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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]

Abstract The Paraná Basin represents an important sedimentation episode that occurred in the south margin of Gondwana during the Paleozoic and Mesozoic. The evolution of the basin extended mainly from the Ordovician to the Lower Cretaceous, with the continental break-up and the formation of the rift that originated the South Atlantic Ocean. The stratigraphy and depositional architecture of the Triassic strata in the southern portion of the basin are characterized by significant variations in depositional styles, interpreted as a response to tectonic and climatic changes. The sedimentary succession was grouped into three major chronostratigraphic intervals based on vertebrate ages (Late Permian-Early Triassic, Middle-Late Triassic and Early Cretaceous). The integration between stratigraphic and structural data with U-Pb ages of detrital zircon was used to investigate the origin and maximum depositional age of the Santa Maria Formation (Santa Cruz Sequence) which marks the Middle Triassic in the basin. This sequence is composed by conglomeratic sandstones with sandstones at the base, covered by a thick package of reddish mudstones containing vertebrate fossils. Paleocurrent data show N-NE sense of sedimentary transport, indicating that the sedimentation sources came from southwest Gondwana. The transition of the alluvial braidplain deposits of Sanga do Cabral Formation (Early Triassic) to the fluvial braided, floodplains and sinuous/anastomosing deposits, rich vertebrate fauna of the Santa Maria Formation (Middle-Late Triassic) indicates a sedimentation controlled by tectonic processes that uplifted the basement. The elongated positive feature of NW-SE strike named the Rio Grande Arch represented a topographic high and limited the deposition of the Triassic strata to south of the basin. The analyzed detrital zircon grains record the basement units located in southern Brazil and Uruguay. The main sources are the Tonian to Ediacaran rocks of the Dom Feliciano Belt and the sedimentary layers of the Paraná Basin deposited between the Carboniferous and the Permian that occur in the Sul-rio-grandense Shield, the source of the Paleozoic and Mesozoic age zircons. Archean to Mesoproterozoic ages are subordinate, between 2.7 and 2.0 Ga and 1.5–1.0 Ga. The siltstones of the upper portion of the sequence show elongated prismatic and euhedral zircon, aged 237 ± 1.5 Ma, defining the maximum deposition to the top of the Santa Cruz Sequence. These crystals zircon were deposited from ashes, probably originated from volcanic rocks of central and southern Argentina and associated with an extensional environment after the magmatism of the Choiyoi Province. Graphical abstract Image 1 Highlights • Triassic sedimentation controlled by tectonic processes. • U-Pb detrital zircon data show provenance of the Sul-rio-grandense Shield rocks area. • Permian zircon grains are associated to reworking of Paraná Basin rocks (Rio Bonito and Irati formations). • The ash fall zircons came from the Andean volcanism. • 237 Ma is the maximum deposition age of Santa Cruz Sequence (Santa Maria Formation). [ABSTRACT FROM AUTHOR]

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]

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 ‘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]

The first dicynodont reported for the Permian of South America is described in detail here. The specimen consists of a partial skull and associated lower jaws, collected from the Serra do Cadeado locality, Rio do Rasto Formation, Brazil. The specimen was assigned to the genus Endothiodon Owen in a preliminarily description published in the 1970s. This identification implied a direct correlation with some of the well-established biozones of the Beaufort Group, South Africa, where this taxon is known to occur. Although badly weathered, the Brazilian material preserves several features that allow us to confirm its assignment to Endothiodon, such as the pineal foramen situated on a boss, the bulbous swellings of the dentaries, a boss situated on the ventral margin of the jugal, the extensive number of dentary teeth and the upturned pointed beak of the lower jaw. However, this set of characters is not enough to establish a specific taxonomic assignment for the specimen, although it seems to be more closely related to E. bathystoma, E. uniseries and E. whaitsi than to E. mahalanobisi. The biostratigraphical correlations proposed for the tetrapod faunas of the Rio do Rasto Formation highlight the similarities between these associations and others from the Mid and Late Permian of South Africa and Eastern Europe. However, until now, these correlations are tentative because only a few faunal elements have been recovered from Brazil, and most of them lack stratigraphic data on the levels from where they were collected. Due to the presence of Endothiodon, at least part of the Rio do Rasto Formation can be correlated with deposits in India, Malawi, Mozambique, South Africa, Tanzania, Zambia and Zimbabwe. [ABSTRACT FROM AUTHOR]

