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The nasal cavity of living mammals is a unique structural complex among tetrapods, acquired along a series of major morphological transformations that occurred mainly during the Mesozoic Era, within the Synapsida clade. Particularly, non-mammaliaform cynodonts document several morphological changes in the skull, during the Triassic Period, that represent the first steps of the mammalian bauplan. We here explore the nasal cavity of five cynodont taxa, namely Thrinaxodon, Chiniquodon, Prozostrodon, Riograndia, and Brasilodon, in order to discuss the main changes within this skull region. We did not identify ossified turbinals in the nasal cavity of these taxa and if present, as non-ossified structures, they would not necessarily be associated with temperature control or the development of endothermy. We do, however, notice a complexification of the cartilage anchoring structures that divide the nasal cavity and separate it from the brain region in these forerunners of mammals. [ABSTRACT FROM AUTHOR]

A new sauropodomorph dinosaur from the Late Triassic Candelária Sequence (Santa Maria Formation), south Brazil, Bagualosaurus agudoensis gen. et sp. nov. helps to fill a morphological gap between the previously known Carnian members of the group and younger sauropodomorphs. In some aspects, the skull, lower jaw, and dental anatomy of the new taxon approaches that seen in Norian forms like Pantydraco caducus, Efraasia minor, and Plateosaurus engelhardti. On the contrary, the post-cranial skeleton is broadly reminiscent of coeval, early dinosaurs. Although not reaching the size of most Norian and younger sauropodomorphs, B. agudoensis is significantly larger than coeval forms. The new data thus suggest that modifications in skull anatomy, possibly related to more efficient herbivorous habits, appeared early in sauropodomorph evolution, along with a moderate increase in size, followed in post-Carnian times by further increase in size, accompanied by more radical changes in post-cranial anatomy. [ABSTRACT FROM AUTHOR]

Dicynodonts were a highly successful group of herbivorous therapsids that inhabited terrestrial ecosystems from the Middle Permian through the end of the Triassic periods. Permian dicynodonts are extremely abundant in African deposits, but are comparatively poorly known from the other regions of Gondwana. Here we describe a new South American dicynodont, Rastodon procurvidens gen. et sp. nov., from the Boqueirão farm site of the Rio do Rasto Formation, Paraná Basin, Guadalupian/Lopingian of Brazil. Diagnostic features of R. procurvidens include uniquely anteriorly-curved maxillary tusks, well-developed ridges extending from the crista oesophagea anteriorly along the pterygoid rami, strong posterior angulation of the posterior pterygoid rami, and a bulbous, well-developed retroarticular process of the articular. Phylogenetic analysis indicates that R. procurvidens is the earliest and most basal member of Bidentalia, a cosmopolitan clade that includes Permian and Triassic dicynodonts whose dentition is usually reduced to a pair of maxillary tusks. [ABSTRACT FROM AUTHOR]

The ‘Rauisuchia’ are a group of Triassic pseudosuchian archosaurs that displayed a near worldwide distribution. In Brazil, their fossils are found only in the Santa Maria Formation (Paraná Basin) of the Rio Grande do Sul State, specifically in the Middle Triassic Dinodontosaurus assemblage zone (AZ) and the Late Triassic Hyperodapedon AZ (Rauisuchus tiradentes). Between these two cenozones is the Santacruzodon AZ (Middle Triassic), whose record was, until now, restricted to non-mammalian cynodonts and the proterochampsian Chanaresuchus bonapartei. Here we present the first occurrence of a rauisuchian archosaur for this cenozone, from the Schoenstatt outcrop, located near the city of Santa Cruz do Sul and propose a new species, based on biostratigraphical evidence and a comparative osteological analysis. [ABSTRACT FROM AUTHOR]

An amendment to this paper has been published and can be accessed via a link at the top of the paper. [ABSTRACT FROM AUTHOR]

