Robison Eggshell Site (CM): Early Cenomanian, Utah
collected by Robison 1990-1991

List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
Osteichthyes
Fiorillo 1999
Actinopteri - Aulopiformes - Enchodontidae
Fiorillo 1999
Actinopteri - Pycnodontiformes - Pycnodontidae
Fiorillo 1999
Actinopteri - Lepisosteiformes
Fiorillo 1999
Actinopteri - Amiiformes
Fiorillo 1999
Amphibia - Temnospondyli
Fiorillo 1999 1 specimen
Reptilia
Fiorillo 1999
Reptilia - Spheroolithidae
Fiorillo 1999
Reptilia - Theropoda
Fiorillo 1999 1 specimen
see Fiorillo & Currie 1994
Fiorillo 1999
Reptilia - Dromaeosauridae
Fiorillo 1999
Fiorillo 1999
Reptilia
Fiorillo 1999 1 specimen
Reptilia - Tyrannosauridae
Fiorillo 1999 1 specimen
Reptilia - Elongatoolithidae
Fiorillo 1999
Reptilia
Fiorillo 1999
    = Mesoeucrocodylia indet. Whetstone and Whybrow 1983
Tennant et al. 2016
Reptilia - Pholidosauridae
Fiorillo 1999
Reptilia - Crocodylia
Crocodylia indet. (Owen 1842)
Reptilia
Fiorillo 1999
Reptilia - Lacertilia
Fiorillo 1999 1 specimen
Reptilia - Testudines
Chelonia indet. (Latreille 1800)
Fiorillo 1999
Reptilia - Testudines - Trionychidae
Fiorillo 1999 1 specimen
Reptilia
Fiorillo 1999
Mammalia
2 specimens
Chondrichthyes
Fiorillo 1999
Chondrichthyes - Hybodontiformes - Hybodontidae
Fiorillo 1999
Chondrichthyes - Rajiformes
Fiorillo 1999
Chondrichthyes - Orectolobiformes - Orectolobidae
Fiorillo 1999 1 specimen
see common names

Geography
Country:United States State/province:Utah County:Emery
Coordinates: 39.1° North, 111.0° West (view map)
Paleocoordinates:46.2° North, 69.1° West (Wright 2013)
Basis of coordinate:estimated from map
Geographic resolution:small collection
Time
Period: Cretaceous Epoch: Late Cretaceous
Stage: Cenomanian 10 m.y. bin: Cretaceous 5
*International age/stage:Beriasian - Danian
Key time interval: Early Cenomanian
Age range of interval: 100.5 - 93.9 m.y. ago
* legacy (obsolete) database fields
Stratigraphy
Geological group:Dakota Formation:Cedar Mountain Member:Mussentuchit
Stratigraphic resolution:bed
Stratigraphy comments: Tucker et al. 2020: sedimentary history of the Mussentuchit Member within the region of Mussentuchit Wash, Central Utah and compare these data with previous approaches. This study finds that emplacement of contemporaneous volcanilithics occurred in two distinct phases. The first phase occurred no older than 96 Ma, and a subsequent younger phase occurred no older than 94 Ma.

