# Santa Maria Formation

The Santa Maria Formation is a sedimentary rock formation found in Rio Grande do Sul, Brazil. It is primarily Carnian in age (Late Triassic), and is notable for its fossils of cynodonts, "rauisuchian" pseudosuchians, and early dinosaurs and other dinosauromorphs, including the herrerasaurid Staurikosaurus, the basal sauropodomorphs Buriolestes and Saturnalia, and the lagerpetid Ixalerpeton. The formation is named after the city of Santa Maria in the central region of Rio Grande do Sul, where outcrops were first studied.
The Santa Maria Formation makes up the majority of the Santa Maria Supersequence, which extends through the entire Late Triassic. The Santa Maria Supersequence is divided into four geological sequences, separated from each other by short unconformities. The first two of these sequences (Pinheiros-Chiniquá and Santa Cruz sequences) lie entirely within the Santa Maria Formation, while the third (the Candelária sequence) is shared with the overlying Norian-age Caturrita Formation. The fourth and youngest sequence (the Mata sequence) is equivalent to the Rhaetian-age Mata Sandstone.
The oldest sequence in the formation is the Pinheiros-Chiniquá Sequence (latest Ladinian-earliest Carnian, ~237 Ma), which is biostratigraphically equivalent to the Dinodontosaurus Assemblage Zone. It is followed by the shorter Santa Cruz Sequence (early Carnian-middle Carnian, ~236 Ma), biostratigraphically equivalent to the Santacruzodon Assemblage Zone.
The final sequence, which is only partially present within the formation, is the Candelária Sequence (middle Carnian-latest Carnian, ~233-228 Ma). The lower portion of this sequence, coinciding with the upper part of the Santa Maria Formation, is equivalent to the Hyperodapedon Assemblage Zone.The Hyperodapedon Assemblage Zone is itself subdivided into Hyperodapedon Acme Zone (most of the zone, where the rhynchosaur Hyperodapedon is widely reported) and Exaeretodon Zone (restricted to about three known and sampled localities, where rhynchsaurs are almost completely absent, but the traversodontid cynodont Exaeretodon is widely reported). These subdivisions are also known as Lower and Upper Hyperodapedon Assemblage Zone, respectively.
U-Pb radiometric dating of Cerro da Alemoa (the type locality of Saturnalia tupiniquim) in the Upper portion of the Santa Maria Formation found an estimated age of 233.23±0.73 million years ago, putting that locality 1.5 million years older than the Ischigualasto Formation and younger than Los Chañares Formation. The Santa Maria and Ischigualasto formations are approximately equal as having the earliest dinosaur localities.

## Vertebrate paleofauna

Most of the information below was included on a revision of the Triassic faunal successions of the Paraná Basin, southern Brazil by Schultz et al. (2020).

### Temnospondyls

Temnospondyls of the Santa Maria Formation :
| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
| Compsocerops | C. sp. | Restinga Sêca | Upper Santa Maria Formation, Alemoa Member, Candelária Sequence, Hyperodapedon Assemblage Zone, Hyperodapedon Acme Zone | A partial skull | A chigutisaurid temnospondyl | |

### Fish

Temnospondyls of the Santa Maria Formation :
| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
| Ptychoceratodus | P. cf. phillipsi | | Upper Santa Maria Formation, Alemoa Member, Candelária Sequence, Hyperodapedon Assemblage Zone, Hyperodapedon Acme Zone | | A ptychoceratodontid lungfish | |

### Synapsids
#### Dicynodonts

Dicynodonts of the Santa Maria Formation :
| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
| Dinodontosaurus | D. pedroanum | São Pedro do Sul, Candelária, Dona Francisca, Bom Retiro, Vale Verde, Novo Cabrais, Bom Retiro do Sul, Dilermando de Aguiar | Lower Santa Maria Formation, Alemoa Member, Pinheiros-Chiniquá Sequence, Dinodontosaurus Assemblage Zone | Cranial and postcranial remains | A kannemeyeriiform dicynodont | |
| Stahleckeria | S. potens | Dona Francisca, Candelária | Lower Santa Maria Formation, Alemoa Member, Pinheiros-Chiniquá Sequence, Dinodontosaurus Assemblage Zone | Cranial and postcranial remains | A stahleckeriid dicyndont | |

