Roadcut along Stagebarn Canyon Road, about 24 km WNW of Rapid City (OMNH V1254) (Cretaceous to of the United States)

Where: Meade County, South Dakota (44.2° N, 103.3° W: paleocoordinates 41.7° N, 51.8° W)

• coordinate stated in text

• outcrop-level geographic resolution

When: Fuson Member (Lakota Formation), Late/Upper Valanginian to Late/Upper Valanginian (140.2 - 125.5 Ma)

• The Stage Barn Canyon Road section has been measured and sampled for ostracods in horizons bracketing and including OMNH locality V1254 (Fig. 4). We interpret this section to represent much of (and perhaps only) the Fuson Member, including fluvial units 3 and 4 (S3 and S4, after Dahlstrom and Fox 1995) of the Lakota Formation (Fig. 3).

•Estimated age constraints for the section including OMNH locality V1254, and other ostracod assemblages of the eastern sequences, are late Valanginian–early Barremian (Fig. 2).

• bed-level stratigraphic resolution

Environment/lithology: lacustrine - large; sandstone

• The mammal specimens derive from the lacustrine sandstone within the variegated mudstones intercalated between these fluvial units. The bone-yielding horizon lies at the base of this sandstone, and includes clayballs as well as vertebrate remains.

Size classes: mesofossils, microfossils

Collected by OMNH field parties in 2001–2003

Collection methods: bulk, sieve,

• OMNH, Sam Noble Oklahoma Museum of Natural History

•The specimens described in this study were collected and prepared following standard methods of microvertebrate sampling detailed by Cifelli (1996).

Primary reference: R. L. Cifelli, B. M. Davis, and B. Sames. 2014. Earliest Cretaceous mammals from the western United States. Acta Palaeontologica Polonica 59(1):31-52 [R. Benson/R. Benson/J. Tennant]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 135450: authorized by Roger Benson, entered by Roger Benson on 26.10.2012

Creative Commons license: CC BY (attribution)

Taxonomic list

• Other vertebrate groups are also represented in the OMNH collection from the Lakota Formation, including various chondrichthyans, osteichthyans, amphibians, lepidosaurs, crocodilians, and dinosaurs (to be described elsewhere).
Mammalia
 Eutriconodonta - Triconodontidae
Triconodontidae indet. Marsh 1887 mammal
OMNH 62800, a right lower molar, very small (L = [0.96 mm], W = 0.39 mm)
? Triconodontidae indet. Marsh 1887 mammal
OMNH 62855, right mesial lower premolar, comparatively long mesiodistally (L = 1.04 mm) and low-crowned
 Tribosphenida -
Tribosphenida indet. mammal
OMNH 64193, trigonid of left lower molar, lacks the talonid but is otherwise well preserved (L = [0.80 mm])
 Theriiformes - Dryolestidae
cf. Lakotalestes luoi Cifelli et al. 2014 mammal
OMNH 62854, OMNH 62854 is a moderately to well-worn right lower molar lacking the talonid, which appears to have been abraded off (L = [0.69 mm], W = 0.84 mm)
 Theriiformes -
Zatheria indet. McKenna 1975 mammal
OMNH 67137 is a very small (maximum length of preserved part < 0.6 mm) lightly worn right lower molar missing the paraconid, most of the protoconid, and the apex of the hypoconid; the enamel is otherwise well preserved