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The Anteosauridae (Dinocephalia) were the largest predators of Guadalupian (Middle Permian) land communities. The, thus far, only known South American anteosaurid is the medium-sized syodontine Pampaphoneus biccai. This taxon was, until now, known only by its holotype, recovered from an outcrop of the Rio do Rasto Formation, Southern Brazil. Here we describe in detail an almost complete Pampaphoneus biccai skull associated with a few postcranial remains (UNIPAMPA 759) recently recovered from the type locality. The novel morphological information provided by this novel, better-preserved, specimen revealed that most characters previously proposed to distinguish Pampaphoneus biccai from Syodon biarmicum are probably ontogenetically constrained. We identify, however, new features that clearly distinguish these two taxa, and provide an updated diagnosis for Pampaphoneus biccai. Our phylogenetic reassessment of the taxon echoes previous propositions in which Pampaphoneus biccai was recovered as an early-divergent Syodontinae. Additionally, we tentatively indicate that a larger fragmentary specimen (UFRGS-PV-0249-P) may represent the mature size of the species, with the similar-sized holotype and UNIPAMPA 759 probably representing subadult individuals. [ABSTRACT FROM AUTHOR]

One of the main "databases", on which palaeontologists carry on their studies, is constituted by palaeontological collections. These collections are the final result of fieldwork and surveys, sampling activities, preparation and curatorial processes, and analyses. However, the content of a palaeontological collection can also be strongly biased, leading researchers to post-collection skewed results. Post-collection biases (e.g., breakage, loss of fragments, etc.) are directly linked to human activities, occurring during excavation, transport, preparation, and storage. Here, we present the case of the vertebrate remains from the Brazilian lower Carnian Santacruzodon Assemblage Zone (Santa Cruz Sequence, Santa Maria Supersequence, Paraná Basin). The studied specimens came from the Schoenstatt Sanctuary fossil site, a key outcrop for both the sequence and Santacruzodon AZ. We evaluated vertebrate remains from three Brazilian scientific collections, compiled through more than 25 years of fieldwork. The specimens housed in the three collections present high degrees of post-collection fragmentation, as well as significant differences in the bone elements present, when comparing cranial vs. post-cranial elements. Moreover, some differences in curatorial attitude have also been noticed, especially in restoration choices, leading to "discrimination" in post-collection fossil quality and highlighting the existence of the "craniocentrism" problem. [ABSTRACT FROM AUTHOR]

We describe for the first time the presence of straight, curved and quasi‐helical burrows preserved in plan, oblique and transversal views in the aeolian strata of the Permo‐Triassic Buena Vista Formation (Paraná Basin), Rio Grande do Sul, southern Brazil. The morphology of the burrows is similar to that of others found in Guadalupian to Early Triassic‐aged deposits in several parts of the world. Of these, middle Permian dicynodont‐bearing helical burrows (Daimonelix) and Early–Middle Triassic kidney‐shaped burrows (Reniformichnus), both from the Karoo Basin of South Africa, show a remarkable similarity to the Brazilian burrows, prompting a discussion of the probable producers. Dicynodonts, cynodonts, therocephalian and/or procolophonians are among the probable producers of such burrows, based on size compatibility between the burrows and estimates of body size for the fossil taxa, along with the presence of skeletal adaptations in Permo‐Triassic tetrapods for digging (bone micro‐ and macrostructure). Last, we discuss some behavioural aspects of the producer of the burrows, mainly due to the presence of passive filling and bilobate bottoms in the tunnels, which indicates that they remained open as long as they were occupied. The burrows were excavated in a dry aeolian system that occurred in the Guadalupian–Induan interval of Brazil, representing the oldest unambiguous record of tetrapod dwelling structures in such an environment, and providing new and unprecedented information regarding the colonization of deserts by tetrapods during the end‐Permian biotic crisis. [ABSTRACT FROM AUTHOR]

