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This is the microraptor, a carnivorous four-winged dinosaur that was almost two-feet long,
这是一只小盗龙，一个有将近两英尺长的四翼食肉恐龙，
ate fish, and lived about 120 million years ago.
以吃鱼为生，这是地球上十二亿年前的动物。
Most of what we know about it comes from fossils that look like this.
我们从这样的化石上推断出了这些。
So, is its coloration here just an artist's best guess? The answer is no.
那么这只古老的动物究竟是什么颜色的，会像艺术家们画的那样吗？答案是：不是的。
We know this shimmering black color is accurate because paleontologists have analyzed clues contained within the fossil.
据我们所知，这种微微发光的黑色是正确的，因为古生物学家已经从化石的成分中分析出了线索。
But making sense of the evidence requires careful examination of the fossil
但是，得到这样一个结论仍然需要对化石进行细致的检验，
and a good understanding of the physics of light and color.
同样也要求研究人员懂得光学、色彩学的物理知识。
First of all, here's what we actually see on the fossil:
首先，这是我们最初能在化石上看到的：
imprints of bones and feathers that have left telltale mineral deposits.
那些压印暴露出了各种矿物沉积的成分。
And from those imprints, we can determine that these microraptor feathers were similar to modern dinosaur, as in bird, feathers.
从这些痕迹中，我们能知道这些盗龙的羽毛和现代的恐龙很相似，就像鸟类的羽毛。
But what gives birds their signature diverse colorations?
可又是什么让鸟的羽毛也能具有多种多样的色彩呢？
Most feathers contain just one or two dye-like pigments.
大多数羽毛只有一种或者两种色素。
The cardinal's bright red comes from carotenoids, the same pigments that make carrots orange,
比如它们身上的鲜红色来自类胡萝卜素，类胡萝卜素可以让胡萝卜呈橘色，
while the black of its face is from melanin, the pigment that colors our hair and skin.
它们脸上的黑色来自黑色素，我们的头发和皮肤中就有黑色素。
But in bird feathers, melanin isn't simply a dye.
但在鸟的羽毛中，黑色素可不仅仅是起到了着色作用。
It forms hollow nanostructures called melanosomes which can shine in all the colors of the rainbow.
它还构成一种名为黑色素体的中空纳米结构，可以在彩虹的颜色中发出光泽。
To understand how that works, it helps to remember some things about light.
要想进一步了解它是如何产生效果的，这就需要我们重新回忆一些有关光学的知识。
Light is basically a tiny electromagnetic wave traveling through space.
光是穿行在宇宙空间中的一种电磁波。
The top of a wave is called its crest and the distance between two crests is called the wavelength.
波的最高点叫波峰，两个波峰之间的距离叫波长。
The crests in red light are about 700 billionths of a meter apart and the wavelength of purple light is even shorter,
红光的波长大约是七千亿分之一米，紫光的波长就更短了，
about 400 billionths of a meter, or 400 nanometers.
大约是四千亿分之一米，也就是400纳米。
When light hits the thin front surface of a bird's hollow melanosome, some is reflected and some passes through.
当光波到达鸟类羽毛表面的中空黑色素体时，一部分光被反射回来，一部分穿过。
A portion of the transmitted light then reflects off the back surface. The two reflected waves interact.
那一部分穿过的光到达羽毛表面的另一侧时又被反射回来。两束反射光相遇。
Usually they cancel each other out,
通常情况下它们会相互抵消，
but when the wavelength of the reflected light matches the distance between the two reflections, they reinforce each other.
但如果反射光的波长恰好和两束反射光波之间的间距相等时，它们之间会相互增强对方的能量。
Green light has a wavelength of about 500 nanometers,
绿光的波长大概是500纳米，
so melanosomes that are about 500 nanometers across give off green light,
那么黑色素体的直径为500纳米时会散发出绿色的光，
thinner melanosomes give off purple light, and thicker ones give off red light.
更薄的黑色素体散发紫光，厚一点的散发红光。
Of course, it's more complex than this.
当然，实际情况比这个更复杂。
The melanosomes are packed together inside cells,
这些黑色素体会挤在细胞中，
and other factors, like how the melanosomes are arranged within the feather, also matter.
而其它因素，比如这些黑色素体是如何在羽毛中的排列也很重要。
Let's return to the microraptor fossil.
让我们回到这只盗龙的化石来吧。
When scientists examined its feather imprints under a powerful microscope, they found nanostructures that look like melanosomes.
当科学家们用高倍显微镜检查石上的羽毛印迹时，他们发现了一些看起来很像黑色素体的小型纳米结构。
X-ray analysis of the melanosomes further supported that theory.
通过后续的X光实验分析再一次证实了这一结论。
They contained minerals that would result from the decay of melanin.
因为这些结构中含有许多由黑色素衰退遗留下来的矿物元素。
The scientists then chose 20 feathers from one fossil
科学家们又从一个化石中选取了20种羽毛成分，
and found that the melanosomes in all 20 looked alike, so they became pretty sure this dinosaur was one solid color.
发现20种成分中的黑色素体都十分相似，由此他们得出结论：这只恐龙是一种纯色的生物。
They compared these microraptor melanosomes to those of modern birds
他们还把这只盗龙的黑色素体拿来和现代的鸟类做比较，
and found a close similarity, though not a perfect match, to the iridescent teal feathers found on duck wings.
发现盗龙羽毛中的黑色素体和拥有闪色的羽毛的水鸭存在许多相似之处，尽管不是完全吻合。
And by examining the exact size and arrangement of the melanosomes, scientists determined that the feathers were iridescent black.
通过对黑色素体的大小和排列的不断研究，科学家们认为盗龙的羽毛是闪亮的黑色。
Now that we can determine a fossilized feather's color, paleontologists are looking for more fossils with well-preserved melanosomes.
这样一来，我们可以仅通过化石检验出远古时期的动物的体毛颜色，古生物学家还在寻找那些存在着保留完好的黑色素体的化石。
They've found that a lot of dinosaurs, including velociraptor, probably had feathers,
他们发现许多的恐龙，包括迅猛龙，可能都是有羽毛的，
meaning that certain films might not be so biologically accurate. Clever girls.
也就是说从生物学角度，许多科幻电影中呈现的恐龙的样子都不准确。如此机智。
