Tobe locality, Comanche National Grassland (Cretaceous of the United States)

Where: Las Animas County, Colorado (37.2° N, 103.6° W: paleocoordinates 36.9° N, 66.6° W)

• coordinate based on nearby landmark

• outcrop-level geographic resolution

When: Lincoln Limestone Member (Greenhorn Limestone Formation), Middle Cenomanian (99.6 - 93.5 Ma)

• 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).

• group of beds-level stratigraphic resolution

Environment/lithology: deep subtidal ramp; lithified grainstone

• "calcarenite beds"

Size classes: macrofossils, mesofossils

Collection methods: bulk, surface (float), chemical,

• Repository: Sternberg Museum of Natural History, Fort Hays State University (FHSM), Hays, Kansas

Primary reference: 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]more details

Purpose of describing collection: general faunal/floral analysis

PaleoDB collection 35429: authorized by John Alroy, entered by John Alroy on 12.12.2003, edited by Matthew Clapham

Creative Commons license: CC BY (attribution)

Taxonomic list

• some molluscs may be omitted
Bivalvia
 Ostreida - Ostreidae
Ostrea beloiti Logan 1899 oyster
 Myalinida - Inoceramidae
Cephalopoda
 Ammonitida - Acanthoceratidae
Calycoceras sp.2 Hyatt 1900 ammonite
Reptilia
 Plesiosauria -
? Plesiosauria indet.2 de Blainville 1835 plesiosaur
 Plesiosauria - Pliosauridae
cf. Brachauchenius sp. Williston 1903 plesiosaur
 Plesiosauria - Polycotylidae
Polycotylidae indet.2 Williston 1908 plesiosaur
 Squamata -
 Squamata - Dolichosauridae
Coniasaurus crassidens2 Owen 1850 squamates
Actinopteri
 Pachycormiformes - Pachycormidae
Protosphyraena sp. Leidy 1857
 Tselfatiiformes - Plethodidae
? Plethodidae indet.2 Loomis 1900
 Albuliformes - Albulidae
Albulidae indet. Bleeker 1859 bonefish
 Aulopiformes - Enchodontidae
 Ichthyodectiformes - Ichthyodectidae
Xiphactinus audax Leidy 1870
 Crossognathiformes - Pachyrhizodontidae
cf. Pachyrhizodus sp.2 Agassiz 1850
 Pycnodontiformes - Mesturidae
Micropycnodon cf. kansasensis2 Hibbard and Graffham 1941
 Pycnodontiformes - Pycnodontidae
cf. Palaeobalistum sp.2 Blainville 1818
"Nursallia" sp.2 Blot 1987
Chondrichthyes
 Hybodontiformes - Ptychodontidae
Ptychodus cf. anonymus Williston 1900 elasmobranch
Ptychodus decurrens Agassiz 1838 elasmobranch
Ptychodus occidentalis Leidy 1868 elasmobranch
 Euselachii -
Carcharhiniformes indet.2 Compagno 1973 ground shark
 Orectolobiformes - Parascylliidae
cf. Pararhincodon sp.2 Herman 1975 collared carpetshark
 Lamniformes - Pseudoscapanorhynchidae
Cretodus semiplicatus Agassiz 1843 mackerel shark
 Lamniformes - Odontaspididae
"Carcharias tenuiplicatus" = Eostriatolamia tenuiplicatus, "Carcharias saskatchewanensis" = Microcarcharias saskatchewanensis, Johnlongia cf. parvidens2, "Megachasma comanchensis n. sp." = Pseudomegachasma comanchensis1
"Carcharias tenuiplicatus" = Eostriatolamia tenuiplicatus Cappetta and Case 1975 sand tiger shark
"Carcharias saskatchewanensis" = Microcarcharias saskatchewanensis Case et al. 1990 sand tiger shark
Johnlongia cf. parvidens2 Cappetta 1973 sand tiger shark
"Megachasma comanchensis n. sp." = Pseudomegachasma comanchensis1 Shimada 2007 sand tiger shark
 Lamniformes - Otodontidae
"Cretolamna appendiculata" = Cretalamna appendiculata, "Cretalamna appendiculata" = Cretalamna appendiculata2
"Cretolamna appendiculata" = Cretalamna appendiculata Agassiz 1835 mackerel shark
"Cretalamna appendiculata" = Cretalamna appendiculata2 Agassiz 1835 mackerel shark
 Lamniformes - Anacoracidae
Squalicorax sp.2 Whitley 1939 crow shark
Squalicorax curvatus Williston 1900 crow shark
Squalicorax falcatus Agassiz 1843 crow shark
Microcorax crassus2 Cappetta and Case 1975 mackerel shark
 Lamniformes - Archaeolamnidae
Archaeolamna cf. kopingensis2 Davis 1890 mackerel shark
 Lamniformes - Haimirichiidae
"Carcharias amonensis" = Haimirichia amonensis
"Carcharias amonensis" = Haimirichia amonensis Cappetta and Case 1975 mackerel shark
 Lamniformes - Aquilolamnidae
Cretomanta canadensis Case et al. 1990 mackerel shark
 Lamniformes - Cretoxyrhinidae
Cretoxyrhina mantelli Agassiz 1835 mackerel shark
 Rajiformes - Sclerorhynchidae
? Sclerorhynchidae indet.2 Capetta 1974 ray
 Rajiformes - Ptychotrygonidae
Ptychotrygon sp.2 Jaekel 1894 ray
 Rajiformes - Rhinobatidae
Rhinobatos incertus Cappetta 1973 guitarfish