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It's a logical argument, but also an irrelevant one if paleontologists could find a feathered dinosaur, and for years that's been a major goal. Not an easy one to attain, though: even if plumed dinosaurs existed, their fragile feathers would rarely, if ever, be preserved in the fossil record.
But in 1996 a farmer pulled what he thought might be a dragon from the Liaoning fossil beds of northeast China. When it reached Chinese experts, they identified it as a theropod dinosaur--and one that was clearly covered with some sort of downy filaments. Maybe they were feathers, maybe not. "Even I could play both sides," admits Mark Norell, another co-author of the Nature report and a firm adherent of the dinosaurs-into-birds theory.
But the two new turkey-size specimens, discovered last year at Liaoning, leave little room for doubt: they have feathers on their arms and tails and show evidence of body feathers as well. These were clearly not used for flight, but scientists think feathers may not have evolved for flight in the first place. They may instead have originally come about to provide insulation. Or they could have served as colorful body decoration to attract mates or frighten off enemies. By this reasoning, flight was discovered by accident: feathered dinosaurs may have found that flapping their arms while running gave them added speed, and a few million years of flapping could eventually have resulted in a lift-off.
Scientists don't easily switch sides on a controversy that has lasted for decades, however, and even this dramatic discovery hasn't swayed the hard-core skeptics. Alan Feduccia, at the University of North Carolina at Chapel Hill, a vocal critic of the idea that birds come from dinosaurs, won't even concede that these are dinosaurs. They could, he says, be flightless birds, like ostriches or kiwis, evolved from more conventional flying ancestors. If so, argues Feduccia, "I would reserve judgment as to just how important they are in telling us about the origin of birds."
Another problem the skeptics have with the new fossils is that they date from about 120 million years ago, making them some 30 million years younger than archaeopteryx, the oldest known bird. How could these dinos be ancestral to birds if they came later? No problem, says Kevin Padian, at the University of California, Berkeley: "We don't always get everything in the fossil record in perfect order." Or the newly found dinosaurs may be descendants of much earlier animals that just haven't been found yet.
Feduccia's views were already in the minority, and this find hasn't helped gain converts to his side. If the dinosaur-bird link was convincing before, it's now pretty close to rock solid. And if Michael Crichton gets around to another Jurassic Park sequel, he may have to do some research in a henhouse.
--Reported by Andrea Dorfman/New York and Anat Shiloach/Washington