The members of the mammalian orders Pholidota (the Old World pangolins, or scaly anteaters) and Xenarthra (the New World armadillos, anteaters and sloths and their extinct kin) are among the most unusual of all placental mammals. Despite the differences in anatomy, ecology and geographic distribution presented by these mammals, previous studies have suggested that these two orders share a close common ancestry, as evidenced by the reduction or elimination of their teeth and a handful of other detailed anatomical similarities. Unfortunately, the potential relationship of these two groups to one another or to other groups of placental mammals remains one of the least investigated portions of placental mammal phylogeny. The goal of the proposed study is twofold: (a) to support research at the National Museum of Natural History in Washington, D.C. including preparation, illustration and description of a complete skeleton of the fossil pangolin Patriomanis americanus.; and (b) to conduct an analysis of the phylogenetic relationships of the order Pholidota, including all seven living species as well as the three other well-known extinct pangolins, Eomanis and Necromanis, from the Eocene and Oligo-Miocene of Europe respectively, as well as an undescribed taxon from the Eocene of Mongolia. The results from this new phylogenetic study will be combined with the results of previous studies on the systematic relationships within the order Xenarthra to form the foundation of a broader study on the phylogeny of the Cohort Edentata, a group that ostensibly includes the pholidotans, xenarthrans and an extinct early Tertiary group of burrowing mammals, the Palaeanodonta. The proposed study will examine skeletal characteristics in representatives of each of the major extinct and living family level groupings within Pholidota, Xenarthra and Palaeanodonta. These characters will then be compared to the condition in a range of living and extinct placental and marsupial ingroup and outgroup taxa. This study will be the first comprehensive cladistic investigation of edentate relationships based on anatomical features. It will also be the only such study to incorporate all the major edentate lineages, as well as a broad sampling of other placental orders, including representatives of each of the major placental supraordinal groups identified by previous studies. The results of the proposed study will serve as an important groundwork for understanding the evolution of the various unusual anatomical and ecological specializations that characterize pholidotan and xenarthran mammals, the prevalence of convergent adaptations in these groups, and the biogeographic history that underlies their diversification. Furthermore, some previous work has suggested that some or all of these edentate groups diverged from other placental mammals at or near the base of the placental radiation. If this is indeed the case, an improved understanding of edentate evolution may yield insight into the early biogeographic history and adaptive radiation of all placental mammals. One or more undergraduate students will be trained in various aspects of paleontological and systematics research.
