How do we know what color dinosaurs were? - Len Bloch
-
0:09 - 0:13This is the microraptor,
-
0:13 - 0:17a carnivorous four-winged dinosaur
that was almost two-feet long, -
0:17 - 0:18ate fish,
-
0:18 - 0:21and lived about 120 million years ago.
-
0:21 - 0:26Most of what we know about it
comes from fossils that look like this. -
0:26 - 0:30So, is its coloration here
just an artist's best guess? -
0:30 - 0:32The answer is no.
-
0:32 - 0:35We know this shimmering
black color is accurate -
0:35 - 0:41because paleontologists have analyzed
clues contained within the fossil. -
0:41 - 0:45But making sense of the evidence
requires careful examination of the fossil -
0:45 - 0:50and a good understanding of the physics
of light and color. -
0:50 - 0:54First of all, here's what we actually see
on the fossil: -
0:54 - 0:58imprints of bones and feathers that have
left telltale mineral deposits. -
0:58 - 1:00And from those imprints,
-
1:00 - 1:02we can determine that these
microraptor feathers -
1:02 - 1:08were similar to modern dinosaur,
as in bird, feathers. -
1:08 - 1:11But what gives birds their signature
diverse colorations? -
1:11 - 1:16Most feathers contain just one
or two dye-like pigments. -
1:16 - 1:18The cardinal's bright red
comes from carotenoids, -
1:18 - 1:21the same pigments
that make carrots orange, -
1:21 - 1:24while the black of its face
is from melanin, -
1:24 - 1:27the pigment that colors our hair and skin.
-
1:27 - 1:30But in bird feathers,
melanin isn't simply a dye. -
1:30 - 1:34It forms hollow nanostructures
called melanosomes -
1:34 - 1:37which can shine in all the colors
of the rainbow. -
1:37 - 1:39To understand how that works,
-
1:39 - 1:42it helps to remember
some things about light. -
1:42 - 1:47Light is basically a tiny electromagnetic
wave traveling through space. -
1:47 - 1:49The top of a wave is called its crest
-
1:49 - 1:53and the distance between two crests
is called the wavelength. -
1:53 - 1:58The crests in red light are about
700 billionths of a meter apart -
1:58 - 2:01and the wavelength of purple light
is even shorter, -
2:01 - 2:06about 400 billionths of a meter,
or 400 nanometers. -
2:06 - 2:10When light hits the thin front surface
of a bird's hollow melanosome, -
2:10 - 2:14some is reflected and some passes through.
-
2:14 - 2:18A portion of the transmitted light
then reflects off the back surface. -
2:18 - 2:21The two reflected waves interact.
-
2:21 - 2:22Usually they cancel each other out,
-
2:22 - 2:25but when the wavelength
of the reflected light -
2:25 - 2:28matches the distance between
the two reflections, -
2:28 - 2:30they reinforce each other.
-
2:30 - 2:33Green light has a wavelength
of about 500 nanometers, -
2:33 - 2:36so melanosomes that are
about 500 nanometers across -
2:36 - 2:38give off green light,
-
2:38 - 2:41thinner melanosomes give off purple light,
-
2:41 - 2:44and thicker ones give off red light.
-
2:44 - 2:46Of course, it's more complex than this.
-
2:46 - 2:50The melanosomes are packed together
inside cells, and other factors, -
2:50 - 2:54like how the melanosomes are arranged
within the feather, also matter. -
2:54 - 2:57Let's return to the microraptor fossil.
-
2:57 - 3:01When scientists examined its feather
imprints under a powerful microscope, -
3:01 - 3:04they found nanostructures
that look like melanosomes. -
3:04 - 3:09X-ray analysis of the melanosomes
further supported that theory. -
3:09 - 3:13They contained minerals that would
result from the decay of melanin. -
3:13 - 3:17The scientists then chose 20 feathers
from one fossil -
3:17 - 3:21and found that
the melanosomes in all 20 looked alike, -
3:21 - 3:25so they became pretty sure this dinosaur
was one solid color. -
3:25 - 3:29They compared these microraptor
melanosomes to those of modern birds -
3:29 - 3:33and found a close similarity,
though not a perfect match, -
3:33 - 3:37to the iridescent teal feathers
found on duck wings. -
3:37 - 3:41And by examining the exact size
and arrangement of the melanosomes, -
3:41 - 3:46scientists determined that the feathers
were iridescent black. -
3:46 - 3:49Now that we can determine
a fossilized feather's color, -
3:49 - 3:54paleontologists are looking for more
fossils with well-preserved melanosomes. -
3:54 - 3:58They've found that a lot of dinosaurs,
including velociraptor, -
3:58 - 4:00probably had feathers,
-
4:00 - 4:05meaning that certain films might not be
so biologically accurate. -
4:05 - 4:07Clever girls.
- Title:
- How do we know what color dinosaurs were? - Len Bloch
- Description:
-
View full lesson: http://ed.ted.com/lessons/how-do-we-know-what-color-dinosaurs-were-len-bloch
The microraptor was a four-winged carnivorous dinosaur with iridescent black feathers. But if our information about this dinosaur comes from fossils, how can we be certain about its color? Len Bloch shows how making sense of the evidence requires careful examination of the fossil and a good understanding of the physics of light and color.
Lesson by Len Bloch, animation by Paul Newell.
- Video Language:
- English
- Team:
- closed TED
- Project:
- TED-Ed
- Duration:
- 04:24
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Jessica Ruby edited English subtitles for How do we know what color dinosaurs were? - Len Bloch | ||
Jessica Ruby edited English subtitles for How do we know what color dinosaurs were? - Len Bloch | ||
Jessica Ruby edited English subtitles for How do we know what color dinosaurs were? - Len Bloch | ||
Jessica Ruby edited English subtitles for How do we know what color dinosaurs were? - Len Bloch | ||
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