This book describes the body, habitat, feeding habits, and mating of the Pachycephalosaurus.

A changing world -- A very hard head -- Finding pachycephalosaurus -- Little hard heads grow up -- Vegetarian meals -- Butting heads -- Fighting with your head -- Inside Pachycephalosaurus -- Finding Pachycephalosaurians fossils -- Pachycephalosaurians -- The great extinction -- A dinosaur's family tree.