Jack Horner: Shape-shifting dinosaurs

譯者: Michelle Fan 審譯者: Joan Liu

可以請各位舉手

Shall I ask for a show of hands or a clapping

或是鼓掌

讓我知道各位的年齡嗎？

of people in different generations?

I'm interested in how many are three to 12 years old.

我想知道在座有多少人

年齡在3到12歲？

(Laughter)

(笑聲)

一個也沒有 嗯？

None, huh?

(Laughter)

好吧

All right.

今天我的主題是恐龍

I'm going to talk about dinosaurs.

Do you remember dinosaurs when you were that age?

各位還記得恐龍嗎？ 你們3到12歲時很愛的？

(Applause)

(掌聲)

Dinosaurs are kind of funny, you know.

話說恐龍還蠻搞笑的

(Laughter)

(笑聲)

We're going to kind of go in a different direction right now.

今天我切入的角度會不太一樣

希望各位已經感覺到了

I hope you all realize that.

So I'll just give you my message up front:

那我就開門見山地講明主旨了

請不要滅絕

Try not to go extinct.

(笑聲)

(Laughter)

That's it.

完了

(Laughter)

(笑聲)

人們常常問我

People ask me a lot --

事實上 我最常遇到的問題是

in fact, one of the most asked questions I get

is, why do children like dinosaurs so much?

爲什麽孩子們這麼喜歡恐龍？

What's the fascination?

恐龍的魅力在哪？

And I usually just say,

我通常只會說：

"Well, dinosaurs were big,

「呃 恐龍很大隻

很特別、而且已經消失了」

different and gone."

全部消失了

They're all gone.

Well that's not true,

嗯，也不盡然如此

but we'll get to the goose in a minute.

但我們等一下再來講這個

所以重點差不多就是這樣

So that's sort of the theme:

big, different and gone.

大隻、特別、消失了

The title of my talk:

我演講的題目是：

Shape-shifting Dinosaurs:

變形的恐龍

The cause of a premature extinction.

過早滅絕的原因

現在我假設各位都記得恐龍

Now I assume that we remember dinosaurs.

恐龍有各種體型

And there's lots of different shapes.

許多種類

Lots of different kinds.

A long time ago,

很久以前

back in the early 1900s, museums were out looking for dinosaurs.

1900年代早期時

博物館競相尋找恐龍

他們四處尋找、搜集恐龍

They went out and gathered them up.

And this is an interesting story.

整件事情的發展非常有趣

每個博物館都想要更大、更好的恐龍

Every museum wanted a little bigger or better one than anybody else had.

把其他博物館比下去

So if the museum in Toronto went out and collected a Tyrannosaur, a big one,

所以如果多倫多的博物館

蒐集到一副暴龍的骸骨，大隻的暴龍

那麼渥太華的博物館就想要一隻更大

then the museum in Ottawa wanted a bigger one, and a better one.

更好的暴龍

所有的博物館都打一樣的算盤

And that happened for all museums.

So everyone was out looking for all these bigger and better dinosaurs.

所以每個博物館都出動

要找更大更好的恐龍骸骨

這是1900年代早期的事

And this was in the early 1900s.

By about 1970,

到了大約1970年代

某些科學家聚在一起

some scientists were sitting around and they thought, "What in the world --

開始思索：「搞什麼鬼？

Look at these dinosaurs, they're all big.

「看看這些恐龍

「全都這麼大隻

「小的恐龍哪去了？」

Where are all the little ones?"

(Laughter)

And they thought about it and they even wrote papers about it:

他們想了又想

甚至還寫論文探討

"Where are the little dinosaurs?"

「小型恐龍在哪兒？」

(Laughter)

(笑聲)

去博物館看看吧

Well, go to a museum, you'll see,

see how many baby dinosaurs there are.

看你找不找得到小恐龍

People assumed -- and this was actually a problem --

人們假定─其實這樣是有問題的─

people assumed that if they had little dinosaurs,

不過人們假定

如果有小型恐龍

如果有年幼的恐龍

if they had juvenile dinosaurs, they'd be easy to identify.

