The South American land mammal ages (SALMA) establish a
geologic timescale
The geologic time scale, or geological time scale, (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochronol ...
for
prehistoric
Prehistory, also known as pre-literary history, is the period of human history between the use of the first stone tools by hominins 3.3 million years ago and the beginning of recorded history with the invention of writing systems. The use of ...
South America
South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...
n
fauna
Fauna is all of the animal life present in a particular region or time. The corresponding term for plants is ''flora'', and for fungi, it is '' funga''. Flora, fauna, funga and other forms of life are collectively referred to as '' biota''. Zoo ...
Paleocene
The Paleocene, ( ) or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), E ...
and continuing through to the
Late Pleistocene
The Late Pleistocene is an unofficial Age (geology), age in the international geologic timescale in chronostratigraphy, also known as Upper Pleistocene from a Stratigraphy, stratigraphic perspective. It is intended to be the fourth division of ...
(0.011 Ma). These periods are referred to as ages, stages, or intervals and were established using geographic place names where
fossil
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
materials where obtained.Flynn & Swisher, 1995
The basic unit of measure is the first/last boundary statement. This shows that the first appearance event of one
taxon
In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...
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.
Background
South America was an island continent for much of the
Cenozoic
The Cenozoic ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterised by the dominance of mammals, birds and flowering plants, a cooling and drying climate, and the current configura ...
, or the "Age of Mammals". As a result, its mammals evolved in their own unique directions, as Australia and Madagascar still have today.
Paleogeographic timeline
A simplified
paleogeographic
Palaeogeography (or paleogeography) is the study of historical geography, generally physical landscapes. Palaeogeography can also include the study of human or cultural environments. When the focus is specifically on landforms, the term paleo ...
timeline of South America:Darin A. Croft - South American Fossil Mammals /ref>
* 66 Ma – South America was connected to both North America and Antarctica. Soon after this point, it lost its connection to North America.
* 66–50 Ma – Tiupampan to Casamayoran - South America was connected to Antarctica which, in turn, was connected to Australia. The Antarctica–Australia connection was lost around the end of this interval or perhaps as much as 15 million years later.
* 50–34 Ma – Casamayoran to Tinguirirican - South America was connected to Antarctica, which was not yet covered by ice.
* 34 Ma –
Tinguirirican The Tinguirirican ( es, Tinguiririquense) age is a period of geologic time (36.0–29.0 Ma) within the Late Eocene and Early Oligocene epochs of the Paleogene, used more specifically within the SALMA classification in South America. It follows th ...
- South America and Antarctica became detached and glaciations started to form in Antarctica.
* 34–9 Ma – Tinguirirican to Chasicoan - South America had no land connections to any other continent.
* 9–3 Ma –
Huayquerian The Huayquerian ( es, Huayqueriense) age is a period of geologic time (9.0–6.8 Ma) within the Late Miocene epoch of the Neogene, used more specifically within the SALMA classification. It follows the Mayoan and precedes the Montehermosan age.
...
to
Chapadmalalan
The Chapadmalalan age is a period of geologic time (4.0–3.0 Ma) within the Pliocene epoch of the Neogene used more specifically with South American Land Mammal Ages. It follows the Montehermosan and precedes the Uquian age.
Fossil content
F ...
- islands formed between South and North America. A complete Isthmus of Panama most likely formed near the end of this interval, leading to the Great American Biotic Interchange (GABI).
* 3 Ma to present –
Uquian
The Uquian age is a period of geologic time (3.0–1.5 Ma) within the Pliocene and Pleistocene epochs of the Neogene used more specifically with South American Land Mammal Ages. It follows the Montehermosan and precedes the Ensenadan
The Ensenad ...
to
Holocene
The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togethe ...
- the land connection between South and North America is established and migration between the formerly separated continents occurs. The main migrational route is from north to south, rather than the opposite way. This led to much higher extinction levels of groups in South America than in North America.
* Pleistocene – the glacials and
interglacial
An interglacial period (or alternatively interglacial, interglaciation) is a geological interval of warmer global average temperature lasting thousands of years that separates consecutive glacial periods within an ice age. The current Holocene in ...
s of the Pleistocene caused drastic eustatic sea level changes, widening and narrowing the land bridge at the 'bottleneck' of Panama. As a side-effect, the vegetation changed during this period of strong climatic changes.
* Late Pleistocene – the earliest humans arrived in South America and settled in various parts of the continent. Evidence for cohabitation with the latest Pleistocene megafauna has been found at multiple locations, such as Monte Verde in coastal
Chile
Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...
and
Tibitó
Tibitó is the second-oldest dated archaeological site on the Altiplano Cundiboyacense, Colombia.Altiplano Cundiboyacense in
Colombia
Colombia (, ; ), officially the Republic of Colombia, is a country in South America with insular regions in North America—near Nicaragua's Caribbean coast—as well as in the Pacific Ocean. The Colombian mainland is bordered by the Car ...
.
Definitions
Cenozoic fossiliferous stratigraphic units in South America
The following formations have provided vertebrate, insect or plant fossils, formations with other invertebrates are excluded:
North American land mammal age
The North American land mammal ages (NALMA) establishes a geologic timescale for North American fauna beginning during the Late Cretaceous and continuing through to the present. These periods are referred to as ages or intervals (or stages when ref ...
European land mammal age
The European Land Mammal Mega Zones (abbreviation: ELMMZ, more commonly known as European land mammal ages or ELMA) are zones in rock layers that have a specific assemblage of fossils (biozones) based on occurrences of fossil assemblages of Europe ...
(ELMA or ELMMZ)
*
List of fossiliferous stratigraphic units in Colombia
Several stratigraphic units in Colombia have provided fossils. The richest formations are the Devonian Cuche and Floresta Formations, the Cretaceous Paja Formation, the Paleocene Cerrejón Formation and the Miocene La Venta site. The latter is ...
*
List of fossiliferous stratigraphic units in Ecuador
This is a list of fossiliferous stratigraphic units in Ecuador.
__NOTOC__ List of fossiliferous stratigraphic units
See also
*
* List of gomphothere fossils in South America#Ecuador, Gomphothere fossils in Ecuador
* List of fossiliferous s ...
*
List of fossiliferous stratigraphic units in Paraguay
This is a list of fossiliferous stratigraphic units in Paraguay.
__NOTOC__
List of fossiliferous stratigraphic units
See also
*
* South American land mammal age
* List of gomphothere fossils in South America#Paraguay, Gomphothere fossil ...
*
List of fossiliferous stratigraphic units in Uruguay
This is a list of fossiliferous stratigraphic units in Uruguay.
__NOTOC__
List of fossiliferous stratigraphic units
See also
*
* South American land mammal ages
* List of gomphothere fossils in South America#Uruguay, Gomphothere fossils i ...
*
List of fossiliferous stratigraphic units in Venezuela
This is a list of fossiliferous stratigraphic units in Venezuela.
List of fossiliferous stratigraphic units
See also
*
* List of gomphothere fossils in South America#Venezuela, Gomphothere fossils in Venezuela
* List of fossiliferous str ...