Cómo los dinosaurios aprendieron a volar

The dinosaurs were headed for trouble. They ate nothing but junk food. They never brushed their teeth. They stayed up all night. And though they loved jumping off cliffs, they didn't like the landings much. The early mammals tried to warn them. "Keep that up and you'll all be extinct!" they said. But the dinosaurs just laughed... and over time, they evolved into birds.