In 1971 I published a review of ichnology other concentrating only on traces made (Houston AAPG: SEPM Trace Fossil Field by a certain group of organisms, regardless Trip Guidebook) that I thought could be of their setting. Nevertheless, needless re- dundancy has hopefully been eliminated. expanded rather easily into a worthwhile Some of the chapters are more special- book on the subject. I probed that possi- ized than others (because of the nature of bility for a while, thinking that I would particular topics); hence, these may be write the book myself. As I began to out- somewhat less familiar or "comprehensible" line the chapters in more detail, however, than others-depending upon the reader's it soon became apparent that my personal own interests and background. Other dif- knowledge of too many facets of ichnology ferences in the scope and content of vari- scraped bottom all too soon. I quickly de- ous chapters stem from the simple fact cided that a better book could be produced that a considerably greater backlog of pre- by soliciting specific contributions from vious work is available in certain facets of other workers who, collectively, had first- ichnology than in others. But we hope hand experience with virtually every aspect that all of the chapters will prove to be use- of the field. That became the actual plan, ful to anyone wishing to delve 'into them. the result of which is this book.