Two sets of teeth (diphyodonty) characterise extant mammals but not reptiles, as they generate many replacement sets (polyphyodonty). The transition in long‐extinct species from many sets to only two has to date only been reported in Jurassic eucynodonts. Specimens of the Late Triassic brasilodontid eucynodont Brasilodon have provided anatomical and histological data from three lower jaws of different growth stages. These reveal ordered and timed replacement of deciduous by adult teeth. Therefore, this diphyodont dentition, as contemporary of the oldest known dinosaurs, shows that Brasilodon falls within a range of wide variations of typically mammalian, diphyodont dental patterns. Importantly, these three lower jaws represent distinct ontogenetic stages that reveal classic features for timed control of replacement, by the generation of only one replacement set of teeth. This data shows that the primary premolars reveal a temporal replacement pattern, importantly from directly below each tooth, by controlled regulation of tooth resorption and regeneration. The complexity of the adult prismatic enamel structure with a conspicuous intra‐structural Schmelzmuster array suggests that, as in the case of extant mammals, this extinct species would have probably sustained higher metabolic rates than reptiles. Furthermore, in modern mammals, diphyodonty and prismatic enamel are inextricably linked, anatomically and physiologically, to a set of other traits including placentation, endothermy, fur, lactation and even parental care. Our analysis of the osteodental anatomy of Brasilodon pushes back the origin of diphyodonty and consequently, its related biological traits to the Norian (225.42 ± 0.37 myr), and around 25 myr after the End‐Permian mass extinction event. [ABSTRACT FROM AUTHOR]

Dicynodonts represent a speciose clade of non-mammalian synapsids that lived from the middle Permian to the Late Triassic, exhibiting a Pangaean distribution. The South American Norian fossil record is represented by two species: Jachaleria colorata from Argentina and J. candelariensis from Brazil. The Brazilian specimens come from a relatively small quarry located in the site known as Botucaraí or Botucaraí Hill (Candelária, Rio Grande do Sul). We describe here four dorsal vertebrae of a single individual referred to cf. Jachaleria candelariensis from a site named Alto Guarda Mor, located in the Faxinal do Soturno municipality, State of Rio Grande do Sul, Brazil. This taxonomic proposal and the lithological features of the site support that the outcrop belongs to the Riograndia Assemblage Zone (AZ; Candelária Sequence, Santa Maria Supersequence). Although the specimen cannot be referred unambiguously to Jachaleria candelariensis due to the lack of cranial material, it likely represents the second record of the genus in the Triassic of Brazil. We further discuss the faunal composition and relative age of some sites referred to the Riograndia AZ, which exhibit odd faunal context likely representing an AZ between the top of the Hyperodapedon AZ and the base of the Riograndia AZ. [ABSTRACT FROM AUTHOR]

Rhynchocephalians are a group of lizard-like diapsid reptiles that were very diverse during the Mesozoic but are now restricted to a single extant genus in New Zealand. Recent cladistic analyses have revealed two major clades, Eusphenodontia and the more crownward Neosphenodontia, but relationships of individual taxa have remained difficult to determine because of missing data and an unrevised data matrix. Here we drastically revise the established data matrix on rhynchocephalians by reassessing, evaluating, and adding new characters and operational taxonomic units, differing from any previous analyses in our goal to consider all known rhynchocephalians. In addition, we describe a new genus and species of an early eusphenodontian taxon from the Norian of southern Brazil, with a unique mosaic of plesiomorphic and apomorphic traits, and we re-examine the craniodental anatomy of the eusphenodontian Clevosaurus brasiliensis with µCT imaging, revealing a unique form of acrodonty amongst rhynchocephalians. [ABSTRACT FROM AUTHOR]

Understanding the ontogeny of a taxon is a crucial step to properly elucidate its taxonomy and evolution. However, aside from histological data, osteological criteria for assessing maturity are considered lineage specific or controversial. The sequence of neurocentral suture closure of the axial skeleton of extant crocodilians, which occurs in a posterior–anterior sequence, is a non‐destructive method used to determine maturity in extinct reptiles. However, its use in extinct archosaurs not closely related to crocodilians is debatable, as the ancestral condition of Archosauria is unknown and variation occurs in timing and sequence orientation within the clade. We have assessed the pattern of neurocentral suture closure of Hyperodapedontinae rhynchosaurs, an early archosauromorph clade distantly related to archosaurs. Unlike extant crocodilians, they exhibit an anterior–posterior sequence neurocentral suture closure. Relative size and other ontogenetic markers suggest that neurocentral closure in the Hyperodapedontinae correlates with aging, although closed sutures were rare in the sample. A high number of open or partially open sutures in mature individuals indicate that they remained open during most of their life. Our study indicates that: (1) the delayed neurocentral closure may be a paedomorphic heterochronic process in Hyperodapedontinae, as it contrasts with the fully closed neurocentral sutures of early diverging non‐hyperodapedontine rhynchosaurs; (2) the assumption that open neurocentral sutures indicates immaturity in extinct reptiles is not always correct; and (3) the delayed closure may have originated independently in several archosauromorph lineages, but the ancestral condition of Archosauria probably follows the crocodilian closure pattern. [ABSTRACT FROM AUTHOR]