A new and unusual specimen of a probable azhdarchoid pterosaur is described for the Early Cretaceous (Albian) Romualdo Formation of Brazil. The specimen consists of a palate that, although fragmentary, has a unique morphology differing from all other known pterosaurs with preservation of palatal elements. The new specimen probably indicates the presence of a yet undescribed pterodactyloid taxon for Romualdo Formation and brings new information on pterosaur diversity of this sedimentary unity. Mainly due to the rarity of pterodactyloid specimens with palate preservation, this structure has been overlooked in this clade. Here, we reassess the palatal anatomy of Pterodactyloidea, revealing an intriguing variety of morphotypes and evolutionary trends, some of them described here for the first time. The morphological disparity displayed by different pterodactyloid taxa may be further evidence of the presence of diverse feeding strategies within the clade. [ABSTRACT FROM AUTHOR]

A new neosuchian crocodylomorph, Susisuchus jaguaribensis sp. nov., is described based on fragmentary but diagnostic material. It was found in fluvial-braided sediments of the Lima Campos Basin, north-eastern Brazil, 115 km from where Susisuchus anatoceps was found, in rocks of the Crato Formation, Araripe Basin. S. jaguaribensis and S. anatoceps share a squamosal–parietal contact in the posterior wall of the supratemporal fenestra. A phylogenetic analysis places the genus Susisuchus as the sister group to Eusuchia, confirming earlier studies. Because of its position, we recovered the family name Susisuchidae, but with a new definition, being node-based group including the last common ancestor of Susisuchus anatoceps and Susisuchus jaguaribensis and all of its descendents. This new species corroborates the idea that the origin of eusuchians was a complex evolutionary event and that the fossil record is still very incomplete. [ABSTRACT FROM AUTHOR]

Abstract: In southern Brazil, the eolian facies of the Guará Formation (Late Jurassic) reveal footprints and trackways of vertebrates (dinosaurs), as well as burrows made by small vertebrates. All the footprints and trackways are preserved in dunes and sand sheets. The footprints made in the sand sheets are not well preserved due to intense trampling and can be distinguished only by the deformation of the sandstone laminations. In some cases it is possible to see this deformation in plan and in section. Tracks of theropods, ornithopods and middle-sized sauropods are present. Two footprints preserved in the foreset of a paleodune permitted recognition of slide structures and identification of the trackmaker, a theropod. Burrows horizontally across the foresets were found at this same paleodune. Ribbons of massive sandstone – interpreted as the partial filling of the base of the burrows – covered by little blocks of stratified sandstone – suggest the collapse of the burrow roof inward. There are no body fossils in the Guará Formation, consequently the preservation of these tracks provides unique evidence of widespread dinosaurs activity in southern Brazil near the end of the Jurassic. [Copyright &y& Elsevier]

A new rhynchosaur,Hyperodapedon hueneisp. nov., is described from the Upper Triassic Santa Maria Formation of the Paraná Basin, Brazil. The holotype is an almost complete skull and mandible, collected at Inhamandá, in the state of Rio Grande do Sul, Brazil. The diagnosis of the genusHyperodapedonHuxley is revised to include not onlyH. huxleyiLydekker andH. gordoniHuxley (as generally accepted), but also the new species described here, various specimens usually assigned to 'Scaphonyx fischeri' Woodward, and 'S'.sanjuanensisSill.H. hueneisp. nov. exhibits a number of plesiomorphic features and appears to be the least derived species ofHyperodapedon, forming a sister taxon to the remaining members of the genus. A preliminary phylogenetic analysis for the more derived rhynchosaurs is presented. 'Scaphonyx'sulcognathusAzevedo and Schultz represents the sister taxon ofHyperodapedon, while 'Rhynchosaurus'spenceriBenton is considered to be a more derived Middle Triassic rhynchosaur.key words: Rhynchosauria,Hyperodapedon, Triassic, Brazil. [ABSTRACT FROM AUTHOR]

