Scientists discovered four-winged bird follies in northeastern China, according to a research published Thursday. The four-winged birds are believed to have been the ancestor of the modern crow and turkey.

Xing Xu, a paleontologist at the Chinese Academy of Sciences' Institute of Vertebrate Paleontology and Paleoanthropology in Shandong, China discovered evidence of feathers on the hind limbs of 11 fossil specimens from at least four diverse groups that lived about 100 to 150 million years ago.

"The first birds descended from four-winged dinosaurs, which are not necessarily gliders in the strictest sense," Xu told Discovery News.

"In particular, they provide solid evidence for the existence of enlarged leg feathers on a variety of basal birds, suggest that extensively scaled feet might have appeared secondarily at an early stage" in the development of primitive birds says the abstract of the study.

One key specimen revealed of having at least one hind limb feather longer than 50 millimeters. Although feathers on the feet were shorter, still some were more than 30 millimeters long.

"It is amazing that so many early birds had large leg feathers," Xu says. He noted the first winged fossils that had feathered limbs were discovered just 10 years ago in dinosaur species called the Microraptor and Sinornithosaurus, according to the New York Times. He said these findings "are important for both flight origin and feather evolution."

Xu and his colleagues believed the leg feathers indeed were wings, according to the study stating, they "either provided lift, or created a drag, or enhanced maneuverability or a combination of all of these functions."

However some say the leg fathers do not mean that the ancient birds actually used them, and such small sampling does not prove that four wings was the rule for all early birds, says Mark Norell a paleontologist at the American Museum of Natural History in New York.

"Flight is many things to many people," he notes. "The origin of flight is not going to come from just one discovery."

"I would like to see a denser sampling" before reaching firm conclusions about the specific importance of the four-wing transition in the origin of bird flight," he told the Times.

"No one thinks that these animals flapped their legs," said Kevin Padian, professor of Integrative Biology at the University of California, Berkeley. He was one of the experts who reviewed the research before it was published.

"Some say that the leg feathers would have increased lift, but there is no evidence for this: to increase lift the feathers would have to be arranged in such a way as to form a competent, planar airfoil, and no one thinks (or has shown) that this was the case," Padian told AFP.

"In fact, the authors neither perform nor cite any research in support of any hypothesis that these feathers contributed to any sort of flight," Padian wrote.

Padian appreciated the research, calling it a "great study" because it shows how leg feathers changed over time among bird-like dinosaurs and primitive birds.