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Faxinalipterus minimus was originally described as a purported pterosaur from the Late Triassic (early Norian) Caturrita Formation of southern Brazil. Its holotype comprises fragmentary postcranial elements, whereas a partial maxilla was referred to the species. The assignment of Faxinalipterus minimus to Pterosauria has been questioned by some studies, but the specimen has never been accessed in detail after its original description. Here we provide a reassessment of Faxinalipterus minimus after additional mechanical preparation of the holotype. Our interpretations on the identity of several bones differ from those of the original description, and we found no support favoring pterosaur affinities for the taxon. The maxilla previously referred to Faxinalipterus minimus is disassociated from this taxon and referred to a new putative pterosauromorph described here from a partial skull and fragmentary postcranial elements. Maehary bonapartei gen. et sp. nov. comes from the same fossiliferous site that yielded Faxinalipterus minimus, but the lack of overlapping bones hampers comparisons between the two taxa. Our phylogenetic analysis places Faxinalipterus minimus within Lagerpetidae and Maehary bonapartei gen. et sp. nov. as the earliest-diverging member of Pterosauromorpha. Furthermore, the peculiar morphology of the new taxon reveals a new dental morphotype for archosaurs, characterized by conical, unserrated crowns, with a pair of apicobasally oriented grooves. These two enigmatic archosaurs expand our knowledge on the Caturrita Formation fauna and reinforce the importance of its beds on the understanding of Late Triassic ecosystems. [ABSTRACT FROM AUTHOR]

Our knowledge on the anatomy of the first dinosaurs (Late Triassic, 235–205 Ma) has drastically increased in the last years, mainly due to several new findings of exceptionally well‐preserved specimens. Nevertheless, some structures such as the neurocranium and its associated structures (brain, labyrinth, cranial nerves, and vasculature) remain poorly known, especially due to the lack of specimens preserving a complete and articulated neurocranium. This study helps to fill this gap by investigating the endocranial cavity of one of the earliest sauropodomorphs, Buriolestes schultzi, from the Upper Triassic (Carnian—c. 233 Ma) of Brazil. The endocranial anatomy of this animal sheds light on the ancestral condition of the brain of sauropodomorphs, revealing an elongated olfactory tract combined to a relatively small pituitary gland and well‐developed flocculus of the cerebellum. These traits change drastically across the evolutionary history of sauropodomorphs, reaching the opposite morphology in Jurassic times. Furthermore, we present here the first calculations of the Reptile Encephalization Quotient (REQ) for a Triassic dinosaur. The REQ of B. schultzi is lower than that of Jurassic theropods, but higher than that of later sauropodomorphs. The combination of cerebral, dental, and postcranial data suggest that B. schultzi was an active small predator, able to track moving prey. [ABSTRACT FROM AUTHOR]

The fusion of the sacrum occurs in the major dinosaur lineages, i.e. ornithischians, theropods, and sauropodomorphs, but it is unclear if this trait is a common ancestral condition, or if it evolved independently in each lineage, or even how or if it is related to ontogeny. In addition, the order in which the different structures of the sacrum are fused, as well as the causes that lead to this co‐ossification, are poorly understood. Herein, we described the oldest record of fused sacral vertebrae within dinosaurs, based on two primordial sacral vertebrae from the Late Triassic of Candelária Sequence, southern Brazil. We used computed microtomography (micro‐CT) to analyze the extent of vertebral fusion, which revealed that it occurred only between the centra. We also assessed the occurrence of sacral fusion in Dinosauria and close relatives. The degree of fusion observed in representatives of the major dinosaur lineages suggested that there may be a sequential pattern of fusion of the elements of the sacrum, more clearly observed in Sauropodomorpha. Our analyses suggest that primordial sacral vertebrae fuse earlier in the lineage (as seen in Norian sauropodomorphs). Intervertebral fusion is observed to encompass progressively more vertebral units as sauropodomorphs evolve, reaching up to five or more fully fused sacrals in Neosauropoda. Furthermore, the new specimen described here indicates that the fusion of sacral elements occurred early in the evolution of dinosaurs. Factors such as ontogeny and the increase in body size, combined with the incorporation of vertebrae to the sacrum may have a significant role in the process and in the variation of sacral fusion observed. [ABSTRACT FROM AUTHOR]

