The Ituzaingó Formation ( es, Formación Ituzaingó), in older literature also described as Entre Ríos or Entrerriana Formation, is an extensive

geological formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...

Late Miocene The Late Miocene (also known as Upper Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of two faunal stage, stages. The Tortonian and Messinian stages comprise the Late Miocene sub-epoch, which lasted from 11.63 Ma (million ye ...

(

Tortonian The Tortonian is in the geologic time scale an age or stage of the late Miocene that spans the time between 11.608 ± 0.005 Ma and 7.246 ± 0.005 Ma (million years ago). It follows the Serravallian and is followed by the Messinian. The Torton ...

, or

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. ...

in the SALMA classification) age in the

Paraná Basin The Paraná Basin ( pt, Bacia do Paraná, es, Cuenca del Paraná) is a large cratonic sedimentary basin situated in the central-eastern part of South America. About 75% of its areal distribution occurs in Brazil, from Mato Grosso to Rio Grande d ...

of the

Corrientes Corrientes (; Guaraní language, Guaraní: Taragüí, literally: "Currents") is the capital city of the Provinces of Argentina, province of Corrientes Province, Corrientes, Argentina, located on the eastern shore of the Paraná River, about from ...

, Santa Fe and

Entre Ríos Province Entre Ríos (, "Between Rivers") is a central province of Argentina, located in the Mesopotamia region. It borders the provinces of Buenos Aires (south), Corrientes (north) and Santa Fe (west), and Uruguay in the east. Its capital is Paraná ( ...

s in

Mesopotamia Mesopotamia ''Mesopotamíā''; ar, بِلَاد ٱلرَّافِدَيْن or ; syc, ܐܪܡ ܢܗܪ̈ܝܢ, or , ) is a historical region of Western Asia situated within the Tigris–Euphrates river system, in the northern part of the F ...

, northeastern

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

.Ituzaingó Formation
at

Fossilworks Fossilworks is a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database The Paleobiology Database is an online resource for information on the distribution and classification of fossil animals ...

.org The formation comprises

mudstone Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from '' shale'' by its lack of fissility (parallel layering).Blatt, H., and R.J. Tracy, 1996, ''Petrology. ...

s, cross-bedded

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) ...

s and conglomerates deposited in a fluvio-

deltaic A river delta is a landform shaped like a triangle, created by deposition of sediment that is carried by a river and enters slower-moving or stagnant water. This occurs where a river enters an ocean, sea, estuary, lake, reservoir, or (more rarel ...

environment Environment most often refers to: __NOTOC__ * Natural environment, all living and non-living things occurring naturally * Biophysical environment, the physical and biological factors along with their chemical interactions that affect an organism or ...

and is renowned for the preservation of a rich fossil assemblage, including many

mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...

reptile Reptiles, as most commonly defined are the animals in the class Reptilia ( ), a paraphyletic grouping comprising all sauropsids except birds. Living reptiles comprise turtles, crocodilians, squamates (lizards and snakes) and rhynchocephalians ( ...

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...

bivalve Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bival ...

foraminifera Foraminifera (; Latin for "hole bearers"; informally called "forams") are single-celled organisms, members of a phylum or class of amoeboid protists characterized by streaming granular Ectoplasm (cell biology), ectoplasm for catching food and ot ...

ichnofossil A trace fossil, also known as an ichnofossil (; from el, ἴχνος ''ikhnos'' "trace, track"), is a fossil record of biological activity but not the preserved remains of the plant or animal itself. Trace fossils contrast with body fossils, ...

s and

flora Flora is all the plant life present in a particular region or time, generally the naturally occurring (indigenous) native plants. Sometimes bacteria and fungi are also referred to as flora, as in the terms '' gut flora'' or '' skin flora''. E ...

Description

The Ituzaingó Formation was first described by De Alba in 1953 and later by Herbst in 1971.Vezzosi, 2015, p.27 The up to , but in most areas between thick formation is found in an area of ,Vezzosi, 2015, p.28 stretching from the

Paraná River The Paraná River ( es, Río Paraná, links=no , pt, Rio Paraná, gn, Ysyry Parana) is a river in south-central South America, running through Brazil, Paraguay, and Argentina for some ."Parana River". Encyclopædia Britannica. Encyclopædia Br ...

to east of Tostado.Vezzosi, 2015, p.29 The Ituzaingó Formation crops out in the northeasternmost part of Argentina (

), in the

provinces A province is almost always an administrative division within a country or state. The term derives from the ancient Roman ''provincia'', which was the major territorial and administrative unit of the Roman Empire's territorial possessions outsi ...