很容易就可以認出來

You'd have a big dinosaur and a littler dinosaur.

反正就是一隻大隻的

和一隻小隻的

(Laughter)

但博物館收藏的都是大型恐龍

But all they had were big dinosaurs.

這顯示了幾件事

And it comes down to a couple of things.

First off, scientists have egos,

第一：科學家都自視甚高

而且喜歡替恐龍命名

and scientists like to name dinosaurs.

They like to name anything.

只要能被命名的他們都喜歡

Everybody likes to have their own animal that they named.

大家都希望有自己命名、專屬於自己的動物

(笑聲)

(Laughter)

所以每次他們找到一個看起來不一樣的東西

And so every time they found something that looked a little different,

就會替它取一個不一樣的名字

they named it something different.

And what happened, of course,

當然最後就變成

is we ended up with a whole bunch of different dinosaurs.

我們有了一大群不同的恐龍

In 1975,

在1975年

某人靈光一閃

a light went on in somebody's head.

就是彼得‧德森

Dr. Peter Dodson at the University of Pennsylvania

一位賓州大學的博士

發現

actually realized that dinosaurs grew kind of like birds do,

恐龍成長的方式

與鳥類有點相似

which is different than the way reptiles grow.

而鳥類的成長方式

與爬蟲類不同

And in fact,

事實上

he used the cassowary as an example.

他拿食火雞當例子

And it's kind of cool -- if you look at the cassowary,

還蠻酷的。如果你看食火雞

or any of the birds that have crests on their heads,

或者其他頭上有冠的鳥類

they grow to about 80 percent adult size before the crest starts to grow.

實際上

牠們在長到成年身型的80%時

頭上的冠才開始生長

各位想想

Now think about that.

They're basically retaining their juvenile characteristics

食火雞基本上長時間保留未成年的特徵

very late in what we call ontogeny.

直到個體發生階段的晚期

So allometric cranial ontogeny is relative skull growth.

所以異速頭顱個體發生

就是頭蓋骨的相對生長

So you can see that if you actually found one that was 80 percent grown

所以各位可以看到

如果你發現一隻

只生長發育了80%的動物

and you didn't know that it was going to grow up to a cassowary,

但你不知道牠會長成一隻食火雞

你就會以為牠是別的動物

you would think they were two different animals.

So this was a problem,

這就是問題所在

and Peter Dodson pointed this out using some duck-billed dinosaurs

彼得‧德森指出了這點

他用的例子是某種鴨嘴恐龍

當時被稱為亞冠龍

then called Hypacrosaurus.

And he showed that if you were to take a baby and an adult

他發現

如果你用一隻幼年和一隻成年恐龍

and make an average of what it should look like,

來計算這種恐龍在不同年齡的體型

假設牠是以線性方式生長

if it grew in sort of a linear fashion,

牠就會有頭冠

it would have a crest about half the size of the adult.

頭冠大小約是成年恐龍的一半

But the actual subadult at 65 percent had no crest at all.

但是實際上未成年的恐龍

只發育了65%的

根本沒有頭冠

So this was interesting.

所以這就有意思了

So this is where people went astray again.

這就是

科學家的思路出錯的地方

I mean, if they'd have just taken that,

我是說 如果他們可以接受

接受彼得‧道森的研究結論，然後繼續往下發展

taken Peter Dodson's work, and gone on with that,

那麼我們的恐龍數目

then we would have a lot less dinosaurs than we have.

就會大大減少

But scientists have egos; they like to name things.

但是科學家自視甚高

又喜歡替事物命名

And so they went on naming dinosaurs because they were different.

所以他們繼續給恐龍命名

因為牠們看上去不一樣

Now we have a way of actually testing

不過呢，我們有方法可以確實測量

檢查恐龍或任何動物

to see whether a dinosaur, or any animal, is a young one or an older one.

是年幼的還是較年長的

And that's by actually cutting into their bones.

方法就是真的切骨見髓

但是切開恐龍的骨頭

But cutting into the bones of a dinosaur is hard to do, as you can imagine,

是很困難的，各位想也知道

because in museums, bones are precious.

