Narrator: This is Science Today. Birds weren't the first animals to fly. Before them came pterosaurs, flying reptiles whose behavior was probably similar to that of modern day seabirds. Kevin Padian is a paleontologist at the University of California, Berkeley.

Padian: Pterosaurs were the first flying, in the sense of actively flapping, reptiles, and they evolved first in the late Triassic, maybe about 225 million years ago. They had the skies to themselves until birds evolved, which seems to be about 135, 140 million years ago. 17

Narrator: Birds and pterosaurs coexisted for around 70 million years, until pterosaurs went extinct along with the rest of the dinosaurs. Padian says it's not that unusual for two entirely different families of animals to develop the same means of locomotion.

Padian: It often happens in evolution that two groups of things will get the same bright idea at about the same time.

Narrator: Birds, of course, are still with us, but the last pterosaur perished around 65 million years ago when the climate changed, a huge meteor hit, and the dinosaurs disappeared from the earth. For Science Today, I'm Steve Tokar.