Early Avian Flight
|Fossil of a Prehistoric Bird: This fossil is from the enantiornithine genus, which shows feathers on its hind legs—evidence of an extra pair of wings. |
Photo Credit: Xiaoting Zheng et al/Science
An article, by Katherine Harmon, in Nature says that the earliest birds had four wings instead of the two now common to birds. It is thought that birds (Aves) evolved from Theropod dinosaurs about 150 million years ago, and to its more modern form about 100 million years ago.
Birdlike dinosaurs, such as Microraptor and Sinornithosaurus, are known to have had long, sturdy feathers on their hindlimbs2. But until now, researchers were not sure whether the earliest birds had already abandoned this extra plumage when they emerged to take to the Cretaceous skies over 100 million years ago.
The researchers, led by Xing Xu, a palaeontologist at the Institute of Geology and Paleontology in Shandong, China, found evidence of feathers on the hindlimbs of 11 basal bird specimens (gathered from the Lower Cretaceous Jehol Group in China)3. On some of the individuals, these feathers appeared to be veined flight feathers that stood perpendicular to the leg bones, similar to those in the basal bird Archaeopteryx.
It is amazing that so many early birds had large leg feathers," Xu says. The first winged dinosaurs were discovered just 10 years ago, he notes. These findings "are important for both flight origin and feather evolution". One specimen, attributed to the Sapeornis genus, had at least one hindlimb feather longer than 50 millimetres. Feathers on the feet were shorter, but were still more than 30 millimetres long.These findings are indeed important for the reason that Xu stated; they provide more evidence and knowledge in how species developed flight, always an intriguing subject for humans. Of course there are many ancient myths on human flight— the Greek legend of Daedalus and Icarus the most well- known—centred on the need for escape, discovery and freedom; but that's another topic.
You can read the rest of the article at [Nature]