因為對博物館而言

恐龍骨頭很珍貴

每個博物館都會非常小心地維護這些骨頭

You go into a museum, and they take really good care of them.

They put them in foam, little containers.

把骨頭放在小小的發泡容器中

妥善收藏

They're very well taken care of.

館方不會樂見你一進來

They don't like it if you come in and want to saw them open and look inside.

就打算鋸開骨頭看內部

(笑聲)

(Laughter)

So they don't normally let you do that.

所以他們通常不允許你這樣做

(Laughter)

但是我有一個博物館

But I have a museum and I collect dinosaurs

而且我也蒐集恐龍

我可以鋸我自己的收藏

and I can saw mine open.

我也這麼做了

So that's what I do.

(掌聲)

(Applause)

如果你切開小恐龍的骨頭

So if you cut open a little dinosaur,

it's very spongy inside, like A.

骨頭裡面疏鬆如海綿 像圖A

如果切開的骨頭是較年長恐龍

And if you cut into an older dinosaur, it's very massive.

裡面十分緊密

You can tell it's mature bone.

一看就知道是成熟的骨頭

所以要區分骨頭是很容易的

So it's real easy to tell them apart.

So what I want to do is show you these.

現在

讓各位看看這些東西

In North America in the northern plains of the United States

在北美洲、美國的北美大平原

and the southern plains of Alberta and Saskatchewan,

和加拿大亞伯達省和薩斯喀徹溫省的南部平原上

there's this unit of rock called the Hell Creek Formation

有一處岩石區被稱為地獄溪地層

從這裡找到了最後存活在地球上的恐龍

that produces the last dinosaurs that lived on Earth.

其中的12種

And there are 12 of them that everyone recognizes --

是眾所周知的

I mean the 12 primary dinosaurs that went extinct.

我指的是12種主要的恐龍

後來都滅絕了

And so we will evaluate them.

因此我們測試這些恐龍

這差不多就是我一直在從事的工作

And that's sort of what I've been doing.

我的學生、我的員工

So my students, my staff, we've been cutting them open.

一直在鋸恐龍骨頭

各位一定可以想像

Now as you can imagine, cutting open a leg bone is one thing,

切開腿骨是一回事

but when you go to a museum

但當你走進一間博物館

說：「你們應該不介意

and say, "You don't mind if I cut open your dinosaur's skull, do you?"

「我切開貴館恐龍的頭骨吧？」

they say, "Go away."

館員會說：「滾開」

(Laughter)

(笑聲)

這就是那12種恐龍

So here are 12 dinosaurs.

And we want to look at these three first.

我們先看這三種

這些恐龍被稱為腫頭龍

So these are dinosaurs that are called Pachycephalosaurus.

大家都知道

And everybody knows that these three animals are related.

這三種恐龍是親戚

我們假設

And the assumption is that they're related like cousins or whatever.

牠們的血緣關係

是類似堂兄弟之類的

But no one ever considered that they might be more closely related.

但沒有人想過

牠們可能有更緊密的關係

換句話說

In other words,

people looked at them and they saw the differences.

科學家觀察牠們 看到了不同之處

And you all know that if you are going to determine

大家都知道

如果你要確定

whether you're related to your brother or your sister,

你跟你的兄弟姐妹有沒有血緣關係

不能只根據你們的相異之處做判斷

you can't do it by looking at differences.

You can only determine relatedness by looking for similarities.

要確認血緣關係

要從相似之處下手

So people were looking at these

因此人們看著這些恐龍時

and they were talking about how different they are.

總是只注意牠們有多麼不同

Pachycephalosaurus has a big, thick dome on its head,

腫頭龍的頭上 有一個又大又厚的圓頂

頭部背面有一些小的凸起物

and it's got some little bumps on the back of its head,

鼻子末端有一堆瘤狀物

and it's got a bunch of gnarly things on the end of its nose.

這是冥河龍 另一種恐龍

And then Stygimoloch, another dinosaur from the same age, lived at the same time,

跟腫頭龍生存的時代相同

has spikes sticking out the back of its head.

