The dinosaur's long tail probably worked like the elevator and flaps of an aircraft, helping to control the animal's pitch and reduce speed for landing (Stephanie Abramowicz/Dinosaur Institute NHM)
A report in the journal Nature Communications, says the 1.2-metre-long raptor named Changyuraptor yangi, was covered with plumage, including 30-centimetre-long tail feathers.
This discovery shows this 125-million-year-old raptor was flying long before birds split off from dinosaurs, says one of the study's authors Dr Luis Chiappe, a palaeontologist at the Natural History Museum of Los Angeles County.
"What makes this special is its size," says Chiappe.
"This four-kilogram dinosaur is much bigger than previous dinosaurs that we thought could fly, so it extends our understanding of what these animals were capable of doing."
The long feathered tail is thought to have played an important flight role, given the raptor's relatively large body size.
Chiappe and colleagues believe the long tail worked like the elevator and flaps of an aircraft, helping the dinosaur to control up and down pitch movements, and reduce speed for landing.
"If you're a heavy animal you could injure yourself unless you can slow down to land safely," says Chiappe.
Four-winged dinosaurChangyuraptor is part of a group of predatory, feathered, non-avian dinosaurs called Microraptorines which include several small 'four-winged' species.
"We refer to these as 'four-winged', not because they had four wings, but because they had very long feathers on their hind legs," says Chiappe.
He says the dinosaur's sharp steak-knife-like serrated teeth indicate "it was definitely a predator."
"Stomach contents from its close cousin the microraptor showed bird and fish remains," says Chiappe. "Presumably they also ate small mammals and lizards."
The dinosaur was discovered in north-eastern China's Liaoning Province, a region which has developed into a prolific dinosaur fossil bed over the last decade.
"This is an incredible place with spectacular fossils, offering us a ten-million-year window on an ecosystem that existed between 130 and 120 million years ago," says Chiappe.
Changyuraptor yangi lived in what was a temperate forest of mostly conifers, with an undergrowth of ferns and some of the earliest flowering plants.
The forest surrounded a series of interconnected lakes and streams, dominated by active volcanos erupting clouds of ash and deadly pyroclastic flows.
These flows pushed the remains of these animals into the lakes where they were covered by volcanic ash and sediments.
"This quick burial and lack of oxygen helped preserve this animal from predators and microbial decay, allowing us to find it," says Chiappe.
"To many people the idea of flying dinosaurs is a novel concept, feathered flight has always been assumed to be the domain of birds," says Chiappe.
"There's now plenty of evidence to show that birds were descended from dinosaurs, and we're also learning that these dinosaurs were also capable of flight."