English - Where are the baby dinosaurs?

English subtitles

← Where are the baby dinosaurs?

3 Followers
325 Lines

Where are the baby dinosaurs? In a spellbinding talk from TEDxVancouver paleontologist Jack Horner describes how slicing open fossil skulls revealed a shocking secret about some of our most beloved dinosaurs.

30 Languages

Edit Subtitles

Download

Showing Revision 5 created 11/29/2016 by Krystian Aparta.

Title:
Where are the baby dinosaurs?
Description:

Where are the baby dinosaurs? In a spellbinding talk from TEDxVancouver paleontologist Jack Horner describes how slicing open fossil skulls revealed a shocking secret about some of our most beloved dinosaurs.
Speaker:
Jack Horner
984 0:01 - 0:05

Shall I ask for a show
of hands or a clapping
6144 0:06 - 0:08

of people in different generations?
8268 0:08 - 0:12

I'm interested in how many
are three to 12 years old.
12000 0:12 - 0:17

(Laughter)
¶
17274 0:17 - 0:19

None, huh?
¶
18584 0:19 - 0:20

(Laughter)
¶
19983 0:20 - 0:21

All right.
21809 0:22 - 0:24

I'm going to talk about dinosaurs.
23591 0:24 - 0:26

Do you remember dinosaurs
when you were that age?
26000 0:26 - 0:31

(Applause)
¶
33595 0:34 - 0:36

Dinosaurs are kind of funny, you know.
¶
36000 0:36 - 0:38

(Laughter)
¶
38521 0:39 - 0:41

We're going to kind of go
in a different direction right now.
¶
41454 0:41 - 0:43

I hope you all realize that.
43554 0:44 - 0:46

So I'll just give you my message up front:
46355 0:46 - 0:48

Try not to go extinct.
47994 0:48 - 0:49

(Laughter)
¶
49356 0:49 - 0:51

That's it.
¶
50566 0:51 - 0:55

(Laughter)
¶
55919 0:56 - 0:57

People ask me a lot --
¶
58014 0:58 - 1:01

in fact, one of the most asked
questions I get
60690 1:01 - 1:04

is, why do children
like dinosaurs so much?
64000 1:04 - 1:06

What's the fascination?
66481 1:06 - 1:09

And I usually just say,
69000 1:09 - 1:11

"Well, dinosaurs were big,
71831 1:12 - 1:14

different and gone."
75196 1:15 - 1:16

They're all gone.
76518 1:17 - 1:18

Well that's not true,
78588 1:19 - 1:21

but we'll get to the goose in a minute.
80747 1:21 - 1:23

So that's sort of the theme:
83268 1:23 - 1:26

big, different and gone.
87144 1:27 - 1:29

The title of my talk:
88833 1:29 - 1:31

Shape-shifting Dinosaurs:
90899 1:31 - 1:33

The cause of a premature extinction.
94005 1:34 - 1:37

Now I assume that we remember dinosaurs.
¶
96818 1:37 - 1:40

And there's lots of different shapes.
99745 1:40 - 1:42

Lots of different kinds.
102222 1:42 - 1:44

A long time ago,
104690 1:45 - 1:50

back in the early 1900s,
museums were out looking for dinosaurs.
109862 1:50 - 1:52

They went out and gathered them up.
112601 1:53 - 1:54

And this is an interesting story.
115203 1:55 - 1:59

Every museum wanted a little bigger
or better one than anybody else had.
119258 1:59 - 2:06

So if the museum in Toronto went out
and collected a Tyrannosaur, a big one,
126070 2:06 - 2:10

then the museum in Ottawa
wanted a bigger one, and a better one.
130792 2:11 - 2:13

And that happened for all museums.
132644 2:13 - 2:17

So everyone was out looking
for all these bigger and better dinosaurs.
137901 2:18 - 2:20

And this was in the early 1900s.
141146 2:21 - 2:24

By about 1970,
¶
144861 2:25 - 2:29

some scientists were sitting around
and they thought, "What in the world --
149715 2:30 - 2:32

