6 Things You Need to Know About the Newly Discovered "Rainbow Dinosaur"

Saturday, January 20, 2018

An artist's depiction of Caihong juji, a species of theropod dinosaur that lived 160 million years ago in what's now northeastern China.  ILLUSTRATION BY VELIZAR SIMEONOVSKI, THE FIELD MUSEUM

The newly discovered dinosaur species in China, nicked named the "rainbow dinosaur," has attracted widespread attention and raised many questions. How did researchers examine the colors of its feathers? What does the new species reveal about the evolution from dinosaur to bird? What is the significance of the findings? Here are six things you need to know to better understand the discovery.

-- What is the rainbow dinosaur?

The rainbow dinosaur is officially named Caihong juji, with caihong meaning rainbow and juji meaning big crest, due to the iridescent plumage on its head, chest and parts of its tail, as well as the bony crest on its head.

Paleontologists have partially reconstructed the dinosaur's original plumage colors based on melanosomes in the fossil. To a large extent, it resembles the iridescent feathers of hummingbirds.

More amazingly, the new dinosaur, a paravian theropod, changes its plumage colors at different observation angles.

The fossil was found by a farmer in Qinglong Manchu Autonomous County, Hebei Province in north China. It is now kept in the Paleontological Museum of Liaoning, northeast China.

-- When and where did the rainbow dinosaur live?

Paleontological examination shows that the new dinosaur lived around 140 million years ago in the mid-late Jurassic age. The place where it was fossilized might have been a forest surrounded by mountains and shallow lakes.

Given that there are feathers on its hind limbs, which are not suitable for running on the ground, there is a good chance that it lived in trees.

Like other theropods, the rainbow dinosaur may have fed on small mammals and lizards. Though being rooster-sized and beautifully feathered, its half-moon-shaped teeth and sharp digits suggest it was ferocious.

-- Could the rainbow dinosaur fly?

Imagining giant dinosaurs flying in the sky seems to go against common sense. However, there remains the possibility that the rainbow dinosaur could take off for a short flight due to its similar morphological traits to birds. But this is merely a hypothesis waiting to be proved.

"The basic structure for flying has emerged, but the short forelimbs make its body disproportionate for flying," says Xu Xing, co-author of the thesis on the new dinosaur published in Nature Communication and researcher at the Institute of Vertebrate Paleontology and Paleoanthropology.

-- Why is the rainbow dinosaur so important?

The discovery of the new dinosaur has drawn widespread attention from across the world, because it completes a critical part of the evolutionary tree from dinosaurs to birds.

According to paleontological studies, the fossil shows the earliest asymmetrical feathers in dinosaur as well as the earliest proof for melanosomes, which are platelet-shaped nanostructures in dinosaur feathers.

"The rainbow dinosaur, which existed at least 10 million years earlier than the Archaeopteryx, already had asymmetrical feathers, which may have helped increase control force and stability and thus been key for flight. It means that the evolution from the dinosaur to the bird might have happened earlier than we thought," Xu Xing says.

"However, while feathers on its tail are asymmetrical, feathers on its forelimbs, commonly considered as a source of power for flight, are still symmetrical.

"It either means that asymmetrical feathers were first developed not for flight, but for other functions such as the display of courtship and confirmation of species identity, or it means that the balance-controlling feathers on tail played a more important role in flight than we thought."

-- Where does it fit in the evolutionary tree?

In 1868, Thomas Henry Huxley made the controversial hypothesis that birds were evolved from dinosaurs. However, the idea was deemed absurd by most scholars for roughly a century.

In the 1970s, the hypothesis was revived by U.S. paleontologists with a series of fossil evidence. In 1996, the fossil of Sinosauropteryx, which has soft feathers akin to birds, was found in Jehol Biota in northeast China. In the following years, more fossils of feathered dinosaurs were found in west Liaoning regions in northeast China. In 2009, the fossil of Anchiornis huxleyi, the earliest dinosaur with flight feathers, was unearthed in Liaoning Province. Anchiornis huxleyi existed around 160 million years ago, about 20 million to 30 million years earlier than Sinosauropteryx.

The rainbow dinosaur has even longer feathers in its forelimbs and hind limbs than that of Anchiornis huxleyi. It shows more bird-like traits, such as its bony structure and plumage characteristics. In the evolutionary tree, it perfectly fills in the vacancy between Anchiornis huxleyi, Sinosauropteryx and Archaeopteryx, the earliest known bird.

-- Why did dinosaurs evolve into birds?

Bird-like dinosaurs probably appeared because they had to adapt to the environment, otherwise they would not survive. But it is still unclear what kind of natural changes brought about the external pressure on their evolution.

"It is mostly likely that only those that could fly escaped the dinosaur extinction around 65 million years ago. The rainbow dinosaur, one of the lucky survivors, was a precursor to the evolution from dinosaurs to birds," says Xu Xing.

Source: www.xinhuanet.com