Notes

Ten dinosaurs are described. A timeline links them to each other, and to animals without backbones, other reptiles, mammals, and birds. Dinosaurs dominated the earth for 160 million years, but 65 million years ago, when intense vulcanism in Asia was already causing dark skies, an asteroid hit the earth and made world temperatures plummet. Plants died, and all the dinosaurs became extinct. The animals that survived were mostly small.