The South American land mammal ages (SALMA) establish a geologic timescale for prehistoric South American fauna beginning 64.5 Ma during the Paleocene and continuing through to the Late Pleistocene (0.011 Ma). These periods are referred to as ages, stages, or intervals and were established using geographic place names where fossil materials where obtained. [1]
The basic unit of measurement is the first/last boundary statement. This shows that the first appearance event of one taxon is known to predate the last appearance event of another. If two taxa are found in the same fossil quarry or at the same stratigraphic horizon, then their age-range zones overlap.
South America was an island continent for much of the Cenozoic, or the "Age of Mammals". As a result, its mammals evolved in their own unique directions, as Australia and Madagascar still have today.
A simplified paleogeographic timeline of South America: [2]
The following formations have provided vertebrate, insect or plant fossils, formations with other invertebrates are excluded:
The Magallanes Basin or Austral Basin is a major sedimentary basin in southern Patagonia. The basin covers a surface of about 170,000 to 200,000 square kilometres and has a NNW-SSE oriented shape. The basin is bounded to the west by the Andes mountains and is separated from the Malvinas Basin to the east by the Río Chico-Dungeness High. The basin evolved from being an extensional back-arc basin in the Mesozoic to being a compressional foreland basin in the Cenozoic. Rocks within the basin are Jurassic in age and include the Cerro Toro Formation. Three ages of the SALMA classification are defined in the basin; the Early Miocene Santacrucian from the Santa Cruz Formation and Friasian from the Río Frías Formation and the Pleistocene Ensenadan from the La Ensenada Formation.
The Casamayoran age is a period of geologic time within the Early Eocene epoch of the Paleogene, used more specifically within the South American land mammal age (SALMA) classification. It follows the Itaboraian and precedes the Mustersan age.
The Tinguirirican age is a period of geologic time within the Late Eocene and Early Oligocene epochs of the Paleogene, used more specifically within the SALMA classification in South America. It follows the Divisaderan and precedes the Deseadan age.
The Deseadan age is a period of geologic time within the Oligocene epoch of the Paleogene to the Early Miocene epoch of the Neogene, used more specifically within the SALMA classification of South America. It follows the Tinguirirican and precedes the Colhuehuapian age.
The Colhuehuapian age is a period of geologic time within the Early Miocene epoch of the Neogene, used more specifically within the SALMA classification in South America. It follows the Deseadan and precedes the Santacrucian age.
The Santacrucian age is a period of geologic time within the Early Miocene epoch of the Neogene, used more specifically with SALMA classification in South America. It follows the Colhuehuapian and precedes the Friasian age.
The Friasian age is a period of geologic time within the Early Miocene epoch of the Neogene, used more specifically within the SALMA classification of South America. It follows the Santacrucian and precedes the Colloncuran age.
The Colloncuran age is a period of geologic time within the Middle Miocene epoch of the Neogene, used more specifically within the SALMA classification in South America. It follows the Friasian and precedes the Laventan age.
The Laventan age is a period of geologic time within the Middle Miocene epoch of the Neogene, used more specifically within the SALMA classification in South America. It follows the Colloncuran and precedes the Mayoan age.
The Mayoan age is a period of geologic time from 11.8 to 10 Ma, within the Middle to Late Miocene epoch of the Neogene, used more specifically within the SALMA classification in South America. It follows the Laventan and precedes the Chasicoan age.
The Chasicoan age is a period of geologic time from 10–9 Ma within the Late Miocene epoch of the Neogene, used more specifically within the SALMA classification in South America. It follows the Mayoan and precedes the Huayquerian age.
The Huayquerian age is a period of geologic time within the Late Miocene epoch of the Neogene, used more specifically within the SALMA classification. It follows the Chasicoan and precedes the Montehermosan age.
Neuquén Basin is a sedimentary basin covering most of Neuquén Province in Argentina. The basin originated in the Jurassic and developed through alternating continental and marine conditions well into the Tertiary. The basin bounds to the west with the Andean Volcanic Belt, to the southeast with the North Patagonian Massif and to the northeast with the San Rafael Block and to the east with the Sierra Pintada System. The basin covers an area of approximately 120,000 square kilometres (46,000 sq mi). One age of the SALMA classification, the Colloncuran, is defined in the basin, based on the Collón Curá Formation, named after the Collón Curá River, a tributary of the Limay River.
The Pisco Formation is a geologic formation located in Peru, on the southern coastal desert of Ica and Arequipa. The approximately 640 metres (2,100 ft) thick formation was deposited in the Pisco Basin, spanning an age from the Late Miocene up to the Early Pliocene, roughly from 9.6 to 4.5 Ma. The tuffaceous sandstones, diatomaceous siltstones, conglomerates and dolomites were deposited in a lagoonal to near-shore environment, in bays similar to other Pacific South American formations as the Bahía Inglesa and Coquimbo Formations of Chile.
Salta Basin or Salta Rift Basin is a sedimentary basin located in the Argentine Northwest. The basin started to accumulate sediments in the Early Cretaceous (Neocomian) and at present it has sedimentary deposits reaching thicknesses of 5,000 metres (16,000 ft). The basin contains seven sub-basins: Tres Cruces, Lomas de Olmedo, Metán, Alemanía, Salfity, El Rey, Sey and Brealito. The basin environment has variously been described as a "foreland rift" and an "intra-continental rift". The basin developed under conditions of extensional tectonics and rift-associated volcanism.
The Ituzaingó Formation, in older literature also described as Entre Ríos or Entrerriana Formation, is an extensive geological formation of Late Miocene age in the Paraná Basin of the Corrientes, Santa Fe and Entre Ríos Provinces in Mesopotamia, northeastern Argentina. The formation comprises mudstones, cross-bedded sandstones and conglomerates deposited in a fluvio-deltaic environment and is renowned for the preservation of a rich fossil assemblage, including many mammals, birds, reptiles, fish, bivalves, foraminifera, ichnofossils and flora.
The Collón Curá Formation is a Middle Miocene fossiliferous geological formation of the southern Neuquén Basin in northwestern Patagonia and the western Cañadón Asfalto Basin of central Patagonia, Argentina. The formation crops out from the southern Neuquén Province, the western Río Negro Province to the northern Chubut Province.
The Colorado Basin is a sedimentary basin located in northeastern Patagonia. The basin stretches across an area of approximately 180,000 square kilometres (69,000 sq mi), of which 37,000 square kilometres (14,000 sq mi) onshore in the southern Buenos Aires Province and the easternmost Río Negro Province extending offshore in the South Atlantic Ocean.
The Cerro Azul Formation, also described as Epecuén Formation, is a geological formation of Late Miocene age in the Colorado Basin of the Buenos Aires and La Pampa Provinces in northeastern Argentina.
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