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

• coordinate estimated from map

• small collection-level geographic resolution

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

• 15 m below overlying Naturita Fm.

•

•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: crevasse splay; mudstone

Size classes: macrofossils, mesofossils

Primary reference: R. L. Cifelli and S. K. Madsen. 1998. Triconodont mammals from the medial Cretaceous of Utah. Journal of Vertebrate Paleontology 18(2):403-411 [J. Alroy/J. Alroy/M. Carrano]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 14398: authorized by John Alroy, entered by John Alroy on 21.09.1998, edited by Roger Benson and Matthew Carrano

Creative Commons license: CC BY (attribution)