just one of several species of feathered dinosaurs preceding modern birds. It may not even be a direct ancestor.

Such revisions make paleontology a science of second thoughts. Reconstructing the history of life, researchers thrash out theories of ancestry, behavior and biomechanics guided by hints from ancient bones. Archaeopteryx -- combining the feathers, wishbone and wings of a bird with the reptilian tail, teeth and claws of a dinosaur -- had already become a question mark.

Newly discovered fossils have prompted scientists to revamp their assumptions about archaeopteryx's distinguishing features over the last decade.

A cornucopia of fossil finds in China demonstrated that feathers coated many dinosaur species, not just birds. The newest finding, though, demonstrates that our understanding of even well-studied fossils like archaeopteryx -- scrutinized, measured, modeled for 150 years -- can still be upended.

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