Dinosaurs Of A Feather

Michael Crichton is probably heaving a huge sigh of relief. The author of Jurassic Park and The Lost World is known as a stickler for scientific accuracy in his books and the films made from them. But honestly, how much terror could readers and filmgoers have worked up at the idea of people trapped on a tropical island and chased around by a pack of large chickens? That sort of thing is more in Woody Allen’s line.

If he were writing about rampaging dinos today, though, Crichton might have to deal with just such a poultry problem. The reason: a team of paleontologists from China, Canada and the U.S. announced last week that they’ve discovered not one, but two new species of small dinosaur, each of which was clearly covered with feathers. According to their report, which appears in the latest issue of Nature, the specimens not only cement the increasingly popular theory that birds are descended directly from dinos. They also suggest that many kinds of dinosaur, including the vicious velociraptors that slashed their way through Crichton’s fiction, may have been festooned with their own colorful plumage.

For now, all the scientists can say for sure is that these are definitely dinosaurs and that they definitely have feathers. And that alone is a big deal, as the paleontologists involved in the discovery are swift to point out. “It is,” says Philip Currie, of Canada’s Royal Tyrrell Museum of Paleontology and a co-author of the Nature report, “one of the most exciting discoveries of the century, if not the discovery of the century.”

It is more than a century, in fact, since Darwin’s friend Thomas Henry Huxley first proposed a theory, based on his observation of broad anatomical similarities, that birds might be descended from the dinosaurs. But for decades, nobody could produce much detailed physical evidence to back up the theory. It wasn’t until the 1970s that Yale paleontologist John Ostrom began building a bone-by-bone case for the link–at least for theropod dinosaurs, which include velociraptors and tyrannosaurs. By the mid-1990s, the list of parts common to birds and dinos included wishbones, breastbones, three-toed feet, hollow bones and swiveling wrist joints.

That has been enough to convince most dinosaur experts, but some paleontologists who specialize in birds didn’t much like the theory. Both birds and dinosaurs, they contend, evolved from some older common ancestor. Any similarities between the two groups, they say, have to do with that parentage, and also with the fact that evolution can often produce the same features, even in utterly unrelated animals. Sharks and dolphins, for example, have comparable body shapes, though one is a fish and the other a mammal. Such disparate creatures as bats, birds and butterflies all have wings in common.

But when the number of shared features reaches critical mass, scientists have to consider a direct evolutionary relationship. A dinosaur with feathers would clearly tip the scales: they’re by far birds’ most characteristic feature, and they had to evolve from somewhere. The skeptics have always contended that birds’ ancestors were tree-dwelling lizards, and that feathers evolved to help the lizards flap their way from branch to branch. Fast-running, ground-dwelling dinos like velociraptors would never have needed feathers.

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