牠的頭部後面有棘突出

頭上有個很小的圓頂

It's got a little, tiny dome,

而且鼻子上也有一堆瘤狀物

and it's got a bunch of gnarly stuff on its nose.

And then there's this thing called Dracorex hogwartsia.

然後這隻是名為龍王龍的傢伙

霍格華茲

猜猜牠的名字源自哪裡？龍

Guess where that came from?

Dragon.

這頭恐龍

So here's a dinosaur that has spikes sticking out of its head,

頭上有棘 沒有圓頂

no dome and gnarly stuff on its nose.

鼻子上有瘤狀物

Nobody noticed the gnarly stuff sort of looked alike.

沒人注意到這些瘤狀物有點相似

但人們看著這三隻恐龍

But they did look at these three

and they said, "These are three different dinosaurs,

心裡想：「這是三種不同的恐龍

「龍王龍也許是其中最原始的

and Dracorex is probably the most primitive of them.

這隻比另一隻更早期一點」

And the other one is more primitive than the other."

我不是很確定

It's unclear to me how they actually sorted these three of them out.

他們究竟是怎麼挑出這三種恐龍的

But if you line them up,

但如果你把牠們一字排開

if you just take those three skulls and just line them up,

把牠們的頭骨排成一列

they line up like this.

排起來會像這樣

Dracorex is the littlest one,

龍王龍的最小

Stygimoloch is the middle-size one,

冥河龍在中間

腫頭龍是最大的

Pachycephalosaurus is the largest one.

And one would think, that should give me a clue.

你們可能認為

這應該很明顯了吧

(Laughter)

(笑聲)

But it didn't give them a clue.

但科學家什麼都沒察覺

(Laughter)

Because, well we know why.

我們都知道為什麼

Scientists like to name things.

因為科學家喜歡替東西命名

所以如果我們

So if we cut open Dracorex --

對龍王龍下手

I cut open our Dracorex --

把我們的龍王龍鋸開

and look, it was spongy inside, really spongy inside.

你看 骨頭裡面是海綿狀的

非常明顯的海綿

I mean, it is a juvenile and it's growing really fast.

意思是說牠還年幼

而且長得很快

所以牠會長得更大

So it is going to get bigger.

如果你鋸開冥河龍

If you cut open Stygimoloch, it is doing the same thing.

也會發現一樣的事情

The dome, that little dome, is growing really fast.

那個小小的圓頂

長得非常快

It's inflating very fast.

迅速地膨脹

What's interesting is the spike on the back of the Dracorex

有趣的是 龍王龍背上的棘

也長得非常快

was growing very fast as well.

冥河龍背上的棘

The spikes on the back of the Stygimoloch are actually resorbing,

其實在萎縮

which means they're getting smaller as that dome is getting bigger.

也就是越變越小

而頭上的圓頂則越變越大

And if we look at Pachycephalosaurus,

如果我們看看腫頭龍

Pachycephalosaurus has a solid dome

牠頭上有堅硬的圓頂

and its little bumps on the back of its head were also resorbing.

頭部背面的凸起物

也在萎縮

So just with these three dinosaurs,

因此只要看這三種恐龍

科學家很容易就能夠

as a scientist, we can easily hypothesize

做出假設

that it is just a growth series of the same animal.

牠們代表不同的成長階段

其實都是同一種動物

當然這就表示

Which of course means

冥河龍和龍王龍

that Stygimoloch and Dracorex are extinct.

都絕種了

(Laughter)

(笑聲)

OK.

好吧

(Laughter)

當然這就表示

Which of course means we have 10 primary dinosaurs to deal with.

我們有10種主要恐龍要對付

So a colleague of mine at Berkeley -- he and I were looking at Triceratops.

因此我在柏克萊的一位同事

和我一起研究三觭龍

And before the year 2000 --

2000年之前

now remember, Triceratops was first found in the 1800s --

請記住

三觭龍最初是在1800年代發現的

before 2000, no one had ever seen a juvenile Triceratops.

在2000年之前 沒有人看過

幼年的三觭龍

There's a Triceratops in every museum in the world,

全世界每座博物館都有一隻三觭龍

但不曾有人找到幼年三觭龍過

but no one had ever collected a juvenile.

