TEDxVancouver
Jack Horner: Where are the baby dinosaurs?
杰克·霍纳：恐龙也变形
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这世界上的小恐龙都去了哪里？在温哥华的TEDx大会上，古生物学家杰克·霍纳向我们讲述了他是怎样通过头骨化石切片技术发现了关于我们最爱的恐龙不为人知的秘密。
Jack Horner - Dinosaur digger
Jack Horner and his dig teams have discovered the first evidence of parental care in dinosaurs, extensive nesting grounds, evidence of dinosaur herds, and the world’s first dinosaur embryos. He's now exploring how to build a dinosaur. Full bio
Jack Horner and his dig teams have discovered the first evidence of parental care in dinosaurs, extensive nesting grounds, evidence of dinosaur herds, and the world’s first dinosaur embryos. He's now exploring how to build a dinosaur. Full bio
Double-click the English transcript below to play the video.
00:15
Shall I ask for a show of hands
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现在我想就年龄问题
00:18
or a clapping
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请大家举个手
00:20
of people in different generations?
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或是鼓个掌
00:23
I'm interested in how many
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我想知道
00:25
are three to 12 years old.
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在座有多少人的年龄介于3至12岁之间？
00:27
(Laughter)
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（笑声）
00:31
None, huh?
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没有是吧？
00:34
All right.
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我知道了
00:36
I'm going to talk about dinosaurs.
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今天我要来讲一讲恐龙
00:38
Do you remember dinosaurs when you were that age?
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你还记得你小时候有多喜欢恐龙吗？
00:41
(Applause)
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（鼓掌）
00:48
Dinosaurs are kind of funny, you know.
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恐龙是种很有趣的东西
00:51
(Laughter)
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（笑声）
00:53
We're going to kind of go in a different direction right now.
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不过今天
00:55
I hope you all realize that.
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我们要从另一个角度来看待它们
00:58
So I'll just give you my message up front:
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从恐龙身上我学到了一些东西
01:00
Try not to go extinct.
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那就是尽量别让自己灭绝了
01:02
(Laughter)
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（笑声）
01:04
That's it.
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就这么简单
01:06
(Laughter)
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（笑声）
01:10
People ask me a lot --
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人们常常问我
01:12
in fact, one of the most asked questions I get
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事实上，我被问得最多的问题就是
01:15
is, why do children like dinosaurs so much?
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为什么小孩子都那么喜欢恐龙？
01:19
What's the fascination?
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恐龙到底有哪里特别吸引人？
01:21
And I usually just say,
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这时候我一般会这么回答
01:24
"Well dinosaurs were big,
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因为恐龙很大，很与众不同
01:26
different and gone."
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而且它们灭绝了
01:29
They're all gone.
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是的，所有恐龙都灭绝了
01:31
Well that's not true,
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虽然我也不能百分百肯定
01:33
but we'll get to the goose in a minute.
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不过我们马上就要讲到重点了
01:35
So that's sort of the theme:
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所以恐龙总体来说就是
01:38
big, different and gone.
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很大，很与众不同，而且已经灭亡
01:42
The title of my talk:
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我今天演讲的主题是：
01:44
Shape-shifting Dinosaurs:
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会“变形”的恐龙
01:46
The Cause of a Premature Extinction.
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及它们过早灭亡的原因
01:48
Now I assume that we remember dinosaurs.
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我们印象中的恐龙
01:51
And there's lots of different shapes.
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有大有小，形态各异
01:54
Lots of different kinds.
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有许多不同的种类
01:57
A long time ago,
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很久以前
01:59
back in the early 1900s,
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大概是二十世纪初的时候
02:01
museums were out looking for dinosaurs.
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各大博物馆都对恐龙很感兴趣
02:04
They went out and gathered them up.
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他们四处搜集恐龙化石
02:07
And this is an interesting story.
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这个过程非常有趣
02:09
Every museum wanted a little bigger or better one
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因为每个博物馆都想要比别人更大更好的
02:12
than anybody else had.
