Six specimens of the rare taeniodont, †Stylinodon mirus, are recorded from the Lower part of the Adobe Town Member (TWkA1), Washakie Formation, Late Bridgerian–Early Uintan Land Mammal Age of the Washakie Basin. They are described and compared with other similarly aged specimens from other western North American basins. †S. mirus is the last of the taeniodonts, one of the early lines in the mammalian adaptive radiation that followed the demise of the dinosaurs. The most important of them is the articulated partial skeleton, FMNH PM 3895. It shows much new anatomical detail and it exhibits three notable specializations that provide a firm basis for speculation about its habitus. †Stylinodon inexplicatus Schoch and Lucas, 1981a, is shown to be a juvenile of †S. mirus, and is thereby put into synonymy with that species.