Where are the baby dinosaurs? | Jack Horner | TEDxVancouver
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0:17 - 0:21Shall I ask for a show
of hands or a clapping -
0:22 - 0:25of people in different generations?
-
0:25 - 0:28I'm interested in how many
are three to 12 years old. -
0:28 - 0:34(Laughter)
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0:34 - 0:35None, huh?
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0:35 - 0:36(Laughter)
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0:36 - 0:37All right.
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0:38 - 0:40I'm going to talk about dinosaurs.
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0:40 - 0:42Do you remember dinosaurs
when you were that age? -
0:42 - 0:48(Applause)
-
0:50 - 0:52Dinosaurs are kind of funny, you know.
-
0:52 - 0:55(Laughter)
-
0:55 - 0:58We're going to kind of go
in a different direction right now. -
0:58 - 0:59I hope you all realize that.
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1:00 - 1:02So I'll just give you my message up front:
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1:03 - 1:04Try not to go extinct.
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1:04 - 1:06(Laughter)
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1:06 - 1:07That's it.
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1:07 - 1:11(Laughter)
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1:14 - 1:15People ask me a lot...
-
1:16 - 1:19In fact, one of the most asked
questions I get -
1:19 - 1:22is, why do children
like dinosaurs so much? -
1:22 - 1:24What's the fascination?
-
1:24 - 1:27And I usually just say,
-
1:27 - 1:29"Well, dinosaurs were big,
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1:30 - 1:32different and gone."
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1:33 - 1:34They're all gone.
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1:34 - 1:36Well that's not true,
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1:36 - 1:39but we'll get to the goose in a minute.
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1:42 - 1:45So that's sort of the theme:
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1:45 - 1:47big, different and gone.
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1:49 - 1:50The title of my talk:
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1:50 - 1:52Shape-shifting Dinosaurs:
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1:52 - 1:55The cause of a premature extinction.
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1:56 - 1:58Now I assume that we remember dinosaurs.
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1:58 - 2:01And there's lots of different shapes.
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2:01 - 2:04Lots of different kinds.
-
2:06 - 2:08A long time ago,
-
2:09 - 2:15back in the early 1900s,
museums were out looking for dinosaurs. -
2:15 - 2:17They went out and gathered them up.
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2:17 - 2:19And this is an interesting story.
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2:20 - 2:24Every museum wanted a little bigger
or better one than anybody else had. -
2:24 - 2:31So if the museum in Toronto went out
and collected a Tyrannosaur, a big one, -
2:31 - 2:35then the museum in Ottawa
wanted a bigger one, and a better one. -
2:36 - 2:37And that happened for all museums.
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2:37 - 2:42So everyone was out looking
for all these bigger and better dinosaurs. -
2:43 - 2:45And this was in the early 1900s.
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2:46 - 2:49By about 1970,
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2:50 - 2:54some scientists were sitting around
and they thought, "What in the world... -
2:55 - 2:57Look at these dinosaurs, they're all big.
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2:59 - 3:00Where are all the little ones?"
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3:01 - 3:02(Laughter)
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3:03 - 3:07And they thought about it
and they even wrote papers about it: -
3:07 - 3:09"Where are the little dinosaurs?"
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3:09 - 3:14(Laughter)
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3:19 - 3:21Well, go to a museum, you'll see,
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3:21 - 3:24see how many baby dinosaurs there are.
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3:27 - 3:29People assumed...
And this was actually a problem... -
3:29 - 3:35People assumed
that if they had little dinosaurs, -
3:35 - 3:39if they had juvenile dinosaurs,
they'd be easy to identify. -
3:39 - 3:43You'd have a big dinosaur
and a littler dinosaur. -
3:43 - 3:44(Laughter)
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3:44 - 3:47But all they had were big dinosaurs.
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3:48 - 3:50And it comes down to a couple of things.
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3:50 - 3:54First off, scientists have egos,
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3:54 - 3:58and scientists like to name dinosaurs.
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3:58 - 4:00They like to name anything.
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4:00 - 4:04Everybody likes to have
their own animal that they named. -
4:04 - 4:07(Laughter)
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4:07 - 4:10And so every time they found something
that looked a little different, -
4:10 - 4:12they named it something different.