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恐龙化石
02:14
So if the museum in Toronto went out
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所以如果多伦多的博物馆
02:17
and collected a Tyrannosaur, a big one,
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找到一个大家伙——霸王龙
02:20
then the museum in Ottawa wanted a bigger one
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那么渥太华的博物馆就一定要找到一个更大、更好的
02:23
and a better one.
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才肯罢休
02:25
And that happened for all museums.
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当时几乎所有博物馆都是这样
02:27
So everyone was out looking
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所以所有人都在四处寻找
02:29
for all these bigger and better dinosaurs.
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大型的恐龙化石
02:32
And this was in the early 1900s.
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这是在上世纪初的时候
02:36
By about 1970,
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到了1970年
02:39
some scientists were sitting around
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有些科学家就开始思考
02:41
and they thought, "What in the world?
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怎么回事
02:44
Look at these dinosaurs.
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看看我们找到的这些恐龙化石
02:46
They're all big.
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全都这么大
02:48
Where are all the little ones?"
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那小恐龙去哪了？
02:53
And they thought about it
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科学家们就开始思考这个问题
02:55
and they even wrote papers about it:
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针对这个问题做研究、写论文
02:57
"Where are the little dinosaurs?"
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“小恐龙到哪里去了？”
02:59
(Laughter)
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（笑声）
03:07
Well, go to a museum, you'll see,
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你要是去博物馆就能发现
03:11
see how many baby dinosaurs there are.
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那里根本就没有几个小恐龙
03:14
People assumed -- and this was actually a problem --
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人们假设——这也正是问题所在
03:17
people assumed
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人们假设
03:19
that if they had little dinosaurs,
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如果小恐龙、或者说幼年时期的恐龙
03:21
if they had juvenile dinosaurs,
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真的存在的话
03:23
they'd be easy to identify.
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应该很容易被辨别出来
03:25
You'd have a big dinosaur
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既然有大恐龙
03:27
and a littler dinosaur.
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就应该有小恐龙
03:30
But all they had were big dinosaurs.
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但是我们现在看到的全是些大家伙
03:33
And it comes down to a couple of things.
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这就让我们发现了几个问题
03:36
First off, scientists have egos,
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首先，科学家都是很自负的
03:40
and scientists like to name dinosaurs.
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他们都很喜欢给恐龙起名字
03:44
They like to name anything.
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他们喜欢给任何东西起名字
03:46
Everybody likes to have their own animal that they named.
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所有人都想要一个自己亲自给起名的新动物
03:49
(Laughter)
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（笑声）
03:52
And so every time they found something that looked a little different,
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所以每当他们发现一个新物种看起来有一点点不一样
03:55
they named it something different.
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他们就给它起一个新名字
03:58
And what happened, of course,
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这样一来
04:00
is we ended up with a whole bunch of different dinosaurs.
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我们就有了一大堆不同名字的恐龙
04:05
In 1975,
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1975年
04:08
a light went on in somebody's head.
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有个人脑子里突然灵光一现
04:11
Dr. Peter Dodson
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这个人就是宾夕法尼亚大学的
04:13
at the University of Pennsylvania
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彼得·道森博士
04:15
actually realized
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他意识到
04:18
that dinosaurs grew
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恐龙的发育过程
04:21
kind of like birds do,
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其实和鸟类很相似
04:23
which is different
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而与爬行类动物
04:25
than the way reptiles grow.
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却不怎么一样
04:27
And in fact,
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然后
04:29
he used the cassowary as an example.
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他拿食火鸡举了个例子
04:32
And it's kind of cool -- if you look at the cassowary,
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食火鸡这种鸟很酷——事实上
04:35
or any of the birds that have crests on their heads,
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所有头上有冠的鸟都很酷
04:38
they actually grow
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因为它们直到
04:40
to about 80 percent adult size
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发育到成年个体的百分之八十的时候
04:42
before the crest starts to grow.
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头上的冠才会开始生长
04:45
Now think about that.
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现在我们仔细想想
04:48
They're basically retaining their juvenile characteristics
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它们实际上一直保持着幼年时期的特征
04:51
very late in what we call ontogeny.
