A new early Pleistocene dwarf pocket gopher species is described from the Short Haul, Aries A, and Nash 72 assemblages in the Borchers Badlands of Meade County, Kansas. Geomys tyrioni is defined by its diminutive size and modern dental and mandibular masseter muscle configuration. G. tyrioni, currently known from the interval of about 2.0–1.70 millions of years ago (Ma), replaced the larger G. floralindae and G. quinni of the slightly earlier (2.11 Ma) Borchers assemblage. Mandibular and dental characters place G. tyrioni in the group of Geomys including the extant Great Plains G. bursarius. Within about 24,000 years after the Nash 72 assemblage, G. tyrioni was replaced by modern-sized Geomys cf. G. bursarius in the Rick Forester assemblage, the earliest record of the extant plains pocket gopher in the Meade Basin and North America. G. tobinensis Hibbard is synonymized with G. bursarius. An evolutionary scenario is provided for the Meade Basin geomyines based on current information, and it is suggested that ashfalls may have played a significant role in geomyine cladogenesis and turnover.