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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]

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 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]

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]

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 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]

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]

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]