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直到发育过程的后期
04:54
So allometric cranial ontogeny
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这种颅骨发育
04:58
is relative skull growth.
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非常的迅速
05:01
So you can see
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所以
05:03
that if you actually found one
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如果你看到一只
05:05
that was 80 percent grown
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发育到百分之八十的小食火鸡
05:08
and you didn't know that it was going to grow up to a cassowary,
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你也认不出来它是一只食火鸡
05:11
you would think they were two different animals.
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你会觉得这是两种不同的动物
05:15
So this was a problem,
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这就是问题所在
05:18
and Peter Dodson pointed this out
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彼得·道森认识到了这一点
05:21
using some duck-billed dinosaurs
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于是他拿鸭嘴恐龙
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then called Hypacrosaurus.
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来举例说明
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And he showed
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他把幼年鸭嘴龙
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that if you were to take a baby and an adult
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和成年鸭嘴龙放在一起比较
05:30
and make an average of what it should look like,
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如果它的生长
05:33
if it grew in sort of a linear fashion,
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是呈线性发展的
05:36
it would have a crest
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那么幼年鸭嘴龙应该有一个
05:38
about half the size of the adult.
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差不多成年鸭嘴龙一半大小的顶冠
05:41
But the actual sub-adult
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但事实上
05:43
at 65 percent
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百分之六十五即将成年的小鸭嘴龙
05:45
had no crest at all.
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都没有顶冠
05:47
So this was interesting.
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这就很有意思了
05:49
So this is where
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看来这就是使人们的思维
05:52
people went astray again.
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走入误区的地方
05:55
I mean, if they'd have just taken that,
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我的意思是
05:57
taken Peter Dodson's work, and gone on with that,
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如果人们能接受并发展彼得·道森的发现
06:00
then we would have a lot less dinosaurs
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我们现在所拥有的恐龙种类
06:02
than we have.
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就会少得多
06:04
But scientists have egos;
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但是别忘了，科学家都是很自负的
06:06
they like to name things.
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而且特别喜欢给东西起名字
06:09
And so they went on naming dinosaurs
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所以当他们发现了与原先不一样的恐龙
06:12
because they were different.
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还是会不断地给它们取新名字
06:15
Now we have a way of actually testing
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现在我们有了一种方法
06:17
to see whether a dinosaur, or any animal,
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可以测定一只恐龙，或是任何一种动物
06:20
is a young one or an older one.
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是幼年的还是成年的
06:23
And that's by actually cutting into their bones.
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那就是切开它们的骨头进行分析
06:26
But cutting into the bones of a dinosaur
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但是你也能够想象
06:30
is hard to do, as you can imagine,
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要去切一只恐龙的骨头还是挺困难的
06:33
because in museums
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因为在博物馆里
06:36
bones are precious.
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这些骨头相当珍贵
06:40
You go into a museum and they take really good care of them.
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他们把每一块骨头
06:43
They put them in foam, little containers.
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都包着泡沫放进小罐子里
06:46
They're very well taken care of.
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保存得好好的
06:50
They don't like it if you come in
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如果你拿着锯子走进去说要切开这些骨头看看
06:52
and want to saw them open and look inside.
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恐怕不会受到太多欢迎
06:54
(Laughter)
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（笑声）
06:56
So they don't normally let you do that.
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所以一般情况下我们没这个机会
06:59
But I have a museum
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但是我也有一个博物馆
07:02
and I collect dinosaurs
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我也搜集恐龙化石
07:04
and I can saw mine open.
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而且我一点也不介意把这些骨头切开
07:06
So that's what I do.
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所以我就把它切开了
07:08
(Applause)
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（掌声）
07:13
So if you cut open a little dinosaur,
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如果你切开小恐龙的骨头
07:18
it's very spongy inside like A.
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会发现里面空隙很大呈海绵状，如图A
07:20
And if you cut into an older dinosaur,
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如果你切开老恐龙的骨头
07:22
it's very massive.
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则会发现里面的骨质排列很紧密
07:24
You can tell it's mature bone.