我們都知道為什麼，對吧？

And we know why, right?

因為每個人都想要大隻的

Because everybody wants to have a big one.

所以大家的都是大隻的

So everyone had a big one.

我們去考古時找到一大堆東西

So we went out and collected a whole bunch of stuff

一大堆小三觭龍的骸骨

and we found a whole bunch of little ones.

到處都是，遍佈整個區域

They're everywhere, they're all over the place.

So we have a whole bunch of them at our museum.

因此我們博物館裡有一大堆

(笑聲)

(Laughter)

And everybody says it's because I have a little museum.

大家都說這是因為我有一座小博物館

當你有小博物館，你就會有小恐龍

When you have a little museum, you have little dinosaurs.

(笑聲)

(Laughter)

如果各位觀察三觭龍

If you look at the Triceratops,

you can see it's changing, it's shape-shifting.

就會發現牠在改變 變形

當幼年的個體長大時

As the juveniles are growing up, their horns actually curve backwards.

牠們的角會往後彎

接著越長越大之後

And then as they get older, the horns grow forward.

角會再往前彎

還蠻酷的

And that's pretty cool.

If you look along the edge of the frill,

請各位看看頭骨的邊緣

they have these little triangular bones that actually grow big as triangles

上面三角狀的小骨頭

會長大變成三角形

然後在邊緣扁下去變平

and then they flatten against the frill

pretty much like the spikes do on the Pachycephalosaurs.

就像剛剛講過的棘一樣

長在腫頭龍背上的棘

And then, because the juveniles are in my collection,

然後因為我有蒐集幼年三觭龍

I cut them open ...

我就把牠們鋸開

(Laughter)

觀察內部

and look inside.

And the little one is really spongy.

小隻的恐龍骨頭裡面很像海綿

And the middle-size one is really spongy.

中型的也很像海綿

But what was interesting was the adult Triceratops was also spongy.

有趣的是

成年的三觭龍 骨頭內部也像海綿

And this is a skull that is two meters long.

這副頭蓋骨有兩公尺長

是非常大的頭

It's a big skull.

但還有另一種恐龍

But there's another dinosaur that is found in this formation

樣子也長這樣

that looks like a Triceratops, except it's bigger,

長得像三觭龍 但是更大隻

叫做牛角龍

and it's called Torosaurus.

當我們把牛角龍切開時

And Torosaurus, when we cut into it, has mature bone.

發現牠有成熟的骨頭

But it's got these big holes in its shield.

不過牠的頭盾上有大洞

And everybody says,

大家都說三觭龍和牛角龍

"A Triceratops and a Torosaurus can't possibly be the same animal

不可能是同一種動物

because one of them's bigger than the other one."

因為牛角龍比三觭龍大

(笑聲)

(Laughter)

"And it has holes in its frill."

頭盾上還有洞

我說：「呃，那我們有幼年的牛角龍嗎？」

And I said, "Well do we have any juvenile Torosauruses?"

他們回答：「嗯，沒有」

And they said, "Well, no, but it has holes in its frill."

「但是牠的頭盾上有洞」

So one of my graduate students, John Scannella,

因此我的一位研究生約翰‧史坎納拉

研究了我們所有的蒐藏

looked through our whole collection

and he actually discovered that the hole starting to form in Triceratops

赫然發現

這些洞的成形

源自三觭龍

當然在牛角龍頭上已經是完整的洞

and, of course it's open, in Torosaurus --

所以他發現的恐龍

so he found the transitional ones between Triceratops and Torosaurus,

處於三觭龍和牛角龍之間的過渡時期

還蠻酷的

which was pretty cool.

So now we know that Torosaurus is actually a grown-up Triceratops.

因此現在我們知道

牛角龍

其實是成年的三觭龍

當我們在替恐龍命名

Now when we name dinosaurs,

或任何其他東西命名時

when we name anything, the original name gets to stick

第一個名字都會長存

and the second name is thrown out.

第二個名字都會被遺忘

因此牛角龍也滅絕了

So Torosaurus is extinct.

如果你有看新聞，講到三觭龍時

Triceratops, if you've heard the news, a lot of the newscasters got it all wrong.

