Feathers fly over dinosaurs

A lizard that glided through the trees of prehistory 220 million years ago has overturned an established theory of how birds evolved from feathered dinosaurs.

The 24cm lizard, which lived 75 million years before the first known bird, may have sported a set of feathers yet was not a dinosaur, a study has found.

Finding feathers on a lizard which belongs to the ancestral stock of dinosaurs suggests that these most bird-like of biological structures are far more ancient than anyone has until now realised.

The scientists who made the discovery, reported in the journal Science, believe that the existence of a 220 million-year-old fossil with feathers blows a hole in the idea that birds are "living dinosaurs."

The research has focused on the fossils of Longisquama insignis, an archosaur - the group which gave rise to the dinosaurs, crocodiles and birds - that lived in the forests of what is now central Asia, probably jumping from tree to tree.

"These are some amazing fossils which, at the very least, prove that feathers did not evolve from dinosaurs," says John Ruben, professor of zoology at Oregon State University.

"The supposed link between dinosaurs and birds is pretty entrenched in palaeontology, but it's not as solid as the public has been led to believe."

Soviet scientists found the fossils in Kyrgyzstan in 1969 but they remained in a museum drawer in Moscow for many years after an initial examination concluded that two parallel rows of appendages on the back of the animal were scales, not feathers.

Closer scrutiny of the "scales" by a team of Russian and American scientists found that they had several key features in common with feathers.

The appendages had a long, thin tube or shaft running down the centre with projections, or pinnae, extending from the sides of the base, just like modern feathers but quite unlike reptilian scales.

Another feature is that in common with modern birds, Longisquama appears to have a feather growing in the same manner as modern feathers, where the pinnae unfurl inside a tube called a feather sheath.

"A point that too many people always ignored, however, is that the most bird-like of the dinosaurs, such as Bambiraptor and Velociraptor, lived 70 million years after the earliest bird, Archaeopteryx," Professor Ruben said.

"So you have birds flying before the evolution of the first bird-like dinosaurs.

"We now question very strongly whether there were any feathered dinosaurs at all ...

"They were probably flightless birds."

- INDEPENDENT