The Jigsaw Fossil

Stephen Czerkas first spied the curious specimen for sale in Utah and arranged for his Dinosaur Museum to buy it. The 125-million-year-old creature seemed to have the body of a bird but also a long, bony tail. Czerkas wondered: Could it be the earliest flying dinosaur? The missing evolutionary link tying dinosaurs to birds?

Czerkas--along with Philip J. Currie of the Royal Tyrell Museum of Paleontology and Xing Xu of the Institute of Vertebrate Paleontology and Paleoanthropology--was convinced of it. And so on October 15, the trio unveiled the fossil (with two others) during a press conference at National Geographic headquarters--before they published the find in a peer-reviewed journal.

The turkey-size fossil had hollow bones, feathers, sharp claws and teeth. Its shoulders, wishbone and large sternum resembled those of modern birds. And its stiff, long tail was characteristic of meat-eating dromaeosaurid dinosaurs, which include velociraptors of Jurassic Park fame. Because it was excavated in Liaoning, China, the group named it Archaeoraptor liaoningensis, or the "ancient robber from Liaoning."

Now, three short months later, A. liaoningensis has robbed Czerkas and his team of their glory. Indeed, the fossil seems to contain the pieces from two different archaeological puzzles: the head, chest and feet appear to be from a bird, but the tail is an exact mirror image of one that Xu tracked down, with the help of Chinese fossil dealers, on a dromaeosaurid in December. Xu believes that the dromaeosaurid tail is in fact the other half of A. liaoningensis's tail, which was joined to the bird fossil to make it more valuable.

Computer-tomography scans of the fossil (see sidebar), funded by National Geographic, support Xu's suspicions. But some optimism remains. Czerkas for one is waiting to see the two tails side by side before he decides. And Christopher Sloan, a senior associate editor at National Geographic who wrote about the discovery in the magazine's November issue, notes that although "it was disappointing to learn that Archaeoraptor may be a combination of animals ... we're still convinced that [it] is an important specimen."

At the very least, Currie has stated that even though this particular fossil may not support the idea that birds are descended from dinosaurs, it does not discredit it either. In the future, fossil evidence may come forward with a little more caution, but the dino-bird debate will surely rage on.