Tobe locality, Comanche National Grassland: Middle Cenomanian, Colorado

List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
Bivalvia - Ostreida - Ostreidae
Ostrea beloiti Logan 1899
Bivalvia - Myalinida - Inoceramidae
Inoceramus cf. rutherfordi
Cephalopoda - Ammonitida - Acanthoceratidae
Eucalycoceras sp. Spath 1923
    = Calycoceras sp. Hyatt 1900
Shimada et al. 2006
Chondrichthyes - Hybodontiformes - Ptychodontidae
Ptychodus occidentalis Leidy 1868
Ptychodus cf. anonymus Williston 1900
Ptychodus decurrens Agassiz 1838
Chondrichthyes - Orectolobiformes - Parascylliidae
cf. Pararhincodon sp. Herman 1975
Shimada et al. 2006
Chondrichthyes - Lamniformes - Aquilolamnidae
Cretomanta canadensis Case et al. 1990
Chondrichthyes - Lamniformes - Otodontidae
Cretolamna appendiculata (Agassiz 1835)
recombined as Cretalamna appendiculata
Cretolamna cf. woodwardi Herman 1977
    = Cretalamna appendiculata Agassiz 1835
Shimada et al. 2006
Chondrichthyes - Lamniformes - Cretoxyrhinidae
Cretoxyrhina mantelli (Agassiz 1835)
Chondrichthyes - Lamniformes - Odontaspididae
Johnlongia cf. parvidens (Cappetta 1973)
Shimada et al. 2006
cf. Johnlongia sp. Siverson 1996
Shimada et al. 2006
    = Megachasma comanchensis n. sp. Shimada 2007
Shimada 2007
recombined as Pseudomegachasma comanchensis
Carcharias saskatchewanensis (Case et al. 1990)
recombined as Microcarcharias saskatchewanensis
Carcharias tenuiplicatus (Cappetta and Case 1975)
recombined as Eostriatolamia tenuiplicatus
Chondrichthyes - Lamniformes - Pseudoscapanorhynchidae
Cretodus semiplicatus (Agassiz 1843)
Chondrichthyes - Lamniformes - Anacoracidae
Squalicorax sp. Whitley 1939
Shimada et al. 2006
Squalicorax falcatus (Agassiz 1843)
Squalicorax curvatus (Williston 1900)
Microcorax crassus Cappetta and Case 1975
Shimada et al. 2006
Chondrichthyes - Lamniformes - Haimirichiidae
Carcharias amonensis (Cappetta and Case 1975)
recombined as Haimirichia amonensis
Chondrichthyes - Lamniformes - Archaeolamnidae
Archaeolamna sp. Siverson 1992
    = Archaeolamna cf. kopingensis Davis 1890
Shimada et al. 2006
Chondrichthyes - Carcharhiniformes
Carcharhiniformes indet. Compagno 1973
Shimada et al. 2006
Chondrichthyes - Rajiformes - Sclerorhynchidae
? Sclerorhynchidae indet. Capetta 1974
Shimada et al. 2006
Chondrichthyes - Rajiformes - Ptychotrygonidae
Ptychotrygon sp. Jaekel 1894
Shimada et al. 2006
Chondrichthyes - Rajiformes - Rhinobatidae
Rhinobatos incertus Cappetta 1973
Actinopteri - Pycnodontiformes - Pycnodontidae
"Nursallia" sp. Blot 1987
Shimada et al. 2006
cf. Palaeobalistum sp. Blainville 1818
Shimada et al. 2006
Actinopteri - Pycnodontiformes - Mesturidae
Pycnodontidae indet. (Agassiz 1833)
    = Micropycnodon cf. kansasensis Hibbard and Graffham 1941
Shimada et al. 2006
Actinopteri - Ichthyodectiformes - Ichthyodectidae
Xiphactinus audax (Leidy 1870)
Actinopteri - Tselfatiiformes - Plethodidae
? Plethodidae indet. Loomis 1900
Shimada et al. 2006
Actinopteri - Albuliformes - Albulidae
Albulidae indet. Bleeker 1859
Actinopteri - Aulopiformes - Enchodontidae
Enchodus cf. shumardi Leidy 1856
Enchodus cf. gladiolus Cope 1872
Actinopteri - Crossognathiformes - Pachyrhizodontidae
cf. Pachyrhizodus sp. Agassiz 1850
Shimada et al. 2006
cf. Pachyrhizodus minimus Stewart 1899
Shimada et al. 2006
Actinopteri - Pachycormiformes - Pachycormidae
Protosphyraena sp. Leidy 1857
Reptilia - Plesiosauria
? Plesiosauria indet. de Blainville 1835
Shimada et al. 2006
Reptilia - Plesiosauria - Polycotylidae
cf. Trinacromerum sp. Cragin 1888
    = Polycotylidae indet. Williston 1908
Shimada et al. 2006
Reptilia - Plesiosauria - Pliosauridae
cf. Brachauchenius sp. Williston 1903
Reptilia
Mosasauroidea indet. ()
Shimada et al. 2006
spelled with current rank as Mosasauria
Coniasaurus cf. crassidens Owen 1850
    = Coniasaurus crassidens Owen 1850
Shimada et al. 2006
see common names

