Here is the fourth supplement to "Dinosaurs: The Encyclopedia", a 1998 American Library Association Outstanding Reference Book (ARBA called it "a reference legend...lavishly illustrated, cleverly written, and extraordinarily comprehensive"). This volume updates the concepts discussed in the encyclopedia and its earlier supplements. It includes a discussion of the Mesozoic Era, covers recent discoveries in paleontology, and furthers the ectothermy/endothermy debate from previous installments. It also offers lengthy sections on dinosaurian schematics and genera and updates the encyclopedia's list of excluded genera. Appendices discuss Pterosaurs and Mesozoic birds, and a glossary is included to aid students and scientists alike. The extensive bibliography lists the most recent peer-evaluated paleontology literature.