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]

The Paraná Basin was filled by a sedimentary package deposited in successive sedimentation episodes related to the tectonic events that hit the SW portion of the Gondwana. The Triassic portion of this package, known worldwide for its continental tetrapod fauna, occurs only in the southern portion of the basin and is represented by 2 s-order sequences: the Sanga do Cabral Supersequence (SCS - Early Triassic) and the Santa Maria Supersequence (SMS - Middle-Late Triassic). The SCS fauna, including temnospondyls, parareptiles (mainly Procolophon), archosauromorphs, putative synapsids, and a number of indeterminate specimens, is traditionally considered Early Triassic and corresponds to the " Procolophon abundant zone" of the Karoo Basin (the upper levels of the Lystrosaurus AZ), in the upper Katberg Formation, which is Induan to early Olenekian in age. The sedimentary environment of the SCS is thought to be a wide alluvial plain, in which small and shallow channels spread northwards into a vast semiarid environment. By its turn, the Middle-Upper Triassic Santa Maria Supersequence is divided into four third-order sequences, from base to top: Pinheiros-Chiniquá, Santa Cruz, Candelária and Mata. Each of these sequences begins with fluvial deposition (low sinuosity rivers) that is overlain by transgressive shallow lacustrine deposits. The first three of these sequences present a very rich record of fossil tetrapods, including four successive faunal associations: Dinodontosaurus Assemblage Zone (Ladinian, within the Pinheiros-Chiniquá Sequence), Santacruzodon AZ (Ladinian/Carnian, in the Santa Cruz Sequence), Hyperodapedon AZ (Carnian) and the Riograndia AZ (early Norian), the latter two respectively at the base and top of the Candelária Sequence. In general, the lower portion of the package (Pinheiros-Chiniquá and Santa Cruz Sequences) was deposited under more basic and dried environmental conditions and are dominated by synapsids, while the top of the section (Candelária Sequence) is characterized by more acid and humid conditions and by a shift in the faunal content, with diapsids as dominating forms and presenting an increase of diversity compared to the lower biozones. • In Brazil, Triassic tetrapods are known only in the extreme south of the country. • The south Brazilian Triassic package includes four biozones based on tetrapods. • The lower tetrapod biozone of the Triassic package is Early Triassic and corresponds to the " Procolophon abundant zone" of the Karoo Basin. • Lower portion of the Middle-Late Triassic was deposited under more basic and dried environmental conditions and is dominated by synapsids. • Upper portion of the Middle-Late Triassic is characterized by more acid and humid conditions and presents an increase of diapsids compared to the lower portion. [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]

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]

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]

Knowledge on the faunal record from the mid-Cretaceous of northern South America has come mainly from the Araripe Basin, northeastern Brazil. However, the Cenomanian Alcântara Formation of the São Luís-Grajaú Basin has recently increased in paleontological importance. Regarding their non-avian dinosaur diversity, the formation has yielded body and trace fossils of spinosaurid, carcharodontosaurid, noasaurid, and maniraptoran theropods, rebbachisaurid and titanosaur sauropods, and possible ornithopods. Here, we report the first unequivocal record of an abelisaurid theropod from the Alcântara Formation, consisting of two shed tooth crowns from the Baronesa Beach locality. They are the oldest occurrence of Abelisauridae from Brazil. With this new record, the non-avian dinosaur assemblage from the Alcântara Formation is most similar to that of the Kem Kem Beds, as suggested by previous works and supported here by similarity analyses of mid-Cretaceous dinosaur-bearing units. Our results also indicate a faunal heterogeneity within northern South America, previously overlooked by studies of this whole landmass as a single sampling unit. We also suggest future approaches treat the dinosaur assemblage from each fossil site or formation as a particular sample unit instead of combining geographically and temporally distinct records. [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]