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所以你知道这是一根已经发育成熟了的骨头
07:26
So it's real easy to tell them apart.
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这就很容易分清楚了
07:29
So what I want to do
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现在
07:31
is show you these.
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我们来看看这个
07:33
In North America in the Northern Plains of the United States
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在北美洲，美国的北部平原
07:37
and the Southern Plains of Alberta and Saskatchewan,
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和加拿大的阿尔伯塔及萨斯喀彻温省南部平原
07:41
there's this unit of rock called the Hell Creek Formation
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有一种叫做“地狱溪地层”的岩石群
07:44
that produces the last dinosaurs that lived on Earth.
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在那里发现了最晚生活在地球上的恐龙化石
07:47
And there are 12 of them
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一共有12个
07:49
that everyone recognizes --
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我们可以看到
07:51
I mean the 12 primary dinosaurs
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这是12个已经灭绝了的
07:53
that went extinct.
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恐龙化石
07:55
And so we will evaluate them.
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我们现在就是要
07:58
And that's sort of what I've been doing.
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研究这些化石
08:00
So my students, my staff,
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我的学生，还有其他工作人员
08:03
we've been cutting them open.
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我们一起把这些骨头切开
08:06
Now as you can imagine,
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你也知道
08:08
cutting open a leg bone is one thing,
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切开一条恐龙的腿骨也就算了
08:10
but when you go to a museum
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但是你要是去博物馆
08:13
and say, "You don't mind if I cut open
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问他们：“你介不介意我把你们的
08:15
your dinosaur's skull do you?"
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恐龙头骨切开？”
08:18
they say, "Go away."
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他们一定会说：“给我滚。”
08:21
(Laughter)
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（笑声）
08:26
So here are 12 dinosaurs.
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所以，在这12个恐龙化石里
08:30
And we want to look at these three first.
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我们先看看这三个
08:33
So these are dinosaurs that are called Pachycephalosaurs.
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这三个都属于厚头龙类
08:36
And everybody knows
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大家都看得出来
08:38
that these three animals are related.
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它们之间是有亲缘关系的
08:40
And the assumption is
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人们普遍假设
08:42
is that they're related
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它们是堂兄弟
08:44
like cousins or whatever.
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或者这之类的关系
08:47
But no one ever considered
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但从来没有人想过
08:49
that they might be more closely related.
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它们的关系可能比这还要近得多
08:52
In other words,
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换句话说
08:54
people looked at them and they saw the differences.
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人们看到的是它们之间的差异
08:57
And you all know
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但是
08:59
that if you are going to determine
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如果你想判断
09:01
whether you're related to your brother or your sister,
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两个人之间是否有亲缘关系
09:03
you can't do it by looking at differences.
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你肯定不会去看他们有多不同
09:07
You can only determine relatedness
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而是寻找他们的
09:09
by looking for similarities.
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相同之处
09:11
So people were looking at these
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现在人们只注意到了
09:13
and they were talking about how different they are.
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这三种恐龙不同的地方
09:15
Pachycephalosaurus has a big, thick dome on its head,
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厚头龙的颅顶大而厚
09:18
and it's got some little bumps on the back of its head,
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脑后有一些小的突起
09:21
and it's got a bunch of gnarly things on the end of its nose.
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鼻端也有不少瘤状物
09:25
And then Stygimoloch, another dinosaur
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第二种恐龙——冥河龙
09:27
from the same age, lived at the same time,
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和厚头龙生活在同一时期
09:31
has spikes sticking out the back of its head.
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它的脑后有数根钉状尖刺
09:33
It's got a little, tiny dome,
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颅顶很小
09:35
and it's got a bunch of gnarly stuff on its nose.
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鼻子上也有瘤状物
09:39
And then there's this thing called Dracorex,
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第三种恐龙叫做龙王龙
09:41
Hogwart's Eye.
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它还有一个名字叫做“霍格沃茨之眼”
09:43
Guess where that came from? Dragon.
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因为它和小说中描写的“龙”
09:46
So here's a dinosaur
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非常相似
09:48
that has spikes sticking out of its head, no dome
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它脑后也有钉状的尖刺，鼻子上有瘤状物
09:51
and gnarly stuff on its nose.
