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
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
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
| Reptilia | |
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Peltosaurus sp. Cope 1873 squamates | |
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Glyptosaurus sp. Marsh 1871 squamates | |
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Stylemys sp. Leidy 1851 turtle | |
| Mammalia | |
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Hyaenodon crucians Leidy 1853 creodont | |
"Daphoenocyon dodgei" = Brachyrhynchocyon dodgei, Daphoenus sp.
"Daphoenocyon dodgei" = Brachyrhynchocyon dodgei Scott 1898 bear-dog | |
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"Hoplophoneus mentalis" = Hoplophoneus primaevus
"Hoplophoneus mentalis" = Hoplophoneus primaevus Leidy and Owen 1851 false sabre-tooth | |
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Brontotheriidae indet. Marsh 1873 brontothere | |
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Trigonias osborni Lucas 1900 rhinoceros
Subhyracodon sp. Wood 1927 rhinoceros | |
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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
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Heptacodon cf. occidentalis Osborn and Wortman 1894 anthracothere
Aepinacodon americanus Leidy 1856 anthracothere | |
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Archaeotherium mortoni Leidy 1850 even-toed ungulate | |
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Leptochoeridae indet. Marsh 1894 even-toed ungulate
Stibarus sp. Cope 1873 even-toed ungulate | |
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Merycoidodon sp. Leidy 1848 oreodont | |
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Poebrotherium cf. wilsoni Leidy 1847 camel | |
Pseudoprotoceras longinaris n. sp.2
Pseudoprotoceras longinaris n. sp.2 Cook 1934 protoceratid "Lower Chadron... about 9 miles north of Crawford"
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Agriochoerus sp. Leidy 1850 agriochoerid | |
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Hypertragulus chadronensis n. sp.2 Cook 1934 ruminant "nine miles north of Crawford... lower part of the Chadron formation"
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Hypisodus paululus n. sp.2 Cook 1934 ruminant "Lower Chadron formation, about nine miles north of Crawford": omitted by Ostrander
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Leptomeryx sp. Leidy 1853 ruminant | |
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Centetodon chadronensis Lillegraven et al. 1981 placental | |
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Domnina gradata Cope 1873 shrew | |
Chadronia margaretae n. gen. n. sp.3
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Megalagus brachyodon Matthew 1903 rabbit
Palaeolagus temnodon Douglass 1902 rabbit | |
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Pseudocylindrodon neglectus Burke 1935 rodent | |
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Pipestoneomys bisulcatus Donohoe 1956 rodent | |
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Heliscomys vetus Cope 1873 rodent | |
Eomyidae indet., Aulolithomys bounites, "Yoderimys burkei" = Zemiodontomys burkei, "Paradjidaumo trilophus" = Adjidaumo trilophus, Adjidaumo minimus
Eomyidae indet. Winge 1887 rodent
Aulolithomys bounites Black 1965 rodent
"Yoderimys burkei" = Zemiodontomys burkei Black 1965 rodent
"Paradjidaumo trilophus" = Adjidaumo trilophus Cope 1873 rodent
Adjidaumo minimus Matthew 1903 rodent | |
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Ischyromys veterior Matthew 1903 rodent | |
"Peratherium fugax" = Herpetotherium fugax
"Peratherium fugax" = Herpetotherium fugax Cope 1873 marsupial | |
| Actinopteri | |
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Amia sp. Linnaeus 1766 bowfin | |