The term geology is a combination of two Greek expressions: “Geo” refers to the earth, and “logos” refers to the logic and language used to explain your observations. So think of geology as a way to organize and explain the earth processes that we see all around us. For some of the strange shapes we see, an educated explanation would be great. Most of what we know is good guesswork, based on lab experiments and inferences that take many detailed drawings to explain and a lifetime to understand. Fortunately, the more you see, the better things fall into place. <...>

The last decade has witnessed the expansion of field work and the recovery of many important new fossil vertebrates from a number of areas in the Rocky Mountain Interior. This has resulted in (among other things) discovery of many previously unknown taxa and of much better preserved specimens of known forms, significant geographic and temporal range extensions, the development of greater temporal resolution and sampling density for many taxa (leading to much more precise biochronology), and the creation and applicaton of models for examining faunal relations and evolutionary patterns. When the opportunity for this symposium arose, we were faced with the dilemma of how to incorporate as much of this new information as possible, yet limit the resulting monograph to manageable proportions. We decided to confine the subject matter geographically and temporally, to a region and a time span with which we are most familiar and within which much of the exciting new research is now being conducted—the latest Cretaceous and early Tertiary of the northern Rocky Mountain region. This volume is derived from papers presented at that symposium on May 2,1987, at the annual regional meeting of the Rocky Mountain Section of the Geological Society of America, held at the University of Colorado in Boulder <...>