March 9, 2012
Microraptor was an exquisitely feathered dinosaur. The small, sickle-clawed predator, which lived about 120 million years ago, was covered in well-developed plumage, including long feathers on its arms and legs. But we now know that Microraptor was not only beautiful in an anatomical structure sense. A detailed new study has painted this dinosaur in a glossy black sheen.
The range of the dinosaur palette has been one of the most mysterious aspects of dinosaur biology. For most species, we just don’t know—bones and teeth can’t tell us anything about skin color. But feathered dinosaurs contain evidence of their hues within their feathers. Microscopic organelles called melanosomes are the key. In fossil creatures—just as in living ones—the size, shape, density and distribution of these tiny, pigment-filled blobs created different colors. By studying the characteristics of melanosomes in feathered dinosaurs and comparing the patterns with those that create the colors of modern birds, paleontologists can reconstruct dinosaur feather colors.
Several dinosaurs have already received a color treatment. After establishing that fossil melanosomes are faithful indicators of prehistoric color in ancient birds, paleontologist Jakob Vinther and colleagues restored the full-body coloring of the feathered, non-avian dinosaur Anchiornis. This small dinosaur looked something like a magpie with a bright red splash of feathers on top of its head. Earlier this year, Vinther, Ryan Carney and co-authors determined that the famous feather used to name the earliest known bird—Archaeopteryx—was black. And a different team of researchers, led by paleontologist Fucheng Zhang, hypothesized that the fuzzy Sinosauropteryx had a candy-cane tail ringed in white and rusty red. Paper by paper, dinosaurs are being colored in.
In the case of Microraptor, the dinosaur did not turn out quite like any of the restorations that artists had previously composed. Many Microraptor illustrations envisioned the dinosaur in shades of brown, white and blue. But when Vinther, Quanguo Li and collaborators studied the melanosomes sampled from 26 different locations on a Microraptor specimen designated BMNHC PH881, they didn’t find those colors. Microraptor feathers were iridescent blue-black. In appearance, Vinther said via email, Microraptor would have looked similar to “grackles or a magpie, or indeed a crow.”
Black was apparently quite fashionable among feathered dinosaurs. Anchiornis, while overall more colorful, was also predominantly black, and the lone Archaeopteryx feather was also black. Why black was so common for dinosaurs with complex, specialized feathers isn’t clear. Vinther pointed out that the small sample size might be creating this pattern, especially since other, unpublished specimens show different colors. Then again, black and other dark shades might have had something to do with where the animals lived. Citing a phenomenon called Gloger’s rule, Vinther explained that mammals and birds that live in hot, humid environments near the equator have more of the pigment melanin, and therefore appear darker, than those living closer to the poles, though “sample size needs to be increased to make any generalizations like these,” he cautioned.
Vinther is confident that further studies will increase the number of dinosaurs for comparison. “The material is clearly there,” he said. It is only a matter of time before paleontologists can start to understand how color varied between individuals, and possibly even between the sexes. For the moment, though, the handful of dinosaurs that have been restored in color have shown that intricate avian traits existed far back in the past. “We were speculating about how deep iridescent colors might be and we were pretty excited when we realized that Microraptor indeed is iridescent,” Vinther said, and this discovery can tell us something about how feathers and even behaviors evolved among early birds and their dinosaurian kin.
“We can see that the paravian clade,” the group that contains birds and non-avian dinosaurs more closely related to birds than dinosaurs , “has complex feather morphologies and exhibit colors and color patterns for display and even iridescence like in modern birds, so these features are ancient and indeed suggest that at least the derived theropod dinosaurs were more similar in ecology and behavior to birds,” Vinther said. And, as research continues on feathered dinosaurs more distantly related to birds, Vinther suspects that many characteristics of modern birds will be pulled “deep down” the dinosaurian tree. The more we learn about feathered dinosaurs, the further back we can draw traits seen among birds today.