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]

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]

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]

A histological investigation of the feeding apparatus of a Stereosternum specimen revealed a great number of adaptations in the structure and insertion of teeth, to deal with breakage risks. The tooth wall is composed of different layers of dentine, varying in orientation and composition. This mixed arrangement may have increased tooth resistance to lateral tension. The tooth insertion also involves more than one mechanism. The teeth are located inside shallow tooth sockets and are held in place by a tripartite periodontium (composed of alveolar bone, cementum and possibly soft periodontal tissue) and accessory structures, here termed anchorage trabeculae (mainly composed of cementum). Fully grown teeth are ankylosed to the bottom of the tooth socket. The recognition of alveolar bone and cementum (and the possible presence of a soft periodontal ligament) reinforces the idea that these tissues were widespread among Amniota, not being exclusive to mammals and archosaurs. The adaptations identified here reinforce the hypothesis that Stereosternum was an active aquatic predator. [ABSTRACT FROM AUTHOR]

Sampling bias and repeated resampling can lead to misinterpretation of the taphonomic history of a fossiliferous deposit. This is the case of the Schoenstatt Sanctuary site (Santa Cruz do Sul, Rio Grande do Sul, Brazil), the type-locality and richest vertebrate fossil occurrence of the early Carnian Santacruzodon Assemblage Zone (Santa Cruz Sequence, Santa Maria Supersequence, Paraná Basin). This site is characterized by the abundance of traversodontid non-mammalian cynodonts, especially Santacruzodon hopsoni and Menadon besairiei (plus Massetognathus ochagaviae). The abundance of cranial remains in a 2.5 m-thick massive mudstone led earlier workers to conclude that the accumulation was biogenically controlled (e.g., selective scavenging). Here we propose a new taphonomic interpretation, based on re-investigation of >2700 fossils, collected at the site over the past 27 years. Rhizoliths and early diagenetic features (e.g., micrite crusts) indicate the occurrence of several pedogenically modified levels within the outcrop. This occurrence of multiple calcic vertisols, added to the absolute dating already obtained for the Santa Cruz Sequence, may be related to the global Carnian Pluvial Event. Re -analysis of the historical fossil collections from this site provides the basis for a biostratigraphic division of Massetognathus (lower strata), Menadon (lower and middle strata) and Santacruzodon (upper strata), leading to a three-fold sub-zonation of the assemblage zone (AZ). The taphonomic mode of some Menadon skeletons suggest they were scattered by floodwaters, while burrowing and co-habitation behaviours are indicated for Santacruzodon. The revision led also to identification of at least 12 new non-cynodont morphotypes, including kannemeyeriiform dicynodont (already known for the AZ), archosauriform, rhynchosaurian and procolophoid taxa, increasing the faunal diversity of outcrop and Santacruzodon AZ. • Taphonomic revision of the Santacruzodon AZ type-locality. • Rhizoliths and diagenetic features indicate multiple depositional events. • Possible three-fold sub-zonation for this AZ. • Evidence for burrowing and gregarious behaviour in Santacruzodon. • First occurrences of rhynchosaurs and procolophonoids in Santacruzodon AZ. [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]

Pinheiro F.L., Horn B.L.D., Schultz C.L., de Andrade J.A.F.G. and Sucerquia P.A., 2012: Fossilized bacteria in a Cretaceous pterosaur headcrest. Lethaia, Vol. 45, pp. 495-499. We report herein the first evidence of bacterial autolithification in the Crato Formation of Araripe Basin, Brazil. The fossilized bacteria are associated with a tapejarid pterosaur skull, replacing the soft-tissue extension of the headcrest. EDS analyses indicate that the bacteria were replaced by phosphate minerals, probably apatite. The bacterial biofilm was likely part of the prokaryotic mat that decomposed the pterosaur carcass at the bottom of the Araripe lagoon. This work suggests that bacterial autolithification could have played a key-role on soft-tissue preservation of Crato Formation Lagerstätte. □ Bacterial autolithification, Crato Formation, phosphatization, pterosaur, soft-tissue preservation. [ABSTRACT FROM AUTHOR]

