Acknowledgements

We are grateful to M. A. Abello for allowing us access to her 2007 Abello, M. A. 2007. Sistemática y bioestratigrafía de los Paucituberculata (Mammalia, Marsupialia) del Cenozoico de América del Sur. Universidad Nacional de La Plata, La Plata, 381 pp. [Google Scholar] thesis and unpublished research. We thank M. A. Abello, M. Benard, J. Fleagle, F. J. Goin, S. S. B. Hopkins, G. M. Martin, P. Pérez, S. Simpson and K. J. Travouillon for helpful discussions on a variety of topics related to this paper. We thank R. McCord (Arizona Museum of Natural History) for loans from the Larry Marshall Marsupial Dentition Collection; R. Wherley and G. Svenson (Cleveland Museum of Natural History) for generating high-resolution photographs of the specimens; B. Rubin and colleagues and S. Simpson for their help in diagnosing the pathology of UF 27883; M. A. Abello, S. Alvarez, and J. Fleagle for providing data used to create the reconstruction of A. maddeni in Figure 10; and M. A. Abello, M. O. Woodburne and an anonymous reviewer for their comments on earlier drafts of this manuscript. We also thank J. Bloch, R. Hulbert and B. MacFadden (UF) for allowing us to describe the palaeothentid specimens at UF and providing us information on their provenance. Finally, we wish to thank the members of the UF, University of Rochester, CWRU and UATF field crews responsible for collecting specimens at Quebrada Honda, without the efforts of whom much of this paper could never have been written. This research was originally conducted as part of an undergraduate honors thesis by R. K. Engelman at Case Western Reserve University. Funding for this research was provided by the National Science Foundation [EAR 0958733 and 1423058 to D. Croft] and the National Geographic Foundation [NGS 8115-06 to D. Croft].