Our paper is based on material collected and studied over many years with funds from the National Science Foundation (OPP-9714975, DPP 91-03859, EAR 92-04789 to FAJ and DBI-9974424 to SMG) and the Putnam Foundation of Harvard University. We thank K. Middleton, A. Clifford, and two anonymous reviewers for comments, as well as S. Kunz and K. Kenny for SEM assistance, and Alias for software support.
In presenting anaglyphs of theropod footprints, we remember with great affection a friend and colleague who devoted his professional life to promoting the exploration of the vertebrate fossil record throughout the world. Will Downs joined us in the deserts of American southwest, in the foothills of the Atlas Mountains of North Africa, and across the vast landscapes of Arctic Greenland. With little money and few possessions, he carried with him an indefatigable spirit of curiosity and seemingly relentless energy. The techniques described in this paper would have appealed to Will, for he was always keen to try new approaches and eager to experience new ways of seeing the world. We affectionately dedicate our contribution to his memory.