MONTANA

CARTER COUNTY

ALZADA

BELLE FOURCHE FORMATION

EARLY CENOMANIAN STAGE

UPPER MIDDLE GALLIC SUBEPOCH

LOWERMOST GULF EPOCH

MIDDLE CRETACEOUS
NOTE: WAS BENTON FORMATION, TURONIAN, LATE CRETACEOUS

STEM: TETRAPODA GOODRICH, 1930

SUPERCLASS: AMNIOTA HAECKEL, 1866

CLASS: REPTILIA LAURENTI, 1768

SUBCLASS: DIAPSIDA OSBORN, 1904

INFRACLASS: EURYAPSIDA COLBERT, 1945

SUPERORDER: SAUROPTERYGIA OWEN 1860

GRANDORDER: EOSAUROPTERYGIA emend RIEPPEL, 1994

ORDER: PLESIOSAURIA OWEN, 1840 NON BLAINVILLE, 1835

SUBORDER: PLESIOSAURIA OWEN, 1840 NON BLAINVILLE, 1835

INFRAORDER: PLESIOSAUROMORPHA NOVA

EUPLESIOSAURIA O’KEEFE, 2001

Superfamily: ELASMOSAUROIDEA Cope, 1869

Family: ELASMOSAURIDAE Cope, 1869

Thalassomeodon haningtoni
= *Alzadasaurus riggsi
= Elasmosaurus serpentinus

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