Gran Barranca (Eocene to of Argentina)

Also known as South of Lake Colhué-Huapí, Puesto Almendra, Colhué-Huapí

Where: Chubut, Argentina (45.7° S, 68.7° W: paleocoordinates 47.5° S, 59.9° W)

• coordinate estimated from map

• local area-level geographic resolution

When: Sarmiento Formation, Middle Eocene to Middle Eocene (47.8 - 16.0 Ma)

• Deposits of the Sarmiento Formation, ranging in age from the Barrancan to "Pinturan" SALMAs (Middle Eocene to Early Miocene). This locality has yielded a long, complex, and very important sequence of mammal-bearing fossil deposits. This collection lists a small number of specimens of uncertain stratigraphic provenance; other collections are listed below.

•Gran Barranca was discovered in the 1890s and the first extensive collections were made by Carlos Ameghino. Later, many others have collected here, including the Scarritt Expedition under G.G. Simpson in the 1930s. On the basis of more recent collections, Madden et al. (2010) reviewed the complete stratigraphic sequence, spanning at least five South American Land Mammal Ages and more than 20 million years.

•Stratigraphically, all deposits at Gran Barranca are assigned to the Sarmiento Formation. From bottom to top, it includes the Gran Barranca, Rosado, Lower Puesto Almendra, Vera, Upper Puesto Almendra, and Colhue-Huapi Members (Bellosi, 2010). Absolute dates for the succession were provided by Ré et al. (2010) and Dunn et al. (2013).

•Collections based on material from Gran Barranca are listed below. Older collections frequently only include a general stratigraphic origin (corresponding to a SALMA), but recent collections (reviewed by Madden et al., 2010) use a sequence of localities prefixed with GBV.

•Barrancan SALMA

•----------------------

•The Barrancan "sub-age" of the Casamayoran SALMA was proposed by Cifelli (1985) on the basis of the oldest fossils preserved at Gran Barranca. This age coincides with the Gran Barranca Member. Cifelli (1985) provided species lists for a number of faunules within the Barrancan of Gran Barranca, based on Scarritt Expedition collections, but several of these faunules are post-Barrancan in age and listed below. Most Barrancan material cannot be assigned to a more precise level.

•Collections:

•- 13779, general Barrancan locality

•- 176176, faunule 1

•- 176177, faunule 2

•- 176178, faunule 3

•- 176180, faunule 5

•- 176181, faunule 6

•- 176182, faunule 7

•- 176183, faunule 9

•- 176184, faunule 10

•- 176185, faunule 11

•- 176186, aunule 12

•- 176187, faunule 13

•- 176188, faunule 14

•- 176190, faunule 18

•- 176191, faunule 19

•- 176192, faunule 20

•- 176193, faunule 21

•El Nuevo and Mustersan SALMA

•----------------------

•The main modern Mustersan locality is known as El Rosado and located in the Rosado Member. Lower in the Rosado Member is another fossiliferous level known as El Nuevo, which appears to contain a fauna intermediate in age between the Barrancan and Mustersan. The Scaritt Expedition also found Mustersan fossils in the overlying Lower Puesto Almendra Member, but apparently all modern collections come from the Rosado Member. A number of old specimens do not have a more precise provenance than "Mustersan of Gran Barranca".

•Collections:

•- 176287, general Mustersan locality

•- 23371, Feruglio collection (assigned to Mustersan but presence of _Eomorphippus_ suggests a Tinguirican age instead)

•- 105837, invertebrates only ("MACN Gran Barranca 1")

•- 176189, GBV-60 El Nuevo = faunule 15 (Madden et al. 2010:428).

•- 176194, GBV-3 El Rosado = faunule 8. Madden et al. (2010:428) says that Cifelli (1985) assigned this level to the Barrancan and recorded only _Notostylops_ sp. and _Antepithecus brachystephanus_, which matches only faunule 8.

•- 176169, GBV-64 Coley's Quarry = faunule 4. Cifelli (1985) already assigned this faunule to the Mustersan and Madden et al. (2010:429) gave an informal faunal list that matches only faunule 4. GBV-65 is also said to be possibly Mustersan, but there is no further information about it.

•Tinguirirican SALMA

•----------------------

•The Tinguirirican is represented at Gran Barranca in the Vera Member. Ameghino apparently found some Tinguirican specimens here, which he assigned to the "Astraponotéen plus supérieure" (APS; =upper Mustersan). The main modern collection is known as La Cancha. Two of Cifelli's (1985) faunules, 16 and 17, are also Tinguirican in age. Both Ameghino's APS specimens and the specimens from the modern La Cancha collection tend to be covered in manganese.

