Also known as Yolomécatl; Inyoo
Where: Oaxaca, Mexico (17.4° N, 97.6° W: paleocoordinates 19.3° N, 89.0° W)
• coordinate estimated from map
• local area-level geographic resolution
When: Yolomécatl Formation, Uintan (46.2 - 40.4 Ma)
• a tuff sheet interbedded in the namesake formation was 40Ar/39Ar-dated as 40.3 ±1.0Ma (Ferrusquia-Villafranca et al., 2016), contradicting the Chadronian estimate of Jimenez-Hidalgo et al. (2015)
• group of beds-level stratigraphic resolution
Environment/lithology: fluvial-lacustrine; mudstone and chert
•mudstones with occasional coarse lenses and some beds of volcanic
•and limestone pebble, cobble and some boulder clasts, and unlike
•the Yanhuitlan Formation in all other areas, paleosols horizons are
•abundant. Some thinly bedded chert layers are also intercalated
•with the fine-grained strata. The beds of the Yolomecatl unit are
•much thicker (around 1 m or more) than those of the typical
•Yanhuitlan, showing a bimodal grain-size distribution, with minor
•pebble content."
Size classes: macrofossils, mesofossils
Preservation: trace
Collection methods: Specimens reposited in the Coleccion Científica del Laboratorio de Paleobiología, campus Puerto Escondido, Universidad del Mar under the acronyms UMPE for vertebrates and UMPLIC for ichnofossils.
Primary reference: E. Jiménez-Hidalgo, K. T. Smith, R. Guerrero-Arenas and J. Alvarado-Ortega. 2015. The first Late Eocene continental faunal assemblage from tropical North America. Journal of South American Earth Sciences 57:39-48 [P. Holroyd/P. Holroyd/P. Mannion]more details
Purpose of describing collection: general faunal/floral analysis
PaleoDB collection 166797: authorized by Patricia Holroyd, entered by Patricia Holroyd on 26.02.2015, edited by Clint Boyd
Creative Commons license: CC BY (attribution)
Taxonomic list
unclassified | |
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Reptilia | |
aff. Hadrianus sp. Cope 1872 turtle | |
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Mammalia | |
aff. Jimomys sp. Wahlert 1976 rodent "Aff. Jimomys nov." UMPE 0316, mandible fragment with p3 alveolus and p4-m2.
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Sciuridae indet. Gray 1821 squirrel | |
Gregorymys sp. Wood 1936 pocket gopher UMPE 0156, skull fragment with P4-M3. UMPE 0178, mandible fragment with p4-m3.
Gregorymys veloxikua n. sp. Jimenez-Hidalgo et al. 2018 pocket gopher UMPE 626, almost complete skull with an associated mandible with teeth.
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Chalicotheriidae indet. Gill 1872 chalicothere UMPE 0042, mandible fragment with dp3 and dp4 talonid.
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cf. Amynodontopsis sp. Stock 1933 odd-toed ungulate UMPE 0623, mandible fragment with p4 and roots of m1em3.
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Perchoerus probus Leidy 1856 peccary UMPE 0031, mandible fragment with m2em3. UMPE 0442, upper canine.
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Leptochoerus sp. Leidy 1856 even-toed ungulate UMPE 0175 M1eM2; UMPE 0570 mandible fragment with p3-m3.
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Nanotragulus sp. Lull 1922 ruminant UMPE 0609, mandible fragment with p4-m3; UMPE 192, M3; UMPE 0086, astragalus
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