Already, the breakthrough has yielded a payoff. Schweitzer and the Harvard scientists found molecular similarities between the Tyrannosaurus rex and modern chickens. They say the finding strengthens a growing case that birds are living relatives of dinosaurs. More tests are needed to see whether the bits of dinosaur proteins match those in other living creatures — including alligators and crocodiles, which, by outward appearances, seem closely related to the ancient species. Molecular maps of proteins in those reptiles are not yet available.
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The very existence of the molecular relics had been unimaginable. Until now, scientists thought such soft stuff survived no more than a million years in animal remains. Usually, tissue degrades and bone gets replaced by mineral, yielding fossils molded precisely like the originals. Although the fossils enable scientists to piece together a skeletal sketch of ancient life forms, they tell only so much.

The discovery of the protein fragments, detailed in the journal Science today, suggests that new molecular clues may be buried in other well-preserved fossils around the world. And those clues could help explain the biology of dinosaurs and other extinct animals. The newly discovered microscopic fragments are not DNA — the inherited code stored in billions of cells that defines every living creature. As a result, no one should expect any Jurassic Park-like replicas of dinosaurs to result from Schweitzer’s finding.