9321482 McClearn This is a proposal to use anatomical features of the primitive eutherian (placental) mammals to generate hypotheses about the phylogenetic (genealogical) relationships of these animals. These hypotheses will be used as the framework for a study of the unusual feeding mechanisms of primitive eutherians. Many of these creatures, which include armadillos, sloths, anteaters and pangolins, are specialized for feeding on ants, and the various peculiarities of the tongue and digestive tract may have been developed independently in some of these mammalian lines. Little is known about the comparability of the anatomical features among these mammals. %%% This study will yield much useful information about relationships among early mammals and their specializations for myrmecophagy (ant-eating). This mammalian group has received little recent attention in phylogenetic research and this study will allow resolution of questions about transformations in the musculature of the tongue, palate and pharynx and the innervation of these structures in early mammals.