Imagine a dinosaur called the Microraptor. It was a small, meat-eating dinosaur with four wings, about two feet long, and lived around 120 million years ago. Most of what we know about it comes from fossils. But how do we know what color it was? Is it just a guess by artists? Surprisingly, the answer is no. Scientists have figured out its color by studying clues in the fossils, using a mix of fossil examination and understanding how light and color work.
When scientists look at a Microraptor fossil, they see imprints of bones and feathers. These imprints leave behind mineral deposits that tell us a lot. The feathers of the Microraptor were similar to those of modern birds. But what makes bird feathers so colorful? Most feathers have one or two pigments. For example, the bright red of a cardinal comes from carotenoids, the same pigments that make carrots orange. The black color comes from melanin, the pigment that colors our hair and skin. In bird feathers, melanin forms tiny structures called melanosomes, which can reflect all the colors of the rainbow.
To understand how melanosomes work, we need to know a bit about light. Light is a tiny electromagnetic wave moving through space. The top of a wave is called its crest, and the distance between two crests is the wavelength. Red light has a wavelength of about 700 nanometers, while purple light is around 400 nanometers.
When light hits the surface of a bird’s melanosome, some of it reflects, and some passes through. The light that passes through can reflect off the back surface. These two reflected waves can interact. Usually, they cancel each other out, but if the wavelength matches the distance between the reflections, they reinforce each other. For example, green light has a wavelength of about 500 nanometers, so melanosomes that size give off green light. Thinner melanosomes give off purple light, and thicker ones give off red light. The arrangement of melanosomes in the feather also affects the color.
When scientists examined the Microraptor’s feather imprints under a microscope, they found structures similar to melanosomes. X-ray analysis showed minerals that form from decayed melanin. By studying 20 feathers from one fossil, scientists found that all the melanosomes looked alike, suggesting the dinosaur was one solid color. Comparing these melanosomes to those of modern birds, they found a similarity to the iridescent teal feathers on duck wings. By analyzing the size and arrangement of the melanosomes, they concluded that the Microraptor had iridescent black feathers.
Now that scientists can determine the color of fossilized feathers, they are searching for more fossils with well-preserved melanosomes. They’ve discovered that many dinosaurs, like the Velociraptor, probably had feathers. This suggests that some movies might not be entirely accurate in their portrayal of dinosaurs.
Understanding the color of dinosaurs helps us learn more about their behavior and environment. It’s amazing how much we can discover from fossils with the help of science!
Imagine you’re a paleontologist! Use clay and small objects like leaves or feathers to create your own fossil imprints. Once the clay hardens, observe the imprints and discuss how scientists might use similar techniques to study dinosaur fossils. Think about what information you can gather from your imprints.
Use a prism to split light into its component colors. Observe how light behaves and discuss how this relates to the way melanosomes in feathers reflect light to create colors. Consider how different wavelengths of light contribute to the colors we see in nature.
Based on what you’ve learned about melanosomes and feather colors, draw your own dinosaur with realistic colors. Use modern birds as inspiration and explain your color choices based on the science of light and melanosomes. Share your design with the class and discuss the reasoning behind your color selections.
Examine feathers from different birds under a magnifying glass or microscope. Identify the colors and patterns you see. Discuss how these observations might help scientists infer the colors of dinosaur feathers. Consider how melanosomes might be arranged to produce the colors you observe.
Investigate how the portrayal of dinosaurs in movies and media has changed over time. Create a timeline showing these changes and discuss how scientific discoveries, like the color of dinosaur feathers, have influenced these portrayals. Reflect on how new findings might continue to change our understanding of dinosaurs.
Here’s a sanitized version of the transcript:
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This is the Microraptor, a carnivorous four-winged dinosaur that was nearly two feet long, ate fish, and lived about 120 million years ago. Most of what we know about it comes from fossils that look like this. So, is its coloration just an artist’s best guess? The answer is no. We know this shimmering black color is accurate because paleontologists have analyzed clues contained within the fossil. However, making sense of the evidence requires careful examination of the fossil and a good understanding of the physics of light and color.
First of all, here’s what we actually see on the fossil: imprints of bones and feathers that have left telltale mineral deposits. From those imprints, we can determine that these Microraptor feathers were similar to modern bird feathers. But what gives birds their signature diverse colorations? Most feathers contain just one or two dye-like pigments. For example, the bright red of a cardinal 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. In bird feathers, melanin isn’t simply a dye; it forms hollow nanostructures called melanosomes, which can shine in all the colors of the rainbow.
To understand how that works, it helps to remember some things about light. Light is essentially a tiny electromagnetic wave traveling through space. The top of a wave is called its crest, and the distance between two crests is called the wavelength. The crests in red light are about 700 billionths of a meter apart, while the wavelength of purple light is even shorter, about 400 billionths of a meter, or 400 nanometers.
When light hits the thin front surface of a bird’s hollow melanosome, some is reflected and some passes through. A portion of the transmitted light then reflects off the back surface. The two reflected waves interact. 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. 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. Of course, it’s more complex than this. The melanosomes are packed together inside cells, and other factors, like how the melanosomes are arranged within the feather, also matter.
Returning to the Microraptor fossil, when scientists examined its feather imprints under a powerful microscope, they found nanostructures that resemble melanosomes. X-ray analysis of the melanosomes further supported that theory, as they contained minerals that would result from the decay of melanin. The scientists then chose 20 feathers from one fossil and found that the melanosomes in all 20 looked alike, leading them to conclude that this dinosaur was one solid color. 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. By examining the exact size and arrangement of the melanosomes, scientists determined that the feathers were iridescent black.
Now that we can determine a fossilized feather’s color, paleontologists are looking for more fossils with well-preserved melanosomes. They’ve found that many dinosaurs, including Velociraptor, probably had feathers, suggesting that certain films might not be entirely biologically accurate.
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This version maintains the informative content while removing any informal language or phrases that could be considered inappropriate.
Dinosaur – A group of reptiles that lived millions of years ago, known for their large size and diverse species. – The Tyrannosaurus rex is one of the most famous dinosaurs studied in paleontology.
Microraptor – A small, four-winged dinosaur that lived during the early Cretaceous period. – The microraptor is known for its unique ability to glide using its feathered limbs.
Fossil – The preserved remains or traces of organisms that lived in the past, often found in sedimentary rock. – Scientists discovered a fossil of a prehistoric fish embedded in the rock layer.
Feather – A structure made of keratin that covers the bodies of birds and some dinosaurs, used for flight, insulation, and display. – The discovery of feather impressions on a dinosaur fossil provided evidence of its ability to glide.
Pigment – A substance that gives color to tissues in living organisms, often used for camouflage or signaling. – The bright pigment in the butterfly’s wings helps it attract mates and deter predators.
Light – A form of energy that travels in waves and can be seen by the human eye, essential for vision and photosynthesis. – Plants use light from the sun to produce food through the process of photosynthesis.
Melanin – A natural pigment found in most organisms, responsible for coloration in skin, hair, and eyes. – Melanin in the skin provides protection against harmful ultraviolet rays from the sun.
Wavelength – The distance between consecutive peaks of a wave, such as light or sound, determining its properties like color or pitch. – Different colors of light have different wavelengths, with red having the longest wavelength visible to the human eye.
Color – The characteristic of visual perception described through categories such as red, blue, and green, determined by the wavelength of light. – The color of a leaf changes in autumn due to the breakdown of chlorophyll and the presence of other pigments.
Science – The systematic study of the natural world through observation and experiment, leading to knowledge and understanding. – Science helps us understand the processes that govern life on Earth, from the smallest cells to the largest ecosystems.
