Duncan Ranch (Upper) (Eocene of the United States)

Where: Fremont County, Wyoming (43.2° N, 108.2° W: paleocoordinates 47.0° N, 94.0° W)

• coordinate based on political unit

When: Aycross Formation, Bridgerian (50.3 - 46.2 Ma)

Environment/lithology: terrestrial

Primary reference: T. M. Bown. 1982. Geology, Paleontology, and Correlation of Eocene Volcaniclastic Rocks, Southeast Absaroka Range, Hot Springs County, Wyoming. United States Geological Survey Professional Paper 1201-A:A1-A75 [J. Alroy/J. Alroy/J. Marcot]more details

PaleoDB collection 16213: authorized by John Alroy, entered by John Alroy on 18.02.1993

Creative Commons license: CC BY (attribution)

Taxonomic list

• type area of Aycross Fm. (see Love 1939)
this appears to be the Duncan Ranch L.F. sensu stricto (see Bown); hence, I assume the date applies only to this list
KA date of 49.2 (=50.3: see Krishtalka et al. 1987) +/- 0.5 Ma for "Aycross rocks exposed at Duncan Ranch" (Bown p. A19); "Low in type section... near Bridgerian mammals" (Krishtalka et al. 1987 p. 92)
late Bridgerian (Bridger C?)
 Cimolesta - Esthonychidae
cf. Trogosus sp. Leidy 1871 tillodont
 Amblypoda - Uintatheriidae
Uintatherium cf. anceps Marsh 1871 uintathere
 Perissodactyla - Brontotheriidae
"Telmatherium cf. cultridens" = Telmatherium validus, Telmatherium cf. validum
"Telmatherium cf. cultridens" = Telmatherium validus Marsh 1872 brontothere
Telmatherium cf. validum Marsh 1872 brontothere
 Perissodactyla - Hyrachyidae
Hyrachyus cf. modestus Leidy 1870 odd-toed ungulate
Hyrachyus eximius Leidy 1871 odd-toed ungulate
 Creodonta - Oxyaenidae
Patriofelis ferox Marsh 1872 creodont