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4:12 - 4:14And what happened, of course,
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4:14 - 4:17is we ended up with a whole
bunch of different dinosaurs. -
4:19 - 4:22In 1975,
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4:22 - 4:24someone finaly got -
-
4:24 - 4:27a light went on in somebody's head.
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4:27 - 4:31Dr. Peter Dodson
at the University of Pennsylvania -
4:31 - 4:39actually realized that dinosaurs
grew kind of like birds do, -
4:40 - 4:43which is different
than the way reptiles grow. -
4:43 - 4:45And in fact,
-
4:45 - 4:49he used the cassowary as an example.
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4:49 - 4:52And it's kind of cool...
If you look at the cassowary, -
4:52 - 4:55or any of the birds
that have crests on their heads, -
4:55 - 5:03they grow to about 80 percent adult size
before the crest starts to grow. -
5:05 - 5:06Now think about that.
-
5:06 - 5:09They're basically retaining
their juvenile characteristics -
5:09 - 5:13very late in what we call ontogeny.
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5:13 - 5:20So allometric cranial ontogeny
is relative skull growth. -
5:21 - 5:28So you can see that if you actually found
one that was 80 percent grown -
5:28 - 5:31and you didn't know that it was going
to grow up to a cassowary, -
5:32 - 5:34you would think
they were two different animals. -
5:35 - 5:38So this was a problem,
-
5:38 - 5:44and Peter Dodson pointed this out
using some duck-billed dinosaurs -
5:44 - 5:45then called Hypacrosaurus.
-
5:45 - 5:50And he showed that if you were to take
a baby and an adult -
5:50 - 5:53and make an average
of what it should look like, -
5:54 - 5:56if it grew in sort of a linear fashion,
-
5:57 - 6:01it would have a crest
about half the size of the adult. -
6:01 - 6:07But the actual subadult at 65 percent
had no crest at all. -
6:07 - 6:09So this was interesting.
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6:12 - 6:17So this is where people went astray again.
-
6:17 - 6:19I mean, if they'd have just taken that,
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6:19 - 6:22taken Peter Dodson's work,
and gone on with that, -
6:22 - 6:26then we would have a lot less
dinosaurs than we have. -
6:26 - 6:30But scientists have egos;
they like to name things. -
6:31 - 6:36And so they went on naming dinosaurs
because they were different. -
6:37 - 6:39Now we have a way of actually testing
-
6:39 - 6:45to see whether a dinosaur, or any animal,
is a young one or an older one. -
6:45 - 6:48And that's by actually
cutting into their bones. -
6:49 - 6:56But cutting into the bones of a dinosaur
is hard to do, as you can imagine, -
6:56 - 7:01because in museums, bones are precious.
-
7:03 - 7:06You go into a museum,
and they take really good care of them. -
7:06 - 7:09They put them in foam, little containers.
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7:09 - 7:11They're very well taken care of.
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7:15 - 7:19They don't like it if you come in
and want to saw them open and look inside. -
7:19 - 7:20(Laughter)
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7:20 - 7:24So they don't normally let you do that.
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7:24 - 7:25(Laughter)
-
7:25 - 7:28But I have a museum
and I collect dinosaurs -
7:29 - 7:31and I can saw mine open.
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7:31 - 7:33So that's what I do.
-
7:33 - 7:38(Applause)
-
7:40 - 7:43So if you cut open a little dinosaur,
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7:43 - 7:45it's very spongy inside, like A.
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7:45 - 7:48And if you cut into an older dinosaur,
it's very massive. -
7:50 - 7:52You can tell it's mature bone.
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7:52 - 7:54So it's real easy to tell them apart.
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7:54 - 7:58So what I want to do is show you these.
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8:00 - 8:06In North America in the northern plains
of the United States -
8:10 - 8:13and the southern plains
of Alberta and Saskatchewan, -
8:15 - 8:19there's this unit of rock
called the Hell Creek Formation -
8:19 - 8:22that produces the last
dinosaurs that lived on Earth. -
8:22 - 8:25And there are 12 of them
that everyone recognizes... -
8:25 - 8:29I mean the 12 primary dinosaurs
that went extinct. -
8:30 - 8:32And so we will evaluate them.
-
8:35 - 8:37And that's sort of what I've been doing.