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但没有颅顶
09:54
Nobody noticed the gnarly stuff sort of looked alike.
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没有人注意到这三种恐龙鼻子上的瘤状物非常相似
09:57
But they did look at these three
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他们一下子就下了结论：
09:59
and they said, "These are three different dinosaurs,
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“这是三种不同的恐龙
10:01
and Dracorex is probably the most primitive of them.
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龙王龙应该是最原始的一种
10:04
And the other one is more primitive than the other.
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这种又应该比那种原始”
10:07
It's unclear to me
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我就不明白了
10:10
how they actually sorted these three of them out.
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他们是怎么看出来的呢？
10:13
But if you line them up,
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如果光从头骨来看的话
10:15
if you just take those three skulls and just line them up,
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把它们以大小顺序排成一列
10:18
they line up like this.
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就成了这样
10:20
Dracorex is the littlest one,
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龙王龙是最小的
10:22
Stygimoloch is the middle size one,
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其次是冥河龙
10:24
Pachycephalosaurus is the largest one.
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厚头龙最大
10:27
And one would think,
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这是不是应该
10:29
that should give me a clue.
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给我们一点启示了？
10:31
(Laughter)
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（笑声）
10:33
But it didn't give them a clue.
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但可惜他们都没发现
10:36
Because, well we know why.
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我们也知道是为什么了
10:39
Scientists like to name things.
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因为科学家们最爱给东西起名字
10:42
So if we cut open
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那么，如果我们把这些头骨切开的话
10:44
Dracorex --
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龙王龙——
10:46
I cut open our Dracorex --
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我把我的龙王龙给切了——
10:48
and look, it was spongy inside,
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看！里面是海绵状的
10:50
really spongy inside.
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非常疏松
10:52
I mean, it is a juvenile
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这说明这是一只幼年的恐龙
10:54
and it's growing really fast.
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而且它长得很快
10:56
So it is going to get bigger.
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会越长越大
10:58
If you cut open Stygimoloch,
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如果你切开冥河龙的骨头
11:00
it is doing the same thing.
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会发现也是一样
11:02
The dome, that little dome,
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它的颅顶虽小
11:04
is growing really fast.
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却发育得
11:06
It's inflating very fast.
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非常迅速
11:08
What's interesting is the spike on the back of the Dracorex
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最有意思的还是龙王龙脑袋后面的尖刺
11:11
was growing very fast as well.
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它也长得非常快
11:13
The spikes on the back of the Stygimoloch
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而冥河龙脑后的刺
11:15
are actually resorbing,
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却是在退化的
11:17
which means they're getting smaller
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也就是说它在颅顶变大的同时
11:19
as that dome is getting bigger.
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尖刺会越来越小
11:21
And if we look at Pachycephalosaurus,
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我们再看厚头龙
11:24
Pachycephalosaurus has a solid dome
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它的颅顶非常坚实
11:27
and its little bumps on the back of its head
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而它脑后的突起
11:30
were also resorbing.
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也是在退化的
11:32
So just with these three dinosaurs,
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所以，就光从这三种恐龙来看
11:34
you can easily -- as a scientist --
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作为一个科学家
11:36
we can easily hypothesize
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我们很容易就能做出这样的假设：
11:38
that it is just a growth series
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这是同一种动物的
11:40
of the same animal.
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生长序列
11:43
Which of course means
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这样一来
11:46
that Stygimoloch and Dracorex
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冥河龙和龙王龙
11:50
are extinct.
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就不得不“灭绝”了
11:52
(Laughter)
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（笑声）
11:57
Okay.
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好了
12:01
Which of course means
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现在我们还剩下
12:04
we have 10 primary dinosaurs to deal with.
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10种恐龙要研究
12:08
So a colleague of mine at Berkley,
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我和一个在伯克利的同事
12:10
he and I were looking at Triceratops.
