Pigments preserved in fossils may reveal the color of dinosaurs.
Dinosaur colors. I’m Bob Hirshon and this is Science Update.
Paleontologists agree that many dinosaurs had feathers, but what color were they? Brown University researcher Ryan Carney and his colleagues report in the journal Scientific Reports that they’ve confirmed the presence of black pigments in a dinosaur feather fossil using new chemical analysis methods.
Now is an exciting time, to be able to leverage these new analytical techniques for looking into the past and trying to reconstruct the full palette of colors to the best extent possible.
The team compared the fossil pigment chemical structure to pigments from both modern animals and bacteria and confirmed they came from the dinosaur, and not bacteria contaminating the fossil. Now they’ll look for traces of pigment in other fossils and gradually replace some of the current guesswork about dinosaur skin and feather color with evidence. I’m Bob Hirshon, for AAAS, the science society.
Making Sense of the Research
The skin or feather color of dinosaurs we see in museums has long been the work of paleontologists' educated guesses and illustrators' imaginations. Since the soft tissue of these long-extinct animals does not normally survive the march of time, paleontologists are usually left with the fossils of the dinosaurs' skeletons. These fossils allow scientists to reconstruct the animals' structures but they have to use guesswork to make determinations about what colors they might have been.
With the discovery of some preserved dinosaur feather fossils, however, Ryan Carney and his colleagues have been able to determine the coloring of at least one type of dinosaur: Anchiornis huxleyi. How was this possible?
In 2010, research conducted by a team of scientists from the United Kingdom and China, and published in the journal Nature, indicated that structures visible in preserved dinosaur feathers from China resembled similar sacs that dictate feather color in modern birds. This finding made paleontologists realize that they could determine the feather color of some extinct dinosaurs. The discovery, however, was met with some skepticism by those who argued that what the team thought were melanosomes (small organelles found in bird feathers and mammal hair that are different shapes depending on the color of pigment they contain) were in fact fossilized bacteria.
In order to make a definitive analysis of the fossilized feathers, in 2015 Carney and his colleagues used a chemical analysis method called time-of-flight (TOF) secondary ion mass spectrometry to confirm that the structures they found in the feathers were in fact melanosomes. The TOF secondary ion mass spectrometry is a technique that removes molecules from the very outermost surface of a sample. These particles are then accelerated into a "flight tube" and their mass is determined by measuring the exact time at which they reach the detector. By using this technique, the researchers were able to confirm that the structures they found were indeed melanosomes, particularly eumelanosomes (rod-shaped organelles found in black feathers), and not bacteria. So, the chemical makeup of what looked like fossil eumelanosomes was virtually identical to that found in living birds.
“This evidence of animal-specific melanin in fossil feathers is the final nail in the coffin that shows that these microbodies are indeed melanosomes and not microbes,” said Carney. With this discovery, scientists can be more confident about using fossilized melanosomes in determining the color of dinosaurs from preserved feathers.
Now try and answer these questions:
- Before this research, how did paleontologists determined the color of dinosaurs?
- What did the team of researchers from the United Kingdom and China discover in 2010? What is the significance of their discovery?
- What was the main challenge to the discovery?
- What kind of analysis was done to figure out if the structures the researchers found in the feathers were melanosomes or bacteria?
- Can you think of other ways that paleontologists can determine the color of dinosaurs?
In T. Rex Bully, you can hear about how scientists examining the fossils of this dinosaur think that instead of being ferocious predators, T. Rexes were more likely scavengers that muscled in on the kills of other dinosaurs.
You might want to listen to this encore presentation of this Science Update Podcast on ancient anatomy that includes: what dental records from the Mesozoic era can tell us about the lives of dinosaurs, how humans are uniquely adapted to throw baseballs, an automated nature recording system that's monitoring environmental change, and if vaccinating children could protect the elderly as well.
You can extend the ideas in this Science Update by having your students listen to another Science Update called From Teeth to Beaks, which looks at how the ancestors of birds lost their teeth.
This Science Update is also a great way to help your students understand how scientists build on the research conducted by others and how they remain skeptical and question each other's work. The related resources here can help you encourage your students to ask questions and conduct their own investigations.
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