Jack Horner: Shape-shifting dinosaurs

Translator: Linda Magáthová Reviewer: Petra Aquamarine

Môžem vás požiadať, aby zdvihli ruku

Shall I ask for a show of hands or a clapping

alebo zatlieskali

ľudia rôznych generácií?

of people in different generations?

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

Zaujíma ma, koľko z vás

má 3 – 12 rokov.

(Laughter)

(smiech)

None, huh?

Nikto, čo?

(Laughter)

All right.

No dobre.

Budem hovoriť o dinosauroch.

I'm going to talk about dinosaurs.

Do you remember dinosaurs when you were that age?

Spomínate si na tie dinosaury, keď ste mali toľko?

(Applause)

(potlesk)

Dinosaurs are kind of funny, you know.

Dinosaury sú celkom zábavné, že.

(Laughter)

(smiech)

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

Teraz hneď zmeníme tému.

Dúfam, že si to všetci uvedomujete.

I hope you all realize that.

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

Takže vám to dôležité poviem hneď teraz:

Try not to go extinct.

Snažte sa nevyhynúť.

(Laughter)

(smiech)

That's it.

To je všetko.

(Laughter)

(smiech)

Ľudia sa ma často pýtajú –

People ask me a lot --

v podstate je to najčastejšia otázka, ktorú dostávam –

in fact, one of the most asked questions I get

is, why do children like dinosaurs so much?

prečo majú deti tak rady dinosaury?

What's the fascination?

Čo ich na nich tak fascinuje?

And I usually just say,

Zvyčajne odpovedám:

"Well, dinosaurs were big,

„Dinosaury boli veľké,

iné a už vymreli.“

different and gone."

Všetky sú preč.

They're all gone.

Well that's not true,

Čo ale nie je pravda,

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

ale k tomu sa dostaneme o chvíľu.

Takže asi takto:

So that's sort of the theme:

big, different and gone.

veľké, iné a vyhynuté.

The title of my talk:

Názov mojej prednášky je:

Shape-shifting Dinosaurs:

Prevteľovanie dinosaurov:

The cause of a premature extinction.

príčina predčasného vyhynutia.

Now I assume that we remember dinosaurs.

Predpokladám, že si na dinosaury spomínate.

And there's lots of different shapes.

Majú rozličné formy.

Lots of different kinds.

Mnoho rôznych druhov.

A long time ago,

Pred mnohými rokmi,

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

na začiatku 20. storočia,

múzeá pátrali po dinosauroch.

They went out and gathered them up.

Vyrážali do terénu a zbierali ich.

And this is an interesting story.

Je to zaujímavý príbeh.

Každé múzeum chcelo trochu väčší alebo lepší kúsok,

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

ako mali ostatné.

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

Takže keď múzeum v Toronte vyrazilo von

a našlo veľkého Tyranosaura,

tak múzeum v Ottave chcelo ešte väčšieho

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

a lepšieho.

Tak to bolo so všetkými múzeami.

And that happened for all museums.

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

Všetci vyhľadávali

všetky tie väčšie a lepšie dinosaury.

To bolo na začiatku 20. storočia.

And this was in the early 1900s.

By about 1970,

Ale okolo roku 1970

sa niekoľko vedcov

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

zamyslelo: „Čo to má znamenať?

Look at these dinosaurs, they're all big.

Pozrite sa na tie dinosaury.

Všetky sú veľké.

Kde sú všetky tie mladé?“

Where are all the little ones?"

(Laughter)

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

Premýšľali o tom

a dokonca o tom napísali aj článok:

"Where are the little dinosaurs?"

„Kde sú malé dinosaury?“

(Laughter)

(smiech)

No, choďte do múzea a uvidíte,

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

see how many baby dinosaurs there are.

koľko je tam mláďat dinosaurov.

