Ahearn: Chadronian, South Dakota

List of taxa
Where & when
Taphonomy & methods
Metadata & references
Taxonomic list
Salientia - Pelobatidae
Eopelobates grandis Zweifel 1956
Reptilia - Testudines - Trionychidae
Amyda sp. Geoffroy Saint-Hilaire 1809
    = Apalone leucopotamica Cope 1891
Hutchison 1996
original and current combination Trionyx leucopotamicus
Reptilia - Testudines
Dermatemydidae indet. Baur 1888
"Pseudanosteira or Anosteira... scrap"
    = Anosteirinae indet. Lydekker 1889
Hutchison 1996
Reptilia - Testudines - Emydidae
Graptemys sp. Agassiz 1857
    = Emydidae indet. Rafinesque 1815
Alroy 2010
Trachemys sp. Agassiz 1857
    = Emydidae indet. Rafinesque 1815
Alroy 2010
Reptilia - Alligatoridae
Alligator cf. prenasalis (Loomis 1904)
Reptilia - Squamata
Peltosaurus sp. Cope 1872
Mammalia - Rodentia - Eomyidae
Eomyidae indet. Winge 1887
Mammalia - Rodentia - Ischyromyidae
Ischyromys sp. Leidy 1856
Mammalia - Perissodactyla - Brontotheriidae
Menodus sp. (Pomel 1848)
    = Brontotheriidae indet. Marsh 1873
Alroy 2002
could include any of three genera; see Mader 1989
Mammalia - Perissodactyla - Hyracodontidae
Hyracodon cf. priscidens Lambe 1905
probably OK in light of Prothero 1996e
Mammalia - Perissodactyla - Rhinocerotidae
Caenopus mitis (Cope 1875)
    = Subhyracodon mitis Cope 1875
Alroy 2002
Trigonias sp. Lucas 1900
Mammalia - Perissodactyla - Tapiridae
Colodon occidentalis (Leidy 1868)
Mammalia - Perissodactyla - Equidae
Mesohippus viejensis Clark and Beerbower 1967
(1 measurement)
    = Mesohippus bairdi Leidy 1850
Alroy 2002
also includes "M. celer" and "M. hypostylus"; Forsten 1970b lists specimens from the head of Indian Creek; Big Corral Draw; and across the Cheyenne River from Battle Creek Canyon in Custer Co.; not clear if this includes Forsten's "M. proteulophus" from all the same localities
Mammalia - Carnivora - Ursidae
Parictis gilpini n. sp. Clark and Guensburg 1972
Clark and Guensburg 1972
Little Corral Draw, Pennington Co.
Parictis parvus n. sp. Clark and Beerbower 1967
from west flank of Quinn Draw, Shannon Co.: see Clark and Guensburg 1972
Parictis dakotensis Clark 1936
Clark and Guensburg 1972
SE 1/4 NE 14 NW 1/4 sec 5 T4S R12E, Pennington Co.; same as type locality of P. gilpini
Mammalia - Carnivora - Amphicyonidae
Daphoenocyon minor n. sp. Clark et al. 1967
    = Brachyrhynchocyon dodgei Scott 1898
Alroy 2002
from Indian Creek
Mammalia - Carnivora - Nimravidae
? Eusmilus sp. Gervais 1876
Mammalia - Ungulata - Merycoidodontidae
Miniochoerus cf. forsythae (Schultz and Falkenbach 1968)
Stevens and Stevens 1996
one specimen of "Merycoidodon sp."; said to to "probably" be this species
Merycoidodon sp. Leidy 1848
"Big Corral Draw... Pennington Co.:" discussed by Stevens and Stevens 1996
Mammalia - Ungulata - Tayassuidae
Perchoerus cf. minor Cook 1922
    = Tayassuidae indet. Palmer 1897
Wright 1998
    = Perchoerus minor Cook 1922
Prothero 2009
FMNH PM22407
Mammalia - Ungulata - Entelodontidae
Archaeotherium cf. coarctatum (Cope 1889)
Archaeotherium cf. mortoni Leidy 1850
Archaeotherium cf. scotti Sinclair 1922
    = Archaeotherium cf. altidens Sinclair 1922
Alroy 2002
original and current combination Scaptohyus altidens
Mammalia - Ungulata - Tylopoda
Tylopoda indet. Illiger 1811
"camelid new genus and species": may be Montanatylopus; specimens not discussed by Prothero 1986
Mammalia - Ungulata - Camelidae
Poebrotherium cf. andersoni Troxell 1917
    = Poebrotherium sp. Leidy 1847
Alroy 2002
species not recognized by Honey et al. 1998, who list P. eximium in the Chadron Fm. of South Dakota; slab includes Mesohippus, hypertragulid, Parictis parvus, and new camelid
Mammalia - Ungulata - Agriochoeridae
Agriochoerus cf. antiquus Leidy 1850
Mammalia - Ungulata - Anthracotheriidae
Bothriodon sp. Aymard 1846
    = Anthracotheriidae indet. Leidy 1869
Kron and Manning 1998
this is indeterminate and could be Aepinacodon
Mammalia - Ungulata - Protoceratidae
Poabromylus kayi Peterson 1932
(1 measurement)
    = Pseudoprotoceras longinaris Cook 1934
Emry and Storer 1981
replaces ID of Wilson 1974; FMNH collection
Mammalia - Ungulata - Hypertragulidae
Hypertragulidae indet. Cope 1879
Mammalia - Hyaenodonta - Hyaenodontidae
Hyaenodon cf. montanus Douglass 1902
Hyaenodon cf. horridus Leidy 1853
see common names

