Since its discovery in 1860,Archaeopteryx was widely considered to be the earliest known bird. But in 2009 a team of scientists decided it was more dinosaurlike than avian. Because of its reptilian metabolism and growth rate (slower than that of a bird),the transitional species should be removed from
the bird family tree,the scientists said.
Now the discovery of a pheasant-size fossilone that researchers say dates back even earlier than the 150-million-year-old Archaeopteryxhas prompted a re-examination of the entire lineage. According to an international team of scientists led by the Royal Belgian Institute of Natural Sciences,Archaeopteryx should indeed be considered an early bird.
We decided to start the analysis from zero, said Pascal Godefroit,a paleontologist with the Royal Belgian Institute and lead author of the new report,which appeared in Nature. And we decided that the traditional view is the best one. Archaeopteryx is a primitive bird.
The newly discovered fossil,which Chinese scientists pulled from a shale bed in Liaoning Province in northeastern China,reveals a chickenlike creature that lived 160 million years ago,making it the oldest known creature within the avian lineage. Researchers have named it Aurornis,which means dawn bird.
Restoring Archaeopteryx to the avian family tree solves a thorny evolutionary problem that emerged when it was removed. Because many researchers believe the creature could fly,placing it on the dinosaur lineage suggested that the ability evolved twice,or was subsequently lost and then recovered. Placing the animal back among the birds supports a single origin of powered flight, the study said.