How do we know what color dinosaurs were? - Len Bloch

899,392 views ・ 2016-01-04

TED-Ed


Please double-click on the English subtitles below to play the video.

Prevodilac: Mile Živković Lektor: Milenka Okuka
00:09
This is the microraptor,
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Ovo je mikroraptor,
00:12
a carnivorous four-winged dinosaur that was almost two-feet long,
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dinosaurus mesožder sa četiri krila koji je bio dug skoro 60cm,
00:17
ate fish,
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jeo je ribu
00:18
and lived about 120 million years ago.
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i živeo pre oko 120 miliona godina.
00:21
Most of what we know about it comes from fossils that look like this.
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Većina toga što znamo o njemu proizilazi iz ovakvih fosila.
00:26
So, is its coloration here just an artist's best guess?
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Pa, da li je ova boja samo nagađanje umetnika?
00:29
The answer is no.
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Odgovor je: ne.
00:32
We know this shimmering black color is accurate
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Znamo da je ova svetlucavo crna boja tačna
00:35
because paleontologists have analyzed clues contained within the fossil.
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jer su paleontolozi analizirali tragove unutar fosila.
00:40
But making sense of the evidence requires careful examination of the fossil
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Ali davanje smisla dokazima zahteva pažljivo ispitivanje fosila
00:44
and a good understanding of the physics of light and color.
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i dobro razumevanje fizike svetla i boja.
00:50
First of all, here's what we actually see on the fossil:
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Pre svega, ovo zapravo vidimo na fosilu:
00:53
imprints of bones and feathers that have left telltale mineral deposits.
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otisak kostiju i perja sa nagoveštajima ostataka minerala.
00:58
And from those imprints,
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Od tih otisaka,
00:59
we can determine that these microraptor feathers
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možemo utvrditi da je ovo perje mikroraptora
01:02
were similar to modern dinosaur, as in bird, feathers.
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bilo slično perju modernog dinosaurusa, ptice.
01:07
But what gives birds their signature diverse colorations?
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Ali šta pticama daje njihove prepoznatljive razne boje?
01:11
Most feathers contain just one or two dye-like pigments.
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Većina perja sadrži samo jedan ili dva pigmenta nalik na boju.
01:15
The cardinal's bright red comes from carotenoids,
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Jarko crvena boja ptice kardinal dolazi iz karotenoida,
01:18
the same pigments that make carrots orange,
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istih pigmenata koji šargarepu čine narandžastom,
01:21
while the black of its face is from melanin,
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dok je crna boja njenog lica od melanina,
01:23
the pigment that colors our hair and skin.
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pigmenta koji boji našu kosu i kožu.
01:27
But in bird feathers, melanin isn't simply a dye.
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Ali kod ptičjeg perja, melanin nije samo boja.
01:30
It forms hollow nanostructures called melanosomes
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On stvara šuplje infrastrukture zvane melanozomi
01:34
which can shine in all the colors of the rainbow.
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koje mogu da sijaju u svim bojama duge.
Kako bismo razumeli kako ovo funkcioniše,
01:37
To understand how that works,
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pomaže da se prisetimo nekih stvari u vezi sa svetlošću.
01:39
it helps to remember some things about light.
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01:41
Light is basically a tiny electromagnetic wave traveling through space.
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Svetlost je zapravo mali elektromagnetni talas
koji putuje kroz prostor.
01:46
The top of a wave is called its crest
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Gornji deo talasa naziva se vrhom
01:49
and the distance between two crests is called the wavelength.
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i razdaljina između dva vrha naziva se talasnom dužinom.
01:53
The crests in red light are about 700 billionths of a meter apart
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Vrhovi kod crvene svetlosti su udaljeni oko 700 milijardi delova metra
01:58
and the wavelength of purple light is even shorter,
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a talasna dužina ljubičaste svetlosti još je kraća,
02:01
about 400 billionths of a meter, or 400 nanometers.
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oko 400 milijardi delova metra, ili 400 nanometara.
02:06
When light hits the thin front surface of a bird's hollow melanosome,
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Kada svetlost padne na tanku prednju površinu
