The Chacoan pygmy opossum is a recently described genus and species of didelphimorph marsupial. The only species in Chacodelphys, C. formosa, was known until 2004 from only one specimen collected in 1920 in the Chaco of Formosa Province, Argentina. The species is gaining popularity as a pocket pet.
Aeolosaurus is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous Period of what is now South America. Like most sauropods, it would have been a quadrupedal herbivore with a long neck and tail. Aeolosaurus is well known for a titanosaur, as it is represented by the remains of several individuals belonging to at least two species. However, like most titanosaurs, no remains of the skull are known. The holotype of Aeolosaurus rionegrinus consists of a series of seven tail vertebrae, as well as parts of both forelimbs and the right hindlimb. It was discovered in the Angostura Colorada Formation in Argentina, which dates from the Campanian stage of the Late Cretaceous, about 83 to 74 million years ago. The species A. maximus was transferred over to the new genus Arrudatitan in 2021.
Bonatitan is a genus of titanosaurian dinosaur from the Late Cretaceous Allen Formation of Argentina. It was named in 2004.
Mesembriornis is a genus of intermediate-sized phorusrhacids that grew up to 1.5 metres (4.9 ft) in height. They represent a well-distinct lineage of terror birds, differing from the massive large groups and the smaller Psilopterinae. In general proportions, they most resembled the Patagornithinae which flourished somewhat earlier, mainly to the south of the range of Mesembriornis. Fossils of the terror bird have been found in Montehermosan deposits of the Monte Hermoso Formation, as well as the Andalgala Formation and Chapadmalal Formation in Argentina.
Scalabrinitherium is an extinct genus of mammals of the family Macraucheniidae. Fossils of this animal were found among the fossils of prehistoric xenarthrans in the Ituzaingó Formation of Argentina.
Physornis is an extinct genus of giant flightless predatory birds of the family Phorusrhacidae or "terror birds", most closely related to Paraphysornis, that lived in Argentina. The type species is P. fortis. It lived during the Middle to Late Oligocene (Deseadan). Few fossils are known, but the available material suggests that Physornis was one of the largest phorusrhacids.
Proterotheriidae is an extinct family of litoptern ungulates known from the Oligocene-Late Pleistocene of South America. Members of the group were small-medium sized cursorial herbivores with brachydont teeth, with their toes showing progressive reduction, with later members of the group bearing weight on a single large toe similar to living horses.
Elaltitan is an extinct genus of large lithostrotian titanosaur sauropod dinosaur known from the Late Cretaceous of Chubut Province, southern Argentina. It contains a single species, Elaltitan lilloi.
Neosclerocalyptus was an extinct genus of glyptodont that lived during the Pliocene, Pleistocene, and Holocene of Southern South America, mostly Argentina. It was small compared to many Glyptodonts at only around 2 meters long and 360 kilograms.
Pseudochampsa is an extinct genus of proterochampsid archosauriform known from the Late Triassic (Carnian) Cancha de Bochas Member of the Ischigualasto Formation of San Juan Province, Ischigualasto-Villa Unión Basin in northwestern Argentina. It contains a single species, Pseudochampsa ischigualastensis, originally named as a second species of the closely related Chanaresuchus, based on a fairly complete articulated skeleton and skull. A revision of the remains concluded that it was best to move to species to its own genus, as no traits were found to unite P. ischigualastensis and the type species of Chanaresuchus to the exclusion of other proterochampsids. A phylogenetic analysis places both species in a polytomy with Gualosuchus as the most advanced members of Proterochampsia.
Neusticemys is an extinct genus of thalassochelydian sea turtle. Its type species is Eurysternum neuquinum. It is known from the Late Jurassic (Tithonian) aged Vaca Muerta of Patagonia, Argentina
Kelenkura is an extinct genus of heavily armored mammals belonging to the subfamily Glyptodontinae, from the family Chlamyphoridae that contain most of the modern armadillos. It was a medium-sized South American animal, distantly related to Doedicurus. Fossils of this genus were recovered in the Arroyo Chasicó Formation and in the Loma de Las Tapias Formation of Argentina in rocks dating back to the Late Miocene epoch.
Cullinia is an extinct genus of litoptern, an order of South American native ungulates that included horse-like and camel-like animals such as Macrauchenia. It is only known from fragmentary remains. Cullinia levis is known from Chasicoan remains found in the Arroyo Chasicó Formation of Argentina, and remains from the Brazilian state of Acre and the Huayquerian Ituzaingó Formation have been assigned to Cullinia sp..
Huallasaurus is an extinct genus of saurolophine hadrosaur from the Late Cretaceous Los Alamitos Formation of Patagonia in Argentina. The type and only species is H. australis. Originally named as a species of Kritosaurus in 1984, it was long considered a synonym of Secernosaurus before being recognized as its own distinct genus in a 2022 study, different from other members of Kritosaurini.
Brachytherium is an extinct genus of proterotheriid mammal from the Late Miocene to Late Pliocene of Argentina. It is represented by the type and only species B. cuspidatum, a taxon named in 1883 by Ameghino for a partial mandible with teeth. Though it was considered a dubious taxon at times, Brachytherium was revised as valid by Schmidt in 2015, who also synonymized the species Proterotherium gradatum and Lophogonodon paranensis, expanding the material known, all of which is from the Ituzaingó Formation. Some material previously referred to Brachytherium has been given the new name Neobrachytherium.
Thoatheriopsis is an extinct genus of proterotheriid from the Miocene of Mendoza Province, Argentina. The taxon is known only from the specimen MLP 81-XI-28-1, which includes an upper tooth row, and was named as the new binomial Thoatheriopsis mendocensis by Miguel Soria posthumously in 2001. The only provenance information known about the specimen is that it comes from the Anfiteatro de Cacheuta, and it is probably from the Mariño Formation, of which it could be from either the Areniscas Entrecruzadas or the Estratos de Mariño Member, which are both present at the known location of discovery. This means that the age for Thoatheriopsis cannot be determined beyond either being from the Santacrucian or Laventan South American Land Mammal Ages in the Early or Middle Miocene. Thoatheriopsis was found to be a close relative of Diadiaphorus and Neobrachytherium.
Anisolophus is an extinct genus of proterotheriid from the Early to Middle Miocene of Argentina. The genus was named by Burmeister in 1885 to accommodate the species Anchitherium australe, which they had named earlier in 1879. Soria then referred the species Licaphrium floweri and Anisolophus minisculus to the genus, making Licaphrium, named in 1887 by Florentino Ameghino, a junior synonym of the genus. Both A. australis and A. floweri are known from the Santacrucian age Santa Cruz Formation, while A. minisculus is known from the Collón Curá Formation.
Dasypus neogaeus is an extinct species of armadillo, belonging to the genus Dasypus, alongside the modern nine-banded armadillo. The only known fossil is a single osteoderm, though it has been lost, that was found in the Late Miocene strata of Argentina.
Caiman australis is an extinct species of caiman described in 1858 on the basis of a left maxilla that was collected from the Upper Miocene age Ituzaingó Formation of Entre Rios, Argentina.
Chasicobradys is an extinct genus of ground sloths of the family Nothrotheriidae that lived in what is now Argentina. Chasicobradys was discovered in the Arroyo Chasicó Formation, in Buenos Aires Province. It is only known from jaw fragments and teeth, which allowed the identification of this species, and was classified as a member of the nothrotheriid subfamily Nothrotheriinae, which comprises small to medium-sized species of ground sloths.
