This book reads in part like a scientific detective story. It not only offers an amazingly believable description of the great creatures roaming the Earth one hundred million years ago-- and of the Earth itself---, but tells how, year after year, scientists have collected and correlated information to arrive at such conclusions. Here are word-pictures of astonishing animals---60 foot-long dinosaurs weighing several tons, awesome winged creatures, ominous amphibious killers, jawed carnivorous bats, and so on. Then the theories of why they became extinct, and the guide to footprints and relics we have of them today, are equally stimulating. The book is made even more useful by long lists of classifications, Illustrations, and a guide to bone collections in various museums. Very readable for the lay public.