, Santa Fe and Entre Ríos, among other locations along the banks of the

.Franco, 2014, p.16

Stratigraphy

The formation overlies the marine Paraná Formation and is unconformably overlain by the Puerto Alvear,Brunetto, 2013, p.22 Hernandarías and Yupoí Formations of

Early Pleistocene The Early Pleistocene is an unofficial sub-epoch in the international geologic timescale in chronostratigraphy, being the earliest division of the Pleistocene Epoch within the ongoing Quaternary Period. It is currently estimated to span the time ...

(

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 ...

and

Ensenadan The Ensenadan age is a period of geologic time (1.2–0.8 Ma) within the Early Pleistocene epoch of the Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the ...

respectively) age.Cione et al., 2000, p.195Cione et al., 2009, p.3 At the shores of the Paraná River, the formation underlies the Timbúes Formation.Vezzosi, 2015, p.41 In certain places along the same river, the formation cuts into the underlying Rosario Formation.Vezzosi, 2015, p.75 The formation contains a basal conglomeratic member "Conglomerado osífero" (''bony conglomerate'') with abundant vertebrate remains.Cione et al., 2005, p.49 This conglomerate is overlain by almost unfossiliferous whitish to yellow brown sandstones and green mudstones. The Ituzaingó Formation (as Entre Ríos Formation) was correlated with the Puelches Formation of the subsurface of

Buenos Aires Province Buenos Aires (), officially the Buenos Aires Province (''Provincia de Buenos Aires'' ), is the largest and most populous Argentine province. It takes its name from the city of Buenos Aires, the capital of the country, which used to be part of th ...

. According to the mammals occurring in the conglomerate and the stratigraphic relationships, the age of the base of Ituzaingo Formation is almost exclusively

(

) or

in the SALMA classification.Colonia La Celina
at

.org

Depositional environment

The formation, as the Paraná and Puelches Formations, has been deposited in a vast Miocene tidal flat environment.Torra, 2005, p.46 Both the terrestrial and freshwater fauna of the Ituzaingó Formation indicates a climate warmer than present. The freshwater vertebrate record suggests important basin connections with Amazonian basins. Alternatively, the Conglomerado Osífero Member has been interpreted as

tide Tides are the rise and fall of sea levels caused by the combined effects of the gravity, gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another. Tide t ...

-dominated fluvial channels, pertaining to the marine Paraná Formation.Martín Pérez, 2013, p.291

Fossil content

The Ituzaingó Formation has provided a large variety of fossils, of various groups, from mammals to birds and reptiles to fish and flora. The terrestrial fauna is predominant while a few marine genera are also present.Martín Pérez, 2013, p.27 The presence of typical Amazonian freshwater fish and absence of austral fauna in both the underlying Paraná and the Ituzaingó Formation suggests a connection with northern areas of South America. The faunas has been correlated to the older Miocene faunas of the Honda Group at

La Venta La Venta is a pre-Columbian archaeological site of the Olmec civilization located in the present-day Mexican state of Tabasco. Some of the artifacts have been moved to the museum "Parque - Museo de La Venta", which is in nearby Villahermosa, ...

in Colombia, the

Urumaco Formation The Urumaco Formation is a formation in Venezuela that includes deposits from the Late Miocene. It is the site of several "giant forms": the turtles, crocodiles, sloths and rodents of Urumaco are among the largest of their groups. Location Th ...

Urumaco Urumaco is a town in Falcón State in Venezuela. It is of interest to paleontologists due to its rich fossil history. The arid climate of the region means that the fossils are not hidden by vegetation. The fossils were first made known to scienc ...

in Venezuela and the

Pebas Formation The Pebas Formation is a lithostratigraphic unit of Miocene age, found in western Amazonia. The formation extends over , including parts of Brazil, Peru, Ecuador and Colombia.Wesselingh et al., 2006 It is interpreted as representing the deposits ...

of the Amazon region of Colombia, Ecuador, Peru and Brazil.Cione et al., 2005, p.58 Several

ground sloth Ground sloths are a diverse group of extinct sloths in the mammalian superorder Xenarthra. The term is used to refer to all extinct sloths because of the large size of the earliest forms discovered, compared to existing tree sloths. The Caribbe ...

genera present in the Ituzaingó Formation are endemic from this unit, whereas other are also present in the Arroyo Chasicó Formation of

, the Andalhuala and Corral Quemado Formations of

Catamarca Province Catamarca () is a province of Argentina, located in the northwest of the country. The province had a population of 334,568 as per the , and covers an area of 102,602 km2. Its literacy rate is 95.5%. Neighbouring provinces are (clockwise, fr ...

, and the Toro Negro Formation of La Rioja Province.Brandoni, 2013, p.135

Huayquerian correlations

References

Bibliography

* ''El Neógeno de la Mesopotamia argentina'' ** ** ** ** ** * * * * * * * * * * * * * * * * * * * * *