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First Dinosaur Feathers for Show, Not Flight?

Charles Q. Choi
for National Geographic News
October 22, 2008
 
One of the oldest known dinosaur relatives of birds had "bizarre" anatomy, including long, ribbon-like tail feathers that suggest plumage may have first evolved for show rather than for flight, scientists say.

Farmers unearthed a fossil of the new dino species, dubbed Epidexipteryx hui, from the hills of Inner Mongolia in late 2007.

The remains date back to 152 million to 168 million years ago, making the newfound creature slightly older than Archaeopteryx, the most primitive known bird.

(Related: "Earliest Bird Had Feet Like Dinosaur, Fossil Shows" [December 1, 2005].)

Like other avialans—birds and their closest dinosaur relatives—Epidexipteryx is a theropod, a group of two-legged animals that includes Tyrannosaurus rex.

Researchers think the pigeon-size Epidexipteryx might have used its plumes as flashy ornaments, since it was mostly covered in short feathers that lack the structure necessary for flight.

"For example, [the feathers] could potentially have played a role in displays intended to attract a mate, scare off a rival, or send a warning signal to other individuals of the same species," said study co-author Fucheng Zhang, a paleontologist at the Chinese Academy of Sciences in Beijing.

"This is very exciting indeed, since it gives us a window into a stage of avialan history just preceding the appearance of the classic 'first bird,'" Zhang said.

"It shows that the use of feathers for visual communication—as opposed to other functions such as insulation and flight—was a very early development."

"Bizarre" Anatomy

Epidexipteryx lived in the mid- to late Jurassic period in a lush, well-vegetated area that was rich in salamanders and other possible prey.

The dinosaur had claws similar to those of ground-foraging birds, such as ostriches and turkeys, and its front teeth were large and protruding.

"One can certainly imagine [the teeth] being used to snatch at small prey, such as lizards, small mammals, or even insects," Zhang said.

Epidexipteryx's anatomy seems to be a hodgepodge of features taken from a variety of animals.

For instance, its front limb bones and short, bony tail resemble those of living birds. But its short, high skull and large front teeth look like those of small theropods called oviraptors.

"It's not uncommon for features present in one group to appear independently in another," Zhang said of the newfound dino's "bizarre" anatomy.

"It's also typical for different parts of the body to evolve at different rates, so that some bits end up looking very specialized whereas others remain primitive."

(See pictures of other "bizarre" dinosaurs.)

Zhang and his colleagues report their findings this week in the journal Nature.

Evolution Experiments?

Luis Chiappe is a paleontologist with the Natural History Museum of Los Angeles County and a former National Geographic Society grantee. (National Geographic News is part of the National Geographic Society.)

He said that the mosaic of features suggests "there was a lot of evolutionary experimentation around the origin of birds, with many different kinds of lineages reaching different levels of 'birdness.'"

But Chiappe, who was not involved in the new study, is skeptical of the idea that feathers originated as ornaments.

"Feathers could have served an aerodynamic function of some sort whether you fly or not. You could flap feathered wings and run faster," he said.

"Still, these ornamental feathers are a really interesting new piece of evidence into why feathers first originated."
 

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