Chadronia Pocket: Chadronian, Nebraska
collected by H. J. Cook, M. C. Cook

List of taxa
Where & when
Taphonomy & methods
Metadata & references
Taxonomic list
Leptictis acutidens (Douglass 1902)
    = informal Novacek leptictid acutidens
Alroy 2002
Actinopteri - Amiiformes - Amiidae
Amia sp. Linnaeus 1766
Reptilia - Testudines - Testudinidae
Stylemys sp. Leidy 1851
Reptilia - Squamata
Peltosaurus sp. Cope 1872
Reptilia - Squamata - Anguidae
Glyptosaurus sp. Marsh 1871
Mammalia - Pantolestidae
Chadronia margaretae n. gen., n. sp. Cook 1954
Cook 1954
(1 measurement)
Mammalia - Rodentia - Pipestoneomyidae
Pipestoneomys bisulcatus Donohoe 1956
Mammalia - Rodentia - Eomyidae
Eomyidae indet. Winge 1887
Yoderimys burkei Black 1965
recombined as Zemiodontomys burkei
Paradjidaumo trilophus (Cope 1873)
Adjidaumo minimus (Matthew 1903)
Aulolithomys bounites Black 1965
Mammalia - Rodentia - Heliscomyidae
Heliscomys vetus Cope 1873
Mammalia - Rodentia - Ischyromyidae
Ischyromys veterior Matthew 1903
Mammalia - Rodentia - Cylindrodontidae
Pseudocylindrodon neglectus Burke 1935
Cylindrodon fontis Douglass 1902
    = Cylindrodon sp. Douglass 1902
Alroy 2002
see discussion of this species by Emry and Korth 1996a
Mammalia - Lagomorpha - Leporidae
Palaeolagus temnodon Douglass 1902
Megalagus brachyodon (Matthew 1903)
Mammalia - Lipotyphla - Geolabididae
Centetodon chadronensis Lillegraven et al. 1981
Mammalia - Perissodactyla - Brontotheriidae
Brontotheriidae indet. (Marsh 1873)
Mammalia - Perissodactyla - Hyracodontidae
Hyracodon nebraskensis (Leidy 1850)
confirmed by Prothero 1996e; "H. priscidens" is omitted by this author, who treats the two species as a chronocline
Mammalia - Perissodactyla - Rhinocerotidae
Subhyracodon sp. Wood 1927
Trigonias osborni Lucas 1900
Trigonias wellsi Wood 1927
Prothero 2005
Mammalia - Perissodactyla - Equidae
Mesohippus sp. Marsh 1875
    = Equidae indet. Gray 1821
Alroy 2002
Mammalia - Heterosoricidae
Domnina gradata Cope 1873
Mammalia - Carnivora - Amphicyonidae
Daphoenus sp. Leidy 1853
confirmed by Hunt 1998b
Daphoenocyon dodgei (Scott 1898)
recombined as Brachyrhynchocyon dodgei
Mammalia - Carnivora - Canidae
Hesperocyon sp. Scott 1890
    = Hesperocyon gregarius Cope 1873
Wang 1994
Mammalia - Carnivora - Nimravidae
Hoplophoneus mentalis Sinclair 1921
Mammalia - Ungulata - Merycoidodontidae
Merycoidodon sp. Leidy 1848
Mammalia - Ungulata - Tayassuidae
Perchoerus minor Cook 1922
    = Tayassuidae indet. Palmer 1897
Alroy 2002
may include type of Scott 1940
Mammalia - Ungulata - Leptochoeridae
Leptochoeridae indet. Marsh 1894
Stibarus sp. Cope 1873
Mammalia - Ungulata - Entelodontidae
Archaeotherium mortoni Leidy 1850
Mammalia - Ungulata - Camelidae
Poebrotherium cf. wilsoni Leidy 1847
Mammalia - Ungulata - Agriochoeridae
Agriochoerus sp. Leidy 1850
Mammalia - Ungulata - Anthracotheriidae
Aepinacodon americanus (Leidy 1856)
Heptacodon cf. occidentalis (Osborn and Wortman 1894)
recombined as Heptacodon occidentale
Mammalia - Ungulata - Protoceratidae
Pseudoprotoceras longinaris n. sp. Cook 1934
Cook 1934
"Lower Chadron... about 9 miles north of Crawford" (7 measurements)
Mammalia - Ungulata - Hypertragulidae
Hypertragulus chadronensis n. sp. Cook 1934
Cook 1934
"nine miles north of Crawford... lower part of the Chadron formation" (1 measurement)
Hypertragulus crawfordensis n. sp. Cook 1934
Cook 1934
"Lower Chadron formation, north of Crawford" (1 measurement)
Mammalia - Ungulata - Hypisodontidae
Hypisodus minimus (Cope 1873)
may include "H. paululus" type of Cook 1934
Hypisodus paululus n. sp. Cook 1934
Cook 1934
"Lower Chadron formation, about nine miles north of Crawford": omitted by Ostrander (1 measurement)
Mammalia - Ungulata - Leptomerycidae
Leptomeryx sp. Leidy 1853
Mammalia - Hyaenodonta - Hyaenodontidae
Hyaenodon crucians Leidy 1853
Peratherium fugax (Cope 1873)
(1 measurement)
see common names

