Chadronia Pocket (Eocene of the United States)

Where: Dawes County, Nebraska (42.8° N, 103.4° W: paleocoordinates 44.2° N, 94.7° W)

• coordinate stated in text

• outcrop-level geographic resolution

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

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

•from "a section a few feet thick... well down in the local section of the Chadron" (Wood 1969)

• group of beds-level stratigraphic resolution

Environment/lithology: terrestrial; poorly lithified, argillaceous siltstone

• "grey-green... clay-silt" that includes some solid blocks but is also screenable in part (Cook 1954)

Size class: macrofossils

Collected by H. J. Cook, M. C. Cook; reposited in the AMNH, UCMP

Collection methods: bulk, surface (in situ), sieve

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

Purpose of describing collection: general faunal/floral analysis

PaleoDB collection 16930: authorized by John Alroy, entered by John Alroy on 18.02.1993, edited by Jonathan Marcot

Creative Commons license: CC BY (attribution)

Taxonomic list

• rodents and lagomorphs described by Wood 1969
NOT the same as Chadron Anthill, which is in Sioux Co.
"has Orellan species that have been mixed from overlying strata": Korth 1989a; this probably refers to the three records noted below
NW 1/4 sec 36 T33N R52W, i.e., 7 - 8 mi N of Crawford
includes "9 miles north of Crawford" collection of Cook 1934: Patton and Taylor 1934
"Palaeolagus haydeni" is argued to be reworked; probably includes "Protolagus cf. affinis" of Cook 1934

"Adjidaumo minutus" is a composite of more than one species probably including some Orellan material: Korth 1989a

"Eumys cf. elegans" is argued to be reworked
Actinopteri
 Amiiformes - Amiidae
Amia sp. Linnaeus 1766 bowfin
Reptilia
 Testudines - Pantestudinidae
Stylemys sp. Leidy 1851 turtle
 Squamata -
Peltosaurus sp. Cope 1872 lizard
 Squamata - Anguidae
Glyptosaurus sp. Marsh 1871 lizard
Mammalia
 Cimolesta - Pantolestidae
Chadronia margaretae n. gen. n. sp.3
Chadronia margaretae n. gen. n. sp.3 Cook 1954 eutherian
 Rodentia - Pipestoneomyidae
Pipestoneomys bisulcatus Donohoe 1956 rodent
 Rodentia - Eomyidae
Eomyidae indet. Winge 1887 rodent
"Yoderimys burkei" = Zemiodontomys burkei Black 1965 rodent
Paradjidaumo trilophus Cope 1873 rodent
Adjidaumo minimus Matthew 1903 rodent
Aulolithomys bounites Black 1965 rodent
 Rodentia - Heliscomyidae
Heliscomys vetus Cope 1873 rodent
 Rodentia - Ischyromyidae
Ischyromys veterior Matthew 1903 rodent
 Rodentia - Cylindrodontidae
Pseudocylindrodon neglectus Burke 1935 rodent
Cylindrodon sp.1 Douglass 1902 rodent
 Lagomorpha - Leporidae
Palaeolagus temnodon Douglass 1902 rabbit
Megalagus brachyodon Matthew 1903 rabbit
 Lipotyphla - Geolabididae
Centetodon chadronensis Lillegraven et al. 1981 placental
 Perissodactyla - Brontotheriidae
Brontotheriidae indet. Marsh 1873 brontothere
 Perissodactyla - Hyracodontidae
Hyracodon nebraskensis Leidy 1850 odd-toed ungulate
confirmed by Prothero 1996e; "H. priscidens" is omitted by this author, who treats the two species as a chronocline
 Perissodactyla - Rhinocerotidae
Subhyracodon sp. Wood 1927 rhinoceros
Trigonias osborni Lucas 1900 rhinoceros
Trigonias wellsi4 Wood 1927 rhinoceros
 Perissodactyla - Equidae
Equidae indet.1 Gray 1821 horse
 Tribosphenida - Heterosoricidae
Domnina gradata Cope 1873 placental
 Carnivora - Amphicyonidae
Daphoenus sp., "Daphoenocyon dodgei" = Brachyrhynchocyon dodgei
Daphoenus sp. Leidy 1853 bear-dog
confirmed by Hunt 1998b
"Daphoenocyon dodgei" = Brachyrhynchocyon dodgei Scott 1898 bear-dog
 Carnivora - Canidae
Hesperocyon gregarius5 Cope 1873 canid
 Carnivora - Nimravidae
Hoplophoneus mentalis Sinclair 1921 false sabre-tooth
 Hyaenodonta - Hyaenodontidae
Hyaenodon crucians Leidy 1853 eutherian
 Theriiformes - Herpetotheriidae
Peratherium fugax Cope 1873 marsupial
 Artiodactyla - Tayassuidae
Tayassuidae indet.1 Palmer 1897 peccary
 Artiodactyla - Leptochoeridae
Leptochoeridae indet. Marsh 1894 even-toed ungulate
Stibarus sp. Cope 1873 even-toed ungulate
 Artiodactyla - Entelodontidae
Archaeotherium mortoni Leidy 1850 even-toed ungulate
 Artiodactyla - Camelidae
Poebrotherium cf. wilsoni Leidy 1847 camel
 Artiodactyla - Merycoidodontidae
Merycoidodon sp. Leidy 1848 oreodont
 Artiodactyla - Agriochoeridae
Agriochoerus sp. Leidy 1850 agriochoerid
 Artiodactyla -
"Aepinacodon americanus" = Bothriodon americanus Leidy 1856 even-toed ungulate
Heptacodon cf. occidentalis Scott 1940 even-toed ungulate
 Artiodactyla - Protoceratidae
Pseudoprotoceras longinaris n. sp.2 Cook 1934 protoceratid
"Lower Chadron... about 9 miles north of Crawford"
 Artiodactyla - Hypertragulidae
Hypertragulus chadronensis n. sp.2 Cook 1934 ruminant
"nine miles north of Crawford... lower part of the Chadron formation"
Hypertragulus crawfordensis n. sp.2 Cook 1934 ruminant
"Lower Chadron formation, north of Crawford"
 Artiodactyla - Hypisodontidae
Hypisodus minimus Cope 1873 ruminant
may include "H. paululus" type of Cook 1934
Hypisodus paululus n. sp.2 Cook 1934 ruminant
"Lower Chadron formation, about nine miles north of Crawford": omitted by Ostrander
 Artiodactyla - Leptomerycidae
Leptomeryx sp. Leidy 1853 ruminant