Until now the Doswelliidae was considered a monospecific family including Doswellia kaltenbachi from the Late Triassic of North America. The phylogenetic position of this taxon remained enigmatic until recently, when a sister-group relationship with the Proterochampsidae was suggested. In the present contribution we describe the new doswelliid species et from the Middle-Late Triassic of Brazil. A cladistic analysis recovered Archeopelta, Doswellia, and Tarjadia within a monophyletic group of basal archosauriforms, the Doswelliidae. The monophyly of this family is supported by the presence of osteoderm ornamentation that is coarse, incised, and composed of regular pits and the presence of an unornamented anterior articular lamina. Archeopelta is more closely related to Doswellia than to other archosauriforms by the presence of basipterygoid processes anterolaterally orientated, dorsal centra with a convex surface, width of the neural arch plus ribs of the first primordial sacral that are three times the length of the neural arch, and iliac blade laterally deflected, with strongly convex dorsal margin, and a length less than three times its height. The phylogenetic analysis indicates that Doswellidae is the closest large monophyletic entity to Archosauria, which achieved a wide palaeolatitudinal distribution during the late Middle and Late Triassic time span. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, , 839-871. [ABSTRACT FROM AUTHOR]

The tooth arrangement of hyperodapedontine rhynchosaurs shows clear patterns of morphological derivation, which can be summarized as three main apomorphic trends: the increase in the number of tooth rows lateral to the main maxillary groove, the loss of dental structures (medial groove and lingual teeth) medial to the main maxillary groove, and the loss of dental structures (medial crest and lingual teeth) medial to the main dentary crest. The analysis of these trends from a heterochronic viewpoint reveals that acceleration was the most probable process involved in the increase in number of the lateral maxillary tooth rows, while the loss of the medial structures of the maxilla and dentary seem to be related respectively to neoteny and post-displacement. Both peramorphic and paedomorphic processes are, therefore, thought to have directed the main modifications seen in the tooth arrangement of the hyperodapedontine rhynchosaurs. Heterochrony plays an important role in the evolution of the Late Triassic rhynchosaurs, which are differentiated mainly on the basis of their dental morphology. [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]

The search for orbital cycles preserved in the sedimentary record is at the forefront of the refinement of the Geologic Time Scale. Semi-enclosed to restricted environments and epicontinental seas are suited for this type of analysis because they are very responsive to the climate conditions around the basin depocenter. This study presents the first astronomical time scale for the late Paleozoic Irati-Whitehill Sea (southern Gondwana – Paraná basin) using downhole logging of HV-44-RS. Applying orbital tuning and statistical null hypothesis techniques over the natural gamma-ray, we built two floating astronomical time scales for the same record and anchored them on a new U Pb (bentonite) numerical age of 280.8 ± 1.4 Ma. Our results place the Irati Formation between 283.68 and 280.50 ± 2.98 (orbital tuning) and 284.27–280.47 ± 1.41 Ma (null hypothesis), giving the vast epicontinental Irati-Whitehill Sea its most precise minimum duration so far of 3.16 ± 1.02–3.80 ± 0.1 Myr during the late Cisuralian. Spectral analysis suggests a depositional pattern strongly modulated by long (405-kyr) and short (∼ 100-kyr) eccentricity cycles. As an exercise, we compare one of the produced astronomical age models and recently calculated eccentricity solutions that reach the late Paleozoic interval (ZB20d). Such comparison shows a remarkable correlation in variability and amplitude with this eccentricity solution. Astronomical forcing is also related to black shale accumulation with periods of high organic carbon lasting ∼405 kyr and occurring every two long eccentricity cycles after maximum regressive surface, demonstrating a predictive pattern behind these late Cisuralian regional anoxia. Our approach indicates that the Irati Formation and other correlative southern Gondwana basins are a hotspot for cyclostratigraphy still underexplored. Furthermore, we contribute to verifying astronomical solutions in deep geological time. • The first application of cyclostratigraphy to the Irati Formation (Paraná Basin). • Orbital tuning and null hypothesis test indicate eccentricity-modulated deposition. • Two anchored astronomical time scales: 283.68 – 280.50 ± 2.98 and 284.27 – 280.47 ± 1.41 Ma. • Remarkable correlation with the new deep-time astronomical solution (ZB20d). • Black shale accumulation linked to sea level variation and Earth's 405-kyr cycle. [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]

