Chucal (Miocene of Chile)

Where: Chile (18.5° S, 69.2° W: paleocoordinates 19.2° S, 65.1° W)

• coordinate stated in text

• outcrop-level geographic resolution

When: Chucal Formation, Santacrucian (17.5 - 16.3 Ma)

• late early Miocene Santacrucian South American Land Mammal ‘Age’ (SALMA)

•Bond and García, 2002: Palyeidodon? sp. found in the upper layers of the Chucal formation; the fossil material is assigned Colloncuran in age but lies beneath strata radiometrically dated to 17-16Ma (Santacrucian).

•Townsend and Croft 2010: 17.4 ± 0.4 Ma to 21.7 and 21.7 ± 0.8 Ma

• formation-level stratigraphic resolution

Environment/lithology: "floodplain"; sandstone

• Paleobotanical evidence suggests that the area was located at an altitude of ca. 1000 m when the formation was deposited

•Bond and García, 2002: Fine grained, calcareous sedimentary rocks and volcanic rocks.

•fluvial and lacustrine strata deposited in a rather narrow, approximately north–south running intermontane basin

• The Chucal Fauna derives primarily from the Chucal Formation, a 600 m thick sequence of variegated fluvo-lacustrine strata in the Chilean Altiplano

•The base of this suc- cession consists of a channelized conglomerate followed by upward fining sandstones, siltstones, and mudstones with limestone intercalations (200 m). A coarse- to fine-grained, massive, greenish sandstone succession (containing calcare- ous mudstones, limestone, and tuff intercalations) overlies these deposits (225 m). The upper portion of the Chucal Formation consists of gray mudstones followed by cross- bedded sandstones and minor conglomeratic intercalations (172 m). The described succession reflects the following inferred environmental evolution: (1) fluvial or distal alluvial conditions grading to fluctuating lacustrine conditions ending in a well-developed lacustrine environment; (2) a stage of increased transport energy evidenced by the succession of green sandstones that filled the lake and expanded the fluvial plain environment; and (3) flood plain development grading to fluvial plain conditions. This evolution indicates two stages of basin development, one prior to deposition of the green sandstone succession and one after its deposition. Most of the Chucal fossils described in this work derive from the intermediate, green sandstone-bearing interval of the western flank (Member W3 of Charrier et al. 2005).

Size class: macrofossils

Primary reference: D. A. Croft, J. J. Flynn, and A. R. Wyss. 2007. A New Basal Glyptodontid and other Xenarthra of the Early Miocene Chucal Fauna, Northern Chile. Journal of Vertebrate Paleontology 27(4):781-797 [M. Uhen/M. Shalap]more details

Purpose of describing collection: general faunal/floral analysis

PaleoDB collection 103804: authorized by Mark Uhen, entered by Margaret Shalap on 02.02.2011, edited by Mark Uhen, Grace Varnham and Juan Carrillo

Creative Commons license: CC BY (attribution)

Taxonomic list

 Salientia -
Anura indet. Fischer von Waldheim 1813 frog
 Panameriungulata - Macraucheniidae
Theosodon sp.3 Ameghino 1887 placental
 Rodentia -
Octodontoidea indet. Waterhouse 1839 caviomorph
Acarechimys sp. Patterson 1965 caviomorph
 Rodentia - Chinchillidae
Miochinchilla surirense n. gen. n. sp.2
Miochinchilla surirense n. gen. n. sp.2 Croft et al. 2021 chinchilid
Holotype: SGOPV 4118, partial cranium; SGOPV 4140; SGOPV 4082; SGOPV 4092; SGOPV 4138; SGOPV 4079; SGOPV 4094; SGOPV 5060; SGOPV 5195; SGOPV 5061; SGOPV 4148; SGOPV 4073, SGOPV 4080, SGOPV 4088, 4090, SGOPV 4093, SGOPV 4131, SGOPV 4132, SGOPV 4134, SGOPV 4141, SGOPV 4143, SGOPV 4149, SGOPV 4203, SGOPV 5062 to 5069, SGOPV 5145, SGOPV 5153, SGOPV 5167, SGOPV 5181, SGOPV 5185 to 5191, SGOPV 5196 to 5206, SGOPV 5208 to 5216, SGOPV 5218 to 5221
 Rodentia -
Neoreomys sp. Ameghino 1887 caviomorph
 Notoungulata - Toxodontidae
Toxodontidae indet. Ameghino 1889 notoungulate
new taxon
Palyeidodon ? sp.1 Roth 1898 notoungulate
Specimen ID: SNGM 946
Adinotherium sp. Ameghino 1887 notoungulate
Nesodon imbricatus Owen 1846 notoungulate
 Notoungulata - Mesotheriidae
Altitypotherium chucalensis Croft et al. 2004 notoungulate
Altitypotherium paucidens Croft et al. 2004 notoungulate
Eotypotherium chico Croft et al. 2004 notoungulate
 Notoungulata - Hegetotheriidae
Hegetotherium cf. mirabile Ameghino 1887 notoungulate
 Cingulata - Peltephilidae
cf. Peltephilus sp. Ameghino 1887 edentate
 Cingulata - Glyptodontidae
Parapropalaehoplophorus septentrionalis n. gen. n. sp. Croft et al. 2007 glyptodon
 Cingulata - Chlamyphoridae
Stenotatus sp. Ameghino 1891 edentate
New species?
 Paucituberculata - Pichipilidae
"? Pichipilinae indet." = Pichipilidae
"? Pichipilinae indet." = Pichipilidae Marshall 1980 marsupial