And there are still things to learn about the anatomy of feathered dinosaur plumage. While the iridescent hues of Microraptor are the major finding of the new paper, the study also pointed out that specimen BMNHC PH881 had a specialized set of paired feathers at the end of the tail. Similar feathers had been noted in other Microraptor specimens before, but this fossil had an especially lovely set. The structures are “simply too small and the feathers too spaced to create any lift,” Vinther said, so it’s unlikely that they aided the dinosaur in gliding or flying. Instead, citing the assessment of co-author Julia Clarke, Vinther said that the feathers might have been a display structure. Combined with the flashy feathers, these structures might be another clue that display and visual communication were very important factors in the early evolution of feather anatomy and color.
For most of my life, I was told that we would never know what colors dinosaurs were. Now, amazingly, there is a way to restore the appearances of some dinosaurs with a fidelity never thought possible. But I had to wonder if paleo-artists have felt any aggravation about such discoveries. As new studies establish feather colors for dinosaurs, the realistic palettes for those dinosaurs are constrained. I asked Vinther if he has received any irritated comments from artists about his work. He replied that, to the contrary, his research has been greeted with excitement. And while defining dinosaur colors “might take some of the imagination from the artists,” Vinther said, “I think that their fascination with these beasts gives them a desire to make them more scientifically correct.” The colorfully restored dinosaurs seem to be a hit. “I am struck by awe when I google-image Anchiornis and see forty plus versions of Anchiornis by various artists all over the world and even tattoos of it,” Vinther said. With any luck, the new glossy Microraptor will be just as popular.
Carney, R., Vinther, J., Shawkey, M., D’Alba, L., & Ackermann, J. (2012). New evidence on the colour and nature of the isolated Archaeopteryx feather Nature Communications, 3 DOI: 10.1038/ncomms1642
Li, Q., Gao, K., Vinther, J., Shawkey, M., Clarke, J., D’Alba, L., Meng, Q., Briggs, D., & Prum, R. (2010). Plumage Color Patterns of an Extinct Dinosaur Science, 327 (5971), 1369-1372 DOI: 10.1126/science.1186290
Li, Q., Gao, K., Meng, Q., Clarke, J., Shawkey, M., D’Alba, L., Pei, R., Ellison, M., Norell, M., & Vinther, J. (2012). Reconstruction of Microraptor and the Evolution of Iridescent Plumage Science, 335 (6073), 1215-1219 DOI: 10.1126/science.1213780
Zhang, F., Kearns, S., Orr, P., Benton, M., Zhou, Z., Johnson, D., Xu, X., & Wang, X. (2010). Fossilized melanosomes and the colour of Cretaceous dinosaurs and birds Nature, 463 (7284), 1075-1078 DOI: 10.1038/nature08740
August 17, 2011
I’ve seen plenty of roadside dinosaurs out here in the American West, and many of them come in muted shades of green and brown. There are a few exceptions to the rule, though, like this hot pink Stegosaurus spotted by reader David Schey at the Dinosaur Ridge visitors center in Morrison, Colorado. “Is this what paleontologists see after having one too many?” David wonders. I can confidently say, “no.” When I’ve had one too many, I see pink Allosaurus.
Have you seen a dinosaur or other prehistoric creature in an unusual place? Please send your photo to firstname.lastname@example.org.
March 22, 2010
In reaction to my post about Dryptosaurus the other week, paleo-artist Michael Skrepnick told me about the efforts of his colleague Tyler Keillor to create a fleshed-out restoration of the dinosaur. I immediately e-mailed Tyler about the project, and he was kind enough to answer a few of my questions.
Brian: I heard that you have created a restoration of a Dryptosaurus head. Can you tell me a little about the background of the project?