Look at these dinosaurs, they're all big.
153752 2:34 - 2:36

Where are all the little ones?"
155746 2:36 - 2:37

(Laughter)
¶
158574 2:39 - 2:42

And they thought about it
and they even wrote papers about it:
¶
162114 2:42 - 2:44

"Where are the little dinosaurs?"
164000 2:44 - 2:50

(Laughter)
¶
172899 2:53 - 2:56

Well, go to a museum, you'll see,
¶
176540 2:57 - 2:59

see how many baby dinosaurs there are.
179662 3:00 - 3:02

People assumed --
and this was actually a problem --
182473 3:02 - 3:07

people assumed
that if they had little dinosaurs,
186801 3:07 - 3:11

if they had juvenile dinosaurs,
they'd be easy to identify.
190527 3:11 - 3:14

You'd have a big dinosaur
and a littler dinosaur.
194424 3:14 - 3:16

(Laughter)
¶
195866 3:16 - 3:18

But all they had were big dinosaurs.
¶
198983 3:19 - 3:21

And it comes down to a couple of things.
¶
201000 3:21 - 3:25

First off, scientists have egos,
205778 3:26 - 3:29

and scientists like to name dinosaurs.
209655 3:30 - 3:31

They like to name anything.
211000 3:31 - 3:35

Everybody likes to have
their own animal that they named.
214981 3:35 - 3:38

(Laughter)
¶
217982 3:38 - 3:41

And so every time they found something
that looked a little different,
¶
221313 3:41 - 3:43

they named it something different.
223668 3:44 - 3:45

And what happened, of course,
225094 3:45 - 3:49

is we ended up with a whole
bunch of different dinosaurs.
230642 3:51 - 3:53

In 1975,
¶
234296 3:54 - 3:57

a light went on in somebody's head.
236829 3:57 - 4:01

Dr. Peter Dodson
at the University of Pennsylvania
241078 4:01 - 4:08

actually realized that dinosaurs
grew kind of like birds do,
248668 4:09 - 4:12

which is different
than the way reptiles grow.
252246 4:12 - 4:14

And in fact,
253850 4:14 - 4:17

he used the cassowary as an example.
257390 4:17 - 4:20

And it's kind of cool --
if you look at the cassowary,
260465 4:20 - 4:24

or any of the birds
that have crests on their heads,
263716 4:24 - 4:30

they grow to about 80 percent adult size
before the crest starts to grow.
271434 4:31 - 4:33

Now think about that.
273000 4:33 - 4:36

They're basically retaining
their juvenile characteristics
276000 4:36 - 4:40

very late in what we call ontogeny.
279544 4:40 - 4:45

So allometric cranial ontogeny
is relative skull growth.
286000 4:46 - 4:52

So you can see that if you actually found
one that was 80 percent grown
293461 4:53 - 4:57

and you didn't know that it was going
to grow up to a cassowary,
296910 4:57 - 4:59

you would think
they were two different animals.
300170 5:00 - 5:03

So this was a problem,
¶
303000 5:03 - 5:09

and Peter Dodson pointed this out
using some duck-billed dinosaurs
309062 5:09 - 5:11

then called Hypacrosaurus.
310587 5:11 - 5:15

And he showed that if you were to take
a baby and an adult
315477 5:15 - 5:19

and make an average
of what it should look like,
318802 5:19 - 5:22

if it grew in sort of a linear fashion,
322053 5:22 - 5:26

it would have a crest
about half the size of the adult.
326236 5:26 - 5:32

But the actual subadult at 65 percent
had no crest at all.
332321 5:32 - 5:34

So this was interesting.
334000 5:34 - 5:39

So this is where people went astray again.
340111 5:40 - 5:43

I mean, if they'd have just taken that,
342742 5:43 - 5:46

taken Peter Dodson's work,
and gone on with that,
345784 5:46 - 5:49

then we would have a lot less
dinosaurs than we have.
349658 5:50 - 5:53

But scientists have egos;
they like to name things.
354120 5:54 - 5:59

And so they went on naming dinosaurs
because they were different.
360145 6:00 - 6:03