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8:37 - 8:42So my students, my staff,
we've been cutting them open. -
8:42 - 8:46Now as you can imagine,
cutting open a leg bone is one thing, -
8:46 - 8:49but when you go to a museum
-
8:49 - 8:54and say, "You don't mind if I cut open
your dinosaur's skull, do you?" -
8:54 - 8:57they say, "Go away."
-
8:57 - 9:02(Laughter)
-
9:04 - 9:06So here are 12 dinosaurs.
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9:06 - 9:09And we want to look at these three first.
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9:09 - 9:13So these are dinosaurs
that are called Pachycephalosaurus. -
9:13 - 9:16And everybody knows
that these three animals are related. -
9:16 - 9:23And the assumption is that they're related
like cousins or whatever. -
9:24 - 9:30But no one ever considered
that they might be more closely related. -
9:30 - 9:31In other words,
-
9:31 - 9:34people looked at them
and they saw the differences. -
9:35 - 9:38And you all know
that if you are going to determine -
9:38 - 9:41whether you're related
to your brother or your sister, -
9:41 - 9:44you can't do it by looking at differences.
-
9:45 - 9:48You can only determine relatedness
by looking for similarities. -
9:48 - 9:50So people were looking at these
-
9:50 - 9:53and they were talking
about how different they are. -
9:53 - 9:56Pachycephalosaurus has a big,
thick dome on its head, -
9:56 - 9:59and it's got some little bumps
on the back of its head, -
9:59 - 10:02and it's got a bunch of gnarly things
on the end of its nose. -
10:03 - 10:09And then Stygimoloch, another dinosaur
from the same age, lived at the same time, -
10:09 - 10:11has spikes sticking out
the back of its head. -
10:11 - 10:13It's got a little, tiny dome,
-
10:13 - 10:16and it's got a bunch
of gnarly stuff on its nose. -
10:16 - 10:20And then there's this thing
called Dracorex hogwartsia. -
10:21 - 10:23Guess where that came from?
-
10:23 - 10:24Dragon.
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10:24 - 10:28So here's a dinosaur that has spikes
sticking out of its head, -
10:28 - 10:31no dome and gnarly stuff on its nose.
-
10:32 - 10:35Nobody noticed the gnarly stuff
sort of looked alike. -
10:36 - 10:38But they did look at these three
-
10:38 - 10:40and they said, "These
are three different dinosaurs, -
10:40 - 10:43and Dracorex is probably
the most primitive of them. -
10:43 - 10:47And the other one
is more primitive than the other." -
10:47 - 10:51It's unclear to me how they actually
sorted these three of them out. -
10:51 - 10:53But if you line them up,
-
10:53 - 10:56if you just take those three skulls
and just line them up, -
10:56 - 10:58they line up like this.
-
10:58 - 11:00Dracorex is the littlest one,
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11:00 - 11:03Stygimoloch is the middle-size one,
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11:03 - 11:05Pachycephalosaurus is the largest one.
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11:05 - 11:09And one would think,
that should give me a clue. -
11:09 - 11:11(Laughter)
-
11:11 - 11:13But it didn't give them a clue.
-
11:13 - 11:14(Laughter)
-
11:14 - 11:17Because, well we know why.
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11:17 - 11:19Scientists like to name things.
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11:21 - 11:24So if we cut open Dracorex...
-
11:28 - 11:30I cut open our Dracorex...
-
11:30 - 11:34And look, it was spongy inside,
really spongy inside. -
11:34 - 11:38I mean, it is a juvenile
and it's growing really fast. -
11:39 - 11:41So it is going to get bigger.
-
11:45 - 11:48If you cut open Stygimoloch,
it is doing the same thing. -
11:48 - 11:52The dome, that little dome,
is growing really fast. -
11:52 - 11:54It's inflating very fast.
-
11:56 - 11:59What's interesting is the spike
on the back of the Dracorex -
11:59 - 12:01was growing very fast as well.
-
12:01 - 12:05The spikes on the back of the Stygimoloch
are actually resorbing, -
12:05 - 12:09which means they're getting smaller
as that dome is getting bigger. -
12:09 - 12:11And if we look at Pachycephalosaurus,
-
12:11 - 12:14Pachycephalosaurus has a solid dome
-
12:14 - 12:20and its little bumps on the back
of its head were also resorbing. -
12:22 - 12:25So just with these three dinosaurs,
-
12:25 - 12:28as a scientist, we can easily hypothesize
-
12:28 - 12:32that it is just a growth series
of the same animal. -
12:33 - 12:36Which of course means
-
12:37 - 12:42that Stygimoloch and Dracorex are extinct.