šupljeg melanozoma ptice,
02:10
some is reflected and some passes through.
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nešto se odbija, a nešto prolazi.
02:13
A portion of the transmitted light then reflects off the back surface.
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Deo prenešene svetlosti onda se odbija od površine.
02:18
The two reflected waves interact.
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Dva odbijena talasa reaguju međusobno.
02:20
Usually they cancel each other out,
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Obično se poništavaju,
02:22
but when the wavelength of the reflected light
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ali kada je talasna dužina odbijene svetlosti
02:24
matches the distance between the two reflections,
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jednaka udaljenosti između dva odsjaja,
02:27
they reinforce each other.
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onda se pojačavaju međusobno.
02:29
Green light has a wavelength of about 500 nanometers,
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Zelena svetlost ima talasnu dužinu od oko 500 nanometara,
02:33
so melanosomes that are about 500 nanometers across
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tako da melanozomi koji su široki oko 500 nanometara
02:36
give off green light,
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daju zelenu svetlost,
02:38
thinner melanosomes give off purple light,
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tanji melanozomi daju ljubičastu svetlost,
02:40
and thicker ones give off red light.
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a deblji crvenu.
02:43
Of course, it's more complex than this.
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Naravno, komplikovanije je od ovoga.
02:45
The melanosomes are packed together inside cells, and other factors,
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Melanozomi su zbijeni unutar ćelija, i drugi faktori su bitni,
02:49
like how the melanosomes are arranged within the feather, also matter.
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poput toka kako su melanozomi raspoređeni unutar pera.
02:54
Let's return to the microraptor fossil.
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Vratimo se na fosil mikroraptora.
02:56
When scientists examined its feather imprints under a powerful microscope,
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Kada su naučnici ispitali otiske njegovog perja pod mikroskopom,
03:01
they found nanostructures that look like melanosomes.
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otkrili su nanostrukture koje liče na melanozome.
03:04
X-ray analysis of the melanosomes further supported that theory.
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Rendgenska analiza melanozoma išla je u prilog toj teoriji.
03:09
They contained minerals that would result from the decay of melanin.
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One su sadržale minerale koji bi bili posledica raspadanja melanina.
03:13
The scientists then chose 20 feathers from one fossil
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Naučnici su onda odabrali 20 pera od jednog fosila
03:16
and found that the melanosomes in all 20 looked alike,
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i otkrili da su melanozomi ličili jedan na drugog u svih 20,
03:20
so they became pretty sure this dinosaur was one solid color.
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pa su postali prilično sigurni da je ovaj dinousaurus bio u jednoj boji.
03:25
They compared these microraptor melanosomes to those of modern birds
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Uporedili su ove melanozome mikroraptora sa onim na današnjim pticama
03:29
and found a close similarity, though not a perfect match,
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i pronašli su veliku sličnost, ali ne i savršeno podudaranje,
03:32
to the iridescent teal feathers found on duck wings.
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sa perjem na krilima patke, plavozelene boje koja se preliva.
03:37
And by examining the exact size and arrangement of the melanosomes,
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Ispitivanjem tačne veličine i rasporeda melanozoma,
03:40
scientists determined that the feathers were iridescent black.
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naučnici su odredili da je perje bilo crne boje koja se prelivala.
03:45
Now that we can determine a fossilized feather's color,
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Kada možemo da odredimo boju fosilizovanog perja,
03:48
paleontologists are looking for more fossils with well-preserved melanosomes.
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paleontolozi traže još fosila sa dobro očuvanim melanozomima.
03:54
They've found that a lot of dinosaurs, including velociraptor,
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Otkrili su da je dosta dinousaurusa, uključujući velociraptora
03:57
probably had feathers,
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verovatno imalo perje,
03:59
meaning that certain films might not be so biologically accurate.
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što znači da određeni filmovi možda i nisu baš biološki tačni.
04:04
Clever girls.
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Pametnice.
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