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

Ľudia si mysleli, a to bol práve ten problém,

people assumed that if they had little dinosaurs,

mysleli si,

že ak by mali malé dinosaury,

ak by mali mláďatá,

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

bolo by jednoduché ich rozpoznať.

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

Mali by ste veľkého dinosaura

a malého dinosaura.

(Laughter)

Ale mali len veľké dinosaury.

But all they had were big dinosaurs.

Má to niekoľko dôvodov.

And it comes down to a couple of things.

First off, scientists have egos,

Po prvé, vedci majú ego

a radi pomenúvajú dinosaury.

and scientists like to name dinosaurs.

They like to name anything.

Chcú všetko pomenovávať.

Everybody likes to have their own animal that they named.

Každý chce mať nejaké vlastné zviera, ktoré sa po ňom volá, a tak…

(Laughter)

(smiech)

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

Takže vždy, keď našli niečo, čo vyzeralo trochu inak,

they named it something different.

dali tomu iné meno.

And what happened, of course,

Samozrejme to dopadlo tak,

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

že máme kopu rôznych dinosaurov.

In 1975,

V roku 1975

a light went on in somebody's head.

to niekomu napadlo.

Dr. Peter Dodson at the University of Pennsylvania

Dr. Peter Dodson

z Pensylvánskej univerzity

actually realized that dinosaurs grew kind of like birds do,

si uvedomil,

že dinosaury rástli

podobne ako vtáci,

which is different than the way reptiles grow.

čo sa líši od spôsobu

rastu plazov.

And in fact,

V podstate

použil ako príklad kazuáry.

he used the cassowary as an example.

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

Čo bolo múdre, lebo ak sa pozriete na kazuára

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

alebo na akýkoľvek druh vtáka, ktorý má na hlave hrebeň,

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

narastajú do 80 % svojej veľkosti,

kým im začne rásť hrebeň.

Now think about that.

Zamyslite sa nad tým.

They're basically retaining their juvenile characteristics

V podstate si uchovávajú vlastnosti mláďaťa

very late in what we call ontogeny.

až do veku neskorej ontogenézy.

So allometric cranial ontogeny is relative skull growth.

Alometrická kraniálna ontogenéza

je relatívny rast lebky.

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

Vidíte,

že ak by ste našli nejakého,

ktorý dorástol do 80 %,

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

a nevedeli by ste, že z neho bude kazuár,

mysleli by ste si, že ide o dve rôzne zvieratá.

you would think they were two different animals.

So this was a problem,

Takže na tento problém

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

upozornil Peter Dodson

na príklade kačkozubých dinosaurov,

vtedy nazývaných Hypacrosaurus.

then called Hypacrosaurus.

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

Ukázal,

že ak by ste vzali mláďa a dospelého jedinca

and make an average of what it should look like,

a priemerom určili, ako by mal vyzerať,

ak by rástol lineárnym spôsobom,

if it grew in sort of a linear fashion,

mal by hrebeň

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

asi polovičnej veľkosti ako dospelý.

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

Ale skutoční takmer dospelí jedinci

nemajú pri 65 % veľkosti

vôbec žiadny hrebeň.

So this was interesting.

To bolo zaujímavé.

So this is where people went astray again.

Takže tu vedci

znovu zišli zo správnej cesty.

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

Ak by jednoducho prijali prácu

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

Petera Dodsona a pokračovali v nej,

bolo by omnoho menej dinosaurov,

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

než ich máme dnes.

But scientists have egos; they like to name things.

Ale vedci majú ego,

radi pomenúvajú veci.

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

Takže pokračovali v pomenúvaní dinosaurov,

pretože vyzerali inak.

Now we have a way of actually testing

Teraz máme spôsob, ako určiť,

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

či je dinosaurus alebo iné zviera

mláďaťom alebo dospelým jedincom.

And that's by actually cutting into their bones.

Robí sa to rezaním do ich kostí.

