Twin Buttes (Eocene of the United States)

Where: Sioux County, Nebraska (42.4° N, 103.8° W: paleocoordinates 43.8° N, 95.1° W)

• coordinate based on political unit

When: Big Cottonwood Creek Member (Chadron Formation), Chadronian (37.2 - 33.9 Ma)

• member assignment based on LaGarry pers. commun. 19 May 2005

Environment/lithology: terrestrial

Primary reference: G. E. Ostrander. 1985. Correlation of the early Oligocene (Chadronian) in northwestern Nebraska. Dakoterra 2(2):205-231 [J. Alroy/J. Alroy/P. Holroyd]more details

PaleoDB collection 17033: authorized by John Alroy, entered by John Alroy on 18.02.1993

Creative Commons license: CC BY (attribution)

Taxonomic list

• apparently includes UNSM Sx-29
NE 1/4 sec 36 T33N R53W
"Cylindrodon fontis" is probably misidentified, see discussion of this species by Emry and Korth 1996a
Reptilia
 Squamata -
Peltosaurus sp. Cope 1872 squamates
 Squamata - Anguidae
Glyptosaurus sp. Marsh 1871 squamates
Mammalia
 Rodentia - Aplodontidae
Prosciurus vetustus Matthew 1903 mountain beaver
 Rodentia - Sciuridae
Sciuridae indet.1 Gray 1821 squirrel
 Rodentia - Eomyidae
Eomyidae indet. Winge 1887 rodent
Zemiodontomys burkei1 Black 1965 rodent
Paradjidaumo trilophus Cope 1873 rodent
Adjidaumo minimus Matthew 1903 rodent
Adjidaumo minutus Cope 1873 rodent
Aulolithomys bounites Black 1965 rodent
 Rodentia - Castoridae
Agnotocastor sp. Stirton 1935 beaver
 Rodentia - Ischyromyidae
Ischyromys sp. Leidy 1856 rodent
 Rodentia - Cylindrodontidae
Pseudocylindrodon neglectus Burke 1935 rodent
Cylindrodon nebraskensis1 Hough and Alf 1956 rodent
 Lagomorpha - Leporidae
Palaeolagus temnodon Douglass 1902 rabbit
 Lipotyphla - Geolabididae
Centetodon chadronensis Lillegraven et al. 1981 placental
 Perissodactyla - Brontotheriidae
Brontotheriidae indet. Marsh 1873 brontothere
 Perissodactyla - Hyracodontidae
Hyracodon nebraskensis3 Leidy 1850 odd-toed ungulate
 Perissodactyla - Equidae
Equidae indet.1 Gray 1821 horse
 Tribosphenida - Heterosoricidae
Domnina gradata Cope 1873 placental
 Tribosphenida - Apternodontidae
Oligoryctes cameronensis Hough 1956 placental
Apternodus sp.2 Matthew 1903 placental
 Tribosphenida - Micropternodontidae
Micropternodus montrosensis Ostrander 1983 placental
 Carnivora - Canidae
Hesperocyon sp. Scott 1890 canid
 Chiroptera -
Chiroptera indet. Blumenbach 1779 bat
a bat
 Ungulata - Protoceratidae
Pseudoprotoceras longinaris Cook 1934 protoceratid
 Ungulata - Leptomerycidae
Leptomeryx sp. Leidy 1853 ruminant
 Insectivora - Apatemyidae
Sinclairella dakotensis Jepsen 1934 insectivoran
 Theriiformes - Herpetotheriidae
"Herpetotherium fugax" = Peratherium fugax1
"Herpetotherium fugax" = Peratherium fugax1 Cope 1873 marsupial