-
12:42 - 12:47(Laughter)
-
12:47 - 12:48OK.
-
12:48 - 12:50(Laughter)
-
12:53 - 12:58Which of course means
-
13:01 - 13:04we have 10 primary dinosaurs to deal with.
-
13:08 - 13:13So a colleague of mine at Berkeley...
He and I were looking at Triceratops. -
13:13 - 13:15And before the year 2000...
-
13:15 - 13:19Now remember, Triceratops was first
found in the 1800s... -
13:19 - 13:24Before 2000, no one had ever seen
a juvenile Triceratops. -
13:25 - 13:28There's a Triceratops
in every museum in the world, -
13:28 - 13:31but no one had ever collected a juvenile.
-
13:33 - 13:34And we know why, right?
-
13:34 - 13:36Because everybody wants to have a big one.
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13:37 - 13:39So everyone had a big one.
-
13:39 - 13:42So we went out and collected
a whole bunch of stuff -
13:42 - 13:44and we found a whole bunch of little ones.
-
13:44 - 13:46They're everywhere,
they're all over the place. -
13:47 - 13:49So we have a whole bunch
of them at our museum. -
13:49 - 13:54(Laughter)
-
13:54 - 13:56And everybody says
it's because I have a little museum. -
13:56 - 13:59When you have a little museum,
you have little dinosaurs. -
13:59 - 14:02(Laughter)
-
14:02 - 14:04If you look at the Triceratops,
-
14:04 - 14:06you can see it's changing,
it's shape-shifting. -
14:09 - 14:13As the juveniles are growing up,
their horns actually curve backwards. -
14:13 - 14:17And then as they get older,
the horns grow forward. -
14:17 - 14:18And that's pretty cool.
-
14:18 - 14:21If you look along the edge of the frill,
-
14:21 - 14:26they have these little triangular bones
that actually grow big as triangles -
14:26 - 14:29and then they flatten against the frill
-
14:29 - 14:33pretty much like the spikes do
on the Pachycephalosaurs. -
14:36 - 14:40And then, because the juveniles
are in my collection, -
14:40 - 14:42I cut them open...
-
14:42 - 14:43(Laughter)
-
14:43 - 14:44and look inside.
-
14:44 - 14:47And the little one is really spongy.
-
14:47 - 14:50And the middle-size one is really spongy.
-
14:50 - 14:54But what was interesting
was the adult Triceratops was also spongy. -
14:54 - 14:57And this is a skull
that is two meters long. -
14:58 - 15:00It's a big skull.
-
15:01 - 15:05But there's another dinosaur
that is found in this formation -
15:05 - 15:09that looks like a Triceratops,
except it's bigger, -
15:09 - 15:11and it's called Torosaurus.
-
15:12 - 15:16And Torosaurus, when we cut
into it, has mature bone. -
15:16 - 15:18But it's got these big
holes in its shield. -
15:18 - 15:19And everybody says,
-
15:19 - 15:23"A Triceratops and a Torosaurus
can't possibly be the same animal -
15:23 - 15:26because one of them's bigger
than the other one." -
15:26 - 15:30(Laughter)
-
15:30 - 15:33"And it has holes in its frill."
-
15:33 - 15:36And I said, "Well do we have
any juvenile Torosauruses?" -
15:36 - 15:40And they said, "Well, no,
but it has holes in its frill." -
15:41 - 15:45So one of my graduate
students, John Scannella, -
15:46 - 15:47looked through our whole collection
-
15:47 - 15:55and he actually discovered that the hole
starting to form in Triceratops -
15:55 - 15:58and, of course it's open, in Torosaurus...
-
15:58 - 16:03So he found the transitional ones
between Triceratops and Torosaurus, -
16:03 - 16:05which was pretty cool.
-
16:05 - 16:07So now we know
-
16:09 - 16:13that Torosaurus is actually
a grown-up Triceratops. -
16:14 - 16:16Now when we name dinosaurs,
-
16:16 - 16:19when we name anything,
the original name gets to stick -
16:19 - 16:24and the second name is thrown out.
-
16:26 - 16:28So Torosaurus is extinct.