The phylogenetic relationships of Pseudosuchia, the crocodile-line of Archosauria, are still poorly resolved, in part, due to the lack of crucial braincase information for several key taxa. Recently, erpetosuchids and ornithosuchids have been recovered as close relatives to Aetosauria, sharing several braincase features. Here we provide the description of the first braincase of the basal aetosaur Aetosauroides based on specimens from the Upper Triassic Candelária Sequence of Brazil. Our study revealed the presence of an exoccipital lateral ridge and a medial ridge on the supraoccipital (both shared with all aetosaurs and erpetosuchids, but absent in ornithosuchids) and an anterolateral exit for the internal carotids (shared with all aetosaurs and ornithosuchids, but not with erpetosuchids). Aetosauroides lacks a medial contact between the exoccipitals (shared with the aetosaurs Desmatosuchus smalli and Tecovasuchus) and possesses a single hypoglossal foramen (contrasting with Stagonolepis robertsoni and Desmatosuchus spurensis). It also differs from the putative Argentinian Aetosauroides (PVSJ 326) by the presence of a ridge connecting the basal tubera medially (contrasting also with all stagonolepidoideans) and by a bulbous and ventrolaterally recurved basipterygoid process (contrasting with Paratypothorax). These features show that the braincase of aetosaurs is suitable for providing further phylogenetic information and may contribute to resolving controversies within Pseudosuchia relationships. [ABSTRACT FROM AUTHOR]

Tetrapod tracks in eolianites are widespread in the fossil record since the late Paleozoic. Among these ichnofaunas, the ichnogenus Chelichnus is the most representative of the Permian tetrapod ichnological record of eolian deposits of Europe, North America and South America, where the Chelichnus Ichnofacies often occurs. In this contribution, we describe five sets of tracks (one of which is preserved in cross-section), representing the first occurrence of Dicynodontipus and Chelichnus in the “Pirambóia Formation” of southern Brazil. This unit represents a humid desert in southwestern Pangea and its lower and upper contacts lead us to consider its age as Lopingian–Induan. The five sets of tracks studied were compared with several ichnotaxa and body fossils with appendicular elements preserved, allowing us to attribute these tracks to dicynodonts and other indeterminate therapsids. Even though the “Pirambóia Formation” track record is sparse and sub-optimally preserved, it is an important key to better understand the occupation of arid environments by tetrapods across the Permo–Triassic boundary. [ABSTRACT FROM AUTHOR]

Prestosuchus chiniquensis is the most famous "rauisuchian" described by Friedrich von Huene, eight decades ago, and several specimens have been assigned to this taxon since then. In the present contribution, we provide the first detailed description of a complete and very well preserved skull (including the braincase) assigned to Prestosuchus chiniquensis from the Dinodontosaurus Assemblage Zone of the Santa Maria Supersequence of southern Brazil. The detailed description of the skull of Prestosuchus chiniquensis, besides increasing the knowledge about this taxon, may help elucidate the taxonomic relationships of pseudosuchians even further, since most of the characters used in phylogenetic analyzes are cranial. The presence of the subnarial fenestra, a controvertial extra opening on the skull of "rauisuchians", is thoroughly discussed considering the evidence provided by this new specimen. We consider that the small slit-opening between the premaxilla and the maxilla in Prestosuchus chiniquensis, can not safely be considered a true fenestra, but indicates more likely the existence of some degree of cranial kinesis between these elements which can result in different relative positions of the bones after definitive burial and fossilization, so that the size and shape of this opening is taphonomically controlled. Complementarily, the digital reconstruction of its cranial endocast was developed both from the observation of the preserved braincase and from CT scan images, which resulted in obtaining the first endocast known for a "rauisuchian". The endocast of Prestosuchus chiniquensis exhibited some remarkable convergences with that of theropod dinosaurs, which could be a reflection of the similar niches they occupied, since "rauisuchians" were the top predators at the end of the Late Triassic, before the extinction of all non-crocodylomorph pseudosuchians. [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]