Ale rezanie dinosaurích kostí

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

je ťažká vec, ako iste chápete,

because in museums, bones are precious.

lebo v múzeách

sa kosti veľmi cenia.

V múzeách sa o ne veľmi dobre starajú.

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

They put them in foam, little containers.

Ukladajú ich do škatuliek do penovej hmoty.

Starajú sa o ne veľmi dobre.

They're very well taken care of.

Nepáči sa im, keď prídeme

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

a chceme ich rozrezať a pozrieť sa dovnútra.

(Laughter)

(smiech)

So they don't normally let you do that.

Takže nám to zvyčajne nedovolia.

(Laughter)

Ale ja mám múzeum

But I have a museum and I collect dinosaurs

a zbieram dinosaury

a svoje si rozrezať smiem.

and I can saw mine open.

Takže to aj robím.

So that's what I do.

(potlesk)

(Applause)

Čiže keď rozrežem mladého dinosaura,

So if you cut open a little dinosaur,

it's very spongy inside, like A.

je to vnútri veľmi hubovité, ako A.

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

Pri starších dinosauroch

je to veľmi masívne.

You can tell it's mature bone.

Vidíme, že to je dospelá kosť.

So it's real easy to tell them apart.

Je veľmi ľahké ich rozlíšiť.

So what I want to do is show you these.

Takže by som vám to rád ukázal.

In North America in the northern plains of the United States

V Severnej Amerike, na severných pláňach v USA

and the southern plains of Alberta and Saskatchewan,

a na južných pláňach Alberty a Saskatchewanu

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

je geologické súvrstvie zvané Hell Creek,

ktoré ukrývalo posledné dinosaury, ktoré na Zemi žili.

that produces the last dinosaurs that lived on Earth.

And there are 12 of them that everyone recognizes --

Je ich 12,

každý ich pozná –

I mean the 12 primary dinosaurs that went extinct.

myslím tých 12 hlavných dinosaurov,

ktorí vyhynuli.

And so we will evaluate them.

Takže sa na ne pozrieme.

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

Týmto sa zaoberám.

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

Moji študenti, moji zamestnanci,

my ich otvárame.

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

Ako si asi viete predstaviť,

rozrezať kosť nohy je jedna vec,

but when you go to a museum

ale keď idete do múzea

a poviete im: „Neprekážalo by vám,

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

keby som rozrezal dinosauriu lebku, že?“,

they say, "Go away."

odpovedia vám: „Zmiznite.“

(Laughter)

(smiech)

So here are 12 dinosaurs.

Tu máme 12 dinosaurov.

And we want to look at these three first.

Pozrime sa najprv na tieto tri.

Tieto dinosaury sa volajú Pachycefalosaury.

So these are dinosaurs that are called Pachycephalosaurus.

Každý vie,

And everybody knows that these three animals are related.

že tieto tri zvieratá sú príbuzné.

Domnievame sa,

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

že sú príbuzní asi ako bratranci.

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

Ale ešte nikomu nenapadlo,

že by mohli byť ešte viac príbuzní.

Inými slovami,

In other words,

people looked at them and they saw the differences.

ľudia sa na ne dívali a videli rozdiely.

And you all know that if you are going to determine

Všetci viete,

že ak chcete určiť,

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

či ste príbuzný so svojím bratom alebo sestrou,

nepodarí sa vám to hľadaním rozdielov.

you can't do it by looking at differences.

You can only determine relatedness by looking for similarities.

Príbuznosť určíme iba

hľadaním podobností.

So people were looking at these

Takže ľudia sa na ne dívali

and they were talking about how different they are.

a hovorili si, akí sú odlišní.

Pachycephalosaurus has a big, thick dome on its head,

Pachycephalosaurus mal na hlave veľkú, silnú klenbu

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

a na zátylku niekoľko menších

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

a na konci nosa drsné výrastky.

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

Iný dinosaurus, Stygimoloch,

žil v rovnakej dobe

has spikes sticking out the back of its head.

a mal vzadu na hlave ostne.