#### Cynognathians

Cynognathians of the Santa Maria Formation :
| Genus | Species | Location | Stratigraphic position | Material | Notes |
| Exaeretodon | E. major | São Pedro do Sul | Lower Santa Maria Formation, Alemoa Member, Pinheiros-Chiniquá Sequence, Dinodontosaurus Assemblage Zone | Cranial and postcranial remains | A traversodontid cynodont |
| Exaeretodon | E. riograndensis | Agudo, Santa Maria | Upper Santa Maria Formation, Alemoa Member, Candelária Sequence, Hyperodapedon Assemblage Zone, Exaeretodon Zone | Cranial and postcranial remains | A traversodontid cynodont |
| Gomphodontosuchus | G. brasiliensis | Santa Maria | Upper Santa Maria Formation, Alemoa Member, Candelária Sequence, Hyperodapedon Assemblage Zone, Hyperodapedon Acme Zone | Cranial remains | A traversodontid cynodont |
| Luangwa | L. sudamericana | Vera Cruz, Candelária | Lower Santa Maria Formation, Alemoa Member, Pinheiros-Chiniquá Sequence, Dinodontosaurus Assemblage Zone | Cranial remains | A traversodontid cynodont |
| Massetognathus | M. ochagavie | Bom Retiro, Vale Verde, Dona Francisca | Lower and Middle Santa Maria Formation, Alemoa Member, Santa Cruz nad Pinheiros-Chiniquá Sequences, Santacruzodon Assemblage Zone and Dinodontosaurus Assemblage Zone | Cranial and postcranial remains | A traversodontid cynodont |
| Menadon | M. besairiei | Santa Cruz | Middle Santa Maria Formation, Alemoa Member, Santa Cruz Sequence, Santacruzodon Assemblage Zone | Cranial remains | A traversodontid cynodont |
| Protuberum | P. cabralensis | Paraíso do Sul, Novo Cabrais | Lower Santa Maria Formation, Alemoa Member, Pinheiros-Chiniquá Sequence, Dinodontosaurus Assemblage Zone | Partial articulated skeleton including skull, vertebrae and ribs | A traversodontid cynodont |
| Santacruzodon | S. hopsoni | Santa Cruz | Middle Santa Maria Formation, Alemoa Member, Santa Cruz Sequence, Santacruzodon Assemblage Zone | Cranial remains | A traversodontid cynodont |
| Santagnathus | S. mariensis | | Hyperodapedon Assemblage Zone | Numerous cranial and postcranial remains | A traversodontid cynodont |
| Scalenodon | S. ribeiroae | Agudo | Lower Santa Maria Formation, Alemoa Member, Pinheiros-Chiniquá Sequence, Dinodontosaurus Assemblage Zone | Cranial remains | A traversodontid cynodont |
| Traversodon | T. stahleckeri | São Pedro do Sul | Lower Santa Maria Formation, Alemoa Member, Pinheiros-Chiniquá Sequence, Dinodontosaurus Assemblage Zone | Cranial remains | A traversodontid cynodont |

