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英語聽力:恐龍是怎樣煉成的—22

所屬教程:英語聽力:探索與發(fā)現(xiàn)

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2016年12月17日

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https://online2.tingclass.net/lesson/shi0529/0009/9895/80.mp3
https://image.tingclass.net/statics/js/2012
Going back, say, ten years ago, would you ever imagine that you would have been able to tell what colour any dinosaurs would have been?

No, I mean I think at that time I would have said that it’s one of the things we will never know. And so we just focus up and see what we’ve got here.

Using a scanning electron microscope, Mike can find clues about the pigmentation of these ancient fossil feathers.

And if we just have a look at this, the required time amount of locations, that’s 9,000 times. All these sausage shapes then are melanosomes, and then a living feather. They would be full of the chemical melanin, which would in fact give the colour. And these sausage-shaped ones are a sureindicator of a particular kind of melanin, which is the one that gives a black or dark brown colour. So in some cases like this, the field of views is completely packed with the sausage-shaped ones. So we know this must have been intensely black. If they were more loosely spaced, we would know it was a paler colour, maybe dark brown or even gray.

So is it just really the presence or absence of the black pigments that you are able toascertain?

Well, the wonderful thing is there is another form of melanin that gives a ginger colour. And so, and it is packaged in a different shape of melanosome, not this kind of cigar-shaped or sausage-shaped one, but a spherical one, a little ball. Close it up. We get the vacuum going.

A sample taken from a different fossil shows what the structures that carried this gingerpigment look like.

That's entirely different. This surface looks as if they've taken a melon baller and scooped up lots of little spherical hollows. So what colour would these melanosomes have made?

This is definitely ginger. And if you look at this ginger hair from a man of our human being, that's what you see ourselves.

So is it relatively easy to compare your dinosaur feathers with what’s already known about, the feathers of a living bird, to get that comparison to know what colours you were looking at here?

We can put the specimens in one after the other. There is the modern one. There is the fossil. Spot the difference. No difference at all. And who on earth would have thought a dinosaur was close to a bird? But here we are, you know, it's kind of proved in the skeletons. And now if you like, proved in the melatonin of the feathers.

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