Arroyo Chasicó (Miocene of Argentina)

Where: Buenos Aires, Argentina (38.6° S, 63.0° W: paleocoordinates 38.8° S, 60.1° W)

• coordinate estimated from map

• local area-level geographic resolution

When: Arroyo Chasicó Formation, Chasicoan (10.0 - 9.0 Ma)

• A recent interpretation of radiometric and paleomagnetic data of the ACF supports an age between at least 9.43 and 8.7 Ma (Zarate et al., 2007).

• formation-level stratigraphic resolution

Environment/lithology: "floodplain"; sandstone

• The beginning of Chasicoan sedimentation was placed after the general withdrawal of the mid-Miocene transgression (Pascual et al., 1996). According to Ramos (1999b), the transgression extended across most of eastern South America, covering the Pampas, Chaco region, and Patagonia up to the Andean foothill and reaching areas near the central and northern Andes of Argentina. The regional regression that followed was thought to be synchronous with the 10.5 Ma global sea level fall cited by Haq et al. (1987) (see Verzi, 1999, Pascual et al., 1996).
• an extensive plateau capped by a thick calcrete crust, which in turn is covered by a thin apron of late Pleistocene–Holocene eolian deposits.

Size class: macrofossils

Preservation: permineralized

Collection methods: Gonzalez-Ruiz, et al. 2012: their Material was collected during a field trip organized by the Facultad de Ciencias Naturales y Museo de La Plata (Argentina) and Duke University (USA).

Primary reference: M. A. Zárate, P. H. Schultz, A. Blasi, C. Heil, J. King and W. Hames. 2007. Geology and geochronology of type Chasicoan (late Miocene) mammal-bearing deposits of Buenos Aires (Argentina). Journal of South American Earth Sciences 23:81-90 [D. Croft/D. Croft]more details

Purpose of describing collection: biostratigraphic analysis

PaleoDB collection 79180: authorized by Darin Croft, entered by Darin Croft on 27.02.2008, edited by Bettina Kaphingst, Juan Carrillo, Jelle Zijlstra, Miranta Kouvari, Grace Varnham and Evangelos Vlachos

Creative Commons license: CC BY (attribution)

