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
Mammalia
 Rodentia - Ischyromyidae
Ischyromys sp. Leidy 1856 rodent
 Rodentia - Aplodontidae
Prosciurus vetustus Matthew 1903 mountain beaver
 Rodentia - Sciuridae
Sciuridae indet.1 Gray 1821 squirrel
 Rodentia - Eomyidae
Eomyidae indet. Winge 1887 rodent
Adjidaumo minutus Cope 1873 rodent
"Paradjidaumo trilophus" = Adjidaumo trilophus Cope 1873 rodent
Adjidaumo minimus Matthew 1903 rodent
Aulolithomys bounites Black 1965 rodent
"Yoderimys burkei" = Zemiodontomys burkei Black 1965 rodent
 Rodentia - Castoridae
Agnotocastor sp. Stirton 1935 beaver
 Rodentia - Cylindrodontidae
Cylindrodon nebraskensis1 Hough and Alf 1956 rodent
Pseudocylindrodon neglectus Burke 1935 rodent
 Lagomorpha - Leporidae
Palaeolagus temnodon Douglass 1902 rabbit
 Theriamorpha - Soricidae
Domnina gradata Cope 1873 shrew
 Theriamorpha - Geolabididae
Centetodon chadronensis Lillegraven et al. 1981 placental
 Theriamorpha - Oligoryctidae
Oligoryctes cameronensis Hough 1956 placental
 Theriamorpha - Micropternodontidae
Micropternodus montrosensis Ostrander 1983 placental
 Theriamorpha - Apternodontidae
Apternodus sp.2 Matthew 1903 placental
 Placentalia -
Chiroptera indet. Blumenbach 1779 bat
a bat
 Perissodactyla - Brontotheriidae
Brontotheriidae indet. Marsh 1873 brontothere
 Perissodactyla - Hyracodontidae
"Hyracodon doddi n. sp." = Hyracodon nebraskensis
"Hyracodon doddi n. sp." = Hyracodon nebraskensis Leidy 1850 odd-toed ungulate
from UNSM Sx-29
 Perissodactyla - Equidae
Equidae indet.1 Gray 1821 horse
 Artiodactyla - Protoceratidae
Pseudoprotoceras longinaris Cook 1934 protoceratid
 Artiodactyla - Leptomerycidae
Leptomeryx sp. Leidy 1853 ruminant
 Carnivora - Canidae
Hesperocyon sp. Scott 1890 canid
 Cimolesta - Apatemyidae
Sinclairella dakotensis Jepsen 1934 eutherian
 Theriamorpha - Herpetotheriidae
"Peratherium fugax" = Herpetotherium fugax
"Peratherium fugax" = Herpetotherium fugax Cope 1873 marsupial
Reptilia
 Squamata -
Peltosaurus sp. Cope 1873 squamates
 Squamata - Anguidae
Glyptosaurus sp. Marsh 1871 squamates