Tyler: There’s a museum about 50 miles Northwest of Chicago in Wauconda, Illinois, called the Lake County Discovery Museum I’d previously worked with the Exhibits Manager there, Steve Furnett, when we both worked in the Field Museum’s Exhibition Department about 10 years ago. Steve was planning a new temporary exhibit called “Prehistoric Lake County,” which would show the types of animals and environments that would have existed in the area during different segments of time. Paleontologist/scientific advisor to the exhibit, Richard Kissel, helped determine what types of animals could be shown in the exhibit based upon local fossils that have been found, and then speculatively which types of animals might have lived in the area during other chapters of time, but for which we have no remains to observe directly. This is where Dryptosaurus came in. It was also a toss up between a Hadrosaurus, or a Coelophysis. But (happily) the Drypto. won out for the reconstruction. The head served as a great attractor to get visitors into the gallery, where there were lots of real and cast fossils, graphic panels explaining what was known and what was presumed to have lived in the area, as well as a great animation by Chicago animator Pat Bradley.
Brian: Despite being one of the first dinosaurs to be known from a partial skeleton, we still do not know very much about Dryptosaurus. How did you go about restoring such an enigmatic dinosaurs? What other dinosaurs did you use for comparison?
Tyler: We started by familiarizing ourselves with all of the known Dryptosaurus remains; as you know, there aren’t many! An interesting reference was Thomas Carr’s Appalachiosaurus paper (Journal of Vertebrate Paleontology, 25(1): 119–143) which includes a cladogram with skull silhouettes for the species that are represented. It looks to me like the illustration of the Appalachiosaurus skull served as a template for the Dryptosaurus skull in the cladogram, with the known Dryptosaurus skull bones fitting nicely within the outline. I think it’s a fair and conservative glimpse at what a Drypto. skull might have looked like. Fortuitously, I had previously been involved with the Burpee Museum in Rockford, Illinois, for their “Jane” project. Jane is a juvenile tyrannosaur, and while the specimen is beautiful, I did have to sculpt about 40 percent of the skull to reflect parts that weren’t preserved in order to complete it. This restored skull model is remarkably similar to that Appalachiosaurus skull illustration. After completing the Jane skull for the Burpee, I then sculpted the flesh reconstruction atop its skull cast. (On display, along with two Mike Skrepnick paintings of Jane as well as the mounted skeleton, in the exhibit entitled “Jane, Diary of a Dinosaur.”) Since the size of the Drypto. bones seemed pretty close to those of Jane, I felt pretty good about using my Jane head as a starting point to extrapolate a Dryptosaurus flesh head.
Brian: Your restoration of Dryptosaurus has wispy feathers on it. What made you decide to include them?
Tyler: The feathery covering is of course speculative. However, Richard didn’t mind this bit of artistic license, since we can see that Dilong had a feathery coat of some kind. So far, the only skin impressions I’m aware of for tyrannosaurs include tiny rounded scales from footprints, and a description of a dewlap outline (was it for a Tarbosaurus?). So I didn’t think that at least some feathers were out of the question. I applied the feathers along the midline of the neck to top of the head, and tapered them out along the sides of the neck. There’s another stripe of lighter feathers lower on the neck, evoking the patterns of apteria and feather tracts of living birds. For a simple filamentous look, I started with ostrich plumes. I stripped the barbs off of the central vane, and then trimmed these to length before individually adhering them.
Brian: One of the most frequently-asked questions about dinosaurs is “What color were they?” What influenced your decisions in choosing colors for Dryptosaurus?
Tyler: I created a few Photoshop mockups of coloration choices for the museum. My favorite, and one that I’d been wanting to do for a while, had a dark hide ranging from black to dark grey, with a lighter ventral surface. The dewlap gave me a chance to include a pop of color, especially with the possibility that this could have been used as a display structure. I went with a rooster-comb red color for those wrinkled areas of the throat. Overall, a pretty drab coloration, but this actually highlights the eyes, the teeth, the scars, the wattle. In person, it’s a pretty scary face to look at!
