Reptilia - Dinosauria - Pachycephalosauridae

Alternative combination: Troodon wyomingensis

Synonyms: Dracorex hogwartsi Bakker et al. 2006, Dracorex hogwartsia Bakker et al. 2006, Pachycephalosaurus grangeri Brown and Schlaikjer 1943, Pachycephalosaurus reinheimeri Brown and Schlaikjer 1943, Tylosteus ornatus Leidy 1872

Belongs to Pachycephalosaurus according to R. M. Sullivan 2006

Sister taxa: none

Type specimens:

• Pachycephalosaurus wyomingensis: USNM 12031. Its type locality is Warren Post Office, Buck Creek, which is in a Maastrichtian terrestrial horizon in the Lance Formation of Wyoming.
• Dracorex hogwartsia: TCMI 2004.17.1, a partial skeleton. Its type locality is Dracorex type site, which is in a Maastrichtian terrestrial horizon in the Hell Creek Formation of South Dakota.
• Pachycephalosaurus grangeri: AMNH 1696, a skull. Its type locality is William Winkley Ranch, Powder Hill, which is in a Maastrichtian terrestrial horizon in the Hell Creek Formation of Montana.
• Pachycephalosaurus reinheimeri: DMNH 469, a skull. Its type locality is Twito ranch (DMNH), which is in a Maastrichtian terrestrial horizon in the Lance Formation of South Dakota.
• Tylosteus ornatus: ANSP 8568, a partial skull.