Chinese scientists have discovered a 160-million-year-old feathery four-winged dinosaur fossil that sheds new light on the origin of birds.
The dinosaur, excavated from Jianchang County, in the northeastern province of Liaoning, belongs to the Troodontidae, a family of theropods most closely related to birds, Hu Dongyu, head of a research group from the Shenyang Normal University, said Friday.
The fossil is the oldest troodontid reported so far, Hu told reporters in Shenyang, the capital of Liaoning.
It is about 20-30 million years older than the earlier oldest troodontid, found also in Liaoning, the scientist said.
The dinosaur is at least millions of years older than archaeopteryx, the oldest bird, which had been discovered in Germany, Hu said.
The discovery provides strong evidence that birds originated from theropods, he said.
Earlier discoveries of theropod dinosaur fossils have shown resemblances to the oldest birds, but they also created a "temporal paradox" as the fossils are younger than those of the birds.
The specimen has filled the morphological gap between non-avian and avian dinosaurs, the scientists wrote in an article on the website of the top international science magazine, "Nature".
"The extensive feathering of this specimen, particularly the attachment of long pennaceous feathers to the pes, sheds new light on the early evolution of feathers and demonstrates the complex distribution of skeletal and integumentary features close to the dinosaur-bird transition", they wrote.
The research findings will also be published in "Nature" magazine on Oct. 1.