Triassic Tracks from Paraná Basin: The First Data on the Origin of Dinosauria

The central region of Rio Grande do Sul State, in southern BrazilBrazil, has increasing importance due the discoveries of TriassicTriassic fossils, including some of the world’s oldest dinosaurs and their tracks. Tridactyl footprints of CarnianCarnian age, from the Santa Maria FormationSanta Maria formation, have been identified as ?Grallator isp., in addition to indeterminate tracksIndeterminate track of dinosaurs. These footprints are attributed to basal dinosauriformsDinosauriforms and they are considered the earliest examples of dinosaur tracks in BrazilBrazil. These discoveries hold significant implications, as they are associated with a diverse fauna whose dating aligns with the Carnian Pluvial EpisodeCarnian pluvial episode. This is a pivotal period marked by substantial environmental changes linked to global warmingGlobal warming, leading to significant extinctions and transitions in both flora and fauna. Other tracks, dating back to the NorianNorian or possibly RhaetianRhaetian age, were reinterpreted as “TheropodTheropods tracks indet.”, and were produced by large theropodTheropods dinosaurs. These particular occurrences are connected to the Caturrita FormationCaturrita formation and provide valuable insights into a later episode following the climate changes and their resulting effects on faunal and floral composition. Previously registered tracks within the Caturrita FormationCaturrita formation at the Novo TrevisoNovo Treviso site, attributed to prosauropod dinosaurs, have been reinterpreted as belonging to the Guará FormationGuará formation, ranging from the Late JurassicJurassic to the Early Cretaceous. Thus, the Santa Maria-Caturrita sequence, a sedimentary record shaped by diverse processes in ancient fluvial systemsFluvial system, offers an almost continuous timeline of the transition between the emergence of dinosaurs and their eventual establishment as ecologically dominant elements in continental faunas. These Brazilian TriassicTriassic dinosaur tracks, albeit limited to two strata at present, provide valuable supplementary data to the osteological record, further reinforcing these significant events in paleontological history.