#### Probainognathians

Probainognathians of the Santa Maria Formation :
| Genus | Species | Location | Stratigraphic position | Material | Notes |
| Alemoatherium | A. huebneri | Santa Maria | Upper Santa Maria Formation, Alemoa Member, Candelária Sequence, Hyperodapedon Assemblage Zone, Hyperodapedon Acme Zone | A partial dentary | A prozostrodontian cynodont |
| Aleodon | A. cromptoni | Vale Verde, Candelária, Bom Retiro do Sul, Novo Cabrais | Lower Santa Maria Formation, Alemoa Member, Pinheiros-Chiniquá Sequence, Dinodontosaurus Assemblage Zone | Cranial and postcranial remains | A chiniquodontid cynodont |
| Bonacynodon | B. schultzi | Candelária | Lower Santa Maria Formation, Alemoa Member, Pinheiros-Chiniquá Sequence, Dinodontosaurus Assemblage Zone | Cranial remains | A probainognathid cynodont |
| Candelariodon | C. barberenai | Candelária | Lower Santa Maria Formation, Alemoa Member, Pinheiros-Chiniquá Sequence, Dinodontosaurus Assemblage Zone | A partial mandible having some complete teeth | A basal probainognathian cynodont |
| Charruodon | C. tetracuspidatus | Candelária | Upper Santa Maria Formation, Alemoa Member, Candelária Sequence, Hyperodapedon Assemblage Zone, Hyperodapedon Acme Zone | A partial dentary | A basal probainognathian cynodont |
| Chiniquodon | C. theotonicus | São Pedro do Sul | Lower Santa Maria Formation, Alemoa Member, Pinheiros-Chiniquá Sequence, Dinodontosaurus Assemblage Zone | Several cranial remains | A chiniquodontid cynodont |
| Chiniquodon | C. sp. | Santa Cruz | Middle Santa Maria Formation, Alemoa Member, Santa Cruz Sequence, Santacruzodon Assemblage Zone | Cranial and postcranial remains | A chiniquodontid cynodont |
| Protheriodon | P. estudianti | Dona Francisca | Lower Santa Maria Formation, Alemoa Member, Pinheiros-Chiniquá Sequence, Dinodontosaurus Assemblage Zone | Cranial remains | A basal probainognathian cynodont |
| Prozostrodon | P. brasiliensis | Santa Maria, São João do Polêsine | Upper Santa Maria Formation, Alemoa Member, Candelária Sequence, Hyperodapedon Assemblage Zone, Hyperodapedon Acme Zone | Cranial remains | A prozostrodontian cynodont |
| Santacruzgnathus | S. abdalai | Santa Cruz | Middle Santa Maria Formation, Alemoa Member, Santa Cruz Sequence, Santacruzodon Assemblage Zone | Cranial remains | A prozostrodontian cynodont |
| Therioherpeton | T. cargnini | Santa Maria | Upper Santa Maria Formation, Alemoa Member, Candelária Sequence, Hyperodapedon Assemblage Zone, Hyperodapedon Acme Zone | Cranial remains | A prozostrodontian cynodont |
| Trucidocynodon | T. riograndensis | Agudo | Upper Santa Maria Formation, Alemoa Member, Candelária Sequence, Hyperodapedon Assemblage Zone, Exaeretodon Zone | Cranial and postcranial elements of an almost complete skeleton and an additional large skull | An ecteniniid cynodont |

