Tooth remains of the elasmobranch Ptychodus are common in Late Cretaceous marine in both nearshore and deep water deposits worldwide. Although they are typically found as isolated tooth specimens, associated or articulated specimens are very rare. Described here is the first occurrence of an associated tooth set of the Late Cretaceous ptychodontiform shark P. mammillaris (FHSM VP-17989) from the Pfeifer Shale Member (lower middle Turonian) of the Greenhorn Limestone in Russell County, Kansas. The specimen consists of 47 teeth and represents the earliest stratigraphic occurrence of the species in the Western Interior Seaway. Although found disarticulated, this tooth set consists of teeth from eight different tooth file positions which demonstrates the heterodonty within the dentition. This specimen is unique because it is the earliest occurrence of the species and possesses the largest lower medial file teeth of P. mammillaris found in North America to date.