Sérgio Dias-Da-Silva

Upper Triassic (Carnian) strata from the Candelária Sequence of southern Brazil bear the oldest records of dinosaurs worldwide. In consequence, investigation of the specimens yielded by these fossiliferous units is crucial for a more comprehensive knowledge regarding the origin, early diversification and radiation of dinosaurs. Herein we reassess a dinosaur specimen from Brazil, informally known as the ‘Big Saturnalia’, a supposed large-sized sauropodomorph unearthed at the ‘Cerro da Alemoa’ locality in Santa Maria municipality, Rio Grande do Sul State. However, our phylogenetic analyses and comparisons of the known elements of this specimen resulted in herrerasaurid affinities instead. In fact, it is the largest specimen so far of a herrerasaurid from the Candelária Sequence. It preserves cranial and postcranial elements, with the former being unprecedented for dinosaurs from the Alemoa local fauna. The morphology of the specimen allows new insights into the anatomy, evolution and distribution of some character states among Herrerasauridae, including but not limited to the typical craniocaudally short caudal dorsal vertebrae. Moreover, the specimen adds to the dinosauromorph diversity in the Carnian units of southern Brazil and its large size provides further support for herrerasaurids as top-tier predators during the dawn of dinosaurs in south-western Pangaea.

A new fossiliferous site from the Pinheiros-Chiniquá Sequence (Santa Maria Supersequence) with typical tetrapod components of the Dinodontosaurus Assemblage Zone (AZ) is here described. The new site is included in the Faxinal do Soturno Structural Block. The fossil content is characterized by cranial and postcranial material of rauisuchian archosaurs, traversodontid and chiniquodontid cynodonts and dicynodonts, the first occurrence of a large-sized coelacanth fish in the Brazilian Triassic, as well as ichnological material, represented by coprolites. The presence of Luangwa together with Massetognathus raises interesting questions regarding the age of this site included in the Dinodontosaurus AZ when compared with other localities of Southern Brazil, western Argentina and Africa. As in other localities of this AZ, the fossil specimens recovered in Bortolin site exhibit remarkable differences on their fossil preservation: those from the lower portion of the outcrop (distal floodplain) possess a heterogeneous preservation (variable between poor to fairly good) whereas those from the top levels (proximal floodplain) are comparatively better preserved. This new locality, with a large amount of stratigraphically controlled fossils, constitutes a key-locality to study the distribution of Triassic terrestrial tetrapods and to perform comparisons with other sites of this AZ, inwhich several historical records lack a precise provenance. Keywords: Dinodontosaurus Assemblage Zone, Santa Maria Supersequence, Luangwa, coelacanth. Um novo sítio fossilífero é descrito para a Sequência Pinheiros-Chiniquá (Supersequência Santa Maria) com tetrápodes típicos da Zona de Associação (ZA) de Dinodontosaurus. Este novo sítio está incluído no Bloco Estrutural Faxinal do Soturno. O conteúdo fóssil é caracterizado por materiais cranianos e pós-cranianos de arcossauros rauissuquídeos, cinodontes chiniquodontídeos e traversodontídeos e dicinodontes, a primeira ocorrência de um peixe celacanto de grande tamanho, além de materiais icnológicos, representados por coprólitos. A presença de Luangwa juntamente com Massetognathus levanta interessantes questões acerca da idade desse sítio, incluído na ZA de Dinodontosaurus, quando comparado com outras localidades do sul do Brasil, oeste da Argentina e África. Assim como em outras localidades desta ZA, os espécimes fósseis coletados no sítio Bortolin apresentam diferenças notáveis na preservação dos fósseis: fósseis do nível inferior do afloramento (planície de inundação distal) apresentam preservação heterogênea (variando entre pobre a razoavelmente bem preservado) enquanto que nos níveis superiores (planície de inundação proximal), o registro fóssil é comparativamente melhor preservado. Esta nova localidade, com uma grande quantidade de fósseis estratigraficamente controlados, constitui uma localidade chave para o estudo da distribuição dos tetrápodes terrestres do Triássico e sua comparação com outros sítios desta ZA, na qual vários registros históricos carecem de uma proveniência precisa. Palavras-chave: Zona de Associação de Dinodontosaurus, Supersequência Santa Maria, Luangwa, celacanto. A new fossiliferous site from the Pinheiros-Chiniquá Sequence (Santa Maria Supersequence) with typical tetrapod components of the Dinodontosaurus Assemblage Zone (AZ) is here described. The new site is included in the Faxinal do Soturno Structural Block. The fossil content is characterized by cranial and postcranial material of rauisuchian archosaurs, traversodontid and chiniquodontid cynodonts and dicynodonts, the first occurrence of a large-sized coelacanth fish in the Brazilian Triassic, as well as ichnological material, represented by coprolites. The presence of Luangwa together with Massetognathus raises interesting questions regarding the age of this site included in the Dinodontosaurus AZ when compared with other localities of Southern Brazil, western Argentina and Africa. As in other localities of this AZ, the fossil specimens recovered in Bortolin site exhibit remarkable differences on their fossil preservation: those from the lower portion of the outcrop (distal floodplain) possess a heterogeneous preservation (variable between poor to fairly good) whereas those from the top levels (proximal floodplain) are comparatively better preserved. This new locality, with a large amount of stratigraphically controlled fossils, constitutes a key-locality to study the distribution of Triassic terrestrial tetrapods and to perform comparisons with other sites of this AZ, inwhich several historical records lack a precise provenance. Keywords: Dinodontosaurus Assemblage Zone, Santa Maria Supersequence, Luangwa, coelacanth. Um novo sítio fossilífero é descrito para a Sequência Pinheiros-Chiniquá (Supersequência Santa Maria) com tetrápodes típicos da Zona de Associação (ZA) de Dinodontosaurus. Este novo sítio está incluído no Bloco Estrutural Faxinal do Soturno. O conteúdo fóssil é caracterizado por materiais cranianos e pós-cranianos de arcossauros rauissuquídeos, cinodontes chiniquodontídeos e traversodontídeos e dicinodontes, a primeira ocorrência de um peixe celacanto de grande tamanho, além de materiais icnológicos, representados por coprólitos. A presença de Luangwa juntamente com Massetognathus levanta interessantes questões acerca da idade desse sítio, incluído na ZA de Dinodontosaurus, quando comparado com outras localidades do sul do Brasil, oeste da Argentina e África. Assim como em outras localidades desta...