Country:United States State/province:South Dakota County:Pennington and Shannon
Coordinates: 43.6° North, 102.5° West (view map)
Paleocoordinates:44.9° North, 93.6° West
Basis of coordinate:based on political unit
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:Ahearn
Local section:BgBad Local bed:1
Local order:bottom to top
Lithology and environment
Environment:terrestrial indet.
Modes of preservation:body
Collection methods and comments
Reason for describing collection:paleoecologic analysis
Taxonomic list comments:dated at 36.3 +/- 0.7, 35.1, and 36.2 Ma: Emry et al. 1987; average is 35.87 (= 36.80) Ma
Database number:16885
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:2006-09-13 00:29:51
Access level:the public Released:1993-02-18 00:00:00
Creative Commons license:CC BY
Reference information

Primary reference:

1235.ETE 10023J. Clark and J. R. Beerbower. 1967. Geology, paleoecology, and paleoclimatology of the Chadron Formation. Fieldiana 5(5):21-74 [J. Alroy/J. Alroy/J. Alroy]

Secondary references:

6294 J. Alroy. 2002. Synonymies and reidentifications of North American fossil mammals. [J. Alroy/J. Alroy/M. Uhen]
31458 J. Alroy. 2010. Stop the madness. [J. Alroy/J. Alroy]
1238 J. Clark and T. E. Guensburg. 1972. Arctoid genetic characters as related to the genus Parictis. Fieldiana 26(1):1-71 [J. Alroy/J. Alroy/J. Marcot]
1454 R. J. Emry and J. E. Storer. 1981. The Hornless Protoceratid Pseudoprotoceras (Tylopoda: Artiodactyla) in the Early Oligocene of Saskatchewan and Wyoming. Journal of Vertebrate Paleontology 1(1):101-110 [J. Alroy/J. Alroy/M. Uhen]
34290 J. H. Hutchison. 1996. Testudines. In D. R. Prothero and R. J. Emry (eds.), The Terrestrial Eocene-Oligocene Transition in North America 337-353 [J. Alroy/J. Alroy]
6312 D. G. Kron and E. Manning. 1998. Anthracotheriidae. In C. M. Janis, K. M. Scott, and L. L. Jacobs (eds.), Evolution of Tertiary mammals of North America 381-388 [J. Alroy/J. Alroy/J. Alroy]
57282 D. R. Prothero. 2009. The Early Evolution of the North American Peccaries (Artiodactyla: Tayassuidae). Papers on Geology, Vertebrate Paleontology, and Biostratigraphy in Honor of Michael O. Woodburne (Museum of Northern Arizona Bulletin 65) 509-541 [J. Marcot/J. Marcot]
6270 M. S. Stevens and J. B. Stevens. 1996. Merycoidodontinae and Miniochoerinae. In D. R. Prothero and R. J. Emry (eds.), The Terrestrial Eocene-Oligocene Transition in North America 498-573 [J. Alroy/J. Alroy/J. Alroy]
6238 D. B. Wright. 1998. Tayassuidae. In C. M. Janis, K. M. Scott, and L. L. Jacobs (eds.), Evolution of Tertiary mammals of North America 389-401 [J. Alroy/J. Alroy/J. Alroy]