for National Geographic News
A fossil of a primitive feathered dinosaur uncovered in China is helping scientists create a better model of how dinosaurs evolved into modern birds.
The winged dinosaur is still in the process of being dated, and might have lived toward the end of the Jurassic period, which lasted from 208 to 144 million years ago.
In many ways, it is "more basal, or primitive, than Archaeopteryx," said paleontologist Xu Xing at Beijing's Institute of Vertebrate Paleontology and Paleoanthropology. Archaeopteryx, the earliest known bird, lived 150 million years ago.
The protobird is "very close to the point of divergence" at which a new branch of winged dinosaurs first took flight, said Xu.
The new species, called Anchiornis huxleyi, was discovered in the ashes of volcanoes that were active during the Jurassic and Cretaceous (144 to 65 million years ago) periods in what is now northeastern China.
(Read about the prehistoric world.)
Anchiornis, which is Greek for "close to bird," measured just 13 inches (34 centimeters) from head to tail and weighed about 4 ounces (110 grams).
The dinosaur's body and forelimbs were covered with feathers, and it "might have had some aerial capability," Xu said.
"Anchiornis is one of the smallest theropod dinosaurs ever uncovered," Xu explained. Theropods were a group of carnivorous dinosaurs that walked on two legs.
The fossil provides new clues about how feathers, wings, and flight progressively appeared among theropods, along with evidence that certain types of feathered dinosaurs decreased in stature even as their forelimbs became elongated.
The compact structure of Anchiornis "reinforces the deduction that small size evolved early in the history of birds," Xu explained.
SOURCES AND RELATED WEB SITES