YANKTON COUNTY
NEAR YANKTON
MISSOURI RIVER
NIOBRARA FORMATION
LATE CRETACEOUS
STEM: TETRAPODA GOODRICH, 1930
SUPERCLASS: AMNIOTA HAECKEL, 1866
CLASS: REPTILIA LAURENTI, 1768
SUBCLASS: CHELONOMORPHA KUHN, 1960
SUPERCOHORT: TESTUDINES LINNAEUS, 1758
COHORT: CASICHELYDIA emend GAFFNEY & MEYLAN, 1988
MAGANORDER: CRYPTODIRA GAFFNEY & MEYLAN, 1988
SUPERORDER: SELMACRYPTODIRA GAFFNEY, HUTCHISON, JENKINS & MEEKR, 1987
GRANDORDER: DAIOCRYPTODIRA GAFFNEY & MEYLAN, 1988
MICRORDER: CENTROCRYPTODIRA GAFFNEY & MEYLAN, 1988
ORDER: POLYCRPTODIRA GAFFNEY & MEYLAN, 1988
SUBORDER: PROCOELOCRYPTODIRA GAFFNEY & MEYLAN, 1988
INFRAORDER: CHELONOIDEA GAFFNEY & MEYLAN, 1988
Superfamily: DERMOCHELYOIDEA Willams, 1950
Family: TOXOCHELYIDAE Baur, 1895
Subfamily: TOXOCHELYINAE Baur, 1895 (sensu Zangerl, 1953)
Gen sp indet.
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SOUTH DAKOTA
YANKTON COUNTY
NEAR MARINDAHL DAM SPILLWAY
4.6 METERS BELOW NIOBRARA/PIERRE CONTACT
LATE CRETACEOUS
STEM: TETRAPODA GOODRICH, 1930
SUPERCLASS: AMNIOTA HAECKEL, 1866
CLASS: REPTILIA LAURENTI, 1768
SUBCLASS: DIAPSIDA OSBORN, 1903
INFRACLASS: NEODIAPSIDA BENTON, 1985
LEGION: LEPIDOSAUROMORPHA BENTON, 1983
SUBLEGION: LEPIDOSAURIA HAECKEL, 1866 (DUMERIL & BIBRON, 1839)
MAGNORDER: SQUAMATA, OPPEL, 1811
SUPERORDER: LACERTILIA OWEN, 1842
GRANDORDER: SCINCOGEKKONOMORPHA SUKHANOV, 1961
MICRORDER: SCINCOMORPHA CAMP, 1923
ORDER: ANGUIMORPHA FURBRINGER, 1900
SUBORDER: DIPLOGLOSSA COPE, 1864
INFRAORDER: THECAGLOSSA COPE, 1890
PARVORDER: MONSTERSAURIA NORELL & GAO, 1977
Superfamily: VARANOIDEA Gray, 1827 (sensu Camp, 1923)
Family: MOSASAURIDAE Gervais, 1853
Infrafamily: NATANIA
Subfamily: MOSASAURINAE Gervais, 1853 (sensu Williston, 1897)
Tribe: MOSASAURINI Gervais, 1853 (sensu Russell, 1967)
Clidastes propython
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SOUTH DAKOTA
YANKTON COUNTY
MISSOURI RIVER
NIOBRARA FORMATION
LATE CRETACEOUS
STEM: TETRAPODA GOODRICH, 1930
____________________________________________________________________________________SUPERCLASS: AMNIOTA HAECKEL, 1866
CLASS: REPTILIA LAURENTI, 1768
SUBCLASS: DIAPSIDA OSBORN, 1903
INFRACLASS: NEODIAPSIDA BENTON, 1985
LEGION: LEPIDOSAUROMORPHA BENTON, 1983
SUBLEGION: LEPIDOSAURIA HAECKEL, 1866 (DUMERIL & BIBRON, 1839)
MAGNORDER: SQUAMATA, OPPEL, 1811
SUPERORDER: LACERTILIA OWEN, 1842
GRANDORDER: SCINCOGEKKONOMORPHA SUKHANOV, 1961
MICRORDER: SCINCOMORPHA CAMP, 1923
ORDER: ANGUIMORPHA FURBRINGER, 1900
SUBORDER: DIPLOGLOSSA COPE, 1864
INFRAORDER: THECAGLOSSA COPE, 1890
PARVORDER: MONSTERSAURIA NORELL & GAO, 1977
Superfamily: VARANOIDEA Gray, 1827 (sensu Camp, 1923)
Family: MOSASAURIDAE Gervais, 1853
Infrafamily: NATANIA
Subfamily: TYLOSAURINAE Williston, 1897
Tylosaurus proriger
SOUTH DAKOTA
YANKTON COUNTY
MISSOURI RIVER VALLEY NEAR YANKTON
LOWER PIERRE FORMATION
LATE CRETACEOUS
STEM: TETRAPODA GOODRICH, 1930
SUPERCLASS: AMNIOTA HAECKEL, 1866
CLASS: REPTILIA LAURENTI, 1768
SUBCLASS: DIAPSIDA OSBORN, 1903
INFRACLASS: NEODIAPSIDA BENTON, 1985
LEGION: LEPIDOSAUROMORPHA BENTON, 1983
SUBLEGION: LEPIDOSAURIA HAECKEL, 1866 (DUMERIL & BIBRON, 1839)
MAGNORDER: SQUAMATA, OPPEL, 1811
SUPERORDER: LACERTILIA OWEN, 1842
GRANDORDER: SCINCOGEKKONOMORPHA SUKHANOV, 1961
MICRORDER: SCINCOMORPHA CAMP, 1923
ORDER: ANGUIMORPHA FURBRINGER, 1900
SUBORDER: DIPLOGLOSSA COPE, 1864
INFRAORDER: THECAGLOSSA COPE, 1890
PARVORDER: MONSTERSAURIA NORELL & GAO, 1977
Superfamily: VARANOIDEA Gray, 1827 (sensu Camp, 1923)
Family: MOSASAURIDAE Gervais, 1853
Infrafamily: NATANIA
Subfamily: RUSSELLOSAURINAE
Tribe: PLIOPLATECARPINI Dollo, 1884 (sensu Russell, 1967)
Platecarpus ictericus
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