How did feathers evolve? - Carl Zimmer

743,209 views ・ 2013-05-02

TED-Ed


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Translator: Andrea McDonough Reviewer: Bedirhan Cinar
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Translator: Sonia Redondo Reviewer: Marc Isbert
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Feathers are some of the most remarkable things
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Les plomes són una de les coses més excepcionals
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ever made by an animal.
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que mai hagi fet un animal.
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They are gorgeous in their complexity,
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La seva complexitat és meravellosa.
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delicate in their construction,
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La seva estructura, delicada.
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and yet strong enough to hold a bird
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I tot i això, són prou fortes per mantenir un ocell
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thousands of feet in the air.
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a centenars de metres d'alçada.
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Like all things in nature,
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Com tot a la natura,
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feathers evolved over millions of years
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les plomes han evolucionat al llarg de milions d'anys
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into their modern form.
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fins la seva forma actual.
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It could be hard to imagine
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És difícil imaginar
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how this could have happened.
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com pot haver passat.
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After all, what did the intermediate forms look like?
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Com eren les formes intermèdies?
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What good is half a wing,
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De què serveix una quasi ala
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festooned with half-feathers?
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engalanada amb quasi plomes?
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Thanks to science,
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Gràcies a la ciència,
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we now know that birds are living dinosaurs.
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ara sabem que les aus són dinosaures.
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You can see the kinship in their skeletons.
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El parentiu es veu als seus esquelets.
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Certain dinosaurs share some anatomical details with birds
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Alguns dinosaures comparteixen amb els ocells parts de l'anatomia
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found in no other animals, such as wish bones.
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que no es troben en cap altre animal, com la forqueta.
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And in the late 1990s,
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A finals dels anys 90,
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paleontologists started digging up
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els paleontòlegs van desenterrar
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some compelling support for that idea:
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proves convincents que recolzaven aquesta idea:
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dinosaurs with bits of feathers
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dinosaures que encara conservaven
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still preserved on their bodies.
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les plomes als seus cossos.
Des d'aleshores, els científics han trobat
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Since then, scientists have found
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dozens of species of dinosaurs
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dotzenes d'espècies de dinosaures
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with remnants of feathers.
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amb restes de plomes.
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Some were as small as pigeons,
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Alguns eren petits com un colom,
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and some were the size of a school bus.
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d'altres grans com un autocar.
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If you look at how they are related on a family tree,
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Si en mirem la relació en un arbre genealògic,
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the evolution of feathers
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l'evolució de les plomes
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doesn't seem quite so impossible.
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no sembla tan impossible.
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The most distant feathered relatives of birds
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Els parents més llunyans amb plomes dels ocells
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had straight feathers that looked like wires.
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tenien plomes rectes com filferros.
Llavors, aquests filferros es van dividir
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Then these wires split apart,
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producing simple branches.
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formant ramificacions simples.
En molts llinatges de dinosaures,
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In many dinosaur lineages,
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these simple feathers evolved
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aquestes plomes simples van evolucionar
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into more intricate ones,
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cap a unes de més complexes,
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including some that we see today on birds.
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incloses les que podem trobar avui dia a les aus.
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At the same time,
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Alhora,
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the feathers spread across the bodies of dinosaurs,
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les plomes es van escampar pel cos dels dinosaures,
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turning from sparse patches of fuzz
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passant de clapes de borrissol
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into dense plumage,
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a densos plomatges
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which even extended down to their legs.
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que s'estenien fins les potes.
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A few fossils even preserved some of the molecules
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Alguns dels fòssils conserven, fins i tot, algunes de les molècules
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that give feathers color.
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que donen el color a les plomes.
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They reveal a beautiful range of colors:
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Revelen un ventall de colors meravellós:
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glossy, dark plumage, reminiscent of crows,
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plomatges foscs i brillants, com el dels corbs,
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alternating strips of black and white,
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franges blanques i negres,
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or splashes of bright red.
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o taques de vermell llampant.
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Some dinosaurs had high crests on their heads,
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Alguns dinosaures tenien plomalls al cap,
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and others had long, dramatic tail feathers.
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d'altres, llargues plomes a la cua.
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Now, none of these dinosaurs
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Però cap d'aquests dinosaures
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could use their feathers to fly -
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podia fer servir les plomes per volar.
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their arms were too short
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Tenien braços massa curts
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and the rest of their bodies were far too heavy.
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i cossos massa pesats.
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But, birds don't just use feathers to fly.
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Però les aus no utilitzen les plomes tan sols per a volar.
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A woodcock uses feathers to blend in perfectly
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Una becada fa servir les plomes per camuflar-se
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with its forest backdrop.
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al bosc.
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An ostrich stretches its wings over its nest
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Un estruç desplega les ales damunt del niu
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to shade its young.
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per fer ombra a les cries.
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A peacock displays its magnificent tail feathers
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Un gall dindi mostra les meravelloses plomes de la cua
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to attract peahens.
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per atreure les femelles.
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Feathers could have served these functions
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Els dinosaures també podrien fer-les servir
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for dinosaurs too.
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per a aquestes funcions.
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Exactly how feathered dinosaurs took flight
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Encara és un misteri, però, com van alçar el vol
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is still a bit of a mystery.
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els dinosaures amb plomes.
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But if a small-feathered dinosaur flapped
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Però si un dinosaure petit
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its arms as it ran up an incline,
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batés els braços mentre puja un pendent,
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its feathers would have provided extra lift
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les plomes l'ajudarien
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to help it run faster.
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a córrer més de pressa.
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This accident of physics might have led
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Aquest detall físic els podria haver dut
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to the evolution of longer dinosaur arms,
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a l'evolució de braços més llargs
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which would let them run faster
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que els permetéssin córrer més
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and even leap short distances through the air.
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i potser planejar en distàncies curtes.
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Eventually, their arms stretched out into wings.
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Finalment, els braços es van convertir en ales.
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Only then, perhaps 50 million years
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Només llavors, uns 50 milions d'anys
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after the first wiry feathers evolved,
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després de les primeres plomes,
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did feathers lift those dinosaurs into the sky.
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les plomes van alçar els dinosaures cap al cel.
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