Now we have a way of actually testing
¶
362822 6:03 - 6:08

to see whether a dinosaur, or any animal,
is a young one or an older one.
368141 6:08 - 6:11

And that's by actually
cutting into their bones.
371889 6:12 - 6:19

But cutting into the bones of a dinosaur
is hard to do, as you can imagine,
378687 6:19 - 6:24

because in museums, bones are precious.
385842 6:26 - 6:29

You go into a museum,
and they take really good care of them.
388724 6:29 - 6:32

They put them in foam, little containers.
392340 6:32 - 6:34

They're very well taken care of.
396172 6:36 - 6:40

They don't like it if you come in
and want to saw them open and look inside.
400110 6:40 - 6:41

(Laughter)
¶
401135 6:41 - 6:45

So they don't normally let you do that.
¶
404568 6:45 - 6:46

(Laughter)
¶
405593 6:46 - 6:49

But I have a museum
and I collect dinosaurs
¶
410127 6:50 - 6:52

and I can saw mine open.
412015 6:52 - 6:54

So that's what I do.
414016 6:54 - 6:59

(Applause)
¶
420705 7:01 - 7:03

So if you cut open a little dinosaur,
¶
423386 7:03 - 7:06

it's very spongy inside, like A.
426100 7:06 - 7:09

And if you cut into an older dinosaur,
it's very massive.
429000 7:09 - 7:12

You can tell it's mature bone.
432101 7:12 - 7:14

So it's real easy to tell them apart.
434604 7:15 - 7:18

So what I want to do is show you these.
438333 7:18 - 7:22

In North America in the northern plains
of the United States
442258 7:22 - 7:26

and the southern plains
of Alberta and Saskatchewan,
446000 7:26 - 7:30

there's this unit of rock
called the Hell Creek Formation
449750 7:30 - 7:33

that produces the last
dinosaurs that lived on Earth.
453225 7:33 - 7:36

And there are 12 of them
that everyone recognizes --
456173 7:36 - 7:40

I mean the 12 primary dinosaurs
that went extinct.
460613 7:41 - 7:43

And so we will evaluate them.
464139 7:44 - 7:46

And that's sort of what I've been doing.
466119 7:46 - 7:51

So my students, my staff,
we've been cutting them open.
471814 7:52 - 7:56

Now as you can imagine,
cutting open a leg bone is one thing,
475681 7:56 - 7:59

but when you go to a museum
478764 7:59 - 8:03

and say, "You don't mind if I cut open
your dinosaur's skull, do you?"
483454 8:03 - 8:06

they say, "Go away."
486000 8:06 - 8:11

(Laughter)
¶
493548 8:14 - 8:15

So here are 12 dinosaurs.
¶
495000 8:15 - 8:18

And we want to look at these three first.
498745 8:19 - 8:22

So these are dinosaurs
that are called Pachycephalosaurus.
¶
502143 8:22 - 8:26

And everybody knows
that these three animals are related.
505797 8:26 - 8:32

And the assumption is that they're related
like cousins or whatever.
512122 8:32 - 8:38

But no one ever considered
that they might be more closely related.
517982 8:38 - 8:39

In other words,
519230 8:39 - 8:42

people looked at them
and they saw the differences.
522585 8:43 - 8:46

And you all know
that if you are going to determine
526000 8:46 - 8:49

whether you're related
to your brother or your sister,
528930 8:49 - 8:52

you can't do it by looking at differences.
532690 8:53 - 8:56

You can only determine relatedness
by looking for similarities.
536215 8:56 - 8:58

