Ituzaingó Formation
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.
Description
The Ituzaingó Formation was first described by De Alba in 1953 and later by Herbst in 1971. The up to, but in most areas between thick formation is found in an area of, stretching from the Paraná River to east of Tostado. The Ituzaingó Formation crops out in the northeasternmost part of Argentina, in the provinces of Corrientes, Santa Fe and Entre Ríos, among other locations along the banks of the Paraná River.Stratigraphy
The formation overlies the marine Paraná Formation and is unconformably overlain by the Puerto Alvear, Hernandarías and Yupoí Formations of Early Pleistocene age. At the shores of the Paraná River, the formation underlies the Timbúes Formation. In certain places along the same river, the formation cuts into the underlying Rosario Formation.The formation contains a basal conglomeratic member "Conglomerado osífero" with abundant vertebrate remains. This conglomerate is overlain by almost unfossiliferous whitish to yellow brown sandstones and green mudstones. The Ituzaingó Formation was correlated with the Puelches Formation of the subsurface of Buenos Aires Province. According to the mammals occurring in the conglomerate and the stratigraphic relationships, the age of the base of Ituzaingo Formation is almost exclusively Tortonian or Huayquerian in the SALMA classification.
Depositional environment
The formation, as the Paraná and Puelches Formations, has been deposited in a vast Miocene tidal flat environment. 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-dominated fluvial channels, pertaining to the marine Paraná Formation.
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. 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 fauns has been correlated to the older Miocene faunas of the Honda Group at La Venta in Colombia, the Urumaco Formation at Urumaco in Venezuela and the Pebas Formation of the Amazon region of Colombia, Ecuador, Peru and Brazil. Several ground sloth genera present in the Ituzaingó Formation are endemic from this unit, whereas other are also present in the Arroyo Chasicó Formation of Buenos Aires Province, the Andalhuala and Corral Quemado Formations of Catamarca Province, and the Toro Negro Formation of La Rioja Province.| Group | Fossils | Image | Notes |
| Ground sloths | Pronothrotherium mirabilis | ||
| Ground sloths | Amphiocnus paranense, Eomegatherium nanum, Megabradys darwini, Megalonychops primigenius, Menilaus affinis, Mesopotamocnus brevirostrum, Octomylodon aversus, Ortotherium brevirostrum, O. laticurvatum, O. robustum, O. schlosseri, O. scrofum, O. seneum, Paranabradys vucetichae, Pliomegatherium lelongi, Pliomorphus ameghinoi, P. gracilis, P. mutilatus, P. robustus, Prolestodon antiquus, P. paranensis, Promegatherium parvulum, P. smaltatum, Promylodon paranensis, Protomegalonyx doellojuradoi, P. praecursor, Ranculcus scalabrinianus, Sphenotherus paranensis, Strabosodon acuticavus, S. obtusicavus, Torcellia paranense, Pyramiodontherium sp., Scelidotheriinae indet. | ||
| Glyptodonts | Eleutherocercus paranensis | ||
| Glyptodonts | Chasicotatus spinozai, Chlamyphractus pressulus, Comaphorus concisus, Hoplophorus verus, Kraglievichia paranense, Macroeuphractus retusus, Palaehoplophorus antiquus, Paraglyptodon paranensis, Parahoplophorus paranensis, Plohophorus paranensis, Proeuphractus limpidus, Protoglyptodon primiformis, Pseudoeuryurus lelongianus, Scirrotherium carinatum, ?Trachycalyptus cingulatus, Urotherium interundatum, Berthawyleria sp., ?Zaedyus sp. | ||