### Reptiles
#### Pseudosuchians

Pseudosuchians of the Santa Maria Formation :
| Genus | Species | Location | Stratigraphic position | Material | Notes |
| Aetobarbakinoides | A. brasiliensis | Santa Maria | Upper Santa Maria Formation, Alemoa Member, Candelária Sequence, Hyperodapedon Assemblage Zone, Hyperodapedon Acme Zone | Partial postcranial skeleton | A aetosaur |
| Aetosauroides | A. scagliai | Santa Maria, São João do Polêsine, São Pedro do Sul | Upper Santa Maria Formation, Alemoa Member, Candelária Sequence, Hyperodapedon Assemblage Zone, Hyperodapedon Acme Zone | An almost complete skull and incomplete postcranial elements | An aetosaur |
| Archeopelta | A. arborensis | São Pedro do Sul | Lower Santa Maria Formation, Alemoa Member, Pinheiros-Chiniquá Sequence, Dinodontosaurus Assemblage Zone | Cranial and postcranial elements | An erpetosuchid |
| Dagasuchus | D. santacruzensis | Santa Cruz do Sul | Middle Santa Maria Formation, Alemoa Member, Santa Cruz Sequence, Santacruzodon Assemblage Zone | An ilium and a pair of ischia | A loricatan |
| Decuriasuchus | D. quartacolonia | Dona Francisca | Lower Santa Maria Formation, Alemoa Member, Pinheiros-Chiniquá Sequence, Dinodontosaurus Assemblage Zone | Assemblage of several individuals, which together preserved virtually all the skeleton | A loricatan |
| Dynamosuchus | D. collisensis | Agudo | Upper Santa Maria Formation, Alemoa Member, Candelária Sequence, Hyperodapedon Assemblage Zone, Exaeretodon Zone | Semi-articulated partial skull and disarticulated fragmentary postcranial skeleton | An ornithosuchid |
| Pagosvenator | P. candelariensis | Candelária | Lower Santa Maria Formation, Alemoa Member, Pinheiros-Chiniquá Sequence, Dinodontosaurus Assemblage Zone | Poorly preserved skull and cervical elements | An erpetosuchid |
| Parvosuchus | P. aurelioi | Linha Várzea 2, Pinheiros-Chiniquá. | Dinodontosaurus Assemblage Zone. | A largely articulated skeleton, skull, and lower jaws. | A gracilisuchid |
| "Polesinesuchus" | "P. aurelioi" | São João do Polêsine | Upper Santa Maria Formation, Alemoa Member, Candelária Sequence, Hyperodapedon Assemblage Zone, Hyperodapedon Acme Zone | Several postcranial elements | An immature aetosaur, possible synonym of Aetosauroides scagliai |
| Prestosuchus | P. chiniquensis "P. loricatus""Karamuru vorax" | Candelária, Dona Francisca, São Pedro do Sul, and possibly Vale Verde ("K. vorax") | Lower Santa Maria Formation, Alemoa Member, Pinheiros-Chiniquá Sequence, Dinodontosaurus Assemblage Zone | Virtually all the skeleton is known | A loricatan |
| Procerosuchus | P. celer | São Pedro do Sul | Lower Santa Maria Formation, Alemoa Member, Pinheiros-Chiniquá Sequence, Dinodontosaurus Assemblage Zone | Postcranial elements | A loricatan |
| Rauisuchus | R. tiradentes | Santa Maria | Upper Santa Maria Formation, Alemoa Member, Candelária Sequence, Hyperodapedon Assemblage Zone, Hyperodapedon Acme Zone | Incomplete skeleton including skull elements, several vertebrae and partial hindlimb | A loricatan |
| Unnamed loricatan | - | Santa Maria | Upper Santa Maria Formation, Alemoa Member, Candelária Sequence, Hyperodapedon Assemblage Zone, Hyperodapedon Acme Zone | Specimen UFSM 11617, an almost complete right maxilla | A loricatan |

