Cerro Yeso 3 (Eocene to of Argentina)

Also known as CY3

Where: Río Negro, Argentina (41.4° S, 69.6° W: paleocoordinates 43.6° S, 60.6° W)

• coordinate stated in text

• small collection-level geographic resolution

When: Lower Member (Las Chacras Formation), Bartonian to Bartonian (41.3 - 33.9 Ma)

• The proposed stratigraphic correlations and geochronological dates of the Las Chacras Formation indicate that the stratigraphic interval bearing the Lower Las Chacras fauna is younger than the maximum age estimated for the lower basalt flow exposed at Cerro Yeso (44 Ma.) The strong similarity with the Mustersan assemblage from the Rosado Member at Gran Barranca South of Colhué Huapi Lake, with a well constrained age of 38.16 – 37.4 Ma. (Dunn et al., 2013), suggests that the Lower Las Chacras Formation and its fauna is more likely of late Bartonian or early Priabonian age. Fossils occurs 22 m from the base of the formation in the measured section

• bed-level stratigraphic resolution

Environment/lithology: "floodplain"; massive, volcaniclastic, gray, green mudstone

• Floodplain and pyroclastic flow deposits
• light greenish to yellowish gray, laminated or massive volcaniclastic mudstones, intercalated with fine tuffs. Rhizoliths and fragmentary leaves and stems were also recognized.

Size class: macrofossils

Collection methods: This is the site where Casamiquela collected all his fossils (according to Mr. Marileo, a local farmer who accompanied Casamiquela in his prospections). Further collection by Kramarz et al. 2022 in October 2017 and April 2018.

Primary reference: A. Kramarz, E. Bellosi, M. Bond, A. M. Forasiepi, J. C. Fernicola, G. Aguirrezabala, and D. T. Rezende. 2022. Eocene mammals from volcaniclastic deposits of the Somun Cura Plateau: biostratigraphic implications for north Patagonia Paleogene. Andean Geology 49(2) [P. Mannion/G. Varnham/P. Mannion]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 225622: authorized by Philip Mannion, entered by Grace Varnham on 20.05.2022

Creative Commons license: CC BY (attribution)

Taxonomic list

Mammalia
 Notoungulata - Interatheriidae
Interatheriidae indet. Ameghino 1887 notoungulate
MJHG-NCP 28, right maxillary fragment with C1-P1 and roots for P2; MJHG-NCP 276, isolated right c1?
 Notoungulata - Archaeohyracidae
Pseudhyrax eutrachytheroides Ameghino 1901 notoungulate
MJHG-NCP 23, isolated partial lower molar
 Notoungulata - Notohippidae
Puelia sigma Ameghino 1901 notoungulate
MJHG-NCP 25, right mandibular fragment with partial m1-m3; MJHG-NCP 27, right mandibular fragment with p3-p4 and associated incisor and fragments
 Cingulata - Dasypodidae
"Isutaetus depictus" = Pseudeutatus depictus
"Isutaetus depictus" = Pseudeutatus depictus Ameghino 1902 armadillo
MJHG-NCP 24, six probably associated osteoderms (five fixed and one movable); MJHG-NCP 26, three fixed probably associated osteoderms; MJHG-NCP 274, four probably associated isolated osteoderms (three fixed and one fragment movable), and a fragment of one movable osteoderm; MJHG-NCP 274, four probably associated isolated osteoderms (three fixed and one fragment movable), and a fragment of one movable osteoderm
 Paucituberculata - Pichipilidae
Pichipilidae "n. gen." Marshall 1980 marsupial
MJHG-NCP 277, fragment of left dentary with ?m2; MJHG-NCP 278, left mandibular fragment with four alveoli, ?p3, and alveolus for root of ?m1