Fossils of four-winged birds have been discovered in China. ABC News reported that the birds may be the link between feathered dinosaurs and birds we see today with two wings.

A recent report published in the journal Science says that researchers from Shandong Tianyu Museum of Nature in China found 11 four-winged fossils that date back to more than 100 million years ago. ABC News reported that scientists are not sure whether the birds used their four wings to fly.

"These features suggest that the metatarsal feathers were aerodynamic in function, providing lift, creating drag, and/or enhancing maneuverability, and thus played a role in flight," the researchers said in the study.

The Daily Mail reported that its possible the birds flew like a biplane with wings on their legs providing a boost.  However some experts say that the feathers on the legs may not have been used for flying, rather a display of mating.

"Recently, several fossils have shown that some dinosaurs had large feathers on both fore limbs and hind limbs. But, until now, no examples of this four-winged body plan have been described in birds -- or even in their most recently extinct relatives," reported The Daily Mail.

Birds today have vaned feathers on the outside of their body and down feathers that grow underneath them, reported The Daily Mail. However, the team in China found one type of vaned feathers known as pennaceous feathers along each of the birds hind limbs.

The Daily Mail reported that in an article published in Science, Michael Balter said that the birds could be comparable to biplanes in the early 1900s that were replaced  by faster monoplanes.

"A Chinese team presents dramatic new fossils suggesting that early birds went through a similar evolution," he said in the article.  "Starting off with wings on both arms and legs and later adopting the arms-only, monoplane configuration."

See a photo of the fossil here.