The world's first birds, along with dinosaurs and other prehistoric animals, likely sported colorful, patterned exteriors.
Paleontologists have long speculated that such animals were colorful, but finding concrete evidence has been challenging, given that most specimens consist of drab fossilized bones.
Now a scientific team has discovered patterned chemical traces of a pigment, an important component of color, in the remains of species that lived up to 120 million years ago.The findings were described in a new paper in the latest issue of Science Express.
"Color is only what we see," co-author Phil Manning told Discovery News, explaining that it's "a function of structure, chemistry and interplay of light. A bright red apple in sunlight has color, but the same apple has no color in a pitch-black room, as no light is interacting with its surface to yield color."
Since light levels and vision come into play, dinosaur-era animals' "perception of color would have been very different from our own," added Manning, a University of Manchester paleontologist.
Geochemist Roy Wogelius, Manning, and other researchers collaborated with Uwe Bergmann of the Department of Energy's SLAC National Accelerator Laboratory to examine the remnants of prehistoric, now-extinct animals. These included two important fossilized birds: Confuciusornis sanctus, which lived 120 million years ago and featured the world's first known bird-like beak; and Gansus yumenensis, considered by many to be the oldest modern bird. It lived more than 100 million years ago and looked a bit like a modern grebe.
The lab's powerful X-rays unveiled traces of pigment in the specimens. Chief among those was copper, which Manning explained stays behind as a "ghost of the biosynthesis and composition of eumelanin pigment, whose structure compares well with that mapped in living species."
Eumelanin is one of the coloring agents responsible for brown eyes and dark hair in many modern species, including humans. It would have been one of the factors that determined the birds' color patterns, along with structural properties of the birds' feathers and other pigments they ingested as part of their diets.
"We were able to map elevated levels of eumelanin pigment in the neck, body and distal tail feathers of C. sanctus," Manning said. These provide some hint as to how different shades produced eye-catching patterns on the beaked bird.
"G. yumenensis, however, only preserved the distinctive copper biomarker indicating the presence of eumelanin pigment, given the structural data was long lost in the sands of time," he added.
Nevertheless, the study presents the most accurate representation of pigment patterning in a complete extinct species of fossil bird. "Complete" is emphasized, because prior studies were based on isolated chips removed from fossils. This new X-ray technique does not damage the fossils, so it holds promise for many more future investigations.
As it stands, this study, combined with earlier research, has shown that birds and other animals from the Dinosaur Age likely flashed dark black, brown and reddish brown hues. A rainbow of colors probably existed, but concrete evidence for those other shades remains elusive.
The findings so far, however, at least provide clues as to what some now-extinct animals looked like in the flesh.
"These new techniques for teasing out evidence of pigmentation will take a lot of the guesswork out of reconstructing the appearance of extinct dinosaurs and birds," said renowned dinosaur illustrator James Gurney, who authored the best-selling Dinotopia series.
Aside from shedding light on the animals' appearance, Wogelius and his team hope to use such research on pigmentation to learn more about extinct animals' feeding habits, visual communication, use of camouflage, mating behaviors and environments.