A radiometric age of 98.37 ± 0.07 Ma was obtained by the OMNH from volcanic ash within the Mussentuchit Member (Cifelli and others, 1997, 1999). Additional ages by Garrison and others (2007) ranging from 96.7 ± 0.5 to 98.2 ±0.6 Ma indicate that the Mussentuchit Member was deposited over an interval of 1.5 Ma during the early Cenomanian and supports a correlation with the siliceous marine Mowry Shale to the north, which is well-constrained from 40Ar/39Ar sanidine ages obtained from bentonite beds that bracket the Mowry in Wyoming; the basal Arrow Creek Bentonite is 98.5 ± 0.5 Ma and the capping Clay Spur Bentonite is 97.2 ± 0.7 Ma (Obradovich, 1993; Ogg and Hinnov, 2012; Sprinkel and others, 2012) near the base of the Upper Cretaceous.
Lithology and environment
Primary lithology: siltstone
Secondary lithology: mudstone
Includes fossils?Y
Includes fossils?Y
Lithology description: "a variable stilstone-mudstone interval"
Environment:"floodplain"
Geology comments: broad alluvial floodplain
Taphonomy
Modes of preservation:body
Degree of concentration:concentrated
Size of fossils:mesofossils
Disassociated major elements:many
Disassociated minor elements:many
Fragmentation:frequent
Bioerosion:occasional
Feeding/predation traces:gastric dissolution
Collection methods and comments
Collection methods:bulk,surface (in situ),sieve,field collection
Reason for describing collection:general faunal/floral analysis
Museum repositories:CM
Collectors:Robison Collection dates:1990-1991
Metadata
Also known as:Egg Shell Quarry; OMNH V820
Database number:22679
Authorizer:A. Behrensmeyer, P. Mannion, M. Carrano Enterer:A. Behrensmeyer, M. Carrano, P. Mannion
Modifier:M. Carrano
Created:2001-04-23 01:00:00 Last modified:2025-02-22 15:12:02
Access level:the public Released:2001-04-23 01:00:00
Creative Commons license:CC0
Reference information

Primary reference:
62832. M. E. Nelson and J. H. Madsen. 1985. Early Cretaceous mammals from central Utah. Geological Society of America, Rocky Mountain Section, Abstracts with Programs 17(4):258 [M. Carrano/M. Carrano]

Secondary references:

1227 R. L. Cifelli, R. L. Nydam, J. D. Gardner, A. Weil, J. G. Eaton, J. I. Kirkland, and S. K. Madsen. 1999. Medial Cretaceous vertebrates from the Cedar Mountain Formation, Emery County, Utah: the Mussentuchit local fauna. In D. D. Gillette (ed.), Vertebrate Paleontology in Utah. Utah Geological Survey Miscellaneous Publication 99-1:219-242 [J. Alroy/J. Alroy/M. Carrano]
13288ETE A. R. Fiorillo. 1999. Non-mammalian microvertebrate remains from the Robison Eggshell site, Cedar Mountain Formation (Lower Cretaceous), Emery County, Utah. In D. D. Gillette (ed.), Vertebrate Paleontology in Utah, Utah Geological Survey Miscellaneous Publication 99-1:259-268 [M. Carrano/M. Carrano/M. Carrano]
57899 J. I. Kirkland, R. L. Cifelli, B. B. Britt, D. L. Burge, F. L. DeCourten, J. G. Eaton, and J. M. Parrish. 1999. Distribution of vertebrate faunas in the Cedar Mountain Formation, east-central Utah. In D. D. Gillette (ed.), Vertebrate Paleontology in Utah. Utah Geological Survey Miscellaneous Publication 99(1):201-218 [P. Barrett/T. Cleary/M. Carrano]
32617ETE J. I. Kirkland and S. K. Madsen. 2007. The Lower Cretaceous Cedar Mountain Formation, Eastern Utah: the view up an always interesting learning curve. Utah Geological Association Publication 35 1-108 [M. Carrano/M. Carrano/M. Carrano]
15257ETE M. E. Nelson and D. M. Crooks. 1987. Stratigraphy and paleontology of the Cedar Mountain Formation (Lower Cretaceous), eastern Emery County, Utah. In W. R. Averett (ed.), Paleontology and Geology of the Dinosaur Triangle: Guidebook for 1987 Field Trip. Museum of Western Colorado, Grand Junction 55-63 [M. Carrano/M. Carrano/M. Carrano]
59838 J. P. Tennant, P. D. Mannion, and P. Upchurch. 2016. Evolutionary relationships and systematics of Atoposauridae (Crocodylomorpha: Neosuchia): implications for the rise of Eusuchia. Zoological Journal of the Linnean Society 177:854-936 [P. Mannion/P. Mannion]