Taxonomic list

• Rasia & Canela 2017: Arroyo Chasico area, southwest of Buenos Aires Province, Argentina, MLP-Pv 55-IV- 28-43 and MLP-Pv 55-IV-28-44 come from in front of Rado- vitzki farm; MLP-Pv 55-IV-28-42 comes from in front of Torres and Stefanazzi farms; MLP-Pv 60-VI-18-101 comes from the left margin of Stefanazzi farm; MLP-Pv 76-VI-12-47 comes from the left bank of Arroyo Chasic?o, 400 m upstream from Bajada de los Toros; MLP-Pv 60-VI-18-100, MLP-Pv 60-VI-18-107, MLP-Pv 92-XI-19-1, and MLP-Pv 92-XI-19-2 come from the Arroyo Chasic?o area, without more precise geographic provenance.
 Salientia -
Anura indet.2 frog
leg bone
 Testudines - Pantestudinidae
Testudinidae indet.5 Batsch 1788 turtle
 Cariamae - Phorusrhacidae
Psilopterus colzecus2 Tonni and Tambussi 1988 terror bird
 Squamata -
"Carlesia cf. pendolai" = Dicarlesia2
"Carlesia cf. pendolai" = Dicarlesia2 lizard
one partial skeleton
 Notoungulata - Toxodontidae
Pisanodon nazari2 Cabrera and Kraglievich 1931 notoungulate
two specimens
 Notoungulata - Hegetotheriidae
Paedotherium minor2 Cabrera 1937 notoungulate
many specimens (30)
Hegetotheriinae indet.2 Ameghino 1894 notoungulate
six specimens
 Notoungulata - Mesotheriidae
Typotheriopsis sp.2 Cabrera and Kraglievich 1930 notoungulate
nine specimens
 Rodentia - Chinchillidae
Lagostomus telenkechanum n. sp.8 Rasia and Candela 2017 viscacha
Holotype MLP-Pv 60-VI-18-100 and other specimens
Lagostominae indet.2 Wiegmann 1832 chinchilid
three craniodental specimens
 Rodentia - Dinomyidae
? Tetrastylus sp.2 Ameghino 1886 caviomorph
a tooth
 Rodentia - Hydrochoeridae
"Procardiatherium sp." = Cardiatherium2, Cardiatheriinae indet.2
"Procardiatherium sp." = Cardiatherium2 Ameghino 1883 caviomorph
three teeth
Cardiatheriinae indet.2 Kraglievich 1930 caviomorph
one tooth
 Rodentia - Caviidae
Procardiomys martinoi9 Pascual and Bondesio 1961 caviomorph
Orthomyctera sp.2 Ameghino 1889 caviomorph
three specimens
Cardiomys sp.2 Ameghino 1885 caviomorph
two craniodental specimens
Cardiomys leufuensis n. sp.7 Pérez et al. 2018 caviomorph
MLP 55-IV-28-11 (type). Also, specimen MLP 29-IX-3-19 (semi-complete post cranial ref 70039)
? Parodimys sp.2 Kraglievich 1932 caviomorph
 Cingulata - Dasypodidae
Proeuphractus sp.2 Ameghino 1886 armadillo
four specimens
Vetelia perforata2 Scillato-Yané 1979 armadillo
seven specimens
Chasicotatus ameghinoi2 Scillato-Yané 1979 armadillo
eight specimens
 Cingulata - Pampatheriidae
Kraglievichia sp.2 Castellanos 1927 edentate
two osteoderms
 Cingulata - Peltephilidae
Epipeltephilus kanti n. sp.1 Gonzalez-Ruiz et al. 2012 edentate
Holotype: MLP 92-XI-19-7 and others. The type comes from the lower part of the Vivero member
 Xenarthra - Megalonychidae
Protomegalonyx chasicoensis3 Scillato-Yané 1977 edentate
femur MMP M 478
 Xenarthra - Megatheriidae
Anisodontherium halmyronomum n. gen.4 Cabrera 1928 edentate
Holotype: MLP 26-IV-10-1
 Xenarthra - Glyptodontidae
Plohophorini "1"2 Castellanos 1932 glyptodon
one osteoderm and two osteoderms from the tail
Plohophorini "2"2 Castellanos 1932 glyptodon
one osteoderm from the tail
Palaehoplophorini "1"2 Hoffstetter 1958 glyptodon
four osteoderms
Palaehoplophorini "2"2 Hoffstetter 1958 glyptodon
ten osteoderms
Palaehoplophorini "3"2 Hoffstetter 1958 glyptodon
five osteoderms
Palaehoplophorini "4"2 Hoffstetter 1958 glyptodon
two osteoderms
Palaehoplophorini "5"2 Hoffstetter 1958 glyptodon
one osteoderm
Palaehoplophorini "6"2 Hoffstetter 1958 glyptodon
one osteoderm
Palaehoplophorini "7"2 Hoffstetter 1958 glyptodon
one osteoderm
? Palaehoplophorini "8"2 Hoffstetter 1958 glyptodon
four osteoderms
Palaehoplophorini "9"2 Hoffstetter 1958 glyptodon
one osteoderm
"Sclerocalyptini "1"" = Hoplophorini2 Huxley 1864 glyptodon
one osteoderm
"? Sclerocalyptini "2"" = Hoplophorini2 Huxley 1864 glyptodon
one osteoderm
 Ungulata - Proterotheriidae
Proterotheriinae indet.2 Ameghino 1885 eutherian
partial limb bone
 Sparassodonta -
Chasicostylus castroi n. gen. n. sp.6
Chasicostylus castroi n. gen. n. sp.6 Reig 1957 metatherian
MLP 57-XI-9-2, maxilla and dentary, holotype; MLP 55-IV-28-59, right dentary with base of c and alveoli of p1-3, tentatively referred
 Sparassodonta - Borhyaenidae
Pseudolycopsis cabrerai2 Marshall 1976 metatherian
maxilla with three teeth