So people were looking at these
¶
538238 8:58 - 9:01

and they were talking
about how different they are.
540695 9:01 - 9:04

Pachycephalosaurus has a big,
thick dome on its head,
544143 9:04 - 9:07

and it's got some little bumps
on the back of its head,
546864 9:07 - 9:10

and it's got a bunch of gnarly things
on the end of its nose.
550790 9:11 - 9:17

And then Stygimoloch, another dinosaur
from the same age, lived at the same time,
556570 9:17 - 9:19

has spikes sticking out
the back of its head.
558760 9:19 - 9:21

It's got a little, tiny dome,
560756 9:21 - 9:24

and it's got a bunch
of gnarly stuff on its nose.
564289 9:24 - 9:28

And then there's this thing
called Dracorex hogwartsia.
569227 9:29 - 9:31

Guess where that came from?
570681 9:31 - 9:32

Dragon.
571869 9:32 - 9:36

So here's a dinosaur that has spikes
sticking out of its head,
575645 9:36 - 9:39

no dome and gnarly stuff on its nose.
579484 9:39 - 9:42

Nobody noticed the gnarly stuff
sort of looked alike.
¶
583102 9:43 - 9:45

But they did look at these three
584725 9:45 - 9:47

and they said, "These
are three different dinosaurs,
587204 9:47 - 9:50

and Dracorex is probably
the most primitive of them.
590142 9:50 - 9:54

And the other one
is more primitive than the other."
594156 9:54 - 9:58

It's unclear to me how they actually
sorted these three of them out.
598281 9:58 - 10:00

But if you line them up,
600198 10:00 - 10:03

if you just take those three skulls
and just line them up,
603277 10:03 - 10:05

they line up like this.
605288 10:05 - 10:07

Dracorex is the littlest one,
607368 10:07 - 10:10

Stygimoloch is the middle-size one,
610001 10:10 - 10:12

Pachycephalosaurus is the largest one.
612000 10:12 - 10:16

And one would think,
that should give me a clue.
616000 10:16 - 10:18

(Laughter)
¶
618353 10:18 - 10:20

But it didn't give them a clue.
¶
619907 10:20 - 10:21

(Laughter)
¶
621105 10:21 - 10:24

Because, well we know why.
¶
624204 10:24 - 10:27

Scientists like to name things.
628668 10:29 - 10:31

So if we cut open Dracorex --
¶
631428 10:31 - 10:33

I cut open our Dracorex --
633377 10:33 - 10:38

and look, it was spongy inside,
really spongy inside.
637625 10:38 - 10:41

I mean, it is a juvenile
and it's growing really fast.
641904 10:42 - 10:44

So it is going to get bigger.
643915 10:44 - 10:48

If you cut open Stygimoloch,
it is doing the same thing.
647577 10:48 - 10:51

The dome, that little dome,
is growing really fast.
651231 10:51 - 10:53

It's inflating very fast.
653564 10:54 - 10:57

What's interesting is the spike
on the back of the Dracorex
656964 10:57 - 10:59

was growing very fast as well.
659067 10:59 - 11:02

The spikes on the back of the Stygimoloch
are actually resorbing,
662340 11:02 - 11:06

which means they're getting smaller
as that dome is getting bigger.
666498 11:06 - 11:09

And if we look at Pachycephalosaurus,
669000 11:09 - 11:12

Pachycephalosaurus has a solid dome
672275 11:12 - 11:17

and its little bumps on the back
of its head were also resorbing.
677267 11:17 - 11:21

So just with these three dinosaurs,
¶
681000 11:21 - 11:24

as a scientist, we can easily hypothesize
683720 11:24 - 11:28

that it is just a growth series
of the same animal.
689199 11:29 - 11:32

Which of course means
692962 11:33 - 11:38

that Stygimoloch and Dracorex are extinct.
697705 11:38 - 11:43

(Laughter)
¶
702693 11:43 - 11:44

OK.
¶
704054 11:44 - 11:45

(Laughter)
¶
706947 11:47 - 11:52

Which of course means
we have 10 primary dinosaurs to deal with.
¶
713234 11:53 - 11:58

So a colleague of mine at Berkeley --
he and I were looking at Triceratops.
¶
718195 11:58 - 12:01

