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Triassic rhynchocephalians from South America are relatively sparse, based on one taxon from the Norian of Argentina (i.e., Sphenotitan leyesi) and three records from the Late Carnian (i.e., indet. taxon) and Norian (i.e., Clevosaurus brasiliensis and indet. taxon) of Brazil. We described here a new occurrence of rhynchocephalians from a new Late Carnian locality of southern Brazil, based on an isolated palatine with teeth, referred to that group due to the morphological similarity whit the palatines of the other taxa of the same group. The specimen comes from the municipality of Vale do Sol, collected within a layer with abundant material of Hyperodapedon sp. (Rhynchosauria), which is referred to the Hyperodapedon Assemblage Zone (Late Carnian) of the Candelária Sequence, Santa Maria Supersequence. The isolated palatine here described cannot be referred to any hitherto known species, but it provides an additional record for the few putative ones of Carnian age in South America. Moreover, we figure and describe the palatine anatomy of Clevosaurus brasiliensis, based on two specimens, which have relevant data poorly addressed in previous contributions. [ABSTRACT FROM AUTHOR]

Clevosauruswas a cosmopolitan Rhynchocephalia genus restricted to the Late Triassic and the Early Jurassic. In Brazil,C. brasiliensisis one of the most conspicuous species collected from the Candelária Sequence (RiograndiaAssemblage Zone, Norian age) of the Santa Maria Supersequence. Several jaws ofC. brasiliensisare housed in the Laboratório de Paleontologia de Vertebrados of the Instituto de Geociências-UFRGS. Some of these jaws bear a relatively small protuberant bony callus on the anterolateral margin of the dentary, evidenced by a different tissue pattern incorporating small pits and discrete grooves. This pattern closely resembles a common bone infection known in the mandible of the extantSphenodon punctatus. Although this similarity, the infection may be the result of two possible processes: as consequence of orthal jaw shearing movements during feeding at the moments that the dentary impacts with the enlarged premaxillary tooth or due to injuries produced after fights between conspecific individuals (as is the case forS. punctatus). If the second hypothesis is correct, the same pathological processes probably occurred in the Late TriassicC. brasiliensisindicating that similar ethological conditions were already present at the beginning of the Mesozoic, during the initial radiation of the lepidosaurian clade. [ABSTRACT FROM PUBLISHER]

Proterochampsidae is a clade of non-archosaurian archosauriforms restricted to the Middle to the Late Triassic of the Ischigualasto-Villa Unión Basin of Argentina and the Santa Maria Supersequence of Brazil. A reappraisal of proterochampsid specimens from the Brazilian Dinodontosaurus Assemblage Zone (AZ) of the Pinheiros-Chiniquá Sequence (late Ladinian-early Carnian) is presented here. One of the specimens was preliminary assigned to Chanaresuchus sp., whose type species comes from the Massetognathus-Chanaresuchus AZ of the Chañares Formation of Argentina. However, our revision indicates that it differs from Chanaresuchus, being more closely related to the middle-late Carnian Rhadinosuchus gracilis. We therefore propose the new taxon, Pinheirochampsa rodriguesi, to reallocate this specimen. Additionally, we present a revision of other putative Chanaresuchus occurrences in Brazil, including the only known specimen described for the Santacruzodon AZ (Santa Cruz do Sul Sequence; early Carnian), also proposing it as a new taxon: Kuruxuchampsa dornellesi. Both new species are characterized, among other features, by transverse expansion of the anterior end of the rostrum, similar to the condition present in Rhadinosuchus, but absent in Chanaresuchus, Gualosuchus, Pseudochampsa, and non-rhadinosuchine proterochampsids. These two new species expand the growing knowledge of the non-archosaurian archosauriform diversity during the Middle-Late Triassic in South America and enhance faunal and chronological comparisons between approximately coeval geological units between Argentina and Brazil., (© 2023 American Association for Anatomy.)