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]

Abstract The Early Permian Irati Formation records sedimentation of a mixed carbonate-siliciclastic, storm-influenced ramp in a shallow and restricted epeiric sea. It is formally divided in the dark grey mudstones of the lower Taquaral Member, and alternating dark grey mudstones, bituminous black shales, and carbonates of the upper Assistência Member. The formation crops out from central to southern Brazil on the eastern border of the intracratonic Paraná Basin. Fossils of mesosaurid reptiles, pygocephalomorph crustaceans, and subordinate paleonisciform fish form dense concentrations within carbonate tempestites, interpreted as mass mortality events caused by storms. The present study describes the Passo do São Borja outcrop and five new locations, along with 11 drill cores of the complete Irati interval in the Rio Grande do Sul state, applying methods of facies analysis and sequence stratigraphy. Three fourth-order sequences within the Irati Formation were recognized, termed sequences 1, 2, and 3 (S1, S2, S3). S1 is broadly coincident with the Taquaral Member, and S2 and S3 with the Assistência Member. The upper two sequences are composed of a lowstand systems tract (LST), a transgressive systems tract (TST), and a highstand systems tract (HST), whereas the lower sequence lacks a LST. Sequence boundary SB2 was interpreted as coincident with a third-order sequence boundary. Mesosaurid and pygocephalomorph concentrations occur only in S3. Fossil occurrences and concentration were found to be strongly controlled by facies and sequence stratigraphy. Paleonisciform fish fossils are considerably more common at the early HST of S2 and S3, resulting from balanced sedimentation to accommodation rates. Pygocephalomorphs compose intraclasts concentrated in grainstone proximal tempestites of the LST in S3. They are the result of mass mortality events and background bioclastic input, enhanced by firmground formation (hiatal concentration) and subsequent storm reworking. Mesosaurids are also concentrated in grainstone tempestites of the LST, but in cores they were mostly found in distal tempestites of the TST, becoming more common towards the maximum transgressive surface (MTS). Their accumulation is also the result of mass mortality and background sedimentation, enhanced by sediment omission (hiatal concentration) of a severely sediment starved TST (culminating in a condensed section near the MTS), and subsequent storm reworking. Highlights • Interconnected taphonomic models for marine vertebrates and invertebrates in a sequence stratigraphy framework. • Detailed facies description of an unusual mixed carbonate-siliciclastic epeiric ramp with bituminous black shales. • Conceptual review and considerations for third-order sequence stratigraphy of the Paraná Basin. • Discussion of physical factors controlling occurrence and accumulation of marine vertebrate, and invertebrate fossils. • Recognition of lowstand systems tracts in a carbonate ramp. [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]

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]

Triodus is a well-known genus of Xenacanthiformes, previously recorded from the late Bashkirian (Lower Pennsylvanian, Carboniferous) to the middle Artinskian (Cisuralian, Permian), mainly from Laurasian deposits (Europe and USA). For the first time, this genus is recorded from the Western Gondwana, based on isolated teeth that are referred to Triodus richterae sp. nov. The new species were found associated with other shark teeth (another xenacanthiforms and a possible euselachian), palaeoniscoid teeth and scales, labyrinthodont teeth, tetrapod bony remains, macroscopic charcoal and leaf fragments. This fossil assemblage was collected in a conglomerate layer from the Barro Alto site (São Gabriel municipality, Rio Grande do Sul State, Brazil), with an estimated Capitanian age, from the Morro Pelado Member, Rio do Rasto Formation, Paraná Basin. The new species has teeth with an almost oval base and the aboral surface has a smooth concavity and a rounded to horseshoe-shaped basal tubercle. The coronal surface of these teeth has a tricuspid crown, a rhomboid-shaped coronal button with rounded edges with a lingually directed shaft and some oral foramina predominantly situated at the lingual margin of the base and flanking the lingual shaft. The lateral cusps bear a variable number of non-branching vertical cristae, distributed from the apex to their proximal portion, making the transversal section of these cusps asterisk-shaped. Microstructurally, these teeth have both base and cusps composed of orthodentine with an opened pulp cavity. T. richterae sp. nov. represents the youngest species of Triodus , considering it comes from Capitanian (late Guadalupian) beds, which are at least 15 Ma younger than T. kraetschmeri , the previously youngest species of this genus. The depositional interpretation, as well as the fossil assemblage in the type locality of the new species and of the Rio do Rasto Formation as a whole, indicates another freshwater record for xenacanthid sharks. [ABSTRACT FROM AUTHOR]