•- 38611, Astraponotéen plus supérieur (possibly not all from Gran Barranca)

•- 176200, GBV-4 La Cancha

•- 176195, faunule 16

•- 176196, faunule 17

•La Cantera

•----------------------

•La Cantera, also in the Vera Member, is a modern collection that appears to represent a distinct time interval between the Tinguirirican and Deseadan SALMAs, which has been informally called the "Canteran" SALMA.

•- 176201, GBV-19 La Cantera

•Deseadan SALMA

•----------------------

•The Deseadan is represented by some poor collections in the Upper Puesto Almendra Member.

•- 176235, general locality

•- 176202, GBV-1

•- 176203, GBV-34

•- 176204, GBV-35

•Colhuehuapian SALMA

•----------------------

•The Colhuehuapian SALMA is represented by abundant fossils from the Colhue-Huapi Member, collected by Ameghino and by many others since. Modern records assign these to the Lower Fossil Zone of the Colhue-Huapi Member. Many specimens are associated with the place name Puesto Almendra. Within the Lower Fossil Zone, several stratigraphic levels apparently exist, but most literature does not indicate the precise provenance of specimens.

•- 141368, general locality

•- 74771, penguin locality said to be from the Colhuehuapian of Gran Barranca.

•- 176236, GBV-8

•- 176240, GBV-9

•- 176237, GBV-10

•- 176238, GBV-38

•- 176239, GBV-43

•"Pinturan" SALMA

•----------------------

•The uppermost fossil locality on Gran Barranca, still in the Colhue-Huapi Member, is in the Upper Fossil Zone. It is assigned to the informal "Pinturan" SALMA, which is also represented at the Pinturas Formation elsewhere in Patagonia and appears to represent an interval between the Colhuehuapian and Santacrucian SALMAs.

•- 176205, Upper Fossil Zone, GBV-54 and 55

• formation-level stratigraphic resolution

Environment/lithology: terrestrial; claystone

• Bentonite and tuffs

Size classes: macrofossils, mesofossils, microfossils

Primary reference: R. H. Madden, R. F. Kay, M. G. Vucetich and A. A. Carlini. 2010. Gran Barranca: a twenty-three million year record of Middle-Cenozoic faunal evolution in Patagonia. In R. H. Madden, A. A. Carlini, M. G. Vucetich, R. F. Kay (eds.), The Paleontology of Gran Barranca: Evolution and Environmental Change through the Middle Cenozoic of Patagonia 423-439 [J. Zijlstra/J. Zijlstra]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 176461: authorized by Jelle Zijlstra, entered by Jelle Zijlstra on 13.02.2016

Creative Commons license: CC BY (attribution)

Taxonomic list

Mammalia
 Astrapotheria - Astrapotheriidae
Parastrapotherium crassum n. sp.1 Ameghino 1902 placental
Described as being from Colhuehuapian levels at Gran Barranca, but the preservation of the type specimens is characteristic of the Deseadan levels.
 Notoungulata - Oldfieldthomasiidae
Oldfieldthomasia sp.3 Ameghino 1901 notoungulate
MGP-PD 31581, P4?
 Notoungulata - Archaeohyracidae
Archaeohyracidae indet.3 Ameghino 1897 notoungulate
"MGP-PD 29082: two right lower molars, left m3 and right upper molar"
 Notoungulata - Notohippidae
Notohippidae indet.3 Ameghino 1894 notoungulate
MGP-PD 29070 B: left M3?
 Sparassodonta -
Cladosictis sp.2 Ameghino 1887 metatherian
FMNH P 13521, mandible
 Sparassodonta - Proborhyaenidae
Proborhyaena sp.2 Ameghino 1897 metatherian
FMNH P 13526, partial left dentary
 Sparassodonta - Borhyaenidae
"Borhyaena riggsi n. sp." = Acrocyon riggsi2
"Borhyaena riggsi n. sp." = Acrocyon riggsi2 Sinclair 1930 metatherian
FMNH P 13433, skull. Said to come from the "Deseado horizon (Astraponotus beds) at the southern end of Lake Colhue Huapi", suggesting the Deseadan ("Deseado") or Mustersan ("Astraponotus") SALMA, but the species is now thought to be Colhuehuapian in age (e.g., Marshall, 1978; Goin et al., 2007).