Má malinkú klenbu

It's got a little, tiny dome,

a na nose výrastky.

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

And then there's this thing called Dracorex hogwartsia.

Potom je tu takzvaný Dracorex,

oko Rokfortu.

Guess where that came from?

Hádajte, odkiaľ to meno pochádza? Z draka.

Dragon.

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

Tento dinosaurus má ostne na hlave,

no dome and gnarly stuff on its nose.

žiadnu klenbu a drsné výrastky na nose.

Nobody noticed the gnarly stuff sort of looked alike.

Nikto si nevšimol, že tie výrastky vyzerajú podobne.

But they did look at these three

Ale dívali sa na túto trojicu

and they said, "These are three different dinosaurs,

a povedali si: „To sú 3 rôzne dinosaury

and Dracorex is probably the most primitive of them.

a Dracorex je z nich asi najprimitívnejší.“

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

Jeden je primitívnejší ako druhý.

Nie je mi jasné,

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

ako tieto tri rozdelili.

But if you line them up,

Ale keď ich zoradíte,

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

keď vezmete tieto tri lebky a zoradíte ich,

they line up like this.

radia sa takto:

Dracorex is the littlest one,

Dracorex je najmenší,

Stygimoloch is the middle-size one,

Stygimoloch je veľkosťou prostredný,

Pachycephalosaurus je najväčší.

Pachycephalosaurus is the largest one.

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

Jeden by si myslel,

že nám to niečo napovedá. (smiech)

(Laughter)

But it didn't give them a clue.

Ale im to nenapovedalo nič.

(Laughter)

Because, well we know why.

Pretože… no, vieme prečo.

Scientists like to name things.

Vedci radi dávajú mená.

So if we cut open Dracorex --

Ale keď rozrežeme

Dracorexa –

I cut open our Dracorex --

rozrezal som nášho Dracorexa –

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

a pozrite, vo vnútri bol špongiovitý,

veľmi špongiovitý.

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

Je to predsa mláďa,

ktoré rýchlo rastie.

So it is going to get bigger.

Časom bude väčší.

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

Keď rozrežeme Stygimolocha,

vyzerá to rovnako.

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

Tá malá klenba

rastie veľmi rýchlo,

It's inflating very fast.

rýchlo sa vydúva.

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

Je zaujímavé, že osteň na chrbte Dracorexa

tiež rastie veľmi rýchlo.

was growing very fast as well.

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

Ostne na chrbte Stygimolocha

ale ustupujú, čiže sa zmenšujú

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

spolu so zväčšujúcou sa klenbou.

And if we look at Pachycephalosaurus,

Ale keď sa pozrieme na Pachycephalosaura,

Pachycephalosaurus has a solid dome

má poriadnu klenbu

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

a malé výrastky na zátylku

tiež ustupujú.

So just with these three dinosaurs,

Takže už len na tejto trojici dinosaurov

je možné – vedecky –

as a scientist, we can easily hypothesize

jednoducho vysloviť hypotézu,

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

že ide o rastový rad

jedného zvieraťa.

Which of course means

Čo samozrejme znamená,

že Stygimoloch a Dracorex

that Stygimoloch and Dracorex are extinct.

týmto vyhynuli.

(Laughter)

(smiech)

OK.

Dobre.

(Laughter)

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

Čo samozrejme znamená,

že nám ostáva 10 hlavných dinosaurov.

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

Spolu s mojím kolegom z Berkeley

sme sa pozreli na Triceratopsa.

And before the year 2000 --

A pred rokom 2000 –

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

uvedomte si,

že prvého Triceratopsa našli v 19. storočí –

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

pred rokom 2000 nikto nikdy nevidel

mladého Triceratopsa.

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

V každom múzeu po celom svete je Triceratops,

ale nikdy nikto nenašiel mláďa.

but no one had ever collected a juvenile.