Tanystropheidae is a clade of early archosauromorphs with a reported distribution ranging from the Early to the Late Triassic of Asia, Europe, and North America. Although some specimens with possible tanystropheid affinities from the Lower Triassic beds of Brazil have been previously attributed to "Protorosauria", little is known about the tanystropheid record in Gondwana. Here, two new and one previously reported specimen from the Sanga do Cabral Formation (Induan-Olenekian) of Brazil are described and interpreted as Tanystropheidae. These records, together with other tetrapods previously reported for the Sanga do Cabral Formation, increase the knowledge of the biotic diversification during the beginning of the Triassic. This contribution reinforces that the archosauromorph diversification occurred shortly after the Permo-Triassic extinction, making the Sanga do Cabral Formation an important unit for the study of early Mesozoic faunas. [ABSTRACT FROM AUTHOR]

The evolution and diversification of Triassic pseudosuchian lineages has been the subject of much interest and revision in the last couple of decades, fuelled by new and important discoveries, which have allowed for better-sampled phylogenetic analysis. In the present contribution, we add to this by describing a new taxon, Pagosvenator candelariensis gen. et sp. nov. for the Middle–Late Triassic Dinodontosaurus Assemblage Zone of the Santa Maria Supersequence of southernmost Brazil. A comparative osteological analysis combined with a phylogenetic analysis supports its inclusion within the clade Erpetosuchidae and provides an insight into the phylogenetic relationship and evolutionary history of this clade, with two possibilities for the Erpetosuchidae relationship: as an early branch of pseudosuchians, being a sister group of Ornithosuchidae; or a closer relationship with the clade composed by Gracilisuchidae and Paracrodylomorpha with respect to Orntithosuchidae and Aetosauria. Additionally, the results presented and discussed here are of biostratigraphical importance, given that the taxon is from the Ladinian/Carnian age and would fill a temporal gap that exists within Erpetosuchidae between Parringtonia gracilis from the Anisian and Erpetosuchus from late the Carnian to Norian. Furthermore, it would be the first occurrence of a member of this clade in South America. [ABSTRACT FROM AUTHOR]

Terrestrial tetrapod coprolites are abundant in the Middle to Late Triassic of southern Brazil, but only few specimens have been described in just a couple of papers. Here we revisit the already‐known specimens and describe new materials, including their size, shape, external modifications, matrix composition and rare inclusions. Regarding size and shape, the measurements of 152 specimens show that the Triassic coprolites of Brazil follow a normal distribution, in which length and width are positively correlated variables, so that they are not useful for taxonomic purposes. Notwithstanding, two ichnotaxa, Santamariacopros elongatus and Rhynchocopros soutoi, were previously described from the Middle/Upper Triassic Santa Maria Formation, based mainly on morphological (length/width ratio) and preservational features, but we discuss here the validity of such taxa. Once the Santa Maria Formation encompasses at least three tetrapod Assemblage Zones (AZ), Dinodontosaurus AZ, Santacruzodon AZ and Hyperodapedon AZ (from the oldest to the youngest, respectively), it is difficult to attribute these coprolites to any specific animal producers. In addition, the rarity of inclusions and the carbonated composition of the coprolites, related to early diagenetic processes, complicate this attribution too. Nevertheless, some rare inclusions as a hair‐like structure and a parasite egg were found in this study. Although the coprotaxonomy fails to represent the Santa Maria Formation coprolites and the recognition of their producers is a problematic task, these fossil dungs are important elements in the knowledge of the Middle to Late Triassic environments of southern Brazil. [ABSTRACT FROM AUTHOR]

Mato Grosso State is the main area of paleontological investigations in central Brazil, especially regarding Upper Cretaceous beds. Fossil collection in the surroundings of the Morro do Cambambe started as early as late nineteenth century, but prospections and studies are still ongoing. This contribution presents new dinosaur specimens recovered from Upper Cretaceous outcrops of the southeastern portion of Mato Grosso State. These remains enabled the first report of a megaraptoran theropod based on a vertebral centrum and the description of abelisaurid (a fragmentary tooth) and titanosaur remains (a tooth and a fragment of a dorsal vertebra). Based on the amount of compiled reports of tetrapod remains from Mato Grosso, mainly from meeting abstracts and technical reports, the evidence at hand indicates a diverse Upper Cretaceous tetrapod assemblage still poorly explored in comparison to other Upper Cretaceous units of Brazil and Gondwana, in general. [ABSTRACT FROM AUTHOR]

