How do we know what color dinosaurs were? - Len Bloch

譯者: nr chan 審譯者: Ann Chen

This is the microraptor,

這是一隻小盜龍

a carnivorous four-winged dinosaur that was almost two-feet long,

是隻有四翼的肉食性恐龍 將近兩呎長

ate fish,

以吃魚為生

and lived about 120 million years ago.

活在 1 億 2 千萬年前的世界

Most of what we know about it comes from fossils that look like this.

我們對牠的資訊大多是從 像這樣的化石來的

So, is its coloration here just an artist's best guess?

那麼，這些顏色只是畫家的猜測嗎？

The answer is no.

答案是否定的

We know this shimmering black color is accurate

我們知道這閃爍的黑色是正確的

because paleontologists have analyzed clues contained within the fossil.

因為古生物學家分析了 在化石之中的線索

But making sense of the evidence requires careful examination of the fossil

但要搞懂這些証據 必須小心檢驗這些化石

and a good understanding of the physics of light and color.

並了解光與色的物理原理

First of all, here's what we actually see on the fossil:

首先，這是我們實際上在化石看到的：

imprints of bones and feathers that have left telltale mineral deposits.

骨頭和羽毛的刻痕 顯示有礦物沉澱物質

And from those imprints,

從這些刻痕

we can determine that these microraptor feathers

我們可以斷定小盜龍的羽毛

were similar to modern dinosaur, as in bird, feathers.

和現代恐龍 ─ 也就是鳥類 ─ 的羽毛相似

But what gives birds their signature diverse colorations?

但是甚麼讓鳥類有這麼多不同的顏色?

Most feathers contain just one or two dye-like pigments.

多數羽毛只有一兩種類似染料的色素

The cardinal's bright red comes from carotenoids,

北美红雀的鮮紅來自類胡蘿蔔素

the same pigments that make carrots orange,

也就是讓紅蘿蔔呈現橘色的色素

while the black of its face is from melanin,

而牠臉上的黑色來自黑色素

the pigment that colors our hair and skin.

就是讓我們頭髮和皮膚產生顏色的色素

But in bird feathers, melanin isn't simply a dye.

但鳥羽的黑色素不單單是色素

It forms hollow nanostructures called melanosomes

鳥羽內會形成許多 中空奈米結構，稱為「黑色素體」

which can shine in all the colors of the rainbow.

在彩虹的所有顏色下 都會顯得閃閃發光

To understand how that works,

要了解為甚麼會這樣

it helps to remember some things about light.

要先回憶一下有關光的一些知識

Light is basically a tiny electromagnetic wave traveling through space.

基本上，光是在宇宙中穿梭的微小電磁波

The top of a wave is called its crest

波的最高點叫波峰

and the distance between two crests is called the wavelength.

兩波峰之間的距離叫做波長

The crests in red light are about 700 billionths of a meter apart

紅光的波長大約 700 奈米 （700 乘以10 的 負 9 次方公尺）

and the wavelength of purple light is even shorter,

而紫光的波長就更短了

about 400 billionths of a meter, or 400 nanometers.

大約只有 400 奈米 （400 乘以10 的 負 9 次方公尺）

When light hits the thin front surface of a bird's hollow melanosome,

當光射到這隻鳥中空的 黑色素體的前面薄層表面時

some is reflected and some passes through.

有的被反射，而有的穿透過去

A portion of the transmitted light then reflects off the back surface.

部份穿透過去的光 又被後面表面反射回來

The two reflected waves interact.

兩道反射波相互作用

Usually they cancel each other out,

通常會相互抵消

but when the wavelength of the reflected light

但當後面反射光的波長

matches the distance between the two reflections,

和前面反射光的波長相等時

they reinforce each other.

他們就會互相增強

Green light has a wavelength of about 500 nanometers,

綠光波長約 500 奈米

so melanosomes that are about 500 nanometers across

所以寬 500 奈米的黑色素體

give off green light,

會散發綠光

thinner melanosomes give off purple light,

比較細的黑色素就會散發紫光

and thicker ones give off red light.

比較粗的就會散發紅光

Of course, it's more complex than this.

當然，實際情況會更為複雜

The melanosomes are packed together inside cells, and other factors,

黑色素體是成堆擠在細胞裡面， 所以其他因素

like how the melanosomes are arranged within the feather, also matter.

像羽毛裡面的黑色素體 的排列方式也很重要

Let's return to the microraptor fossil.

讓我們回到小盜龍的化石

When scientists examined its feather imprints under a powerful microscope,

當科學家在高倍顯微鏡下 檢視羽毛刻痕時

they found nanostructures that look like melanosomes.

他們發現長得像黑色素體的奈米結構

X-ray analysis of the melanosomes further supported that theory.

透過 X 光分析再次支持這個理論

They contained minerals that would result from the decay of melanin.

它們含有黑色素衰變後的礦物

The scientists then chose 20 feathers from one fossil

接著，科學家在同一個化石 選了 20 根的羽毛

and found that the melanosomes in all 20 looked alike,

發現這 20 根羽毛的 黑色素體都長相一樣

so they became pretty sure this dinosaur was one solid color.

所以他們非常確定這隻恐龍是單一顏色

They compared these microraptor melanosomes to those of modern birds

他們把小盜龍的黑色素體 和現代鳥類做比較

and found a close similarity, though not a perfect match,

發現它和水鴨翅膀閃亮藍綠色羽毛的 黑色素體十分接近，雖然不是完全吻合

to the iridescent teal feathers found on duck wings.

And by examining the exact size and arrangement of the melanosomes,

接著再檢視黑色素體的 實際大小和排列方式

scientists determined that the feathers were iridescent black.

科學家便確定小盜龍羽毛 是閃閃發光的黑色

Now that we can determine a fossilized feather's color,

由於我們已能檢測出 已變成化石的羽毛的顏色

paleontologists are looking for more fossils with well-preserved melanosomes.

古生物學家在尋找更多 保存良好的黑色素體

They've found that a lot of dinosaurs, including velociraptor,

並已發現許恐龍，像是迅猛龍

probably had feathers,

可能也有羽毛

meaning that certain films might not be so biologically accurate.

代表某些電影可能 沒有那麼精確符合生物學

Clever girls.

真聰明！

翻譯：nr Chan