙进化而来的… 我们不知道到底哪些鸟类化石和恐龙能够飞行。

But, gaining a better understanding of how birds fly today is the key to completing that picture of how the dinosaurs were moving through the world.

但是，今天更好地了解鸟类是如何飞行的，这是研究恐龙是如何在世界上移动的的关键。

Merri plans to dig into fossil birds next, in part to learn more about the origins of flight.

梅里计划下一步深入研究鸟类化石，部分是为了了解更多关于飞行起源的知识。

The thing about fossil birds is that a lot of them are flattened into rock slabs.

鸟类化石，很多都被压扁成岩石板。

But there are so many amazing bird fossils, especially from China ….

但是有这么多令人惊奇的鸟类化石，特别是来自中国....

And so they will have to be studied a little bit differently because they may not be able to put them in a three dimensional context, as they did with the modern bird sterna.

因此，必须对它们进行稍微不同的研究，因为它们可能无法像现代鸟类胸骨那样，将它们置于三维环境中。

For now, though, Merri says she’s looking differently at the small, passerine birds that flit by her windows and dominate the tree branches in her backyard in Ontario.

不过现在，梅里说，她对那些从她的窗户旁飞过、在她安大略省后院的树枝上占主导地位的雀形目鸟类有了不同的看法。

They're mostly continuous flapping birds.

这些鸟大多不停地拍打翅膀。

They're flapping pretty quickly.

它们扇动翅膀很快。

They're moving from branch to branch.

他们从一个树枝移动到另一个树枝上。

You know, they're trying to keep away from predators and get some food, whether it's insects or berries.

它们试图远离捕食者，获得一些食物，无论是昆虫还是浆果。

It made me think about how their skeletons are structured and also how their muscles are working much differently than, let's say, a hawk that's soaring above.

这让我思考：这些鸟儿的骨架是如何构造的，以及它们的肌肉是如何工作的，与在高空翱翔的鹰有很大不同。

And so they would require different metabolism and different food sources.

所以它们需要不同的新陈代谢和不同的食物来源。

And how they use that in their body would be very different.

而它们在体内使用这些的方式大不相同。

For 60-Second Science, I’m Emily Schwing.

谢谢大家收听60秒科学。我是艾米莉·施温。