And we know why, right?

A my vieme prečo, že?

Because everybody wants to have a big one.

Pretože všetci chcú mať iba veľké.

Takže všetci mali veľké.

So everyone had a big one.

So we went out and collected a whole bunch of stuff

Tak sme vyrazili von a nazbierali

and we found a whole bunch of little ones.

celú kopu malých.

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

Sú všade. Úplne všade.

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

Takže ich v našom múzeu máme celú kopu.

(Laughter)

(smiech)

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

Všetci hovoria, že to je preto, že mám malé múzeum.

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

Kto má malé múzeum, má malé dinosaury.

(smiech)

(Laughter)

If you look at the Triceratops,

Keď sa pozriete na Triceratopsa,

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

vidíte, že mení tvar.

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

Ako mladé rastú,

ich rohy sa zakláňajú dozadu.

A potom, ako starnú,

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

rohy smerujú dopredu.

And that's pretty cool.

To je zaujímavé.

If you look along the edge of the frill,

Keď sa pozrieme na okraj goliera,

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

vidíme malé trojuholníkové kosti,

ktoré sa rozširujú

and then they flatten against the frill

a nakoniec sa vyhladia

pretty much like the spikes do on the Pachycephalosaurs.

veľmi podobne ako ostne Pachycephalosaura.

[Kosti lebky menia počas rastu svoj tvar.]

And then, because the juveniles are in my collection,

A potom, keďže sú to mladé z mojej zbierky,

I cut them open ...

ich rozrežem

(Laughter)

a pozriem sa dovnútra.

and look inside.

And the little one is really spongy.

Ten malý je veľmi špongiovitý.

And the middle-size one is really spongy.

Ten stredný je veľmi špongiovitý.

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

Zaujímavé bolo,

že dospelý Triceratops bol tiež špongiovitý.

And this is a skull that is two meters long.

Táto lebka je dlhá dva metre.

It's a big skull.

Je to veľká lebka.

Ale je tu ďalší dinosaurus,

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

ktorý sa našiel na tom mieste,

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

a ktorý vyzerá ako Triceratops, len je väčší

and it's called Torosaurus.

a nazýva sa Torosaurus.

Keď rozrežeme Torosaura,

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

má dospelé kosti.

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

Ale má tieto veľké diery v pancieri.

And everybody says,

Všetci hovoria: „Triceratops a Torosaurus

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

vôbec nemôžu byť to isté zviera,

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

lebo jeden z nich je väčší než ten druhý.“

(smiech)

(Laughter)

"And it has holes in its frill."

„A má diery v golieri.“

Povedal som: „Máme nejaké malé Torosaury?“

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

A oni na to: „No, nemáme,

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

ale má diery v golieri.“

So one of my graduate students, John Scannella,

Jeden z mojich študentov, John Scannella,

preskúmal celú zbierku

looked through our whole collection

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

a zistil,

že tá diera sa začína vytvárať

u Triceratopsa

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

a samozrejme je otvorená u Torosaura –

so he found the transitional ones between Triceratops and Torosaurus,

čiže objavil medzičlánok

medzi Triceratopsom a Torosaurom,

which was pretty cool.

čo už bolo niečo.

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

Takže teraz vieme,

že Torosaurus

je v skutočnosti dospelý Triceratops.

Now when we name dinosaurs,

Keď pomenúvame dinosaury,

when we name anything, the original name gets to stick

keď dávame mená čomukoľvek,

pôvodné meno zostáva

and the second name is thrown out.

a druhé meno je zamietnuté.

Takže Torosaurus vyhynul.

So Torosaurus is extinct.

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

Triceratops, ak ste to počuli v správach,

mnoho hlásateľov to úplne poplietlo.

They thought Torosaurus should be kept and Triceratops thrown out,

Mysleli si, že by sme mali ponechať Torosaura a zrušiť Triceratopsa,

but that's not going to happen.

ale to sa nestane.

