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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]

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

The 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]

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

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]

Access to the geochemical conditions of paleoenvironments is made through the analysis of the chemical composition of the hydroxyapatite of fossil bones. This is because the bones were able to incorporate chemical elements from adjacent fluids into their pores and channels during the fossildiagenesis process, and as a result, have their original apatite substituted. The main goal of the present study was to seek geochemical signatures in bones and related sedimentary rocks from three well-known fossiliferous units of the Paraná Basin in southern Brazil: Irati Formation, Cisuralian (three bones/rocks sampled); Rio do Rasto Formation, Guadalupian (three bones/rocks sampled) and Santa Maria Supersequence, Late Ladinian–Early Norian (nine bones/rocks sampled). Fossils and rocks were analyzed by ICP-MS. Although the Permian fossil and rock samples (from Irati + Rio do Rasto Formations) have variations among them, some geochemical parameters are common (high Be–Co–Cu–Zn–Y–W–Pb contents). This composition differentiates them from the Triassic fossils and rocks (from Santa Maria Supersequence - high contents of V–As–Ba). The P content (essential in apatite) was used to determine the degree of preservation of the studied material. The better-preserved Permian specimen has a mean = 434.19 ratio (P content of fossil bones/P content of rock) and the lowest ratio = 1.87. Within the Triassic specimens, the better preserved has ratio = 205.64 and lowest = 2.24. In Permian specimens, Y shares similar ionic radio with Ca. For Triassic specimens, Y replaces Ca and As either replaces P or is associated with minerals in bone cavities. So, Y and As substitute Ca in the analyzed material. Therefore, the Permian samples are better preserved than the Triassic ones based on their P contents; Y and As can be used as indicators to differentiate Permian fossils (high Y values) from Triassic ones (high As values). These geochemical signatures can help in forensic cases, such as robbery or illegal transport of fossils. • Characterize some specific Permian and Triassic beds of the Paraná Basin (Brazil). • P contents, in fossils, can indicate its preservation degree. • The fossils from Irati Formation are better preserved than those from the other units. • Geochemical signatures can help in fossil's robbery or illegal transport cases. [ABSTRACT FROM AUTHOR]