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一起研究了三角龙
12:13
And before the year 2000 --
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我们发现在2000年前——
12:15
now remember,
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我想想
12:17
Triceratops was first found in the 1800s --
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三角龙是在19世纪发现的
12:19
before 2000, no one had ever seen
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但是在2000年之前
12:22
a juvenile Triceratops.
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从来没有人见过幼年的三角龙
12:25
There's a Triceratops in every museum in the world,
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世界上几乎所有博物馆都有三角龙的化石
12:28
but no one had ever collected a juvenile.
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就是没有一个小三角龙
12:32
And we know why, right?
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我们都知道为什么，是吧？
12:34
Because everybody wants to have a big one.
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因为大家都想要大的
12:37
So everyone had a big one.
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所以每家博物馆都有一个大的
12:39
So we went out and collected a whole bunch of stuff
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我和我的同事在外面搜索了一圈
12:41
and we found a whole bunch of little ones.
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结果发现了许多小三角龙
12:43
They're everywhere. They're all over the place.
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它们到处都是
12:47
So we have a whole bunch of them at our museum.
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所以现在我们的博物馆里收藏了一大堆小三角龙
12:49
(Laughter)
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（笑声）
12:54
And everybody says it's because I have a little museum.
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大家都说这是因为我有一个小博物馆
12:56
When you have a little museum, you have little dinosaurs.
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小博物馆里自然是小恐龙
12:59
(Laughter)
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（笑声）
13:02
If you look at the Triceratops,
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仔细观察一下三角龙
13:04
you can see it's changing, it's shape-shifting.
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你能看到它在变化、在“变形”
13:06
As the juveniles are growing up,
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在小三角龙长大的过程中
13:08
their horns actually curve backwards.
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它们的角是向后弯曲的
13:10
And then as they grow older,
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但当它们长大之后
13:12
the horns grow forward.
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角却变成了向前弯曲
13:14
And that's pretty cool.
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这是不是很酷？
13:16
If you look along the edge of the frill,
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我们再看看它头盾的边褶
13:18
they have these little triangular bones
296
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有很多小小的三角形骨突
13:21
that actually grow big as triangles
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这些骨突会逐渐长大
13:23
and then they flatten against the frill
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使头盾的边缘逐渐平滑
13:26
pretty much like the spikes do
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这和厚头龙脑后的尖刺
13:28
on the Pachycephalosaurs.
300
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是类似的
13:31
And then, because the juveniles are in my collection,
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因为我的博物馆里有幼年的三角龙化石
13:35
I cut them open
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我就把它切开
13:37
and look inside.
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来看看
13:39
And the little one is really spongy.
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结果发现小的三角龙骨头内部果然是海绵状的
13:42
And the middle size one is really spongy.
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中等大小的骨头内部也是海绵状的
13:45
But what was interesting
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但最有意思的是
13:47
was the adult Triceratops was also spongy.
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成年三角龙的骨头内部居然也是海绵状的
13:49
And this is a skull that is two meters long.
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它的头骨都达到两米长了
13:52
It's a big skull.
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非常的大
13:55
But there's another dinosaur
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不过在这个地层内出土的化石里面
13:57
that is found in this formation
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还有另一种恐龙
14:00
that looks like a Triceratops, except it's bigger,
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与三角龙非常相似，只不过还要更大些
14:03
and it's called Torosaurus.
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叫做牛角龙
14:06
And Torosaurus, when we cut into it,
314
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当我们切开牛角龙骨头化石的时候
14:09
has mature bone.
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发现骨质发育非常成熟
14:11
But it's got these big holes in its shield.
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但是牛角龙的头盾上有这种很大的孔洞
14:13
And everybody says, "A Triceratops and a Torosaurus
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所有人都说：
14:16
can't possibly be the same animal
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三角龙和牛角龙不可能是同一种动物
14:18
because one of them's bigger than the other one."
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因为这种比那种大太多了
14:20
(Laughter)
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（笑声）
14:25
"And it has holes in its frill."
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而且头上还有洞
14:27
And I said, "Well do we have any juvenile Torosauruses?"
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我就问他们：“你们见过小牛角龙吗？”
14:30
And they said, "Well no,
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他们回答：“这个还没有，
14:33
but it has holes in its frill."
