Genus: Tatankacephalus PARSONS & PARSONS, 2009
Etymology: Oglala language, Tatanka, referes to Bison bison, Latin, cephalus, 'head'; In dorsal view the cranium of Tatankacephalus is silimar in proportions to the cranium of Bison bison.
Species: cooneyorum PARSONS & PARSONS, 2009
Etymology: In honor of the family of John Patrick Cooney.
Holotype: MOR 1073
Locality: Middle Dome region, Harlowton, Wheatland County, Montana.
Horizon: Cloverly Formation.
Age: Cashenranchian, Aptian-Albian Stage, middle Gallic subepoch, lower Cretaceous Epoch, Early Cretaceous.
Material: Partial cranium consistins of a fragmentary portion of the nasal region with a fragmentary internasal septum, premaxillary fragments with three alveoli, maxillary-nasal fragment, orbital-postorbital-quadratojugal fragment, an isolated (maxillary or dentary) tooth, and a large posterior cranial fragment, including partial, squamosal, occiput, dorsal portion of left quadrate, braincase, right postorbital, right orbit, partial pterygoids, basisphenoid, partial basioccipital, parasphenoidal rostrum, rib fragments, and two ventrally concave, hollow, fragmentary osteoderms.