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

Prevodilac: Mile Živković Lektor: Milenka Okuka

This is the microraptor,

Ovo je mikroraptor,

a carnivorous four-winged dinosaur that was almost two-feet long,

dinosaurus mesožder sa četiri krila koji je bio dug skoro 60cm,

ate fish,

jeo je ribu

and lived about 120 million years ago.

i živeo pre oko 120 miliona godina.

Most of what we know about it comes from fossils that look like this.

Većina toga što znamo o njemu proizilazi iz ovakvih fosila.

So, is its coloration here just an artist's best guess?

Pa, da li je ova boja samo nagađanje umetnika?

The answer is no.

Odgovor je: ne.

We know this shimmering black color is accurate

Znamo da je ova svetlucavo crna boja tačna

because paleontologists have analyzed clues contained within the fossil.

jer su paleontolozi analizirali tragove unutar fosila.

But making sense of the evidence requires careful examination of the fossil

Ali davanje smisla dokazima zahteva pažljivo ispitivanje fosila

and a good understanding of the physics of light and color.

i dobro razumevanje fizike svetla i boja.

First of all, here's what we actually see on the fossil:

Pre svega, ovo zapravo vidimo na fosilu:

imprints of bones and feathers that have left telltale mineral deposits.

otisak kostiju i perja sa nagoveštajima ostataka minerala.

And from those imprints,

Od tih otisaka,

we can determine that these microraptor feathers

možemo utvrditi da je ovo perje mikroraptora

were similar to modern dinosaur, as in bird, feathers.

bilo slično perju modernog dinosaurusa, ptice.

But what gives birds their signature diverse colorations?

Ali šta pticama daje njihove prepoznatljive razne boje?

Most feathers contain just one or two dye-like pigments.

Većina perja sadrži samo jedan ili dva pigmenta nalik na boju.

The cardinal's bright red comes from carotenoids,

Jarko crvena boja ptice kardinal dolazi iz karotenoida,

the same pigments that make carrots orange,

istih pigmenata koji šargarepu čine narandžastom,

while the black of its face is from melanin,

dok je crna boja njenog lica od melanina,

the pigment that colors our hair and skin.

pigmenta koji boji našu kosu i kožu.

But in bird feathers, melanin isn't simply a dye.

Ali kod ptičjeg perja, melanin nije samo boja.

It forms hollow nanostructures called melanosomes

On stvara šuplje infrastrukture zvane melanozomi

which can shine in all the colors of the rainbow.

koje mogu da sijaju u svim bojama duge.

Kako bismo razumeli kako ovo funkcioniše,

To understand how that works,

pomaže da se prisetimo nekih stvari u vezi sa svetlošću.

it helps to remember some things about light.

Light is basically a tiny electromagnetic wave traveling through space.

Svetlost je zapravo mali elektromagnetni talas

koji putuje kroz prostor.

The top of a wave is called its crest

Gornji deo talasa naziva se vrhom

and the distance between two crests is called the wavelength.

i razdaljina između dva vrha naziva se talasnom dužinom.

The crests in red light are about 700 billionths of a meter apart

Vrhovi kod crvene svetlosti su udaljeni oko 700 milijardi delova metra

and the wavelength of purple light is even shorter,

a talasna dužina ljubičaste svetlosti još je kraća,

about 400 billionths of a meter, or 400 nanometers.

oko 400 milijardi delova metra, ili 400 nanometara.

When light hits the thin front surface of a bird's hollow melanosome,

Kada svetlost padne na tanku prednju površinu

šupljeg melanozoma ptice,

some is reflected and some passes through.

nešto se odbija, a nešto prolazi.

A portion of the transmitted light then reflects off the back surface.

Deo prenešene svetlosti onda se odbija od površine.

The two reflected waves interact.

Dva odbijena talasa reaguju međusobno.

Usually they cancel each other out,

Obično se poništavaju,

but when the wavelength of the reflected light

ali kada je talasna dužina odbijene svetlosti

matches the distance between the two reflections,

jednaka udaljenosti između dva odsjaja,

they reinforce each other.

onda se pojačavaju međusobno.

Green light has a wavelength of about 500 nanometers,

Zelena svetlost ima talasnu dužinu od oko 500 nanometara,

so melanosomes that are about 500 nanometers across

tako da melanozomi koji su široki oko 500 nanometara

give off green light,

daju zelenu svetlost,

thinner melanosomes give off purple light,

tanji melanozomi daju ljubičastu svetlost,

and thicker ones give off red light.

a deblji crvenu.

Of course, it's more complex than this.

Naravno, komplikovanije je od ovoga.

The melanosomes are packed together inside cells, and other factors,

Melanozomi su zbijeni unutar ćelija, i drugi faktori su bitni,

like how the melanosomes are arranged within the feather, also matter.

poput toka kako su melanozomi raspoređeni unutar pera.

Let's return to the microraptor fossil.

Vratimo se na fosil mikroraptora.

When scientists examined its feather imprints under a powerful microscope,

Kada su naučnici ispitali otiske njegovog perja pod mikroskopom,

they found nanostructures that look like melanosomes.

otkrili su nanostrukture koje liče na melanozome.

X-ray analysis of the melanosomes further supported that theory.

Rendgenska analiza melanozoma išla je u prilog toj teoriji.

They contained minerals that would result from the decay of melanin.

One su sadržale minerale koji bi bili posledica raspadanja melanina.

The scientists then chose 20 feathers from one fossil

Naučnici su onda odabrali 20 pera od jednog fosila

and found that the melanosomes in all 20 looked alike,

i otkrili da su melanozomi ličili jedan na drugog u svih 20,

so they became pretty sure this dinosaur was one solid color.

pa su postali prilično sigurni da je ovaj dinousaurus bio u jednoj boji.

They compared these microraptor melanosomes to those of modern birds

Uporedili su ove melanozome mikroraptora sa onim na današnjim pticama

and found a close similarity, though not a perfect match,

i pronašli su veliku sličnost, ali ne i savršeno podudaranje,

to the iridescent teal feathers found on duck wings.

sa perjem na krilima patke, plavozelene boje koja se preliva.

And by examining the exact size and arrangement of the melanosomes,

Ispitivanjem tačne veličine i rasporeda melanozoma,

scientists determined that the feathers were iridescent black.

naučnici su odredili da je perje bilo crne boje koja se prelivala.

Now that we can determine a fossilized feather's color,

Kada možemo da odredimo boju fosilizovanog perja,

paleontologists are looking for more fossils with well-preserved melanosomes.

paleontolozi traže još fosila sa dobro očuvanim melanozomima.

They've found that a lot of dinosaurs, including velociraptor,

Otkrili su da je dosta dinousaurusa, uključujući velociraptora

probably had feathers,

verovatno imalo perje,

meaning that certain films might not be so biologically accurate.

što znači da određeni filmovi možda i nisu baš biološki tačni.

Clever girls.

Pametnice.