'Feathered' dinosaur makes debut.

In late 1996, Chinese paleontologists reported the discovery of dinosaur fossils covered with featherlike fibers--a bombshell that potentially clinched the relationship between birds and dinosaurs. Since that first sketchy announcement, details of the find have remained scarce and the "feathered" dinosaur has kept a lower profile than reclusive author J.D. Salinger.

Now, Chinese researchers have published their long-awaited report on the small, carnivorous dinosaur, named Sinosauropteryx. In the Jan. 8 Nature, they describe two specimens, about the size of large chickens, that provide unusual evidence of the dinosaurs' soft tissue--internal organs, skin, and other body parts that usually do not fossilize.

Both Sinosauropteryx specimens are surrounded by apparently hollow fibers up to 40 millimeters long, report Pei-ji Chen of the Nanjing Institute of Geology and Paleontology and his colleagues. The filaments resemble extremely simple feathers, called plumules, found on some modern birds. The fibers could represent protofeathers that helped trap body heat or served as a colorful display for attracting mates, suggest the scientists.

One specimen has two oval shapes inside its abdomen--the first clear case of eggs found inside a dinosaur, they report. This discovery suggests that dinosaurs laid eggs in pairs, a pattern closer to that of modern reptiles than birds.

The Sinosauropteryx specimens "are, without a doubt, the best-preserved dinosaur remains yet found," says paleobiologist David M. Unwin of the University of Bristol in England. Unfortunately, the evidence at this point cannot establish whether the fibers surrounding these specimens are related to feathers, he says. To resolve the question, scientists should examine the fossilized soft tissue of birds, mammals, and other dinosaurs from the same site in northeastern China, he says.

Chen and his colleagues briefly mention another carnivorous dinosaur, Protoarchaeopteryx, which was found next to true feathers (SN: 8/23/97, p. 120), although some researchers dismiss this association as coincidence. Perhaps even more important, Chinese scientists have quietly discussed yet another species of dinosaur that apparently bears incontrovertible evidence of actual feathers along its body. Paleontologists expect to report details of this find soon.