INTRODUCTION Used since its inception (Bowdich, 1821) as a “waste-basket” for morphologically disparate, putatively “primitive,” and generally ancient groups of small- to moderate-sized mammals, the traditional “Order Insectivora” of Simpson (1945) simply does not exist as an internally consistent or unified taxonomic grouping. This is true in both a morphological and a phylogenetic sense, and it reflects the considerable, though commonly understated, adaptive breadth of “insectivores.” Collectively, the “insectivorous” mammals are generally referred to by the appellation “primitive.” However, the cranial and dental specializations of hedgehogs (Erinaceidae), and shrews, moles, and apternodontids (Soricomorpha), are anything but primitive. Similarly, though fossil postcrania for most of these groups is poorly known among North American forms, those of moles are uniquely specialized by any definition. Most of the mammals discussed herein are relatively rare components of fossil vertebrate faunas. A few are known only from the type materials and many more only from incomplete upper or lower dentitions. Therefore, the dental anatomy of insectivorous mammals has both largely determined their diagnoses from related forms as well as played an instrumental role in their phylogenetic reconstruction. Notable exceptions to the constraints posed by limited knowledge of the anatomy of fossil forms are the importance of the anatomy of the humerus and the mandible to the taxonomy and phylogeny of, respectively, the moles and shrews. Of the groups of insectivorous mammals discussed herein, only Solenodontidae (including Nesophontidae), Talpidae, and Soricidae survive in North America.