Tetrapod tracks in eolianites are widespread in the fossil record since the late Paleozoic. Among these ichnofaunas, the ichnogenus Chelichnus is the most representative of the Permian tetrapod ichnological record of eolian deposits of Europe, North America and South America, where the Chelichnus Ichnofacies often occurs. In this contribution, we describe five sets of tracks (one of which is preserved in cross-section), representing the first occurrence of Dicynodontipus and Chelichnus in the “Pirambo´ia Formation” of southern Brazil. This unit represents a humid desert in southwestern Pangea and its lower and upper contacts lead us to consider its age as Lopingian–Induan. The five sets of tracks studied were compared with several ichnotaxa and body fossils with appendicular elements preserved, allowing us to attribute these tracks to dicynodonts and other indeterminate therapsids. Even though the “Pirambo´ia Formation” track record is sparse and sub-optimally preserved, it is an important key to better understand the occupation of arid environments by tetrapods across the Permo–Triassic boundary. [ABSTRACT FROM AUTHOR]

The Guará Formation (Paraná Basin, southern Brazil) is an Upper Jurassic unit that yielded a dinosaur ichnoassemblage composed of theropod, ornithopod, and sauropod tracks. A new set of footprints is described herein and its major features are heteropody, paraxony, and both manual and pedal tetradactyly, among others. Using ichnological, osteological, and stratigraphic approaches, we interpret these tracks as produced by an ankylosaur dinosaur. The record of these armored dinosaurs in South America is scarce and restricted to the Cretaceous units of Argentina, Bolivia, and Brazil. Therefore, the presence of these tracks in the Guará Formation provides the oldest evidence of ankylosaurs in western Gondwana and the first uncontroversial record of this group in Brazil. In addition, a comparison between the Guará Formation fossil record and other Kimmeridgian-Tithonian dinosaur-bearing units worldwide indicates that more efforts are needed to better understand the geographical distribution of Late Jurassic dinosaurs. [ABSTRACT FROM AUTHOR]

Fossil sites from Brazil have yielded specimens of spinosaurid theropods, among which the most informative include the cranial remains of Irritator, Angaturama, and Oxalaia. In this work some of their craniodental features are reinterpreted, providing new data for taxonomic and evolutionary issues concerning this particular clade of dinosaurs. The mesial-most tooth of the left maxilla of the holotype of Irritator is regarded as representing the third tooth position, which is also preserved in the holotype of Angaturama. Thus, both specimens cannot belong to the same individual, contrary to previous assumptions, although they could have been the same taxon. In addition, the position of the external nares of Irritator is more comparable to those of Baryonyx and Suchomimus instead of other spinosaurine spinosaurids. In fact, with regards to some craniodental features, Brazilian taxa represent intermediate conditions between Baryonychinae and Spinosaurinae. Such a scenario is corroborated by our cladistic results, which also leave open the possibility of the former subfamily being non-monophyletic. Furthermore, the differences between spinosaurids regarding the position and size of the external nares might be related to distinct feeding habits and degrees of reliance on olfaction. Other issues concerning the evolution and taxonomy of Spinosauridae require descriptions of additional material for their clarification. [ABSTRACT FROM AUTHOR]

The dental anatomy of Candelariodon barberenai from the Dino donto saurus Assemblage Zone (Pinheiros-Chiniquá Sequence, Santa Maria Supersequence, late Ladinian-early Carnian) of south Brazil, is redescribed. Candelariodon was originally classified as Eucynodontia incertae sedis and our analysis recovered this taxon deeply nested within Probainognathia, as the sister taxon of Potheriodon plus Prozostrodontia. The lower postcanine dentition of Candelariodon has several apomorphies shared with Prozostrodon, Santacruzgnathus, Brasilodon/Brasilitherium, and some basal mammaliaforms (Morganucodon, Megazostrodon), such as a lingual cingulum with discrete cusps e and g and two distinct morphologies in the tooth row. The reinterpretation of Candelariodon as a probainognatian cynodont more derived than Probainognathus and the rich Brazilian fossil record document an important adaptive radiation of non-mammaliaform prozostrodontians and closely related forms prior to the origin of the mammaliaform clade. [ABSTRACT FROM AUTHOR]

