Also known as Yolomécatl, Inyoo, Tortugota
Where: Oaxaca, Mexico (17.5° N, 97.6° W: paleocoordinates 18.4° N, 91.1° W)
• coordinate stated in text
• local area-level geographic resolution
When: Yolomécatl Formation, Bartonian to Bartonian (41.3 - 28.1 Ma)
• Originally thought to be middle or late Eocene and described as the Yolomécatl Formation (Ferrusquia-Villafranca et al. 2018), a new U-Pb zircon maximum depositional age of 30.6 ± 0.77 Ma for a sandstone bed that is within the fossiliferous beds indicates an Arikareean 1 North American Land Mammal Age (NALMA) and it has been assigned to the Chilapa Formation instead (Guerrero-Arenas et al., 2020; see Ortiz-Caballero et al. 2020). However, Ferrusquía-Villafranca and Wang (2021) have argued that it is the Yolomécatl Formation, providing a 40Ar-39Ar age of 40.3 ± 1.0 Ma (latest Uintan-earliest Duchesnean NALMA)
•A corrected Ar–Ar age of 27.829 ± 0.716 Ma for the San Marcos Andesite, which overlies the Chilapa/Yolomécatl Formation close to the Yolomécatl fossiliferous beds, indicate an early Oligocene age for the formation (Guerrero-Arenas et al. 2020; Jiménez-Hidalgo et al. 2021).
• 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, Philip Mannion, Grace Varnham and Evangelos Vlachos
Creative Commons license: CC BY (attribution)
Taxonomic list
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| Mammalia | |
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aff. Jimomys sp. Wahlert 1976 rodent "Aff. Jimomys nov." UMPE 0316, mandible fragment with p3 alveolus and p4-m2.
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Gregorymys veloxikua n. sp.2 Jimenez-Hidalgo et al. 2018 rodent UMPE 0156, skull fragment with P4-M3. UMPE 0178, mandible fragment with p4-m3.
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Sciuridae indet. Gray 1821 squirrel | |
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Dzavui landeri n. gen. n. sp.3
Dzavui landeri n. gen. n. sp.3 Jiménez-Hidalgo et al. 2022 hedgehog Holotype: UMPE 945, left dentary fragment preserving the alveolus of the p3, and the p4 and m1
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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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Nanotragulus sp. Lull 1922 ruminant UMPE 0609, mandible fragment with p4-m3; UMPE 192, M3; UMPE 0086, astragalus
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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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Perchoerus probus Leidy 1856 peccary UMPE 0031, mandible fragment with m2em3. UMPE 0442, upper canine.
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| Reptilia | |
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aff. Stylemys gisellae n. sp.1
aff. Stylemys gisellae n. sp.1 Carbot-Chanona et al. 2022 turtle UMPE 0341, several plastron elements
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aff. Hadrianus sp. Cope 1872 turtle | |
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