Late Triassic synapsids of South America

Dinodontosaurus (meaning "terrible-toothed lizard") is a genus of dicynodont therapsid. It was medium to large dicynodont of the Triassic (with skull up to long) and had a beak corneum. It lived in the Middle Triassic but disappeared in the Upper Triassic.

Ischigualastia is an extinct genus of large dicynodont therapsids from the Late Triassic of Argentina. It is named after its place of discovery, the Ischigualasto Formation in the Ischigualasto-Villa Unión Basin of northwestern Argentina. Like other Late Triassic dicynodonts, Ischigualastia is a member of the family Stahleckeriidae.

thumb|left|Life reconstruction of C. theotonicus

Exaeretodon is an extinct genus of fairly large, low-slung traversodontid cynodonts from the southern parts of Pangea. Four species are known, hailing from various formations. E. argentinus is from the Carnian-age (Late Triassic) Cancha de Bochas Member of the Ischigualasto Formation in the Ischigualasto-Villa Unión Basin in northwestern Argentina. E. major and E. riograndensis are from the Carnian-age portion of the Santa Maria Formation of the Paraná Basin in southeastern Brazil. E. statisticae is from the Carnian-age Lower Maleri Formation of India.

Massetognathus ( ; Greek for "chewing muscle jaw") is an extinct genus of plant-eating traversodontid cynodonts. They lived during the Triassic Period about 235 million years ago, and are known from the Chañares Formation in Argentina and the Santa Maria Formation in Brazil.

Trucidocynodon is an extinct genus of ecteniniid cynodonts from the Upper Triassic (Carnian) of Brazil. It is a monotypic genus that contains a single species, Trucidocynodon riograndensis. Fossils of Trucidocynodon were discovered in outcrops of the Upper Santa Maria Formation in Paleorrota Geopark, Agudo. Trucidocynodon is one of the most completely known Triassic cynodonts, as its holotype is a nearly complete and fully articulated skeleton.

Probainognathus meaning "progressive jaw" is an extinct genus of cynodonts that lived around 235 to 221.5 million years ago, during the Late Triassic in what is now Argentina. Together with the genus Bonacynodon from Brazil, Probainognathus forms the family Probainognathidae. Probainognathus was a relatively small, carnivorous or insectivorous cynodont. Like all cynodonts, it was a relative of mammals, and it possessed several mammal-like features. Like some other cynodonts, Probainognathus had a double jaw joint, which not only included the quadrate and articular bones like in more basal syna

Traversodon is an extinct genus of cynodonts. It was a relative of the ancestor to modern mammals.

Prozostrodon is an extinct genus of probainognathian cynodonts that was closely related to mammals. The remains were found in Brazil and are dated to the Carnian age of the Late Triassic. The holotype has an estimated skull length of , indicating that the whole animal may have been the size of a cat. The teeth were typical of advanced cynodonts, and the animal was probably a carnivore hunting reptiles and other small prey.

Bonacynodon is an extinct genus of cynodonts that lived in what is now southern Brazil during the Triassic period (Ladinian–Carnian ages). The genus is monotypic, containing only the type species Bonacynodon schultzi. B. schultzi is known from two specimens, consisting of two partial skulls and some badly preserved parts of the postcranium. Both specimens were recovered from the Pinheiros-Chiniquá Sequence, part of the Santa Maria Supersequence of the Paraná Basin. This sequence preserves a faunal association known as the Dinodontosaurus Assemblage Zone, which contains numerous other species o

Gomphodontosuchus is an extinct genus of cynodonts. It was created to describe the species Gomphodontosuchus brasiliensis.

Ecteninion is an extinct genus of meat-eating cynodonts that lived during the Late Triassic (Carnian) in South America. The type species Ecteninion lunensis was named by R.N. Martinez, C.L. May, and C.A. Forster in 1996. The holotype of E. lunensis is PVSJ 422, it's known from a nearly complete skull of about in length. It was found in the Cancha de Bochas Member of the Ischigualasto Formation in the Ischigualasto-Villa Unión Basin in northwestern Argentina. It has been interpreted as a basal eucynodont. The holotype is in the collection of the Universidad Nacional de San Juan.

Santacruzodon is an extinct genus of cynodonts which existed in Brazil during the Triassic period. The type species is Santacruzodon hopsoni.

Brasilodon ("tooth from Brazil") is an extinct genus of small, mammal-like cynodonts that lived in what is now Brazil during the Norian age of the Late Triassic epoch, about 225.42 million years ago. While no complete skeletons have been found, the length of Brasilodon has been estimated at . Its dentition shows that it was most likely an insectivore. The genus is monotypic, containing only the species B. quadrangularis. Brasilodon belongs to the family Brasilodontidae, whose members were some of the closest relatives of mammals, the only cynodonts alive today. Two other brasilodontid genera,

Candelariodon is an extinct genus of carnivorous probainognathian cynodonts from the Middle to Late Triassic Santa Maria Formation of the Paraná Basin in Rio Grande do Sul state, Brazil. Candelariodon is known from a partial mandible having some complete teeth. It was first named by Téo Veiga de Oliveira, Cesar Leandro Schultz, Marina Bento Soares and Carlos Nunes Rodrigues in 2011 and the type species is Candelariodon barberenai.