Predatory dinosaurs were an important ecological component of terrestrial Mesozoic ecosystems. Though theropod dinosaurs carried this role during the Jurassic and Cretaceous Periods (and probably the post-Carnian portion of the Triassic), it is difficult to depict the Carnian scenario, due to the scarcity of fossils. Until now, knowledge on the earliest predatory dinosaurs mostly relies on herrerasaurids recorded in Carnian strata of South America. Phylogenetic investigations recovered the clade in different positions within Dinosauria, whereas fewer studies challenged its monophyly. Although herrerasaurid fossils are much better recorded in present-day Argentina than in Brazil, Argentinean strata so far yielded no fairly complete skeleton representing a single individual. Here, we describe Gnathovorax cabreirai, a new herrerasaurid based on an exquisite specimen found as part of a multitaxic association form southern Brazil. The type specimen comprises a complete and well-preserved articulated skeleton, preserved in close association (side by side) with rhynchosaur and cynodont remains. Given its superb state of preservation and completeness, the new specimen sheds light into poorly understood aspects of the herrerasaurid anatomy, including endocranial soft tissues. The specimen also reinforces the monophyletic status of the group, and provides clues on the ecomorphology of the early carnivorous dinosaurs. Indeed, an ecomorphological analysis employing dental traits indicates that herrerasaurids occupy a particular area in the morphospace of faunivorous dinosaurs, which partially overlaps the area occupied by post-Carnian theropods. This indicates that herrerasaurid dinosaurs preceded the ecological role that later would be occupied by large to medium-sized theropods. [ABSTRACT FROM AUTHOR]

The Triassic deposits of South America are key to understand the early radiation of Dinosauromorpha. Though the fossil record of the group is relatively abundant in Carnian- and Norian-aged strata from Argentina and Brazil, Middle Triassic dinosauromorphs are scarce, at least in the Brazilian record. In this contribution, we describe a set of fossils collected from a site biostratigraphically correlated to the Dinodontosaurus Assemblage Zone, which is regarded as Ladinian in age. Within the sample, we identified a single partial ilium with anatomical features consistent with Silesauridae. As a result, we propose a new taxon, Gamatavus antiquus gen. et sp. nov. as the first silesaurid from the Brazilian Middle Triassic. Biostratigraphic comparisons suggest the Dinodontosaurus Assemblage Zone to be older than the Argentinean Massetognathus - Chanaresuchus AZ, rendering the new specimen also the oldest South American silesaurid. This contribution adds to recent works that suggest biostratigraphical similarity between the Brazilian Dinodontosaurus AZ and the African Lifua Member and Ntawere Formation, from where the oldest dinosauromorph records are registered. • A new silesaurid, Gamatavus antiquus , is described. • The new material represents the oldest occurrence of the group in South America. • This is the first silesaurid record for the Dinodontosaurus Assemblage Zone. • It increases the similarity of the faunal content of Middle Triassic units in Brazil, Tanzania and Zambia. [ABSTRACT FROM AUTHOR]

