Because of the broad geographic and editorial scope of this book and our intent to make it accurate but non-technical, many creative and scholarly individuals were vital to its development. Diana Turner helped to formulate the character of the project; and two writers, both with scientific expertise and a way with words—Susan Cummins Miller and Mari Jensen—made valuable contributions to portions of the text. Bob MacLeod, David Morton, and Elizabeth Shaw read much of the manuscript and offered helpful suggestions throughout. Sally Antrobus and Linda Gregonis edited the complete text with care, sensitivity, and professionalism found only in the best of editors. We also appreciate the authors and their publishers whose quoted words of wisdom and inspiration have enhanced our text. Thank you all.

The following 21 experts in their fields, mostly within the National Park Service, checked our text as a whole or in part for accuracy and clarity. We are extremely grateful for their enthusiastic and valuable responses—without exception, these friendly and dedicated individuals helped to make this a better book.

Arvid Aase/Fossil Butte National Monument; Sidney Ash, Paleobotanist; Terry Baldino, Assistant Chief of Interpretation/Death Valley National Park; John Bezy, Staff Ranger/Saguaro National Park; Anna Domitrovic, Mineralogist & Collection Manager/Arizona-Sonora Desert Museum; Stephanie Dubois, Chief of Interpretation/Glen Canyon National Recreation Area; Tom Haraden, Acting Chief Naturalist/Zion National Park; Paul Henderson, Chief of Interpretation/Canyonlands National Park; Wilson Hunter, Chief of Interpretation/Canyon de Chelly National Monument; Carol Kruse, Interpretive Specialist/Sunset Crater Volcano National Monument; John Mangimeli, Chief Interpretive Ranger/White Sands National Monument; Will Morris, Chief of Interpretation/Mesa Verde National Park; Thea Nordling, Chief of Interpretation/Capitol Reef National Park; Wanda Olszewski, Interpretive Specialist/Hueco Tanks State Historical Park; Steve Roof, Assistant Professor in Earth & Environmental Science/Hampshire College; Steve Sandell, Chief Ranger/Montezuma Castle National Monument; Tessy Shirakawa, Chief of Interpretation/Petrified Forest National Park; Harry Walters, Director, Hatathli Museum/Dineh College; David Whitman, Chief of Interpretation/Dinosaur National Monument; Justin Wilkinson, NASA Geomorphologist; James Woolsey, Interpretive Branch Manager/Bryce Canyon National Park.

The importance of illustrators and designers in particular often goes unnoticed, but for a book to be inviting, lively, and easy to read, great design is crucial. Carol Haralson has worked wonders with this material, both as a talented designer and as an editor—thank you, Carol! And for the many fine maps and illustrations that embellish our text, we are profoundly grateful to David Fischer, Michael Robinson, Paul Mirocha, Leo Gabaldon, dinosaur sculptor John Fischner, Ray Sterner/Johns Hopkins University, and the team at Eureka Cartography in Berkeley. And we thank the photographers, government agencies, and corporations who provided images to extend our coverage—credits appear with each.

We wish to thank the following individuals, companies, and institutions for loans of the many superb specimens featured in these pages: John Alcorn; Arizona Historical Society; Arizona-Sonora Desert Museum; Arizona State Museum; Bill Hawes' Fossils; Black Hills Institute of Geological Research; Clare's Fossil Quarry; Simon Cohen Fossils; Susan Cummins Miller; Den's Petrified Critters; Jim Work/Dominican Amber Co.; Jimmy Vacek/Forty-Niner Minerals; Gem City, Laramie, Wyoming; Geological Enterprises; Thomas Johnson/House of Phacops; Jerry MacDonald/Paleozoic Trackways Project; David Morton; Phelps Dodge Corporation; Potomac Museum Group; Tucson Marble & Granite Co.; Rick Hebdon & Gael Summer/Warfield Fossils; Klaus Westphal/University of Wisconsin's Museum of Geology; and Richard White/International Wildlife Museum.

A note of gratitude is also due Wild Horizons photographic workshop participants who, over a decade of stimulating conversation and exploration in the Southwest, provided the catalyst for this book. Many other friends and colleagues contributed to the project in smaller but significant ways, and we genuinely appreciate your support and good faith as well.