14 DAY TRIAL // A study whose findings were published this past March 14 in the journal Science argues that, millions of years ago, birds flew with the help of not two, but four wings.
These assumptions are based on the discovery of several bird remains in China, which allegedly stand as proof that the anatomy of early birds was quite different from that of their modern relatives.
Paleontologist Xing Xu, currently working with the Institute of Geology and Paleontology in Shandong, China, claims to have found fossil remains which indicate that some of the bird specimens that roamed the skies roughly 100 million years ago used to have feathers on their hind limbs.
It is Xing Xu's belief that, since these feathers appear to have stood perpendicular to the birds' leg bones, they must have been used for flying.
According to Nature, one specimen whose fossilized remains were unearthed by paleontologist Xing Xu used to have a hind limb feather whose length amounted to 50 millimeters (about 2 inches).
Furthermore, it is being said that, although other feathers located on the birds' legs were a tad shorter, they nonetheless exceeded 30 millimeters (roughly 1.2 inches) in length.
“It is amazing that so many early birds had large leg feathers. These findings are important for both flight origin and feather evolution,” Xing Xu commented with respect to his discovery.
For the time being, researchers are unable to say whether these birds made use of their rear set of feathers for gliding, steering or a combination of the two.
“[The second set of wings] either provided lift, or created drag, or enhanced maneuverability or a combination of all of these functions,” Xing Xu told members of the press.
As well as this, it cannot be determined whether or not all ancient birds displayed such feathers on their back limbs, seeing how the fossilized remains found and analyzed by Xing Xu are simply too few for scientists to be able to make any generalizations.
It is Xing Xu's belief that birds lost this second set of wings once they decided to also spend considerable amounts of time running and walking on the ground.