Beginning with the Paleozoic Era, 542 million years ago, one can trace the history of prehistoric life on our planet up to recent discoveries.  Many facts include information about where fossils were found, diet, and size of animals living on the planet long before humans.  Scientists are able to determine many features, however sometimes a best guess is presented and is indicated with a question mark.  Recorded dinosaur discoveries in the United States and around the world began in the 1800s and continue up to the present day.  The layout is easy to read and the illustrations are created digitally.  Two of the three facthound internet sites were active at the time of this report.  Glossary, index, and books to read are included at the back.  This is a great resource to help put years when particular dinosaurs lived in perspective.