| Rodents | Briaromys trouessartianus, Cardiatherium paranense, Carlesia pendolai, Diaphoromys compressidens, D. gamayensis, D. mesopotamicus, Doellomys parcus, Eumegamys contortus, E. dubius, E. scalabrinianus, E. paranensis, Eumegamysops praependens, Gyriabrus glutinatus, G. holmbergi, G. indivisus, G. rebagliattii, Haplostropha sacabriniana,Isostylomys ameghinoi, I. laurillardi, Lagostomopsis antiquus, L. pallidens, Myocastor obesus, M. paranensis, M. sinuata, Neoepiblema ambrosettianus, N. horridula, Olenopsis typicus, Paradoxomys cancrivorus, Pentastylodon racedi, Pentastylomys seriei, Perimys scalabrinianus, Phoberomys burmeisteri, P. insolita, P. lozanoi, P. minima, P. praecursor, Phugatherium cataclisticum, Potamarchus murinus, P. sigmodon, Protabrocoma paranensis, Protomegamys coligatus, Pseudosigmomys paranensis, Rusconia crassidens, Strophostephanos jheringi, Telodontomys compressidens, Tetrastylomys castellanosi, Tetrastylus aguilari, T. diffusus, T. laevigatus, T. robustus, T. atavus, Anatochoerus, Anchimysops, Cardiatherium, Cardiomys, Caviodon, Colpostemma sp., Contracavia, Kiyutherium, Paleocavia, Parodimys, Plexochoerus, Pliodolichotis, Procardiatherium, Prodolichotis, Protohydrochoerus | ||
| Toxodonts | ?Adinotherium paranense | ||
| Toxodonts | Xotodon doellojuradi, X. foricurvatus | ||
| Toxodonts | Dilobodon lutarius, Dinotoxodon paranensis, Eutomodus elautus, Palaeotoxodon paranensis, ?P. protoburmeisteri, ?P. virgatus, Stenotephanos plicidens, ?Berroia sp. | ||
| Litopterns | Diadiaphorus paranensis | ||
| Litopterns | Brachytherium cuspidatum, Licaphrium mesopotamiense, Neobrachytherium ameghinoi, Oxyodontherium piramydatus, O. zeballosi, Paranauchenia denticulata, Promacrauchenia antiqua, Proterotherium cervioides, P. gradatum, Scalabrinitherium bravardi, S. rothii, Coelosoma eversa, Cullinia sp. | ||
| Sparassodonts | Thylacosmilus atrox | ||
| Sparassodonts | Stylocynus paranensis | ||
| Typotheres | Munizia paranensis, Protypotherium antiquum, Trachytypotherium sp. | - | |
| Cetaceans | Saurocetes gigas, Iniidae indet. | ||
| Bats | Eumysops parodii, Notictis ortizi | - | |
| Other mammals | Cyonasua argentina, Dasypus neogaeus, Haplodontherium limun, Neohapalops rothi, Pachynodon modicus, Philander entrerianus, Toxodontherium compressum, T. reverendum, Zygolestes paranensis, Chironectes sp. | ||
| Birds | Andalgalornis sp. | ||
| Birds | Devincenzia pozzi, Macranhinga paranensis, M. ranzii, Palaelodus cf. ambiguus, Rhea mesopotamica, Megapaloelodus sp., Phoenicopteridae indet., Phorusrhacidae indet., Rallidae indet., Rheidae indet. | ||
| Crocodiles | Caiman latirostris | ||
| Crocodiles | C. cf. yacare | ||
| Crocodiles | Caiman australis, C. gasparinae, C. jacare, C. lutescens, Gryposuchus neogaeus, Mourasuchus arendsi | ||
| Lizards | Tupinambis cf. merianae | ||
| Turtles | Parahydraspis paranaensis, Phrynops cf. geoffroanus, Testudo paranensis | ||
| Fish | Megapiranha paranensis Colossoma macropomus | ||
| Fish | Potamotrygon motoro | ||
| Fish | Squatina dumeril | ||
| Fish | Phractocephalus ivy, Cynodontidae indet. | ||
| Invertebrates | Protelphidium tuberculatum, Ostrea sp. | ||
| Macroflora | Anadenantheroxylon villaurquicense, Astroniumxylon bonplandianum, A. parabalansae, Curtiembreoxylon poledrii, Gleditsioxylon paramorphoides, Guadua morronei, G. zuloagae, Laurinoxylon artabeae, Mangroveoxylon areniensis, Menendoxylon vasallensis, Microlobiusxylon paranaensis, Maytenoxylon, Mimosoxylon, Palmoxylon yuqueriense, Prosopisinoxylon americanum, Prumnopityoxylon gnaedingerae, Ruprechtioxylon breae, Scalarixylon, Schinopsixylon heckii, Soroceaxylon entrerriensis, Syagrus, Uruguaianoxylon striata | ||
| Ichnofossils | Arenicolites |