Irajatherium is an extinct genus of cynodonts, known only of the type species Irajatherium hernandezi. It is named in honor of Irajá Damiani Pinto.

Riograndia is an extinct genus of prozostrodontian cynodonts from the Late Triassic of Brazil. The type and only species is Riograndia guaibensis, named after the State of Rio Grande do Sul and Guaíba Basin, where it was discovered. Remains have been found in the Caturrita Formation of the geopark of Paleorrota. It was a small non-mammalian cynodont, with several advanced features also present in mammals. Several specimens of Riograndia guaibensis have been found in the towns of Candelária and Faxinal do Soturno in the Caturrita Formation. The genus defines the Riograndia Assemblage Zone.

Menadon is an extinct genus of traversodontid cynodonts. The type and only species is Menadon besairiei.

Charruodon is an extinct genus of cynodonts which existed in the Hyperodapedon Assemblage Zone of the Santa Maria Formation in the Paraná Basin in southeastern Brazil during the Late Triassic. The genus contains only the type species Charruodon tetracuspidatus, which is known from a single specimen of uncertain provenance. Upon its first description, Charruodon was tentatively placed within the family Therioherpetidae, but a 2017 study by Agustín G. Martinelli and colleagues instead recovered it as a more basal member of Probainognathia. In 2023, Hoffmann, Ribeiro & de Andrade reinterpreted th

Siriusgnathus is a traversodontid cynodont from the Carnian channel sandstones and mudstones of the Candelária Formation, belonging to the Santa Maria Supersequence of the Paraná Basin in southeastern Brazil. It includes one species, Siriusgnathus niemeyerorum and was described in 2018. The species epithet refers to the Niemeyer locality in Agudo, Rio Grande do Sul. It was found together with various archosauromorphs, dinosauromorphs and other cynodonts, such as Brasilitherium riograndensis, Brasilodon quadrangularis, Irajatherium hernandezi and Prozostrodon brasiliensis.

Diegocanis is an extinct genus of cynodonts from the Late Triassic (Carnian) of Argentina. The type species, Diegocanis elegans, was named in 2013 from fossils found in the Cancha de Bochas Member of the Ischigualasto Formation in the Ischigualasto-Villa Unión Basin. Diegocanis was classified within a new family of probainognathian cynodonts called Ecteniniidae, along with the genera Ecteninion and Trucidocynodon.

Therioherpeton is an extinct genus of small, carnivorous cynodonts belonging to the clade Prozostrodontia, which lived in what is now Brazil during the Late Triassic. Its type species is Therioherpeton cargnini. It was named in 1975 by the palaeontologists José Bonaparte and Mário Costa Barberena based on remains collected in the Hyperodapedon Assemblage Zone of the Santa Maria Formation in the Paraná Basin.

Aleodon is an extinct genus of cynodonts that lived from the Middle to Late Triassic. Relatively few analyses have been conducted to identify the phylogenetic placement of Aleodon, although some have placed it as a sister taxon to Chiniquodon. Two species of Aleodon are recognized: A. brachyrhamphus which was discovered in Tanzania, and A. cromptoni which was discovered most recently in Brazil.

Pseudotherium ("false beast") is an extinct genus of prozostrodontian cynodonts from the Late Triassic of Argentina. It contains one species, P. argentinus, which was first described in 2019 from remains found in the La Peña Member of the Ischigualasto Formation in the Ischigualasto-Villa Unión Basin.

Santacruzgnathus is an extinct genus of small cynodonts from the Late Triassic (Carnian) Santacruzodon Assemblage Zone of Brazil. It contains one species, S. abdalai. Santacruzgnathus is known from a single partial lower jaw with four postcanine teeth, only one of which is well-preserved. Some features of the specimen, including the slender shape of the jaw and the incipiently double-rooted teeth, indicate that the animal was an early member of Prozostrodontia, a group that includes mammals and their close relatives.

Tessellatia is an extinct genus of probainognathian cynodont from the Late Triassic Los Colorados Formation of La Rioja, Argentina. The genus contains a single species, T. bonapartei, known from a partial skull.

Alemoatherium is an extinct genus of prozostrodontian cynodont which lived in the Late Triassic of Brazil. It contains a single species, A. huebneri, named in 2017 by Agustín Martinelli and colleagues. The genus is based on UFSM 11579b, a left lower jaw (dentary) found in the Alemoa Member of the Santa Maria Formation, preserving the late Carnian-age Hyperodapedon Assemblage Zone. Alemoatherium was among the smallest species of cynodonts found in the rich synapsid fauna of the Santa Maria Formation. Its blade-like four-cusped postcanine teeth show many similarities with those of dromatheriids,