I’ve previously written about work identifying the colors of feathers in fossil dinosaurs (birds, of course, evolved from feathered dinosaurs). These colors were assumed by looking at the shapes of melanosomes (pigment granules) in the fossils and judging the color from the shape of the granules—assuming granule shapes were conserved between fossil and modern birds. Now, however, according to a new paper in Science by Wogelius et al., we can guess the colors more directly by a method (Synchrotron Rapid Scanning X-Ray Fluorescence, or SRS-XRF) that can detect trace metals that are attracted by some pigments. Using this, the authors found that a fossil bird, Confuciusornis sanctus, appears to have had had the pigment eumelanin, which is blackish-brown.
C. sanctus is the first known bird that had a true beak, and lived about 120 million years ago. The fossil is to the left below (A, images from the paper) and the SRS-XRF scan, with false color, to the right (B). Copper shows up as red, and is in especially high concentration in the neck feathers. This, along with other analyses, suggested that those regions had high concentrations of the pigment eumelanin, which binds copper.
When they examined the copper-rich region of the neck feathers with scanning electron microscopy, they found the region full of bodies that looked like “eumelanosomes” (pigment granules containing eumelanin). These granules were also found in some of the flight feathers. Here’s one of the copper-rich granules.
To verify that these were not artifacts, they looked at a variety of material from other living or fossil species, including other animal parts known to be high in copper (fish eyes) and feathers of living birds, which also showed a correlation between eumelanin pigment density and high copper detected by SRS-XRF.
Conclusion: C. sanctus had the pigment eumelanin in its neck feathers, so it probably had dark downy feathers, shading into lighter colors at the tips of the flight feathers, where copper concentration is lower. The distal flight feathers had no trace metals, and so were probably white or another color. Our best guess, then, is that this ancient bird was parti-colored.
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Wogelius, R. A. et al. 2011. Trace metals as biomarkers for eumelanin pigment in the fossil record. Science (early view): 10.1126/science.1205748
h/t: Greg Mayer
And of course, the main authors are from the University of Manchester!
I hope City fans!
That is one old bird – I had forgotten that birds were around so early. When you consider that this bird lived as long before the demise as the dinosaurs as we do after – & that the Cretaceous lasted what – 80 million years…! Astounding what science can tell us about the world! Science millions, religions 0.
That’s completely brilliant. Thanks very much.
Very cool stuff, Jerry! I’m currently reading Chiappe & Witmer’s Mesozoic Birds: Above the Heads of Dinosaurs, and Dyke & Kaiser’s Living Dinosaurs. The fossils don’t directly tell us what these birds might’ve looked like in life, so I’ve been wondering, especially since the confucious birds and enantiornithes are pretty new to me. When I was an undergrad, just about all the fossil material for early birds was restricted to three taxa: Archeopteryx, Ichthyornis, and Hesperornis, and that left an 80MY gap in the record, which has only recently begun to be filled in.
Correct me if I’m wrong, but I thought much of the coloration of bird feathers comes from iridescence. So the fact the some feathers show no pigmentation doesn’t mean they were white. Unless the claim is that iridescence evolved much later — but how would we know? Presumably iridescence doesn’t fossilize (since it relies on nanometer-scale structure).
I think almost all of the blues and most of the greens are iridescence. The rest are pigments other than melanin. This seems a black-and-white snapshot of the ancient bird, not a view of its ‘coloration’.
Nanometer-scale structure doesn’t fossilize?
So how small structures have been seen? It would be interesting to know if there is a scale cut-off to get a grasp for these things. And the reason it occurs, natch.
Some bird coloration is definitely from pigmentation, and in some cases the pigment comes directly from the birds’ food (e.g. certain kinds of carotenoids).
It’s theorized that this serves as a signal of health — at least, the ability to obtain plenty of food — for potential mates.
I wonder if you could use the same technique, only in reverse, to test for evidence of feathers in fossils that are not so well preserved – say a dinosaur fossil. Maybe it also would work for pigments associated with hair, opening up a new avenue of researck into mammal fossils.
If only a look-back-in-time machine could ever be invented. I wonder if palaeontologists never dream about that.
I’m sure I wouldn’t not.
I’m frankly amazed that micrometer scale structures are so well preserved and clearly visible in a fossil!