A new basal stereospondyl taxon from the Permian is described. The material used to erect the new taxon consists of a series of mandibles and some postcranial elements. A single badly preserved short-snouted skull is considered as referred material. Rastosuchus hammeri gen. et sp. nov. presents conical teeth along all coronoid bones, the prearticular extending anteriorly at the level of the precoronoid and enlarged anterior meckelian foramina. Based on the referred material, R. hammeri gen. et sp. nov. also presents posterior premaxillary teeth larger than anterior ones, the cultriform process of the parasphenoid compressed laterally forming a medial ventral keel, posterolateral ramus of the vomer extends posterior to the palatine tusks, and rounded orbit with flat orbital bones at the same level of the skull roof, features shared with Australerpeton cosgriffi and other rhinesuchids. Australerpeton cosgriffi and Rastosuchus hammeri gen. et sp. nov. are from the upper layers of the Rio do Rasto Formation (Paraná Basin) in the Paraná State, southern Brazil, and its deposition in freshwater continental environments is reinforced by the presence of temnospodyls amphibians. Keywords: Rhinesuchidae, Temnospondyli, Rastosuchus, Guadalupian–Lopingian, Rio do Rasto Formation. Um novo táxon de estereospôndilo basal brasileiro é descrito para o Permiano. O material utilizado para propor o novo táxon consiste em uma série de mandíbulas e alguns elementos pós-cranianos. Um único crânio mal preservado, de rostro curto, é considerado como material referido. Rastosuchus hammeri gen. et sp. nov. apresenta dentes cônicos ao longo de todos os ossos coronoides, pré-articular se estendendo anteriormente até o nível do pré-coronoide e amplos foramens meckelianos anteriores. Baseado no material referido, R. hammeri gen. et sp. nov. também apresenta dentes pré-maxilares posteriores maiores que os anteriores, o processo cultriforme do paraesfenoide comprimido lateralmente formando um quilha ventral medial, ramo posterolateral do vômer estendendo-se posteriormente às presas do palatino, e órbita arredondada com ossos orbitais achatados e no mesmo nível do teto do crânio, características compartilhadas com Australerpeton cosgriffi e outros rinessuquídeos. Australerpeton cosgriffi e Rastosuchus hammeri gen. et sp. nov. são provenientes das camadas superiores da Formação Rio do Rasto (Bacia do Paraná) no Estado do Paraná, sul do Brasil, e a presença de anfíbios temnospôndilos reforça a interpretação de que esta foi depositada em ambientes continentais dulciaquícolas. Palavras-chave: Rhinesuchidae, Temnospondyli, Rastosuchus, Guadalupiano–Lopingiano, Formação Rio do Rasto.