Geography
Country:United States State/province:Colorado County:Las Animas
Coordinates: 37.2° North, 103.6° West (view map)
Paleocoordinates:36.9° North, 66.6° West
Basis of coordinate:based on nearby landmark
Geographic resolution:outcrop
Time
Period:Cretaceous Epoch:Late/Upper Cretaceous
Stage:Cenomanian 10 m.y. bin:Cretaceous 5
Key time interval:Middle Cenomanian
Age range of interval:100.50000 - 93.90000 m.y. ago
Stratigraphy
Geological group:Colorado Formation:Greenhorn Limestone Member:Lincoln Limestone
Stratigraphic resolution:group of beds
Stratigraphy comments: The vertebrate-rich calcarenite unit discussed in this paper is located approximately 2.5 m above the contact between the noncalcareous Graneros Shale and calcareous Greenhorn Limestone. Ostrea beloiti and I. cf. I. rutherfordi range from the Middle Cenomanian (96 Ma) to the early Late Cenomanian (ca. 94.6 Ma), and from middle Middle Cenomanian (ca. 95 Ma) to possibly as late as early Late Cenomanian (ca. 94.55 Ma), respectively (Kauffman et al., 1993, fig. 7). Thus, the concurrent age of occurrence for these two bivalve taxa is 95–94.5 Ma, which dictates that the vertebrate-rich horizon is no older than the middle Middle Cenomanian (ca. 95 Ma). Based upon the similarity of our data with those presented by Kauffman et al. (1993, fig. 7), and considering the close proximity of the calcarenite layers to the X-bentonite, we think that the age of the vertebrate-rich horizon is somewhere between middle Middle Cenomanian (ca. 95 Ma) and late Middle Cenomanian (ca. 94.7 Ma).
Lithology and environment
Primary lithology: lithified grainstone
Lithology description: "calcarenite beds"
Environment:deep subtidal ramp
Taphonomy
Modes of preservation:body
Size of fossils:macrofossils,mesofossils
Disassociated minor elements:many
Collection methods and comments
Collection methods:bulk,surface (float),chemical,field collection
Reason for describing collection:general faunal/floral analysis
Collection method comments: Repository: Sternberg Museum of Natural History, Fort Hays State University (FHSM), Hays, Kansas
Taxonomic list comments:some molluscs may be omitted
Metadata
Database number:35429
Authorizer:J. Alroy, M. Clapham Enterer:J. Alroy, M. Clapham
Modifier:M. Clapham Research group:marine invertebrate,vertebrate
Created:2003-12-12 11:21:23 Last modified:2020-08-30 22:32:15
Access level:the public Released:2003-12-12 11:21:23
Creative Commons license:CC BY
Reference information

Primary reference:
9572. K. Shimada, J. A. Parkin, J. M. Palermo and B. A. Schumacher. 2003. Late Cretaceous marine vertebrates from the basal Greenhorn Limestone in southeastern Colorado. Journal of Vertebrate Paleontology 23(3):96A [J. Alroy/J. Alroy/J. Alroy]

Secondary references:

73660 K. Shimada. 2007. Mesozoic origin for megamouth shark (Lamniformes: Megachasmidae). Journal of Vertebrate Paleontology 27:512-516 [M. Clapham/M. Clapham]
34831 K. Shimada, B. A. Schumacher, J. A. Parkin and J. M. Palermo. 2006. Fossil marine vertebrates from the lowermost Greenhorn Limestone (Upper Cretaceous: Middle Cenomanian) in southeastern Colorado. Journal of Paleontology 80(sp 63):1-45 [M. Carrano/H. Street]