The Sanga do Cabral Supersequence (SCS), comprises the Brazilian Sanga do Cabral Formation (SCF) and the Uruguayan Buena Vista Formation (BVF). So far, the SCS has yielded temnospondyls, parareptiles, archosauromorphs, putative synapsids, and a number of indeterminate specimens. In the absence of absolute dates for these rocks, a biostratigraphic approach is necessary to establish the ages of the SCF and the BVF. It is well established that the SCF is Early Triassic mainly due to the presence of the widespread Gondwanan reptile Procolophon trigoniceps. Conversely, the age of the BVF is subject of great controversy, being regarded alternatively as Permian, Permo-Triassic, and Early Triassic. The BVF has yielded the definite procolophonid Pintosaurus magnidentis . Procolophonoidea is one of the most diverse and conspicuous terrestrial tetrapod groups of the Lower Triassic Lystrosaurus Assemblage Zone in the Karoo Basin of South Africa, which preserves tetrapods from the aftermath of the end-Permian extinction event. Based on a previous interpretation that the fauna of the BVF is Permian, and in the reinterpretation of disarticulated vertebrae from SCF with ‘swollen’ neural arches as belonging to either seymouriamorphs or diadectomorphs, it was recently suggested that at least part of the SCF is Permian in age, which prompted this comprehensive reevaluation of both SCS's faunal content and geology. Moreoever, new, strikingly large procolophonid specimens (skull, vertebra, and a mandibular fragment) from the SCF are described and referred to the genus Procolophon . The large procolophonid vertebra described here contradicts the recent hypothesis that similar specimens from the SCF belong to seymouriamorphs or diadectomorphs, because its morphology is consistent with that found in Procolophon . There is not a single diagnostic specimen that supports the inference of Permian levels in the SCS. Accordingly, because all diagnostic and biostratigraphically informative fossils from the SCF and the BVF are either Early Triassic or restricted to the Triassic, we conclude that the available biostratigraphic data reinforce an Early Triassic age assignment to the SCS. [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]

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]

A new fossil site, called ‘Canafístula 01’, has yielded the first archosaur remains from the Berriasian–Valanginian Feliz Deserto Formation, Sergipe-Alagoas Basin, northeastern Brazil. Most of them comprise crocodylomorph teeth and osteoderms. However, the most remarkable specimen is a partial tooth assigned to Spinosauridae, based on the unique combination of the following features: (1) unfluted root almost as wide as the crown base, with a large pulp cavity; (2) straight and more regularly spaced flutes of the crown, formed by both the enamel and the dentine; and (3) unserrated carina on a mesiodistal plane coinciding with the main plane of curvature of the crown. This is the oldest occurrence of a spinosaurid from South America. In addition, given the unserrated distal carina, this tooth might have closer affinities with the subfamily Spinosaurinae, which would also represent the oldest spinosaurine record worldwide. Thus, the occurrence of a spinosaurid in the Feliz Deserto Formation points to a latent potential for new relevant findings in northeastern Brazil and the necessity for greater collection efforts in this region. [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]

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]

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]