-
16:29 - 16:33Triceratops, if you've heard the news,
a lot of the newscasters got it all wrong. -
16:33 - 16:37They thought Torosaurus should be kept
and Triceratops thrown out, -
16:37 - 16:39but that's not going to happen.
-
16:39 - 16:44(Laughter)
-
16:44 - 16:47All right, so we can do this
with a bunch of dinosaurs. -
16:47 - 16:50I mean, here's Edmontosaurus
-
16:50 - 16:51and Anatotitan.
-
16:52 - 16:55Anatotitan: giant duck.
-
16:55 - 16:57It's a giant duck-bill dinosaur.
-
16:57 - 16:59Here's another one.
-
16:59 - 17:02So we look at the bone histology.
-
17:02 - 17:07The bone histology tells us
that Edmontosaurus is a juvenile, -
17:07 - 17:08or at least a subadult,
-
17:08 - 17:14and the other one is an adult,
and we have an ontogeny. -
17:15 - 17:17And we get rid of Anatotitan.
-
17:18 - 17:20So we can just keep doing this.
-
17:20 - 17:23And the last one is T. Rex.
-
17:26 - 17:30So there's these two dinosaurs,
T. Rex and Nanotyrannus. -
17:30 - 17:33(Laughter)
-
17:33 - 17:36Again, it makes you wonder.
-
17:36 - 17:39(Laughter)
-
17:39 - 17:42But they had a good question.
-
17:43 - 17:45They were looking at them and they said,
"One's got 17 teeth, -
17:45 - 17:47and the biggest one's got 12 teeth.
-
17:47 - 17:49And that doesn't make any sense at all,
-
17:49 - 17:53because we don't know of any dinosaurs
that gain teeth as they get older. -
17:53 - 17:55So it must be true...
-
17:55 - 17:56They must be different."
-
17:58 - 17:59So we cut into them.
-
18:00 - 18:04And sure enough,
Nanotyrannus has juvenile bone -
18:04 - 18:08and the bigger one has more mature bone.
-
18:09 - 18:11It looks like it could still get bigger.
-
18:11 - 18:13And at the Museum
of the Rockies where we work, -
18:13 - 18:17I have four T. rexes,
so I can cut a whole bunch of them. -
18:17 - 18:19But I didn't have to cut
any of them really, -
18:19 - 18:22because I just lined up their jaws
-
18:22 - 18:25and it turned out
the biggest one had 12 teeth -
18:25 - 18:28and the next smallest one had 13
-
18:28 - 18:30and the next smallest had 14.
-
18:30 - 18:32And of course, Nano has 17.
-
18:32 - 18:35And we just went out and looked
at other people's collections -
18:35 - 18:39and we found one that has
sort of 15 teeth. -
18:40 - 18:42So again, real easy to say
-
18:42 - 18:47that Tyrannosaurus ontogeny
included Nanotyrannus, -
18:48 - 18:52and therefore we can take out
another dinosaur. -
18:52 - 18:54(Laughter)
-
18:57 - 19:00So when it comes down
to our end Cretaceous, -
19:00 - 19:02we have seven left.
-
19:04 - 19:05And that's a good number.
-
19:06 - 19:09That's a good number
to go extinct, I think. -
19:10 - 19:11Now as you can imagine,
-
19:11 - 19:14this is not very popular
with fourth-graders. -
19:14 - 19:15(Laughter)
-
19:15 - 19:19Fourth-graders love their dinosaurs,
they memorize them. -
19:24 - 19:25And they're not happy with this.
-
19:25 - 19:28(Laughter)
-
19:28 - 19:29Thank you very much.
-
19:29 - 19:33(Applause)
- Title:
- Where are the baby dinosaurs? | Jack Horner | TEDxVancouver
- Description:
-
Where are the baby dinosaurs? In this spellbinding talk paleontologist Jack Horner describes how slicing open fossil skulls revealed a shocking secret about some of our most beloved dinosaurs.
- Video Language:
- English
- Team:
- closed TED
- Project:
- TEDxTalks
- Duration:
- 19:44
TED Translators admin edited English subtitles for Where are the baby dinosaurs? | Jack Horner | TEDxVancouver | ||
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Ivana Korom edited English subtitles for Where are the baby dinosaurs? | Jack Horner | TEDxVancouver |