CHAPTER SIXTEEN New Skeletons of Paleocene–Eocene Plesiadapiformes: A Diversity of Arboreal Positional Behaviors in Early Primates Jonathan I. Bloch and Doug M. Boyer INTRODUCTION Knowledge of plesiadapiform skeletal morphology and inferred ecological roles are critical for establishing the evolutionary context that led to the appearance and diversification of Euprimates (see Silcox, this volume). Plesiadapiform dentitions are morphologically diverse, representing over 120 species usually classified in 11 families from the Paleocene and Eocene of North America, Europe, and Asia (Hooker et al., 1999; Silcox, 2001; Silcox and Gunnell, in press). Despite this documented diversity in dentitions, 535 Jonathan I. Bloch ● Florida Museum of Natural History, University of Florida, P. O. Box 117800, Gainesville, FL 32611-7800 Doug M. Boyer ● Department of Anatomical Science, Stony Brook University, Stony Brook, NY 11794-8081