Cottonwood Creek (Lower Bridger) (Eocene of the United States)

Where: Uinta County, Wyoming (41.2° N, 110.5° W: paleocoordinates 45.2° N, 96.8° W)

• coordinate based on political unit

When: lower Member (Bridger Formation), Bridgerian (50.3 - 46.2 Ma)

Environment/lithology: terrestrial

Primary reference: C. L. Gazin. 1976. Mammalian Faunal Zones of the Bridger Middle Eocene. Smithsonian Contributions to Paleobiology 26:1-25 [J. Alroy/J. Alroy/J. Marcot]more details

PaleoDB collection 16205: authorized by John Alroy, entered by John Alroy on 26.03.1995

Creative Commons license: CC BY (attribution)

Taxonomic list

• "Bridger C is exposed along the upper course": Wood 1934
"Viverravus gracilis" Thorpe 1923a: level not stated

AMNH 19231 from B3 is either "Eotrigonias petersoni" or Hyrachyus: Wood 1927
Mammalia
 Primates - Notharctidae
"Notharctus tenebrosus" = Notharctus tenebrosus6, "Notharctus pugnax" = Notharctus tenebrosus, Smilodectes gracilis6
"Notharctus tenebrosus" = Notharctus tenebrosus6 Leidy 1870 primate
Bridger B; may include B4 specimen of Granger and Gregory 1917
"Notharctus pugnax" = Notharctus tenebrosus Leidy 1870 primate
second, much larger group of specimens in chart of Robinson 1957; see also Gingerich 1979a
Smilodectes gracilis6 Marsh 1871 primate
 Rodentia - Ischyromyidae
Pseudotomus hians n. sp. Cope 1872 rodent
"probably B" according to Wood 1962; includes type of "Ischyrotomus superbus"
 Perissodactyla - Brontotheriidae
"Palaeosyops paludosus" = Palaeosyops paludosus5, "Palaeosyops laevidens" = Palaeosyops paludosus5
"Palaeosyops paludosus" = Palaeosyops paludosus5 Leidy 1870 brontothere
"Palaeosyops laevidens" = Palaeosyops paludosus5 Leidy 1870 brontothere
 Perissodactyla - Hyrachyidae
"Hyrachyus modestus" = Hyrachyus modestus8, "Hyrachyus affinis" = Hyrachyus modestus8
"Hyrachyus modestus" = Hyrachyus modestus8 Leidy 1870 odd-toed ungulate
B3
"Hyrachyus affinis" = Hyrachyus modestus8 Leidy 1870 odd-toed ungulate
Bridger B3; may include Cope's "Hyrachyus implicatus"
 Perissodactyla - Equidae
Orohippus pumilus3 Marsh 1871 horse
 Ferae - Metacheiromyidae
Metacheiromys marshi7 Wortman 1903 placental
Bridger B3 "Middle Cottonwood Creek" and Bridger B2 or B3, "Lower Cottonwood Creek"
 Trogontia - Esthonychidae
Trogosus castoridens2 Leidy 1871 tillodont
 Ungulata - Hyopsodontidae
Hyopsodus paulus4 Leidy 1870 condylarth
Cope's type of "H. vicarius"
 Ungulata - Homacodontidae
Antiacodon pygmaeus n. sp. Cope 1872 even-toed ungulate
 Ungulata -
Helohyus plicodon1 Marsh 1872 even-toed ungulate
 Acreodi - Mesonychidae
Mesonyx obtusidens n. sp. Cope 1871 condylarth
said to be from "lower Bridger... 5 miles south of Granger" by Thorpe 1923a
 Hyaenodonta - Hyaenodontidae
Sinopa rapax1 Leidy 1871 eutherian
Sinopa major1 Wortman 1902 eutherian