#### Avemetatarsalians

Avemetatarsalians of the Santa Maria Formation :
| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
| Amanasaurus | A. nesbitti | Restinga Sêca | Upper Santa Maria Formation, Alemoa Member, Candelária Sequence, Hyperodapedon Assemblage Zone, Hyperodapedon Acme Zone | Two partial femora | A silesaurid | |
| Bagualosaurus | B. agudoensis | Agudo | Upper Santa Maria Formation, Alemoa Member, Candelária Sequence, Hyperodapedon Assemblage Zone, Exaeretodon Zone | Almost complete skull with lower jaws, several vertebrae, partial pelvic girdle, partial hindlimbs | A basal sauropodomorph | |
| Buriolestes | B. schultzi | São João do Polêsine | Upper Santa Maria Formation, Alemoa Member, Candelária Sequence, Hyperodapedon Assemblage Zone, Hyperodapedon Acme Zone | Parts of the skull, vertebrae, left forelimb, and left hindlimb | The basalmost sauropodomorph | |
| Gamatavus | G. antiquus | Dilermando de Aguiar | Lower Santa Maria Formation ('Picada do Gama' site), Pinheiros-Chiniquá Sequence, Dinodontosaurus Assemblage Zone | A partial right ilium; a partial left femur and four incomplete vertebrae found in association with the holotype may belong to Gamatavus, but they were not assigned | One of the oldest known silesaurids from South America | |
| Gnathovorax | G. cabreirai | São João do Polêsine | Upper Santa Maria Formation, Alemoa Member, Candelária Sequence, Hyperodapedon Assemblage Zone, Hyperodapedon Acme Zone | A complete semi-articulated skeleton, part of a multiataxic fossil assemblage, including two cynodonts and two rhynchosaurs | A herrerasaurid | |
| Gondwanax | G. paraisensis | Paraíso do Sul | Lower Santa Maria Formation ('Linha Várzea 2' site), Pinheiros-Chiniquá Sequence, Dinodontosaurus Assemblage Zone | Associated remains possibly belonging to multiple individuals, including cervical, dorsal, sacral, and caudal vertebrae, a partial pelvic girdle, and a femur | One of the oldest known silesaurids from South America | |
| Ixalerpeton | I. polesinensis | São João do Polêsine | Upper Santa Maria Formation, Alemoa Member, Candelária Sequence, Hyperodapedon Assemblage Zone, Hyperodapedon Acme Zone | Partial skull including a partial maxilla and both dentaries, most of the presacral vertebrae, two sacral vertebrae, several caudal verterae and associated chevrons, scapula and humerus, femora of at least two individuals, and tibia | A basal lagerpetid | |
| Nhandumirim | N. waldsangae | Santa Maria | Upper Santa Maria Formation, Alemoa Member, Candelária Sequence, Hyperodapedon Assemblage Zone, Hyperodapedon Acme Zone | Some vertebrae, partial pelvic girdle, partial hindlimb | A juvenile saturnaliid sauropodomorph | |
| Pampadromaeus | P. barberenai | Agudo | Upper Santa Maria Formation, Alemoa Member, Candelária Sequence, Hyperodapedon Assemblage Zone, Exaeretodon Zone | Almost complete skull and lower jaws, several vertebrae, partial pectoral girdle, partial forelimb, partial pelvic girdle, partial hindlimb | A basal sauropodomorph | |
| Saturnalia | S. tupinquim | Santa Maria | Upper Santa Maria Formation, Alemoa Member, Candelária Sequence, Hyperodapedon Assemblage Zone, Hyperodapedon Acme Zone | Three partial skeleton, including partial skull and lower jaw, complete cervical, dorsal and partial caudal vertebral series, pectoral girdle, partial forelimb, pelvic girdle, partial hindlimb | A basal sauropodomorph | Saturnalia tupiniquim |
| Spondylosoma | S. absconditum | São Pedro do Sul | Lower Santa Maria Formation, Alemoa Member, Pinheiros-Chiniquá Sequence, Dinodontosaurus Assemblage Zone | Several postcranial remains | An aphanosaurian | |
| Staurikosaurus | S. pricei | Santa Maria | Upper Santa Maria Formation, Alemoa Member, Candelária Sequence, Hyperodapedon Assemblage Zone, Hyperodapedon Acme Zone | Partial postcranial skeleton with mandible | A basal herrerasaurid | |
| Venetoraptor | V. gassenae | São João do Polêsine | Upper Santa Maria Formation, Alemoa Member, Candelária Sequence, Hyperodapedon Assemblage Zone, Hyperodapedon Acme Zone | Partially articulated skeleton consisting of an incomplete skull, cervical, dorsal, and caudal vertebrae, a partial pelvic girdle, and elements of the arms and legs | A lagerpetid. | |
| Unnamed dinosauromorph | - | Dona Francisca | Lower Santa Maria Formation, Alemoa Member, Pinheiros-Chiniquá Sequence, Dinodontosaurus Assemblage Zone | Specimen CAPPA/UFSM 0282, a complete, but poorly preserved right femur | The oldest dinosauromorph from South America | |
| Unnamed herrerasaurid | - | Santa Maria | Upper Santa Maria Formation, Alemoa Member, Candelária Sequence, Hyperodapedon Assemblage Zone, Hyperodapedon Acme Zone | Specimen UFSM 11330, comprised by partial cranial and postcranial remains | The largest Triassic dinosaur skeleton found in Rio Grande do Sul state so far | |
| Unnamed lagerpetid | - | Santa Maria | Upper Santa Maria Formation, Alemoa Member, Candelária Sequence, Hyperodapedon Assemblage Zone, Hyperodapedon Acme Zone | Specimen UFSM 11611 (partial left femur) | A basal lagerpetid distinct from Ixalerpeton | |
| Unnamed silesaurid | - | Santa Maria | Upper Santa Maria Formation, Alemoa Member, Candelária Sequence, Hyperodapedon Assemblage Zone, Hyperodapedon Acme Zone | Specimen UFSM 11579, comprised by cranial and postcranial remains | A silesaurid | |

