National Geographic Daily News
roadrunner-dinosaur-xixiankus--s990x777--p.jpg

Meep-meep! The newfound "roadrunner" dinosaur is seen in an artist's reconstruction.

Illustration courtesy Matt Van Rooijen

Kate Ravilious

for National Geographic News

Published March 31, 2010

A new dinosaur species unearthed in China would have given Wile E. Coyote a run for his money. Nicknamed the roadrunner, the tiny dinosaur is one of the smallest and leggiest Alvarezsaurs ever to have roamed the Earth.

Alvarezsaurs are known for their long-legged bodies adapted for running, and the group has been linked to the larger dinosaur family that includes modern birds. (Related: "Smallest Dinosaur in North America Discovered.")

Remains of the newfound species, Xixianykus zhangi, were found last spring by a local farmer in China's Henan Province, around 250 miles (400 kilometers) south of Beijing. The dinosaur lived about 85 million years ago, during the late Cretaceous period.

Based on the partial fossil, scientists think the creature was around 1.5 feet (0.5 meter) long with 10-inch-long (25-centimeter-long) legs.

Among the roadrunner dinosaur's most notable features are very short upper legs compared with its lower legs and feet—extreme even among Alvarezsaurs.

"These proportions imply it could put great long strides in and move fast," said Dave Hone, a paleontologist based at the Chinese Academy of Sciences in Beijing who has been studying the skeleton.

Roadrunner Dinosaur Also an Ant Eater

Although the roadrunner's forelimbs were not preserved, the dinosaur most likely had the muscular arms and large claws associated with Alvarezsaurs—perfect for pulling apart termite mounds and ripping into logs in its hunt for juicy insect morsels.

Features of the fossil backbone and pelvis confirm that idea: "The front of the body is adapted not to twist, which saves energy when running and provides a brace for digging actions," Hone said.

In addition, scientists think the tiny dinosaur sported feathers, since many of its cousins have been found with preserved plumage. (Related: "Dinosaur True Colors Revealed for First Time.")

X. zhangi was most likely an endurance runner, using minimal energy to cover long distances in its search for food, Hone added.

But if a wily tyrannosaur ever popped up in its path, he said, the roadrunner dinosaur probably could have managed a quick sprint to safety.

The roadrunner dinosaur is described this week in the journal Zootaxa.

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