Science: How Birds Began to Fly

Poking through the fossil collection of The Netherlands' Teyler Museum in September, Yale Paleontologist John H. Ostrom spotted one musty specimen that looked odd to his trained eye. It was labeled pterosaur, a flying reptile that inhabited the earth from 65 to 200 million years ago. But when Ostrom held the fossil to the light, he saw the distinctly unreptilian impression of a feather. "My heartbeat began going up fast," recalls Ostrom, who quickly recognized that the specimen was not a pterosaur at all. It was, in fact, a far rarer prehistoric aviator: an Archaeopteryx (literally "ancient wing"), the earliest known...