There was such a thing as a rainbow dinosaur

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Jan 18, 2018

When you think of dinosaurs, the enormous sauropods and therapods of Jurassic Park probably stomp into your mind, except none of them were flying rainbows.

Cihong juji might have not been anywhere near the size that would let it smash cars under its feet or a human in its powerful jaws (like that one infamous scene), but the 161-million-year-old feathered dinosaur recently unearthed in China by researchers from the University of Texas is dazzling paleontologists for another reason. The birdlike creature is a strange ancient-and-modern mashup with the kind of iridescent feathers you may see shimmering on a hummingbird. No wonder its name translates to “rainbow with a big crest.”

Iridescent feathers—which are the result of microscopic melanosomes, or packages of pigment— aren’t all flash. Just think of how birds of paradise put on a show when breeding season comes around.

“Iridescent coloration is well known to be linked to sexual selection and signaling, and we report its earliest evidence in dinosaurs,” said professor Julia Clarke of the Department of Geological Sciences at the UT Jackson School of Geosciences, who helped lead the study published in Nature along with Chinese scientists Dongyu Hu and Xing Xu. “The dinosaur may have a cute nickname in English, Rainbow, but it has serious scientific implications.”

So we know Cihong juji was eye candy, but that isn’t its only intriguing creature feature. Its iridescent neck feathers might be the first evidence of the same color-shifting magic that we see in hummingbirds and birds of paradise, but it also seems to have inherited its bony crest from more ancient life forms.

The strange skull of Cihong juji. Credit: University of Texas

There is more to this dino’s bizarre DNA. The long and narrow skull and more modern short forelimbs differed from the more triangular, birdlike skulls and elongated forearm bones of other winged dinosaurs. It also had asymmetrical feathers. This is a feature seen in birds, except Cihong juji’s feathers were in the tail instead of the wings. So was this thing more bird or more dinosaur?

“There are crests associated with sexual selection previously known only in earlier dinosaurs, and yet there is also a bird mechanism of signaling or display appearing for the first time,” said Clarke, with Wu adding that “The tail feathers are asymmetrical but wing feathers are not, a bizarre feature previously unknown among dinosaurs including birds.”

Asymmetrical wing feathers are built-in flight control for modern birds, which means that the tail feathers in Cihong juji could suggest that such feathers might have started to evolve from the tail up in the first birds. Postdoctoral researcher Chad Eliason believes the unusual merging of ancient and modern features shows how different traits evolved individually in a phenomenon called mosaic evolution.

While the fossil itself wasn’t a rainbow when it emerged out of rock in China’s Hebei Province, the impressions left in the rock by the creature’s feathers preserved the melanosomes, which were then compared to those in birds that exist now. They came closest to those of the living jewels otherwise known as hummingbirds. Eliason was one of the team members who analyzed microstructures in the fossil to determine the colors of this rainbow reptilian.

“This combination of traits is unusual,” Clarke admitted. “It has a rather velociraptor-looking low and long skull with this fully feathered, shaggy kind of plumage and a big fan tail. It is really cool … or maybe creepy-looking, depending on your perspective.”

Hummingbird gardens just got ten times more fascinating.

(via UT News)