Dinosaurs captivate the imagination of children and adults alike. The more we learn about them — their appearance, their habits, their habitats, and suspected reasons for their demise — the more fascinating they become. But how do we know they really existed? And how do we know so precisely when they lived? The fossilized dinosaur bones and tracks depicted in this still collage produced for Teachers' Domain offer physical evidence — the foundation on which all of scientific theory is built — of the dinosaurs' existence.