Brian: Can you describe the process by which you created the restoration? How did it go from an idea to a finished sculpture?
Tyler: I didn’t want to make a roaring head, which I felt has been done so many times before by so many artists. My personal anatomical philosophy for theropods includes a sealed oral margin (with teeth covered) when in closed-mouth pose, but this would eliminate a lot of the “wow” factor for the museum. So I thought a slightly parted mouth would be a good way to show some teeth, and also represent an unusual pose: as if the animal is panting slightly, or gaping a bit and employing gular flutter to thermoregulate. I also modified the eye size and orientation from previous models I’d done, using some recent studies for reference. By partially closing the eyes, the head took on an eerie, contemplative appearance. I added lots of scars, both healed and fresh, to represent some of facebiting wounds Drypto. may have suffered as other tyrannosaurs did, if not scars from the dangerous predatory lifestyle. Using my Jane molds as a starting point, I resculpted the pose of the jaw and neck, changed the length of the teeth, added a dewlap, resculpted the eye and lacrimal area, changed the nostril openings, added scarring, etc. The display cast is polyurethane resin, with glass eyes, painted with acrylics. I use dental acrylic for the teeth, so they have a natural translucency when viewed from different angles.
Tyler’s Dryptosaurus restoration can be seen at the Lake County Discovery Museum in Wauconda, Illinois.
February 5, 2010
For the first time ever, paleontologists can look at dinosaurs in color.
In last week’s issue of the journal Nature, scientists described the discovery of melanosomes, biological structures that give feathers their color, in the wispy “dinofuzz” of the small theropod Sinosauropteryx. Not only did this provide unequivocal evidence that the dinosaur had a downy coat of feathers, but the presence of the microscopic structures provided scientists the potential to find out what color those feathers were.
When I read the Nature study I wondered how long it would be before scientists would be able to find a way to conclusively determine the colors of feathered dinosaurs from their preserved melanosomes. As it turned out, I would only have to wait a week. In this week’s issue of Science, a second team of scientists has restored a recently-discovered feathered dinosaur, Anchiornis huxleyi, in living color.
As described in last week’s study there are two major varieties of melanosomes: eumelanosomes (associated with black-grey shades) and phaemelanosomes (indicative of reddish to yellow tints). Both of these kinds of structures can be seen in the fossilized feathers of exquisitely-preserved dinosaurs, but the question is how they corresponded to the actual colors of the animal. The melanosomes cannot speak for themselves; they require a key to unlock what colors might have been present.
Acquiring that key was a two-step process. To figure out how melanosomes were distributed across the plumage of Anchiornis, the team behind the Science paper took 29 chips from different parts of a well-preserved specimen. Each chip had a different combination of melanosomes, and to translate these associations into colors the team turned to the closest living relatives of dinosaurs like Anchiornis, birds. By looking at how melanosomes create colors in these modern dinosaurs the scientists could determine how different mixes creates different tints and shades.
While the restoration of Anchiornis the team produced is still provisional, it is the first time that scientists have been able to hypothesize the full coloration of a dinosaur on direct fossil evidence. According to the new research, Anchiornis would have been mostly black with white accents on its wings (which it carried on both its arms and legs). Its head, however, would have been a little more brightly colored. It appears that Anchiornis had a burnt-orange headdress and freckles, possibly meaning that these bright colors played a role in communicating to other birds. (Which makes me wonder if, like modern birds, colors differed between the sexes.)
And this is just the start. In the past decade paleontologists have described dozens of species of feathered dinosaurs from hundreds of known specimens. There is a vast store of paleobiological information just waiting to be tapped, and it will literally change the way we see dinosaurs.
Li, Q., Gao, K., Vinther, J., Shawkey, M., Clarke, J., D’Alba, L., Meng, Q., Briggs, D., Miao, L., & Prum, R. (2010). Plumage Color Patterns of an Extinct Dinosaur Science DOI: 10.1126/science.1186290