Also known as Arroyo de la Carreta; White layer
Where: Guanajuato, Mexico (21.2° N, 100.7° W: paleocoordinates 21.5° N, 99.1° W)
• coordinate based on nearby landmark
• outcrop-level geographic resolution
When: Rancho Viejo Beds Formation, Late/Upper Hemphillian (10.3 - 4.9 Ma)
• level dated at 4.6 Ma FT on zircon; according to Kowallis et al. 1986, this is the youngest of three modes, the others being at 11.0 and 24.5 Ma
•this date is superseded by an Ar/Ar date of 4.74 +/- 0.14 Ma reported by Flynn et al. 2005 for an ash immediately overlying the fauna
•unit is "2-3 m thick, lies disconformably on the lower unit" (Carranza-Castañeda and Walton 1992)
• group of beds-level stratigraphic resolution
Environment/lithology: "channel"; tuffaceous, gray, white claystone and sandstone
Size classes: macrofossils, mesofossils
Collected by O. Carranza-Castañeda, B. Slaughter, C. McKinney
Collection methods: bulk, sieve
• microfossils collected by "screenwashing" (Carranza-Castañeda and Walton 1992)
Primary reference: O. Carranza-Castaneda. 1989. Rinocerontes de la fauna local Rancho el Ocote, Mioceno Tardio (Hemfiliano tardio) de estado de Guanajuato. Universidad Nacional Autónoma de México, Instituto de Geológia, Revista, Publicación Especial 8(1):88-99 [J. Alroy/J. Alroy/M. Uhen]more details
Purpose of describing collection: general faunal/floral analysis
PaleoDB collection 18738: authorized by John Alroy, entered by John Alroy on 26.03.1995
Creative Commons license: CC BY (attribution)
Taxonomic list
Mammalia | |
cf. Stegomastodon sp. Pohlig 1912 gomphothere | |
Dinohippus mexicanus Lance 1950 horse
Astrohippus stockii Lance 1950 horse | |
Platygonus sp. Leconte 1848 peccary | |
"Hemiauchenia vera" = Pleiolama vera2 Matthew 1909 camel probably includes "H. sp."; may also include "Palaeolama guanajuatensis," although this is much smaller
Megatylopus sp. Matthew and Cook 1909 camel | |
Cricetidae indet.1, Prosigmodon oroscoi1, Prosigmodon ferrusquiai n. sp.1, Prosigmodon chihuahuensis1, Neotoma (Paraneotoma) sp.1, Neotoma (Paraneotoma) cf. sawrockensis1, Calomys (Bensonomys) baskini1, Calomys (Bensonomys) elachys1, Calomys (Bensonomys) winklerorum n. sp.1, Baiomys kolbi1
Calomys (Bensonomys) winklerorum n. sp.1 Carranza-Castañeda and Walton 1992 mouse sections GTO 2a and 2b
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Paenemarmota sp. Hibbard and Schultz 1948 squirrel includes "P. mexicana" of Dalquest and Mooser 1980a
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cf. Glossotherium sp. Owen 1840 edentate possibly includes "Pampatherium" of Carranza et al. 2000 from "4.7 Ma" level
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