Fossil Birds with Four Wings

Paleontologists in China have discovered ancient ancestors of birds that had both front and rear wings.

Modern birds generally work with two wings, using small, clawed hind legs for ground travel. A few, like the golden eagle, have fuzzy down on their back limbs, which is for insulating their appendages, not flying. Though researchers have unearthed evidence of downy limbs in feathered dinosaurs, little evidence existed that early birds were using those hind legs for flapping.

But 11 specimens from Liaoning in northeastern China, from several species show evidence of long, stiff feathers with curved shafts jutting out nearly perpendicular to the leg -- a far cry from mere insulation.

The feathers were arranged in a relatively wide, flat plane, making it a potentially flight-worthy design, says a team of Chinese scientists studying feathered fossils.

That design didn't seem to work out too well for the birds, as those species eventually died out. The two-winged versions are more aerodynamic, and using your rear appendages for walking, perching, or catching prey is handy. Read more about the fossils at the Los Angeles Times.