A small lizard-like reptile, which lived 220 million years ago and had feathers like those of modern birds, threatens to turn one of the most hotly debated theories of evolution on its head, it was disclosed yesterday.
The creature was not a dinosaur but possessed features, which are leading scientists to suspect it was the original ancestor of birds.
For years palaeontologists have argued about whether birds evolved from dinosaurs. Most today believe there is an evolutionary link between the two, but now they might have to think again.
The reptile, which lived 75 million years before the oldest known bird, Archeopteryx, was discovered more than 30 years ago in central Russia. The creature, called Longisquama insignis, was an archosaur, a group of primitive reptiles that preceded both dinosaurs and crocodiles.
For years scientists believed the strange long narrow appendages down the fossil's back were extremely long scales. No one suspected they could possibly be feathers in a specimen so old.
Then about 18 months ago the fossil was taken from Russia to the University of Kansas Natural History Museum as part of a travelling exhibit. In Kansas City a team of US and Russian scientists made a new study of the specimen. What they discovered astonished them.
Microscopic analysis showed that the animal had hollow-shafted, quilled feathers almost identical to those of modern birds, the researchers reported yesterday in the journal, Science.
They had obviously evolved for flight rather than insulation, as in the case of some much later dinosaurs, which had downy feathers. Longisquama moulted like modern birds, and had a wishbone like modern birds.
One of the research team was Dr Alan Feduccia, from the University of North Carolina at Chapel Hill, who in 1979 proved for the first time that Archeopteryx could fly.
He said: "These are the earliest structures in the fossil record that can be called feathers. They predate the so-called `fuzzy dinosaurs' from China by at least 100 million years."