Jalteco 26 “Kowallis” - Above Dated Ash (Neogene of Mexico)

Where: Jalisco, Mexico (20.1° N, 104.1° W: paleocoordinates 20.5° N, 102.5° W)

• coordinate stated in text

When: Hh3 mammal zone, San Jose Formation, Hemphillian (10.3 - 4.9 Ma)

• Age control in the localities comes from volcanic ash at the top of the sequence and late Hemphillian

•faunas (Hh3). The volcanic ash was dated at 4.89 ± 0.16 Ma by 40Ar/39Ar

•(Kowallis et al., 1998). Just above this volcanic ash, lenses of sandstone rich in small vertebrates crops out, mainly yielding cricetid rodents, lagomorphs, fishes, amphibians, reptiles and birds

Environment/lithology: fluvial; sandstone

• middle and the top of the succession are dominated by massive strata of siltstones, mudstones

•and fine sandstone: these geological structures are interpreted as fluvial and overbank deposits

Size classes: macrofossils, mesofossils

Collection methods: surface (float), sieve,

Primary reference: A. Pacheco Castro, O. Carranza Castañeda, and E. Jiménez Hidalgo. 2019. A new species of Sigmodontinae (Rodentia) from the late Hemphillian of central Mexico, and comments on the possible radiation of this group. Revista Mexicana de Ciencias Geológicas 36(3):321-342 [P. Holroyd/P. Holroyd]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 232513: authorized by Patricia Holroyd, entered by Patricia Holroyd on 01.12.2023

Creative Commons license: CC BY (attribution)

Taxonomic list

• "cricetid rodents, lagomorphs, fishes, amphibians, reptiles and bird"
Mammalia
 Rodentia - Cricetidae
Prosigmodon tecolotum n. sp. Pacheco Castro et al. 2019 mouse
 Perissodactyla - Equidae
Neohipparion eurystyle Cope 1893 hipparionine horse
Dinohippus mexicanus Lance 1950 horse
 Perissodactyla - Rhinocerotidae
Teleoceras fossiger Cope 1878 rhinoceros