Lroamed the world.
Some grew as big as a barn, others were smaller
than a hen. Some walked on four legs, others on
two. Some were fierce hunters, others were peaceful
plant-eaters. These backboned land animals are
called dinosaurs. Dinosaur means “terrible lizard,”
and like lizards, dinosaurs were reptiles. But instead of
sprawling, they walked upright, and some dinosaurs had
feathers rather than scaly skin. In chilly air, instead of dozing
like a lizard, some dinosaurs could stay active by generating
their own body heat. The dinosaurs ruled Earth for
160 million years—flourishing on land more successfully
than any other group of backboned animals. Then
65 million years ago, they mysteriously died out,
except for one group—the dinosaurs that we call birds.