很多新聞記者根本大錯特錯

They thought Torosaurus should be kept and Triceratops thrown out,

他們認為應該保留牛角龍，剔除三觭龍

但這是不可能發生的

but that's not going to happen.

(Laughter)

(笑聲)

All right, so we can do this with a bunch of dinosaurs.

所以說 我們可以對許多恐龍做同樣的事

I mean, here's Edmontosaurus

像是這隻埃德蒙頓龍

and Anatotitan.

和大鴨龍

Anatotitan: giant duck.

大鴨龍：巨大的鴨子

It's a giant duck-bill dinosaur.

是一種大型的鴨嘴龍

牠們是另一個例子

Here's another one.

So we look at the bone histology.

我們以組織學的角度觀察骨頭

骨骼組織學顯示

The bone histology tells us that Edmontosaurus is a juvenile,

埃德蒙頓龍是幼年恐龍

或至少是未成年的

or at least a subadult,

and the other one is an adult, and we have an ontogeny.

另一隻則是成年恐龍

個體發生歷程很完備

因此大鴨龍也不存在了

And we get rid of Anatotitan.

我們一直重複這個過程

So we can just keep doing this.

And the last one is T. Rex.

到最後一種恐龍

暴龍

So there's these two dinosaurs, T. Rex and Nanotyrannus.

這裡有兩隻恐龍

暴龍和矮暴龍

(Laughter)

(笑聲)

又來了，真讓人疑惑

Again, it makes you wonder.

(Laughter)

(笑聲)

但科學家問了個好問題

But they had a good question.

他們觀察這兩隻恐龍

They were looking at them and they said, "One's got 17 teeth,

說 小隻有17顆牙 大隻的有12顆牙

and the biggest one's got 12 teeth.

這完全沒有道理

And that doesn't make any sense at all,

因為我們從未發現有哪一種恐龍

because we don't know of any dinosaurs that gain teeth as they get older.

年紀越大 牙齒會越多

So it must be true --

因此事實擺在眼前

牠們一定不一樣

they must be different."

So we cut into them.

所以我們鋸開恐龍

果真

And sure enough, Nanotyrannus has juvenile bone

矮暴龍的骨頭是幼年的

and the bigger one has more mature bone.

暴龍的骨頭較成熟

似乎還可以長更大

It looks like it could still get bigger.

然後 在我們工作的洛磯山脈博物館

And at the Museum of the Rockies where we work,

有四隻暴龍

I have four T. rexes, so I can cut a whole bunch of them.

我可以把牠們通通鋸開

但實際上不用這麼做

But I didn't have to cut any of them really,

because I just lined up their jaws

因為我只要把牠們的下巴排開

and it turned out the biggest one had 12 teeth

就會發現 最大隻的有12顆牙

and the next smallest one had 13

第二大的有13顆牙

and the next smallest had 14.

第三大的有14顆牙

當然 矮暴龍有17顆牙

And of course, Nano has 17.

所以我們就去看其他人的蒐藏

And we just went out and looked at other people's collections

發現有一隻恐龍似乎有15顆牙

and we found one that has sort of 15 teeth.

So again, real easy to say

因此很容易得到結論

that Tyrannosaurus ontogeny included Nanotyrannus,

就是暴龍的個體發生歷程

包括矮暴龍

and therefore we can take out another dinosaur.

因此我們又要跟一種恐龍說拜拜了

(Laughter)

(笑聲)

因此

So when it comes down to our end Cretaceous,

到白堊紀末期

we have seven left.

我們只剩七種恐龍

很好的數字

And that's a good number.

That's a good number to go extinct, I think.

很適合絕種 我覺得啦

Now as you can imagine,

各位可以想像

this is not very popular with fourth-graders.

國小四年級生肯定大失所望

(Laughter)

小四生很愛恐龍

Fourth-graders love their dinosaurs, they memorize them.

每一種都如數家珍

聽到這個一定會很沮喪

And they're not happy with this.

(笑聲)

(Laughter)

謝謝各位

Thank you very much.

(Applause)

(掌聲)