#### Other reptiles

Other reptiles of the Santa Maria Formation :
| Genus | Species | Location | Stratigraphic position | Material | Notes |
| Barberenasuchus | B. brasiliensis | Novo Cabrais | Upper Santa Maria Formation, Alemoa Member, Candelária Sequence, Hyperodapedon Assemblage Zone, Hyperodapedon Acme Zone | Poorly preserved skull and axis vertebra | An archosauriform of uncertain affinities |
| Brasinorhynchus | B. mariantensis | Bom Retiro do Sul | Lower Santa Maria Formation, Alemoa Member, Pinheiros-Chiniquá Sequence, Dinodontosaurus Assemblage Zone | A complete skull, atlas, axis, third neck vertebra | A stenaulorhynchine rhynchosaur archosauromorph |
| Candelaria | C. barbouri | Dona Francisca, Candelária, Novo Cabrais | Lower Santa Maria Formation, Alemoa Member, Pinheiros-Chiniquá Sequence, Dinodontosaurus Assemblage Zone | Cranial and postcranial remains | An owenetiid procolophonoid |
| Cerritosaurus | C. binsfeldi | Santa Maria | Upper Santa Maria Formation, Alemoa Member, Candelária Sequence, Hyperodapedon Assemblage Zone, Hyperodapedon Acme Zone | Badly preserved skull and postcranial elements | A proterochampsid archosauriform |
| Clevosaurus | C. hadroprodon | Candelária | Upper Santa Maria Formation, Alemoa Member, Candelária Sequence, Hyperodapedon Assemblage Zone, Exaeretodon Zone | Cranial remains | A clevosaurid rhynchocephalian |
| Hyperodapedon | H. sanjuanensis H. mariensis? H. huenei | Santa Maria, Agudo, Candelária, São João do Polêsine, Venâncio Aires, Restinga Sêca, São Pedro do Sul | Upper Santa Maria Formation, Alemoa Member, Candelária Sequence, Hyperodapedon Assemblage Zone | Complete skulls, and most postcranial elements | A hyperodapedontine rhynchosaur archosauromorph |
| Kuruxuchampsa | K. dornellesi | | Middle Santa Maria Formation, Alemoa Member, Santa Cruz Sequence, Santacruzodon Assemblage Zone | | A proterochampsid archosauriform. Previously referred to Chanaresuchus |
| Macrocephalosaurus | M. mariensis | | Upper Santa Maria Formation, Alemoa Member, Candelária Sequence, Hyperodapedon Assemblage Zone | Skull and front part of the torso | A hyperodapedontine rhynchosaur archosauromorph. Sometimes referred to Hyperodapedon |
| Pinheirochampsa | P. rodriguesi | | Lower Santa Maria Formation, Alemoa Member, Pinheiros-Chiniquá Sequence, Dinodontosaurus Assemblage Zone | | A proterochampsid archosauriform |
| Proterochampsa | P. nodosa | Candelária | Upper Santa Maria Formation, Alemoa Member, Candelária Sequence, Hyperodapedon Assemblage Zone, Hyperodapedon Acme Zone | Skull and partial postcranial elements | A proterochampsid archosauriform |
| Retymaijychampsa | R. beckerorum | Linha Várzea 2 | Lower Santa Maria Formation, Alemoa Member, Pinheiros-Chiniquá Sequence, Dinodontosaurus Assemblage Zone | Complete right hindlimb | A proterochampsid archosauriform |
| Rhadinosuchus | R. gracilis | Santa Maria | Upper Santa Maria Formation, Alemoa Member, Candelária Sequence, Hyperodapedon Assemblage Zone, Hyperodapedon Acme Zone | Badly preserved skull and postcranial elements | A proterochampsid archosauriform |
| Stenoscelida | S. aurantiacus | Agudo | Upper Santa Maria Formation, Alemoa Member, Candelária Sequence, Hyperodapedon Assemblage Zone, Exaeretodon Zone | Almost complete and well preserved hind limb | A proterochampsid archosauriform |
| Unnamed proterochampsid | - | Unknown | Santa Maria Formation, Alemoa Member | Badly preserved skull | A proterochampsid archosauriform |

## Formations

* 1) Serra Geral Formation, Cretaceous
* 2) Botucatu Formation, Cretaceous
* 3) Guará Formation, Jurassic
* 4) Santa Maria Formation & Caturrita Formation, Triassic
* 5) Sanga do Cabral Formation, Triassic
* 6) Piramboia Formation, Permian
* 7) Itararé Group, Permian