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但是它头上有洞啊”
14:36
So one of my graduate students, John Scannella,
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所以，我的学生约翰·斯堪那拉
14:39
looked through our whole collection
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对我们所有馆藏的化石进行了研究
14:41
and he actually discovered
327
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他终于发现
14:43
that the hole starting to form
328
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在三角龙身上
14:45
in Triceratops
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这些洞就开始形成了
14:47
and, of course it's open, in Torosaurus --
330
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当然，到了牛角龙时期才完全打开
14:50
so he found the transitional ones
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约翰发现了一个处于
14:53
between Triceratops and Torosaurus,
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三角龙向牛角龙转型时期的化石
14:55
which was pretty cool.
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非常的神奇
14:57
So now we know
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所以，我们现在知道
14:59
that Torosaurus
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牛角龙其实是
15:01
is actually a grownup Triceratops.
336
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长大了的三角龙
15:04
Now when we name dinosaurs,
337
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当我们给恐龙起名字
15:06
when we name anything,
338
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或者说给任何东西起名字的时候
15:08
the original name gets to stick
339
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都倾向于保留原有的那一个
15:10
and the second name is thrown out.
340
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而放弃新取的那一个
15:14
So Torosaurus is extinct.
341
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所以牛角龙就这么“灭绝”了
15:17
Triceratops, if you've heard the news,
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至于三角龙，如果你看新闻的话
15:20
a lot of the newscasters got it all wrong.
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就会发现好多新闻主播都搞错了
15:22
They thought Torosaurus should be kept and Triceratops thrown out,
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他们认为应该保留“牛角龙”这个名字，而放弃“三角龙”
15:25
but that's not going to happen.
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但这是不会发生的
15:27
(Laughter)
346
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（笑声）
15:33
All right, so we can do this with a bunch of dinosaurs.
347
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好，所以我们可以把这种方法用在许多种恐龙身上
15:36
I mean, here's Edmontosaurus
348
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比如说，埃德蒙顿龙
15:38
and Anatotitan.
349
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和大鸭龙
15:40
Anatotitan: giant duck.
350
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顾名思义
15:43
It's a giant duck-bill dinosaur.
351
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大鸭龙就是很大的鸭嘴恐龙
15:45
Here's another one.
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它们也是一对这样的组合
15:47
So we look at the bone histology.
353
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同样，我们还是从它们的骨组织入手
15:49
The bone histology tells us
354
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骨质分析告诉我们
15:52
that Edmontosaurus is a juvenile,
355
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埃德蒙顿龙是幼年恐龙
15:54
or at least a sub-adult,
356
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或者顶多是青少年恐龙
15:56
and the other one is an adult
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而大鸭龙则是成年恐龙
15:59
and we have an ontogeny.
358
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根据个体发生学
16:02
And we get rid of Anatotitan.
359
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“大鸭龙”也灭绝了
16:05
So we can just keep doing this.
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所以我们就可以一直不断地这么做
16:08
And the last one
361
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最后我要讲的
16:10
is T. Rex.
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是雷克斯暴龙（即霸王龙）
16:12
So there's these two dinosaurs,
363
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现在我们有两种恐龙
16:14
T. Rex and Nanotyrannus.
364
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暴龙和矮暴龙
16:17
(Laughter)
365
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（笑声）
16:19
Again, makes you wonder.
366
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现在我们自然而然产生怀疑了
16:22
(Laughter)
367
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（笑声）
16:25
But they had a good question.
368
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但是他们的理由也很充分
16:27
They were looking at them
369
972000
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他们仔细检查后说：
16:29
and they said, "One's got 17 teeth, and the biggest one's got 12 teeth.
370
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3000
小的那个有17颗牙，大的才12颗牙
16:32
And that doesn't make any sense at all,
371
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这怎么可能是同一种呢？
16:34
because we don't know of any dinosaurs
372
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2000
我们还不知道哪种恐龙
16:36
that gain teeth as they get older.
373
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是越长大牙越少的
16:38
So it must be true --
374
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所以它们肯定
16:40
they must be different."
