Based on different shapes of the cells, palaeontologists can predict the colouring of the dinosaurs' feathers, a technique that was first developed in 2010.
Other interesting features of the dinosaur are the bony crest on its snout, a long and narrow skull, and its short forelimbs that recall modern birds.
Don't be fooled by the fossil's slate hue: Newly discovered Caihong juji, a winged dinosaur that roamed what is now China around 161 million years ago, was likely bursting with color-a shock of blue and green around its face, and streaks of orange highlighting its wings and tail.
A description of the exquisitely preserved, chicken-sized dinosaur was published on January 15 in the journal Nature Communications.
Since that year, the scientists from the University of Texas at Austin and Shenyang Normal University have been examining the body to know more about the dinosaur.
Caihong is the earliest known animal with asymmetrical feathers and the earliest evidence to date of a species that may have had bright iridescent feathers.
It's been named Caihong, the Mandarin word for rainbow.
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"To be honest, I am not sure what function the feathers have, and I don't think that you can completely exclude the possibility that the feathers helped the animal to get in the air", paleontologist Xing Xu of the Chinese Academy of Sciences tells Dunham. The plumage on its neck contain what appears to be traces of melanosomes - wide, pigment-containing packets that give feathers their colour.
Their shape determines the colour and Caihong's feathers had pancake-shaped melanosomes, similar to those of vibrantly coloured hummingbirds.
Caihong's were on its tail, suggesting tail feathers, not arm feathers, were first utilized for aerodynamic locomotion.
The slab of rock, found by a farmer in 2014, contained almost a complete skeleton. The impressions preserved the shape of the melanosomes.
"Here we report a distinctive new Yanliao theropod species bearing prominent lacrimal crests, bony ornaments previously known from more basal theropods", researcher Chad Eliason of the Field Museum in Chicago, said as part of a study published in the journal Nature Communications. "It is really cool ... or maybe creepy looking depending on your perspective". Birds evolved from small feathered dinosaurs near the end of the Jurassic Period. The researchers say it is the earliest known dinosaur to display feathers of this type and, though they are found today on the wingtips of modern birds, Caihong's asymmetrical feathers were found on its tail.
"This combination of traits is rather unusual", said Julia Clarke, from the University of Texas at Austin, a co-author of the study. He helped analyze the microstructural fossil evidence for color in the new specimen while he was a postdoctoral researcher at the UT Jackson School of Geosciences.
This combination of old and new traits is evidence of mosaic evolution, the concept of different traits evolving independently from each other, he says.