Study: early birds had four wings
The ancestors of modern birds probably had four wings rather than two, according to a study of fossils found in a Chinese museum.
The four-winged early birds had been identified from fossilised remains a number of years ago, but it was unclear whether the creatures were precursors to modern birds or whether they represented an evolutionary cul-de-sac and had simply died out.
However, eleven skeletons of primitive birds discovered at the Shandong Tianyu Museum of Nature feature evidence of having large feathers on their hind limbs. The remains date from the early Cretaceous period (around 120 million years ago) and, according to the study, "provide solid evidence for the existence of enlarged leg feathers on a variety of basal birds".
Today's two-winged situation could then be the result of a gradual reduction in feathering of these hind limbs, probably as a result of the birds living on the ground and needing to walk around unencumbered.
"If an animal has big feathers on its legs and feet, it's definitely something that's not good for fast running," said Xing Xu from Linyi University in Shandong province in an interview with New Scientist.
The fossil finds help bolster the case for four-winged early birds, however the evidence is not definitive. As a result, Xu and his fellow researchers intend to look to other remains in the museum's collection as well as investigating whether the feathers and wings would have been capable of flight.