The ebony bones glisten dully at the bottom of a drawer in the basement of the Museum of the Rockies in Bozeman, Montana. Long, thin leg bones sit beside butterfly-winged vertebrae. But the claws are what get your attention: curved and sharp like an eagle's, only larger. Curator Jack Horner holds his hand at Dalmatian-petting height to indicate the size of the wielder of those claws.

Meet Deinonychus, first unearthed by Yale paleontologist John Ostrom in 1964. The claws and joint structure speak of a quick, agile predator. Ligaments in the tail held it stiff, keeping it off the ground and allowing it to act as both rudder and counterbalance. Deinonychus was not a kangaroo but a charging linebacker.

A few years later, Ostrom recognized a close resemblance between Deinonychus' fingers and the early bird Archaeopteryx. Ostrom used this and other similarities between the two to revive the idea that birds weren't just distant relatives of dinosaurs but that birds were dinosaurs.

A controversial new method of classifying organisms, called cladistics, supported Ostrom. The revised family tree, or cladogram, lists 130 shared characteristics between birds and dinosaurs, completely rejecting the tradition that places dinosaurs with reptiles and sets aside birds as their own distinct class. The new classification had a profound effect on the next generation of paleontologists, such as Paul Sereno, who was studying at the University of Chicago in the 1980s at the time cladistics entered the computer age. "The data is the anatomical features of the skeleton, which is the only record from which to work, and the computer is able to quantitively support all this data."

New fossils recently discovered in China have convinced all but the most intransigent skeptics. Protarchaeopteryx and Caudipteryx are both theropod dinosaurs unmistakably covered in feathers. Because they lived after Archaeopteryx, small dinosaurs as a group must have had feathers well before they started down the road to birdhood and flight. The finds perhaps are "the discovery of the century," muses Philip Currie of Canada, one of many paleontologists paving the evolutionary runway of dinosaur-to-bird.

According to Robert Bakker, the Chinese feathered dinosaurs cement the idea that "if you could watch dinosaurs moving around, they would look to you like a lot of ground birds, like really big turkeys with bad attitudes. So yes, birds are descended from dinosaurs, and dinosaurs had already acquired a lot of those active properties we associate with being a bird."