The Vila Botucaraí site is located west of the municipality of Candelária, Rio Grande do Sul State, southern Brazil, and is particularly important because it represents the type locality of the species Exaeretodon riograndensis (Cynodontia, Traversodontidae), Charruodon tetracuspidatus (Cynodontia, Probainognathia) and Proterochampsa nodosa (Archosauriformes, Proterochampsidae). The site is correlated to the Hyperodapedon Assemblage Zone whose fossiliferous content allows to correlate it to the lower half of the Ischigualasto Formation (Ischigualasto-Villa Unión Basin), of late Carnian age, in Argentina. The aim of this study is to record the first remains of dinosaurs from this locality, found in 2001 during the Pró-Guaiba Project and stored in the Scientific Collection of the Paleontology Section of the Museu de Ciências Naturais, Secretaria Estadual do Meio Ambiente e Infraestrutura, Porto Alegre, RS. In addition to the taxa mentioned at the Vila Botucaraí site, the archosauromorph Hyperodapedon sp. was also preliminarily recorded. The Dinosauria specimen includes four dorsal vertebrae (MCN-PV 10347a, b, c, d). The general characteristics observed are: (i) absence of a ventral keel in the vertebral centra, shared with Guaibasaurus , Bagualosaurus , Pampadromaeus ; (ii) amphicoelic centra with concave ventral surface, shared with Bagualosaurus , Guaibasaurus , and most non-sauropod sauropodomorphs (exceptions are, for example, Riojasaurus ; also, this character does not appear in herrerasaurids); (iii) vertebral laminae connected to the diapophysis, and their arrangement results in different fossae, as in Bagualosaurus , Buriolestes , Guaibasaurus , and herrerasaurids; (iv) neural spine anteroposteriorly elongated and transversely narrow, as in Bagualosaurus , Pampadromaeus , Buriolestes , Macrocollum , differing from herrerasaurids and theropods. This set of characters is similar to that observed in basal sauropodomorphs, quite different from the neural spine with a spine table, such as the observed in herrerasaurids. Specimen MCN-PV 10347 is here considered a member of the Sauropodomorpha clade and tentatively identified as cf. Bagualosauria. The features of this specimen are shared among Carnian (e.g., Buriolestes schultzi , Bagualosaurus agudoensis) and Norian (e.g., Unaysaurus tolentinoi , Guaibasaurus candelariensis) sauropodomorphs. In addition to this, the new material expands the knowledge regarding the number of outcrops with the occurrence of sauropodomorphs for the Triassic in Brazil, as well as about the paleofauna of the Vila Botucaraí site, allowing us to infer its biostratigraphic correlation with one of the sub-divisions already proposed for the Hyperodapedon AZ, the Exaeretodon Subzone, interpreted as the top of this AZ. Despite the abundance of sauropodomorphs in Rio Grande do Sul, this record confirms the occurrence of this clade at the Hyperodapedon AZ in the Candelária region. • Taxonomic analysis of the dorsal vertebrae of a non-sauropod sauropodomorph. • The correlations of coeval extracts within the of Hyperodapedon AZ. • First record of a dinosaur cf. Bagualosauria outside the locality -type of Bagualosaurus agudoensis. [ABSTRACT FROM AUTHOR]

Traversodontidae is a less inclusive clade of cynognathian cynodonts that lived during the Triassic. Recently, a traversodontid from the southern Brazilian Triassic beds was described – Siriusgnathus niemeyerorum – based upon specimens found exclusively in its type-locality. No absolute age or index fossils have been reported for this locality, which prevents an accurate biostratigraphic correlation. In the present contribution, we describe the first specimens of S. niemeyerorum found outside its type-locality, comprising skull portions excavated from outcrops in southern Brazil assigned to the Caturrita Formation (upper portion of the Candelária Sequence), Upper Triassic (Norian), Riograndia Assemblage Zone. As a result, we provide an updated biostratigraphic framework and suggest a Norian age for the type-locality of S. niemeyerorum , which, accordingly, possibly comprises the youngest South American traversodontid, pending additional geochronological studies in order to properly evaluate this hypothesis. • New specimens of the traversodontid Siriusgnathus niemeyerorum are described. • They represent the first records of S. niemeyerorum outside its type-locality. • The studied sites are assigned to the Riograndia Assemblage Zone, Norian. • Siriusgnathus niemeyerorum may be the youngest known South American traversodontid so far. [ABSTRACT FROM AUTHOR]