Where: Utah (38.7° N, 111.2° W: paleocoordinates 40.0° N, 73.4° W)

• coordinate based on nearby landmark

• outcrop-level geographic resolution

When: Mussentuchit Member (Cedar Mountain Formation), Early/Lower Cenomanian (99.6 - 93.5 Ma)

• Lower section of Mussentuchit Member in smectitic mudstone, beneath a fine sandstone layer

•

•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. Tucker et al. 2020 also suggested a likely depositional age of ~96-94Ma for the Musseuntuchit member.

• bed-level stratigraphic resolution

Environment/lithology: terrestrial; mudstone

Size class: macrofossils

Preservation: trace

Primary reference: 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]more details

Purpose of describing collection: general faunal/floral analysis

PaleoDB collection 97959: authorized by Matthew Carrano, entered by Matthew Oreska on 09.09.2010

Creative Commons license: CC BY (attribution)