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