The Triassic period (251.9–201.4 Ma) is the first period of the Mesozoic Era, initiating after the Permian-Triassic mass extinction and ending at the Triassic-Jurassic mass extinction. This period witnessed the origin of modern ecosystems, and also the rise of the dinosaurs. This influence on both geological and ecological history of the Earth has prompted close attention to the paleoclimate and paleoecology of the Triassic period over the last 60 years. This review builds on past work to summarize knowledge of Triassic climate and ecology, especially focusing on data acquired over the last decade for key South American strata. The main climatic events that occurred in the Triassic period can be subdivided in three key intervals, from the base to top: pre-, syn- and post-Carnian Pluvial Episode (CPE). Each of these three intervals corresponds with major climatic events or episodes, positioned relative to the Permian-Triassic mass extinction, CPE, and Triassic-Jurassic mass extinction. The pre-CPE interval of the Early and Middle Triassic represents relatively warm and dry conditions. The CPE of the earliest Late Triassic marks a global increase in effective precipitation (precipitation minus evaporation) for at least 1–2 Myr, causing major floristic and faunal turnovers and possibly triggering the rise of the dinosaurs. The post-CPE interval of the Late Triassic represents a return to warm and dry conditions. Triassic deposits in Brazil and Argentina represent windows for investigating the interrelationship(s) between changes in climate, floras, and faunas. Alternate triggers for dinosaur diversification are also evaluated, including classical considerations of competition, opportunism, and body temperature, in addition to more novel and subtle factors. • An update of the Triassic climates over the last decade of studies. • Special focus in South America Triassic strata (Brazil and Argentina). • New information about the CPE and its connection with dinosaurs' empire. • Current hypotheses of the rise of the dinosaurs. [ABSTRACT FROM AUTHOR]

The early evolution of lepidosaurs is marked by an extremely scarce fossil record during the Triassic. Importantly, most Triassic lepidosaur specimens are represented by disarticulated individuals from high energy accretion deposits in Laurasia, thus greatly hampering our understanding of the initial stages of lepidosaur evolution. Here, we describe the fragmentary remains of an associated skull and mandible of Clevosaurus hadroprodon sp. nov., a new taxon of sphenodontian lepidosaur from the Late Triassic (Carnian; 237–228 Mya) of Brazil. Referral to Sphenodontia is supported by the combined presence of a marginal dentition ankylosed to the apex of the dentary, maxilla, and premaxilla; the presence of 'secondary bone' at the bases of the marginal dentition; and a ventrally directed mental process at the symphysis of the dentary. Our phylogenetic analyses recover Clevosaurus hadroprodon as a clevosaurid, either in a polytomy with the Late Triassic to Early Jurassic Clevosaurus and Brachyrhinodon (under Bayesian inference), or nested among different species of Clevosaurus (under maximum parsimony). Clevosaurus hadroprodon represents the oldest known sphenodontian from Gondwana, and its clevosaurid relationships indicates that these sphenodontians achieved a widespread biogeographic distribution much earlier than previously thought. [ABSTRACT FROM AUTHOR]

This study reports the earliest known evidence of osteophagy by invertebrates in a continental setting from the Middle and Upper Triassic Santa Maria Supersequence, Paraná Basin, Brazil. Samples from the Dinodontosaurus Assemblage Zone (Pinheiros-Chiniquá Sequence – Middle Triassic) and the Hyperodapedon Assemblage Zone (Candelária Sequence – Upper Triassic) were analyzed and a number of trace morphologies were found, including tubes, holes and channels. We report the occurrence of Cubiculum inornatus from the Middle Triassic and Osteocallis mandibulus from the Upper Triassic and diagnose a new ichnospecies O. infestans isp. nov. The occurrence of these trace morphologies suggests that insect bone-modification behavior originated in Triassic Gondwanic environments, and dispersed during the Mesozoic, achieving a more cosmopolitan distribution during the Cretaceous. [ABSTRACT FROM AUTHOR]