Probainognathian cynodonts are well represented in the fossil record from the Middle and Upper Triassic of South America, especially in Brazil and Argentina. In this contribution, we describe a new genus and species of non-mammaliaform prozostrodontian cynodont from southern Brazil. The new taxon comes from the Niemeyer Site, a locality in which the traversodontid cynodont Siriusgnathus niemeyerorum is numerically dominant, whereas probainognathians and other tetrapods are comparatively scarce. The fauna from the Niemeyer Site was putatively assigned to the Riograndia Assemblage Zone (Norian age) recently, although none of the index fossils for that biozone (e.g., Riograndia, Clevosaurus, Jachaleria) have so far been discovered at this locality. The new cynodont taxon is based on a left lower jaw with the canine and six (pc2–pc7) well-preserved postcanines (CAPPA/UFSM 0262, holotype), and a second referred specimen (CAPPA/UFSM 0208, paratype), which includes a right lower jaw with incisors, canine, and seven (pc1–pc7) postcanines, with pc6–pc7 being the best preserved. These specimens have a robust dentary, a long and dorsoventrally tall Meckelian groove, unserrated canines, and unserrated, sectorial postcanine teeth with posteriorly inclined cusps and a poorly developed lingual cingulum. This combination of features is unknown in other Carnian and Norian non-mammaliaform cynodonts. The new taxon contributes to our knowledge of the evolutionary radiation of small prozostrodonts that occurred in western Gondwana during the Late Triassic and led to the emergence of several important cynodont groups, including Mammaliaformes. http://zoobank.org/urn:lsid:zoobank.org:pub:FDC21881-532B-490A-96A1-A65EA5F62737

After the Permo-Triassic mass extinction, the archosauromorph fossil record is comparatively abundant and ecologically diverse. Among early archosauromorphs, tanystropheids gained considerable attention due to the presence of extreme skeletal adaptations in response to sometimes overspecialized lifestyles. The origin and early radiation of Tanystropheidae, however, remains elusive. Here, a new Early Triassic archosauromorph is described and phylogenetically recovered as the sister-taxon of Tanystropheidae. The new specimen, considered a new genus and species, comprises a complete posterior limb articulated with pelvic elements. It was recovered from the Sanga do Cabral Formation (Sanga do Cabral Supersequence, Lower Triassic of the Paraná Basin, Southern Brazil), which has already yielded a typical Early Triassic vertebrate assemblage of temnospondyls, procolophonoids, and scarce archosauromorph remains. This new taxon provides insights on the early diversification of tanystropheids and represents further evidence for a premature wide geographical distribution of this clade. The morphology of the new specimen is consistent with a terrestrial lifestyle, suggesting that this condition was plesiomorphic for Tanystropheidae.

Embora o grupo dos dinossauros sauropodomorfos seja amplamente conhecido em virtude dos gigantescos saurópodes, sua origem ainda é pouco compreendida em virtude da escassez de esqueletos completos ou datações precisas. Entretanto, novos achados e datações realizadas em rochas Triássicas do Brasil têm trazido à tona informações valiosas no que tange essa questão. A combinação desses novos dados com técnicas mais avançadas de investigação (e.g. tomografias computadorizadas) vem possibilitando o estabelecimento dos padrões macroevolutivos que direcionaram a evolução inicial do grupo. Através das descobertas realizadas nos leitos Triássicos do Rio Grande do Sul, podemos entender de forma mais refinada como foi que os sauropodomorfos passaram de animais pequenos e pouco abundantes aos maiores animais que já andaram sobre a Terra.