(Laughter)

(smiech)

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

Dobre, tak toto sa dá robiť s kopou dinosaurov.

I mean, here's Edmontosaurus

Tu máme Edmontosaura a Anatotitana.

and Anatotitan.

Anatotitan: giant duck.

Anatotitan: obrovská kačka.

It's a giant duck-bill dinosaur.

Je to obrovský kačkozubý dinosaurus.

Here's another one.

Tu je ďalší.

So we look at the bone histology.

Takže sa pozrieme na histológiu kosti.

The bone histology tells us that Edmontosaurus is a juvenile,

Histológia nám hovorí,

že Edmontosaurus je mláďa,

alebo aspoň dospievajúci

or at least a subadult,

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

a ten druhý je dospelý,

máme tu ontogenézu.

A zbavíme sa Anatotitana.

And we get rid of Anatotitan.

So we can just keep doing this.

A v tomto môžeme pokračovať.

And the last one is T. Rex.

Posledným je

T. Rex.

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

Máme tieto dva dinosaury,

T. Rexa a Nanotyranna.

(Laughter)

(smiech)

Again, it makes you wonder.

(Laughter)

Znovu si hovoríme…

(smiech)

But they had a good question.

Ale napadla im dobrá otázka.

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

Pozreli si ich a povedali:

„Jeden má 17 zubov a ten najväčší má 12 zubov.“

and the biggest one's got 12 teeth.

And that doesn't make any sense at all,

Čo vôbec nedáva zmysel,

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

pretože nepoznáme žiadne dinosaury,

ktorým by s vekom pribúdali zuby.

So it must be true --

Takže to musí byť správne –

they must be different."

sú určite odlišní.“

So we cut into them.

Tak sme ich rozrezali.

And sure enough, Nanotyrannus has juvenile bone

A naozaj, Nanotyrannus má kosti mláďaťa

and the bigger one has more mature bone.

a ten väčší má dospelejšie kosti.

It looks like it could still get bigger.

Zdá sa, že by mohol ešte narásť.

And at the Museum of the Rockies where we work,

V Museum of the Rockies, kde pracujeme,

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

mám štyroch T. Rexov,

takže toho mám na rezanie dosť.

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

Ale to som ani nemusel,

because I just lined up their jaws

iba som zoradil ich čeľuste

and it turned out the biggest one had 12 teeth

a ukázalo sa, že ten najväčší mal 12 zubov

and the next smallest one had 13

a ten menší vedľa mal 13

and the next smallest had 14.

a ten ešte menší 14.

A Nano má 17.

And of course, Nano has 17.

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

Tak sme vyrazili a pozreli si zbierky iných ľudí

a našli sme jedného, ktorý mal 15 zubov.

and we found one that has sort of 15 teeth.

So again, real easy to say

Takže znovu je jasné,

that Tyrannosaurus ontogeny included Nanotyrannus,

že ontogenéza Tyrannosaura

zahŕňa Nanotyranna,

and therefore we can take out another dinosaur.

a preto môžeme zrušiť ďalšieho dinosaura.

(Laughter)

(smiech)

Takže pokiaľ ide

So when it comes down to our end Cretaceous,

o naše obdobie neskorej kriedy,

we have seven left.

zostáva nám ich 7.

And that's a good number.

To je pekné číslo.

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

Dobré číslo na vymretie, povedal by som.

Now as you can imagine,

Ako si asi viete predstaviť,

this is not very popular with fourth-graders.

u štvrtákov to nie je veľmi populárne.

(Laughter)

Štvrtáci milujú svoje dinosaury,

Fourth-graders love their dinosaurs, they memorize them.

učia sa ich naspamäť.

And they're not happy with this.

A toto sa im nepáči.

(Laughter)

(smiech)

Thank you very much.

Ďakujem pekne.

(Applause)

(potlesk)