And before the year 2000 --
720534 12:01 - 12:04

now remember, Triceratops was first
found in the 1800s --
724230 12:04 - 12:09

before 2000, no one had ever seen
a juvenile Triceratops.
730362 12:10 - 12:14

There's a Triceratops
in every museum in the world,
733930 12:14 - 12:17

but no one had ever collected a juvenile.
738418 12:18 - 12:20

And we know why, right?
739844 12:20 - 12:22

Because everybody wants to have a big one.
742844 12:23 - 12:25

So everyone had a big one.
744902 12:25 - 12:27

So we went out and collected
a whole bunch of stuff
747334 12:27 - 12:29

and we found a whole bunch of little ones.
749365 12:29 - 12:32

They're everywhere,
they're all over the place.
752584 12:33 - 12:35

So we have a whole bunch
of them at our museum.
754873 12:35 - 12:39

(Laughter)
¶
759347 12:39 - 12:42

And everybody says
it's because I have a little museum.
¶
762035 12:42 - 12:45

When you have a little museum,
you have little dinosaurs.
764779 12:45 - 12:48

(Laughter)
¶
767889 12:48 - 12:50

If you look at the Triceratops,
¶
769655 12:50 - 12:52

you can see it's changing,
it's shape-shifting.
772324 12:52 - 12:56

As the juveniles are growing up,
their horns actually curve backwards.
776236 12:56 - 13:00

And then as they get older,
the horns grow forward.
779925 13:00 - 13:01

And that's pretty cool.
781328 13:01 - 13:04

If you look along the edge of the frill,
783667 13:04 - 13:09

they have these little triangular bones
that actually grow big as triangles
788857 13:09 - 13:12

and then they flatten against the frill
791585 13:12 - 13:15

pretty much like the spikes do
on the Pachycephalosaurs.
795818 13:16 - 13:20

And then, because the juveniles
are in my collection,
800323 13:20 - 13:22

I cut them open ...
801827 13:22 - 13:23

(Laughter)
¶
803002 13:23 - 13:24

and look inside.
¶
804200 13:24 - 13:27

And the little one is really spongy.
807369 13:27 - 13:30

And the middle-size one is really spongy.
809767 13:30 - 13:35

But what was interesting
was the adult Triceratops was also spongy.
814666 13:35 - 13:38

And this is a skull
that is two meters long.
818113 13:38 - 13:40

It's a big skull.
820828 13:41 - 13:45

But there's another dinosaur
that is found in this formation
¶
825619 13:46 - 13:49

that looks like a Triceratops,
except it's bigger,
829126 13:49 - 13:51

and it's called Torosaurus.
831955 13:52 - 13:56

And Torosaurus, when we cut
into it, has mature bone.
836437 13:56 - 13:58

But it's got these big
holes in its shield.
838503 13:59 - 14:00

And everybody says,
839680 14:00 - 14:03

"A Triceratops and a Torosaurus
can't possibly be the same animal
843364 14:03 - 14:06

because one of them's bigger
than the other one."
845880 14:06 - 14:11

(Laughter)
¶
850539 14:11 - 14:13

"And it has holes in its frill."
¶
853036 14:13 - 14:16

And I said, "Well do we have
any juvenile Torosauruses?"
856019 14:16 - 14:21

And they said, "Well, no,
but it has holes in its frill."
861463 14:21 - 14:25

So one of my graduate
students, John Scannella,
¶
864939 14:25 - 14:27

looked through our whole collection
866682 14:27 - 14:33

and he actually discovered that the hole
starting to form in Triceratops
872822 14:33 - 14:36

and, of course it's open, in Torosaurus --
875981 14:36 - 14:41

so he found the transitional ones
between Triceratops and Torosaurus,
881143 14:41 - 14:42

which was pretty cool.
882399 14:42 - 14:49

So now we know that Torosaurus
is actually a grown-up Triceratops.
889964 14:50 - 14:52

Now when we name dinosaurs,
891768 14:52 - 14:55

when we name anything,
the original name gets to stick
895328 14:55 - 14:59

and the second name is thrown out.
899936 15:00 - 15:02

So Torosaurus is extinct.
903441 15:03 - 15:07

Triceratops, if you've heard the news,
a lot of the newscasters got it all wrong.
907283 15:07 - 15:11

