Twin Buttes (Lower Bridger): Bridgerian, Wyoming

List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
Mammalia - Condylarthra - Hyopsodontidae
Hyopsodus marshi Osborn 1902
    = Hyopsodus paulus Leidy 1870
Alroy 2002
from Bridger B, not C2 contra Matthew 1909
Mammalia - Creodonta - Oxyaenidae
Patriofelis ulta Leidy 1870
from Bridger B, not "very low in Bridger C" contra Gazin 1957; specimen from "Twin Buttes" also mentioned by Wortman 1894
Machaeroides eothen Matthew 1909
Gazin 1946
"low exposures, probably of Bridger 'C', immediately to the north of Twin Buttes" (Bridger B sensu Gazin 1976)
Mammalia
Palaearctonyx meadi n. sp. Matthew 1909
of Matthew 1909 said by him to be Bridger C1
Mammalia - Perissodactyla - Equidae
Orohippus progressus n. sp. Granger 1908
Granger 1908
Mammalia - Perissodactyla - Brontotheriidae
Palaeosyops grangeri n. sp. Osborn 1908
    = Palaeosyops robustus Marsh 1872
Alroy 2002
of Osborn 1908 from "level C1" species not mentioned by Gazin 1976
Mammalia - Homacodontidae
Antiacodon pygmaeus (Cope 1872)
West 1984
Bridger B
Mammalia - Helohyidae
Helohyus plicodon Marsh 1872
West 1984
Bridger B "North of Twin Buttes, near conical butte"
Mammalia - Rodentia - Ischyromyidae
Ischyrotomus oweni n. sp. Wood 1962
(1 measurement)
    = Pseudotomus robustus Marsh 1872
Alroy 2002
see Wood 1962
Mammalia - Primates - Notharctidae
Smilodectes gracilis (Marsh 1871)
specimens said by Robinson 1957 to be from the "upper Bridger"
Mammalia - Dinocerata - Uintatheriidae
Uintatherium anceps (Marsh 1871)
Wheeler 1961
includes type of "U. robustum" from "Bridger C on or near the northeast base of Twin Buttes"; referred specimen from "northeast flank of Twin Buttes, probably Bridger D"
see common names

Geography
Country:United States State/province:Wyoming County:Sweetwater
Coordinates: 41.7° North, 109.0° West (view map)
Paleocoordinates:45.6° North, 95.1° West
Basis of coordinate:based on political unit
Time
Period:Paleogene Epoch:Eocene
10 m.y. bin:Cenozoic 2
*Period:Tertiary
Key time interval:Bridgerian
Age range of interval:50.50000 - 46.20000 m.y. ago
* legacy (obsolete) database fields
Stratigraphy
Formation:Bridger Member:lower
Local section:Bridg Local bed:4
Local order:bottom to top
Lithology and environment
Environment:terrestrial indet.
Taphonomy
Modes of preservation:body
Collection methods and comments
Collection excludes:some genera
Taxonomic list comments:Twin Buttes records of unclear status: "Notharctus robustior" Robinson 1957: supposedly upper Bridger, but probably lower Bridger based on Gazin's discussion of Smilodectes; could be N. pugnax or perhaps N. tenebrosus based on chart Patriofelis ferox Wortman 1894: "Twin Buttes" Limnocyon verus Thorpe 1923a: level not stated Orohippus progressus type if from an unknown level at Twin Buttes according to Gazin but from "Hor. C" according to Granger 1908; see also Kitts 1957b, who implies that O. progressus and O. sylvaticus are present in Bridger C sensu Gazin Palaeosyops robustus Osborn 1929: from "C or "D" Telmatherium cultridens Osborn 1929: "C or D" Mesatirhinus megarhinus Osborn 1929: level not stated "Homogalax bridgerensis" Troxell 1922b: type, level not stated and Isectolophus latidens ranges throughout section according to Gazin Hyrachyus eximius Wood 1934: "Twin Buttes... hence Bridger C or D" and "South Twin Buttes"; referred specimen of "H. princeps"; all are possibly from Bridger B based on revised stratigraphy of Gazin Hyrachyus modestus and type of "Ephyrachyus cristalophus" of Wood 1934: both from "Bridger C3" and based on Wood's map it is not clear whether this is above or below the Sage Creek White Layer "agreeing in size with" Homacodon sp. Sinclair 1914: Bridger "C1"; specimen not mentioned by West 1984, and probably from Bridger B based on stratigraphy of Gazin 1976 "Lophiohyus alticeps" type is from an unknown level; see also Sinclair 1914
Metadata
Database number:16448
Authorizer:J. Alroy, J. Marcot Enterer:J. Alroy, J. Marcot
Modifier:J. Wertheim Research group:vertebrate
Created:1995-03-26 00:00:00 Last modified:2002-07-17 16:47:43
Access level:the public Released:1995-03-26 00:00:00
Creative Commons license:CC BY
Reference information

Primary reference:
1623. 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]

Secondary references:

6294 J. Alroy. 2002. Synonymies and reidentifications of North American fossil mammals. [J. Alroy/J. Alroy/M. Kouvari]
1604 C. L. Gazin. 1946. Machaeroides eothen Matthew, the sabertooth creodont of the Bridger Eocene. Proceedings of the United States National Museum 96(3202):335-347 [J. Alroy/J. Alroy/J. Marcot]
1694 W. Granger. 1908. A revision of the American Eocene horses. Bulletin of the American Museum of Natural History 24(15):221-264 [J. Alroy/J. Alroy/J. Marcot]
3606 R. M. West. 1984. Paleontology and Geology of the Bridger Formation, Southern Green River Basin, Southwestern Wyoming. Part 7. Survey of Bridgerian Artiodactyla, including description of a skull and partial skeleton of Antiacodon pygmaeus. Milwaukee Public Museum Contributions in Biology and Geology 56:1-47 [J. Alroy/J. Alroy/J. Marcot]
3622 W. H. Wheeler. 1961. Revision of the Uintatheres. Peabody Museum of Natural History Bulletin 14:1-93 [J. Alroy/J. Alroy/M. Uhen]