In this contribution we report the first occurrence of the enigmatic African probainognathian genus Aleodon in the Middle-early Late Triassic of several localities from the state of Rio Grande do Sul in southern Brazil. Aleodon is unusual among early probainognathians in having transversely-expanded postcanine teeth, similar to those of gomphodont cynognathians. This genus was previously known from the Manda Beds of Tanzania and the upper Omingonde Formation of Namibia. The Brazilian record of this genus is based upon multiple specimens representing different ontogenetic stages, including three that were previously referred to the sectorial-toothed probainognathian Chiniquodon theotonicus. We propose a new species of Aleodon (A. cromptoni sp. nov.) based on the specimens from Brazil. Additionally, we tentatively refer one specimen from the upper Omingonde Formation of Namibia to this new taxon, strengthening biostratigraphic correlations between these strata. Inclusion of A. cromptoni in a phylogenetic analysis of eucynodonts recovers it as the sister-taxon of A. brachyrhamphus within the family Chiniquodontidae. The discovery of numerous specimens of Aleodon among the supposedly monospecific Chiniquodon samples of Brazil raises concerns about chiniquodontid alpha taxonomy, particularly given the extremely broad geographic distribution of Chiniquodon. The discovery of Brazilian Aleodon and new records of the traversodontid Luangwa supports the hypothesis that at least two subzones can be recognized in the Dinodontosaurus Assemblage Zone. [ABSTRACT FROM AUTHOR]

In this contribution, we report a distal portion of a left humerus that likely belongs to an indeterminate basal archosauromorph from the Guadalupian (mid-Permian) Rio do Rastro Formation (Paraná Basin) of southern Brazil. A precise taxonomy of the fragmented and isolated humerus UFRGS-PV-0546-P is not warranted at generic nor familiar level but, likely, this specimen belongs to an Archosauromorpha due to the lack of both the entepicondylar and the ectepicondylar foramina. The narrow distal end of the humerus, the rounded radial and ulnar condyles, and the moderately developed supinator process with a shallow ectepicondylar groove (not notched) are features reminiscent of tanystropheids rather than that of other archosauromorphs. This material likely represents the first and oldest Permian archosauromorph from South America and indicates the presence of this lineage before the P/T boundary. [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]

Stereospondyls are a diverse and morphologically distinctive clade of basal tetrapods that rapidly reached a global distribution and high abundance during the Early Triassic. Yet, the first stereospondyls appeared in the Middle- Late Permian of Gondwana, mostly represented by Rhinesuchidae. A ustralerpeton cosgriffi is a long-snouted representative of the group and one of the most complete temnospondyls known from the Permian of South America. The elements attributed to Au . cosgriffi were recovered from the Middle- Late Permian deposits of the Rio do Rasto Formation ( Paraná Basin), in the Serra do Cadeado area of Brazil. Here, we review the cranial anatomy of the species, providing a comparative redescription, new anatomical data and previously unrecognized characters. A ustralerpeton cosgriffi is nested within Rhinesuchidae based on the anatomy of the tympanic cavity, but its long-snouted condition is unique amongst rhinesuchids. Based on the recovered information and new morphological data, the systematic position of Au . cosgriffi was assessed using a new matrix of 221 characters; of which 196 were selected from previous studies and the remaining are newly proposed. The results show Rhinesuchidae divided into Rhinesuchinae and Australerpetinae. A unique tympanic cavity formed by a well posteroventrally projected tabular horn, stapedial groove, well-developed oblique crest on the pterygoid, and a dorsal pterygoid crest (new term) characterizes the ear region of Rhinesuchidae. A ustralerpeton cosgriffi is the only undisputed Rhinesuchidae record outside southern Africa and the first long-snouted Stereospondyli, and thus is useful in helping to understand the diversification of the stereospondyls during the Middle/ Late Permian of Gondwana. [ABSTRACT FROM AUTHOR]

The view of spinosaurs as dinosaurs of semi-aquatic habits and strongly associated with marginal and coastal habitats are deeply rooted in both scientific and popular knowledge, but it was never statistically tested. Inspired by a previous analysis of other dinosaur clades and major paleoenvironmental categories, here we present our own statistical evaluation of the association between coastal and terrestrial paleoenvironments and spinosaurids, along with other two theropod taxa: abelisaurids and carcharodontosaurids. We also included a taphonomic perspective and classified the occurrences in categories related to potential biases in order to better address our interpretations. Our main results can be summarized as follows: 1) the taxon with the largest amount of statistical evidence showing it positively associated to coastal paleoenvironments is Spinosauridae; 2) abelisaurids and carcharodontosaurids had more statistical evidence showing them positively associated with terrestrial paleoenvironments; 3) it is likely that spinosaurids also occupied spatially inland areas in a way somehow comparable at least to carcharodontosaurids; 4) abelisaurids may have been more common than the other two taxa in inland habitats. [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]