MONTANA

POWDER RIVER COUNTY

EAST SIDE ALONG POWDER RIVER DRAINAGE

24 KM SOUTH OF POWDERVILLE

HELL CREEK FORMATION

LANCIAN AGE

UPPER MAASTRICHTIAN STAGE

UPPERMOST SENONIAN SUBEPOCH

UPPER UPPER GULF EPOCH

LATE CRETACEOUS

STEM: TETRAPODA GOODRICH, 1930

SUPERCLASS: AMNIOTA HAECKEL, 1866

CLASS: REPTILIA LAURENTI, 1768

SUBCLASS: DIAPSIDA OSBORN, 1904

SUPERLEGION: NEODIAPSIDA BENTON, 1985

LEGION: ARCHOSAUROMORPHA HUENE, 1946

SUBLEGION: DINOSAUROMORPHA BENTON & NORMAN IN BENTON, 1985

INFRALEGION: DINOSAURIFORMES NOVAS, 1992

SUPERCOHORT: DINOSAURIA OWEN, 1842

COHORT: ORNITHISCHIFORMES COOPER, 1985

MAGNORDER: ORNITHISCHIA SEELEY, 1888

SUPERORDER: EURYOPDA SERENO, 1986

GRANDORDER: ARMATOSAURIA ZHAO, 1983 (emend)

ORDER: ANKYLOSAURIA OSBORN, 1923

SUBORDER: SCELIDOSAURIA COOPER, 1985

INFRAORDER: ANKYLOSAURA OSBORN, 1923

Family: ANKYLOSAURIDAE Brown, 1908

Subfamily: ANKYLOSAURINAE Brown, 1908

Ankylosaurus magniventris