The evolution of bird flight: paleontologists have discovered the ancient birds a second pair of wings

Chinese paleontologists reported the researchers of ancient species of birds, the hind legs which could serve as an extra pair of wings.
 
Discovered new evidence of the hypothesis that the hind limbs were used to move the air / Reuters
Scientists from the Institute of Geology and Paleontology in Shandong province found evidence of feathers on the hind legs of 11 different ancient species of birds, according to their study published in the journal Science.

Stringy feathers on the feet of Representatives early Cretaceous period (100-150 million years ago) are identical in structure to the feathers of early birds Representative - Archaeopteryx.

According to the study, one of the individuals assigned to the genus Sapeornis, the feathers on the legs reach a length of 50 millimeters. The foot length of the feathers is also not less than 30 millimeters. Uchenіe consider it a significant achievement in the understanding of the evolution of bird flight.

However, a paleontologist at the American Museum of Natural History, made a counter-arguments of the theory of Chinese. According to the scientist, presented the journal Nature, this small archaeological sample does not mean that the four wings were the norm for ancient birds. Moreover, the very presence of feathers on the hind legs does not prove that they were used during the flight, said the American. Note, there is a theory according to which the bodies of certain groups of ancient flightless dinosaurs were covered in feathers.

Assumptions about the use of feathers hind legs dinosaurs as additional wings were put forward earlier. Thus, it is believed that opened in 2003 Microraptor used including the hind legs with long feathers to plan and hunting on the trees. This hypothesis was confirmed with the help of a flying model feathered lizard in 2010.