Caiman brevirostriswas described based on the basis of late Miocene materials that included a rostral fragment and a right mandibular ramus, but photographs were not provided at that time. In this study, for the first time, we present the holotype materials of this species and a new specimen from the late Miocene of southwestern Amazonia, Brazil. The diagnosis was expanded, and a phylogenetic analysis was conducted. The results from the analysis consistently recoverCaiman brevirostriswithin a clade that includesCaiman latirostris,Caimancf.C. lutescens, andMelanosuchus. The oldest fossil record of the genusCaimanis from the Oligocene of southeastern Brazil, but these materials are regarded in this study as a nomen dubium due to the absence of any diagnostic features for the specimen. Thus, the oldest record considered valid by this study derives from the middle Miocene of Colombia and may represent the initial radiation of the genus. SUPPLEMENTAL DATA—Supplemental materials are available for this article for free atwww.tandfonline.com/UJVP [ABSTRACT FROM AUTHOR]

Krapovickas, V., Mancuso, A.C., Marsicano, C.A., Domnanovich, N.S. & Schultz, C.L. 2013: Large tetrapod burrows from the Middle Triassic of Argentina: a behavioural adaptation to seasonal semi-arid climate? Lethaia, Vol. 46, pp. 154-169. We report the discovery of large burrow casts in the early Middle Triassic Tarjados Formation, at Talampaya National Park, north-western Argentina. Facies analysis indicates the burrows are preserved in sandbars deposited by an ephemeral river under semi-arid and seasonal climatic conditions. The structures are mostly preserved in longitudinal cross-section and consist of an opening, an inclined tunnel (ramp), and a terminal chamber. The ramp is 8-14 cm in height, up to 130 cm in length and penetrates 49-63 cm bellow the palaeosurface with an inclination of 22°-30°. We studied burrow cast dimensions, overall architectural morphology, surficial marks, and compared them with other large burrows of both invertebrate and vertebrate origin. A tetrapod origin of the burrow casts was established based on: distinctive architecture, and size, which is more than twice the most common size range for large terrestrial invertebrate burrows. Comparison with other Upper Permian and Triassic tetrapod burrows allows us to identify three general morphological groups: (1) simple inclined burrows; (2) helical burrows; and (3) burrow network complexes, representing different behaviours. A study of tetrapod body fossils preserved within other Upper Permian and Triassic burrows shows that the Tarjados structures were most likely produced by non-mammalian cynodonts. The environmental and climatic context suggests that aridity and seasonality played a fundamental role selecting burrowing behaviour in therapsids and that by the Early-Middle Triassic their burrowing behaviour attained a complexity comparable to modern mammals. □ Argentina, behaviour, palaeoclimate, Permo-Triassic, Tarjados Formation, Tetrapod burrows. [ABSTRACT FROM AUTHOR]

Remains of parasites in vertebrates are rare from the Mesozoic and Paleozoic. Once most parasites that live in - or pass through - the gastrointestinal tract of vertebrates, fossil feces (coprolites) or even intestinal contents (enterolites) can eventually preserve their remains. Here we announce the discovery of a spiral shark coprolite from the Paleozoic bearing a cluster of 93 small oval-elliptical smooth-shelled structures, interpreted as eggs of a tapeworm.The eggs were found in a thin section of an elasmobranch coprolite. Most of the eggs are filled by pyrite and some have a special polar swelling (operculum), suggesting they are non-erupted eggs. One of the eggs contains a probable developing larva. The eggs are approximately 145-155 φm in length and 88-100 μm in width and vary little in size within the cluster. The depositional and morphological features of the eggs closely resemble those of cestodes. Not only do the individual eggs have features of extant tapeworms, but their deposition all together in an elongate segment is typical to modern tapeworm eggs deposited in mature segments (proglottids). This is the earliest fossil record of tapeworm parasitism of vertebrates and establishes a timeline for the evolution of cestodes. This discovery shows that the fossil record of vertebrate intestinal parasites is much older than was hitherto known and that the interaction between tapeworms and vertebrates occurred at least since the Middle-Late Permian. [ABSTRACT FROM AUTHOR]