For assistance in the field, we thank the remaining members of the 2011 and 2016 AP3 expeditions. We are also grateful to the members of the 1999 US-Argentinean JRB expedition that was jointly sponsored by NSF and the IAA, as well as the members of the NSF-funded 2003 expedition. We also acknowledge the extensive logistical assistance that our expeditions received from personnel from NSF, the US Antarctic Program, the Lockheed Martin Antarctic Support Contract, Raytheon Polar Services Corporation, and Edison Chouest Offshore. M. Reguero, A. Scarano, J. Gelfo, and C. Acosta Hospitaleche provided access to dinosaur specimens housed at the MLP to MCL, JAC1, RCE, and PMO, and F. Novas, M. Ezcurra, F. Agnolín, A. M. Aranciaga Rolando, M. Isasi, and M. Cerroni facilitated access to the Morrosaurus holotype at the MACN for MCL. R. Coria participated in valuable discussions regarding the Trinisaura holotype. A. McAfee produced the figures with his usual skill and care, and K. Gigler assisted with assembling and formatting the bibliography. We also acknowledge S. Hartman for providing many of the silhouettes that appear in Figures 1 and 6 via PhyloPic.org, R. Blakey for permission to reproduce his paleogeographic map as Figure 1c, and P. Currie for permission to reproduce his photograph as Figure 1e. Similarly, we thank E. Olivero for permission to reproduce his photograph as Figure 5a and Cambridge University Press for authorization to reproduce the photograph in Figure 5e. The authors are especially grateful to C. Acosta Hospitaleche, A. Crame, and J. Gelfo for inviting us to contribute to this volume, and to M. Reguero for kindly providing the photographs of the pedal ungual MLP 98-I-10-70 that appear in Figure 3. The manuscript was improved by comments from reviewers R. Coria and S. Poropat and Guest Editor A. Crame. AP3 research has been supported by NSF grants ANT-1142129 to MCL, ANT-1141820 to JAC2, ANT-1142104 to PMO, ANT- 0636639 and ANT-1142052 to R. MacPhee, and OPP-9615933 and ANT-0003844 to JAC1. （）