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4-winged fossil

photo by Xu Xing ,Institute of Vertebrate Paleontology and Paleoanthropology, Beijing
The fossils of six birds that lived 130 million years ago have been discovered which are throwing a huge question mark into the fossil flight record - these birds have four wings. Discovered in Liaoning, China by a team led by Xing Xu, it seems to give credibility to one of the theories of how flight developed. Some think birds' wings evolved from the legs of ground animals while the other theory was that "birds" were tree dwelling gliders who eventually developed true flight. The above fossil is about 3 feet long (1m) and is a relative of the Microraptor.