KANSAS
TWO MILE CREEK
SMOKY HILL MEMBER
NIOBRARA FORMATION
CONIACIAN STAGE
SENONIAN SUBEPOCH
GULF EPOCH
LATE CRETACEOUS
STEM: TETRAPODA GOODRICH, 1930
SUPERCLASS: AMNIOTA HAECKEL, 1866
CLASS: AVES LINNAEUS, 1758
AVEBREVICAUDA PAUL, 2001
SUBCLASS: ODONTORNITHES MARSH, 1873
INFRACLASS: ODONTOHOLCAE NOVA
MAGNORDER: HESPERORNITHES
ORDER: HESPERORNITHIFORMES FURBRINGER, 1888
Family: HESPERORNITHIDAE Marsh, 1872
Subfamily: HESPERORNITHINAE Marsh, 1872
Hesperornis regalis
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