PBDB Collection

Ahearn (Eocene of the United States)

Where: Pennington and Shannon County, South Dakota (43.6° N, 102.5° W: paleocoordinates 44.9° N, 93.6° W)

• coordinate based on political unit

When: Ahearn Member (Chadron Formation), Chadronian (37.2 - 33.9 Ma)

Environment/lithology: terrestrial; lithology not reported

Size class: macrofossils

Primary reference: J. 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]more details

Purpose of describing collection: paleoecologic analysis

PaleoDB collection 16885: authorized by John Alroy, entered by John Alroy on 18.02.1993, edited by Jonathan Marcot

Creative Commons license: CC BY (attribution)

Taxonomic list

• dated at 36.3 +/- 0.7, 35.1, and 36.2 Ma: Emry et al. 1987; average is 35.87 (= 36.80) Ma

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Amphibia
Salientia - Pelobatidae	Eopelobates grandis Eopelobates grandis Zweifel 1956 spadefoot toad
Reptilia
Squamata -	Peltosaurus sp. Peltosaurus sp. Cope 1873 squamates
Crocodylia - Alligatoridae	Alligator cf. prenasalis Alligator cf. prenasalis Loomis 1904 alligator
Testudines - Trionychidae	"Apalone leucopotamica" = Trionyx leucopotamicus⁴ "Apalone leucopotamica" = Trionyx leucopotamicus⁴ Cope 1891 softshell turtle "scrap"
Testudines - Carettochelyidae	Anosteirinae indet.⁴ Anosteirinae indet.⁴ Lydekker 1889 turtle "Pseudanosteira or Anosteira... scrap"
Testudines - Emydidae	Emydidae indet.⁶ Emydidae indet.⁶ Rafinesque 1815 turtle "scrap"
Mammalia
Rodentia - Eomyidae	Eomyidae indet. Eomyidae indet. Winge 1887 rodent
Rodentia - Ischyromyidae	Ischyromys sp. Ischyromys sp. Leidy 1856 rodent
Carnivora - Amphicyonidae	"Daphoenocyon minor n. sp." = Brachyrhynchocyon dodgei "Daphoenocyon minor n. sp." = Brachyrhynchocyon dodgei Scott 1898 bear-dog
Carnivora - Ursidae	Parictis gilpini n. sp.², Parictis parvus n. sp. Parictis gilpini n. sp.² Clark and Guensburg 1972 bear Little Corral Draw, Pennington Co. Parictis parvus n. sp. Clark and Beerbower 1967 bear from west flank of Quinn Draw, Shannon Co.: see Clark and Guensburg 1972
Carnivora - Subparictidae	"Parictis dakotensis" = Subparictis dakotensis² "Parictis dakotensis" = Subparictis dakotensis² Clark 1936 carnivoran SE 1/4 NE 14 NW 1/4 sec 5 T4S R12E, Pennington Co.; same as type locality of P. gilpini
Carnivora - Nimravidae	? Eusmilus sp. ? Eusmilus sp. Gervais 1876 false sabre-tooth
Creodonta - Hyaenodontidae	Hyaenodon cf. montanus, Hyaenodon cf. horridus Hyaenodon cf. montanus Douglass 1902 creodont Hyaenodon cf. horridus Leidy 1853 creodont
Artiodactyla - Merycoidodontidae	Merycoidodon sp., Miniochoerus cf. forsythae⁸ Merycoidodon sp. Leidy 1848 oreodont "Big Corral Draw... Pennington Co.:" discussed by Stevens and Stevens 1996 Miniochoerus cf. forsythae⁸ Schultz and Falkenbach 1968 oreodont one specimen of "Merycoidodon sp."; said to to "probably" be this species
Artiodactyla - Agriochoeridae	Agriochoerus cf. antiquus Agriochoerus cf. antiquus Leidy 1850 agriochoerid
Artiodactyla - Hypertragulidae	Hypertragulidae indet. Hypertragulidae indet. Cope 1879 ruminant
Artiodactyla - Protoceratidae	Pseudoprotoceras longinaris³ Pseudoprotoceras longinaris³ Cook 1934 protoceratid
Artiodactyla - Tylopoda	Tylopoda indet. Tylopoda indet. even-toed ungulate "camelid new genus and species": may be Montanatylopus; specimens not discussed by Prothero 1986
Artiodactyla - Tayassuidae	Perchoerus minor⁷ Perchoerus minor⁷ Cook 1922 peccary
Artiodactyla - Entelodontidae	"Archaeotherium cf. altidens" = Scaptohyus altidens¹, Archaeotherium cf. mortoni, Archaeotherium cf. coarctatum "Archaeotherium cf. altidens" = Scaptohyus altidens¹ Sinclair 1922 even-toed ungulate Archaeotherium cf. mortoni Leidy 1850 even-toed ungulate Archaeotherium cf. coarctatum Cope 1889 even-toed ungulate
Artiodactyla - Anthracotheriidae	Anthracotheriidae indet.⁵ Anthracotheriidae indet.⁵ Leidy 1869 anthracothere
Artiodactyla - Camelidae	Poebrotherium sp.¹ Poebrotherium sp.¹ Leidy 1847 camel
Perissodactyla - Equidae	Mesohippus celer, "Mesohippus hypostylus" = Mesohippus bairdi, "Mesohippus viejensis" = Mesohippus bairdi Mesohippus celer Marsh 1874 anchitheriine horse "Mesohippus hypostylus" = Mesohippus bairdi Leidy 1850 anchitheriine horse "Mesohippus viejensis" = Mesohippus bairdi Leidy 1850 anchitheriine horse
Perissodactyla - Tapiridae	Colodon occidentalis Colodon occidentalis Leidy 1868 tapir
Perissodactyla - Rhinocerotidae	Trigonias sp., Subhyracodon mitis¹ Trigonias sp. Lucas 1900 rhinoceros Subhyracodon mitis¹ Cope 1875 rhinoceros
Perissodactyla - Hyracodontidae	Hyracodon cf. priscidens Hyracodon cf. priscidens Lambe 1905 odd-toed ungulate probably OK in light of Prothero 1996e
Perissodactyla - Brontotheriidae	Brontotheriidae indet.¹ Brontotheriidae indet.¹ Marsh 1873 brontothere

¹Alroy 2002; ²Clark and Guensburg 1972; ³Emry and Storer 1981; ⁴Hutchison 1996; ⁵Kron and Manning 1998; ⁶Lutugin 1894; ⁷Prothero 2009; ⁸Stevens and Stevens 1996