They thought Torosaurus should be kept
and Triceratops thrown out,
910857 15:11 - 15:13

but that's not going to happen.
912665 15:13 - 15:18

(Laughter)
¶
918179 15:18 - 15:21

All right, so we can do this
with a bunch of dinosaurs.
¶
921486 15:21 - 15:24

I mean, here's Edmontosaurus
923556 15:24 - 15:25

and Anatotitan.
925423 15:25 - 15:28

Anatotitan: giant duck.
928632 15:29 - 15:31

It's a giant duck-bill dinosaur.
930807 15:31 - 15:33

Here's another one.
932559 15:33 - 15:35

So we look at the bone histology.
935056 15:35 - 15:40

The bone histology tells us
that Edmontosaurus is a juvenile,
939963 15:40 - 15:42

or at least a subadult,
941615 15:42 - 15:47

and the other one is an adult,
and we have an ontogeny.
948273 15:48 - 15:50

And we get rid of Anatotitan.
951400 15:51 - 15:53

So we can just keep doing this.
¶
953245 15:53 - 15:57

And the last one is T. Rex.
957332 15:57 - 16:02

So there's these two dinosaurs,
T. Rex and Nanotyrannus.
962000 16:02 - 16:05

(Laughter)
¶
964914 16:05 - 16:08

Again, it makes you wonder.
¶
967654 16:08 - 16:11

(Laughter)
¶
970888 16:11 - 16:13

But they had a good question.
¶
973247 16:13 - 16:16

They were looking at them and they said,
"One's got 17 teeth,
976156 16:16 - 16:18

and the biggest one's got 12 teeth.
978044 16:18 - 16:20

And that doesn't make any sense at all,
979938 16:20 - 16:24

because we don't know of any dinosaurs
that gain teeth as they get older.
983630 16:24 - 16:26

So it must be true --
985902 16:26 - 16:27

they must be different."
988643 16:29 - 16:30

So we cut into them.
991373 16:31 - 16:35

And sure enough,
Nanotyrannus has juvenile bone
995274 16:35 - 16:39

and the bigger one has more mature bone.
999439 16:39 - 16:42

It looks like it could still get bigger.
1001866 16:42 - 16:44

And at the Museum
of the Rockies where we work,
1004111 16:44 - 16:48

I have four T. rexes,
so I can cut a whole bunch of them.
1007774 16:48 - 16:50

But I didn't have to cut
any of them really,
1010000 16:50 - 16:53

because I just lined up their jaws
1013000 16:53 - 16:56

and it turned out
the biggest one had 12 teeth
1016334 16:56 - 16:59

and the next smallest one had 13
1018533 16:59 - 17:01

and the next smallest had 14.
1020787 17:01 - 17:03

And of course, Nano has 17.
1022834 17:03 - 17:06

And we just went out and looked
at other people's collections
1025745 17:06 - 17:09

and we found one that has
sort of 15 teeth.
1029504 17:10 - 17:12

So again, real easy to say
1032306 17:12 - 17:17

that Tyrannosaurus ontogeny
included Nanotyrannus,
1037686 17:18 - 17:22

and therefore we can take out
another dinosaur.
1042349 17:22 - 17:24

(Laughter)
¶
1047377 17:27 - 17:31

So when it comes down
to our end Cretaceous,
¶
1050694 17:31 - 17:32

we have seven left.
1054099 17:34 - 17:35

And that's a good number.
1055756 17:36 - 17:39

That's a good number
to go extinct, I think.
1059604 17:40 - 17:41

Now as you can imagine,
1060862 17:41 - 17:44

this is not very popular
with fourth-graders.
1063743 17:44 - 17:45

(Laughter)
¶
1064768 17:45 - 17:50

Fourth-graders love their dinosaurs,
they memorize them.
¶
1073113 17:53 - 17:55

And they're not happy with this.
1074867 17:55 - 17:57

(Laughter)
¶
1077507 17:58 - 17:59

Thank you very much.
¶
1078722 17:59 - 18:03

(Applause)
¶

Add a new language!

This video is in English

English subtitles

← Where are the baby dinosaurs?

Embed video

Share