Iniyoo Local Fauna (Eocene of Mexico)

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

• " ... a sequence of about 200 m in thickness of thinly to thickly bedded

•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

Caniformes indet.
, UMPE 0112, mandible fragment with m2
Fictovichnus sciuttoi
UMPLIC 004 to UMPLIC 006, three moulds.
 Testudines - Pantestudinidae
aff. Hadrianus sp. Cope 1872 turtle
Stylemys sp. Leidy 1851 turtle
UMPE 0341, several plastron elements
 Squamata - Rhineuridae
Rhineura sp. Cope 1861 worm lizard
UMPE 0281, partial skull
 Rodentia -
aff. Jimomys sp. Wahlert 1976 rodent
"Aff. Jimomys nov." UMPE 0316, mandible fragment with p3 alveolus and p4-m2.
 Rodentia - Sciuridae
Sciuridae indet. Gray 1821 squirrel
 Rodentia - Geomyidae
Geomyinae indet. Bonaparte 1845 pocket gopher
UMPE 0116, mandible fragment with dp4-m1.
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.
 Perissodactyla - Chalicotheriidae
Chalicotheriidae indet. Gill 1872 chalicothere
UMPE 0042, mandible fragment with dp3 and dp4 talonid.
 Perissodactyla - Amynodontidae
cf. Amynodontopsis sp. Stock 1933 odd-toed ungulate
UMPE 0623, mandible fragment with p4 and roots of m1em3.
 Perissodactyla - Rhinocerotidae
Trigonias sp. Lucas 1900 rhinoceros
UMPE 0624, left m2 and m3.
 Perissodactyla -
Tapiroidea indet. Gill 1872 odd-toed ungulate
 Perissodactyla - Equidae
Miohippus assinoboiensis anchitheriine horse
UMPE 0612, mandible fragment with p4-m3.
 Artiodactyla - Tayassuidae
Perchoerus probus Leidy 1856 peccary
UMPE 0031, mandible fragment with m2em3. UMPE 0442, upper canine.
 Artiodactyla - Leptochoeridae
Leptochoerus sp. Leidy 1856 even-toed ungulate
UMPE 0175 M1eM2; UMPE 0570 mandible fragment with p3-m3.
 Artiodactyla - Camelidae
Poebrotherium sp. Leidy 1847 camel
UMPE 0037, mandible fragment with m1em3
 Artiodactyla - Merycoidodontidae
Merycoidodon sp. Leidy 1848 oreodont
UMPE 0610, skull fragment
 Artiodactyla - Protoceratidae
Protoceratidae indet. Marsh 1891 protoceratid
UMPE 0283, P4-M2.
 Artiodactyla - Hypertragulidae
Nanotragulus sp. Lull 1922 ruminant
UMPE 0609, mandible fragment with p4-m3; UMPE 192, M3; UMPE 0086, astragalus
 Ichnofossils - Celliformidae
Celliforma curvata
UMPLIC 001 to UMPLIC 003, three internal moulds