375
985000
3000
是两种不同的恐龙
16:43
So we cut into them.
376
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所以我把它们都切开了
16:45
And sure enough,
377
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果然和我想的一样
16:47
Nanotyrannus has juvenile bone
378
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3000
矮暴龙是幼年的恐龙
16:50
and the bigger one has more mature bone.
379
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3000
暴龙的骨头则成熟得多
16:53
It looks like it could still get bigger.
380
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3000
而且看起来还会继续长大
16:56
And at the Museum of the Rockies where we work,
381
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在我工作的洛基博物馆里
16:58
I have four T. Rexes,
382
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有四具暴龙化石
17:00
so I can cut a whole bunch of them.
383
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所以我有机会把它们都切开来
17:02
But I didn't have to cut any of them really,
384
1007000
3000
但是我发现我根本用不着这么做
17:05
because I just lined up their jaws
385
1010000
3000
因为我只是简单地将它们的下颌骨按顺序排列起来
17:08
and it turned out the biggest one had 12 teeth
386
1013000
3000
就发现最大的一个有12颗牙
17:11
and the next smallest one had 13
387
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2000
第二大的有13颗牙
17:13
and the next smallest had 14.
388
1018000
2000
第三大的有14颗牙
17:15
And of course, Nano has 17.
389
1020000
2000
当然了，矮暴龙有17颗牙
17:17
And we just went out and looked at other people's collections
390
1022000
3000
然后我们就跑去其他博物馆里看别人收藏的暴龙
17:20
and we found one that has sort of 15 teeth.
391
1025000
4000
发现了一只有15颗牙的
17:24
So again, real easy to say
392
1029000
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这下事情又简单了
17:27
that Tyrannosaurus ontogeny
393
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暴龙（即霸王龙）的个体发生序列中
17:29
included Nanotyrannus,
394
1034000
3000
是包括矮暴龙的
17:32
and therefore we can take out another dinosaur.
395
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5000
这下我们又能从恐龙名单里划掉一个名字了
17:37
(Laughter)
396
1042000
2000
（笑声）
17:39
So when it comes down
397
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4000
所以
17:43
to our end cretaceous,
398
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2000
到了白垩纪末期
17:45
we have seven left.
399
1050000
3000
我们还剩七种恐龙
17:48
And that's a good number.
400
1053000
3000
这个数字
17:51
That's a good number to go extinct, I think.
401
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3000
听起来就合理多了吧
17:54
Now as you can imagine,
402
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你也知道
17:56
this is not very popular with fourth-graders.
403
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我这次演讲的主题对刚上四年级的小男生可能没什么吸引力
17:59
Fourth-graders love their dinosaurs,
404
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2000
他们喜欢他们的恐龙
18:01
they memorize them.
405
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他们印象中的恐龙
18:06
And they're not happy with this.
406
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可不是这个样子的
18:09
(Laughter)
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（笑声）
18:11
Thank you very much.
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谢谢大家！
18:13
(Applause)
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（鼓掌）
ABOUT THE SPEAKER
Jack Horner - Dinosaur diggerJack Horner and his dig teams have discovered the first evidence of parental care in dinosaurs, extensive nesting grounds, evidence of dinosaur herds, and the world’s first dinosaur embryos. He's now exploring how to build a dinosaur.
Why you should listen
Paleontologist Jack Horner discovered the first dinosaur eggs in the Western Hemisphere, the first evidence of dinosaur colonial nesting, the first evidence of parental care among dinosaurs, and the first dinosaur embryos.
Horner's research covers a wide range of topics about dinosaurs, including their behavior, physiology, ecology and evolution. Due to struggles with the learning disability, dyslexia, Horner does not hold a formal college degree but was awarded an Honorary Doctorate of Science from the University of Montana in 1986. Also in 1986 he was awarded a MacArthur Fellowship.
He's the Curator of Paleontology at the Museum of the Rockies in Bozeman, Montana, and is widely acknowledged to be the inspiration for the main character in the book and film Jurassic Park.
Jack Horner | Speaker | TED.com