Country:United States State/province:Nebraska County:Dawes
Coordinates: 42.8° North, 103.4° West (view map)
Paleocoordinates:44.2° North, 94.7° West
Basis of coordinate:stated in text
Geographic resolution:outcrop
Period:Paleogene Epoch:Eocene
Stage:Priabonian 10 m.y. bin:Cenozoic 3
Key time interval:Chadronian
Age range of interval:37.20000 - 33.90000 m.y. ago
* legacy (obsolete) database fields
Formation:Chadron Member:Big Cottonwood Creek
Local section:PineR Local bed:1
Local order:bottom to top
Stratigraphic resolution:group of beds
Stratigraphy comments: 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)
Lithology and environment
Primary lithology: poorly lithified argillaceous siltstone
Lithology description: "grey-green... clay-silt" that includes some solid blocks but is also screenable in part (Cook 1954)
Environment:terrestrial indet.
Modes of preservation:body
Size of fossils:macrofossils
Collection methods and comments
Collection methods:bulk,surface (in situ),sieve
Collection size:3000 specimens
Reason for describing collection:general faunal/floral analysis
Museum repositories:AMNH,UCMP
Collectors:H. J. Cook, M. C. Cook
Taxonomic list comments: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
Database number:16930
Authorizer:J. Alroy, J. Marcot Enterer:J. Alroy, J. Marcot
Modifier:J. Alroy Research group:vertebrate
Created:1993-02-18 00:00:00 Last modified:2011-09-10 22:07:27
Access level:the public Released:1993-02-18 00:00:00
Creative Commons license:CC BY
Reference information

Primary reference:

2716. G. E. Ostrander. 1985. Correlation of the early Oligocene (Chadronian) in northwestern Nebraska. Dakoterra 2(2):205-231 [J. Alroy/J. Alroy/P. Holroyd]

Secondary references:

6294 J. Alroy. 2002. Synonymies and reidentifications of North American fossil mammals. [J. Alroy/J. Alroy/M. Uhen]
1268 H. J. Cook. 1934. New artiodactyls from the Oligocene and Lower Miocene of Nebraska. American Midland Naturalist 15(2):148-165 [J. Alroy/J. Alroy/J. Alroy]
1269 H. J. Cook. 1954. A remarkable new mammal from the lower Chadron of Nebraska. American Midland Naturalist 52(2):388-391 [J. Alroy/J. Alroy/J. Alroy]
51726 D. R. Prothero. 2005. The Evolution of North American Rhinoceroses. 1-218 [J. Marcot/J. Marcot]
6226 X. Wang. 1994. Phylogenetic systematics of the Hesperocyoninae (Carnivora: Canidae). Bulletin of the American Museum of Natural History 221:1-207 [J. Alroy/J. Alroy/J. Alroy]