Pratique du Shadowing: How do we know what color dinosaurs were? - Len Bloch - Apprendre l'anglais à l'oral avec YouTube

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This is the microraptor, a carnivorous four-winged dinosaur that was almost two-feet long, ate fish, and lived about 120 million years ago.
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This is the microraptor, a carnivorous four-winged dinosaur that was almost two-feet long, ate fish, and lived about 120 million years ago.
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Most of what we know about it comes from fossils that look like this.
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So, is its coloration here just an artist's best guess?
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The answer is no.
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We know this shimmering black color is accurate because paleontologists have analyzed clues contained within the fossil.
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But making sense of the evidence requires careful examination of the fossil and a good understanding of the physics of light and color.
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First of all, here's what we actually see on the fossil: imprints of bones and feathers that have left telltale mineral deposits.
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And from those imprints, we can determine that these microraptor feathers were similar to modern dinosaur, as in bird, feathers.
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But what gives birds their signature diverse colorations?
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Most feathers contain just one or two dye-like pigments.
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The cardinal's bright red comes from carotenoids, the same pigments that make carrots orange, while the black of its face is from melanin, the pigment that colors our hair and skin.
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But in bird feathers, melanin isn't simply a dye.
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It forms hollow nanostructures called melanosomes which can shine in all the colors of the rainbow.
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To understand how that works, it helps to remember some things about light.
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Light is basically a tiny electromagnetic wave traveling through space.
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The top of a wave is called its crest and the distance between two crests is called the wavelength.
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The crests in red light are about 700 billionths of a meter apart and the wavelength of purple light is even shorter, about 400 billionths of a meter, or 400 nanometers.
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When light hits the thin front surface of a bird's hollow melanosome, some is reflected and some passes through.
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A portion of the transmitted light then reflects off the back surface.
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The two reflected waves interact.
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Usually they cancel each other out, but when the wavelength of the reflected light matches the distance between the two reflections, they reinforce each other.
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Green light has a wavelength of about 500 nanometers, so melanosomes that are about 500 nanometers across give off green light, thinner melanosomes give off purple light, and thicker ones give off red light.
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Of course, it's more complex than this.
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The melanosomes are packed together inside cells, and other factors, like how the melanosomes are arranged within the feather, also matter.
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Let's return to the microraptor fossil.
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When scientists examined its feather imprints under a powerful microscope, they found nanostructures that look like melanosomes.
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X-ray analysis of the melanosomes further supported that theory.
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They contained minerals that would result from the decay of melanin.
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The scientists then chose 20 feathers from one fossil and found that the melanosomes in all 20 looked alike, so they became pretty sure this dinosaur was one solid color.
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They compared these microraptor melanosomes to those of modern birds and found a close similarity, though not a perfect match, to the iridescent teal feathers found on duck wings.
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And by examining the exact size and arrangement of the melanosomes, scientists determined that the feathers were iridescent black.
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Now that we can determine a fossilized feather's color, paleontologists are looking for more fossils with well-preserved melanosomes.
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They've found that a lot of dinosaurs, including velociraptor, probably had feathers, meaning that certain films might not be so biologically accurate.
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Clever girls.

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Why practice speaking with this video?

Practicing speaking with the video "How do we know what color dinosaurs were?" offers valuable linguistic and cognitive benefits. Engaging with this content enhances your ability to articulate thoughts clearly about complex topics such as paleontology and the science of color perception in dinosaurs. By using formal scientific language and rich vocabulary, you can significantly improve English pronunciation and comprehension skills while also expanding your vocabulary related to nature and science. The visual elements of the video encourage viewers to visualize concepts, making it easier to remember and discuss similar subjects in English.

Incorporating insights from the dinosaurs' colors into your speaking practice can also help in your IELTS speaking practice, as you learn to formulate detailed descriptions and arguments based on evidence. Shadowing the speaker's delivery can enhance your fluency while allowing you to imitate pronunciation and intonation effectively.

Grammar & Expressions in Context

This video transcript contains several key grammatical structures and expressions that are valuable for English learners:

  • Present Simple Tense: The speaker often uses the present simple to present facts, such as "Most of what we know comes from fossils." This tense helps convey information clearly and directly.
  • Passive Voice: Phrases like "were found" illustrate the passive voice, which is commonly used in scientific contexts to emphasize the action rather than the subject. This structure is useful for learners to describe processes where the doer is less important.
  • Conditional Sentences: The speaker mentions conditions, as in, "if the wavelength of the reflected light matches." Understand this structure to express hypotheses or results in academic discussions.
  • Comparative Forms: "similar to modern bird feathers" highlights comparison, which is essential when discussing similarities and differences in IELTS speaking tasks.

Common Pronunciation Traps

As you engage with this video, pay close attention to the following tricky words and phrases to avoid common pronunciation traps:

  • Microraptor: Pronounced as "my-cro-rap-tor," this specialized term may be difficult due to its length and unfamiliarity.
  • Melanosomes: This term can be tricky, pronounced "mel-uh-no-soams," and requires careful articulation to avoid blending syllables.
  • Iridescent: Often mispronounced, the correct pronunciation is "ir-uh-des-uhnt." Focus on distinct syllables to improve your clarity.

Utilizing the shadowing technique with this video allows you to mimic the speaker's intonation and rhythm, helping you to master these challenging pronunciations while simultaneously absorbing complex vocabulary. As you practice, remember to embrace the science behind the language, making learning both enjoyable and intellectually stimulating!

Qu'est-ce que la technique du Shadowing ?

Le Shadowing est une technique d'apprentissage des langues fondée sur la science, développée à l'origine pour la formation des interprètes professionnels. Le principe est simple mais puissant : vous écoutez de l'anglais natif et le répétez immédiatement à voix haute — comme une ombre suivant le locuteur avec un décalage de 1 à 2 secondes. Les recherches montrent une amélioration significative de la précision de la prononciation, de l'intonation, du rythme, des liaisons, de la compréhension orale et de la fluidité.

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