Recommendation of: A database of conodont occurrences between the Changhsingian (Late Permian) and the Spathian (Olenekian, Early Triassic). Round#3

Author response of: A database of conodont occurrences between the Changhsingian (Late Permian) and the Spathian (Olenekian, Early Triassic). Round#2

Abstract The order Cyclida is a distinct group of crustaceans. However, our knowledge of cyclidan crustaceans is very limited due to their rarity in the fossil record. Usually, only the hard carapaces are preserved, while their antennules and appendages are extremely rare. Here, we describe a new cyclidan species, Yunnanocyclus fortis sp. nov., on the basis of three well‐preserved specimens from the Early Triassic Guiyang biota, which is known as the oldest Mesozoic lagerstätte. The new species has an ovoid carapace, narrow and smooth marginal rim, a pair of antennules, antennae and seven pairs of thoracomeres. Using μ‐XRF analysis, we found that the new species has a pair of strongly ovoid mandibles. The discovery of a new species from South China expands the palaeogeographic distribution of Early Triassic cyclidans. Combining the new species and other reported Cyclida morphological data, we constructed the morphospace of Cyclida using NMDS analysis. The morphospace of Cyclida shows no significant morphological innovations from the Carboniferous to the Triassic, and the high degree of morphological divergence in the Carboniferous supports the early burst model.

Sa Thay high - K granites, situated in the western region of Kontum massif, are predominantly composed of biotite granite and biotite - hornblende granite. The major mineral composition comprises plagioclase (26 – 60%), K - feldspar (8 – 22%), quartz (15 – 33%), biotite (3 – 7%), and hornblende (7 – 10%). Accessory minerals include titanite, apatite, zircon, and magnetite. Their SiO 2 concentration varies from 66.81 to 78.14 wt.%, total alkali content ranges from 6.30 to 6.46 wt.%, and A/CNK ratio goes from 0.99 to 1.09. The granites indicate the relative enrichment of large - ion lithophile elements (Sc, Rb, and K), and the negative anomalies for Nb, Ta, and Ti in mantle - normal ized diagrams. The P 2 O 5 content decreases with the increase of SiO 2 content, whilst there is a coupled increase in Th and Tb contents typical of I - type granites. The U - Pb zircon age was determined by the LA - ICP - MS method as 256.7 Ma, corresponding to the Late Permian stage. The ε Hf (t) values, together with the zircon Hf model ages (T DM2 ) of 1440 – 1861 Ma, suggest that parental magma for the Sa Thay granite is derived from the partial melting of Paleoproterozoic mantle rocks and the input of crustal component, following the subduction - collision processes that resulted in the amalgamation of the South China and Indochina blocks (Indosinian Orogeny). Th is geological activity led to the closure of a branch of the Paleo - Tethys Ocean along the Song Ma suture zone during the Late Permian to Early Triassic period.

Decision Revise: A database of conodont occurrences between the Changhsingian (Late Permian) and the Spathian (Olenekian, Early Triassic). Round#2

Review of: A database of conodont occurrences between the Changhsingian (Late Permian) and the Spathian (Olenekian, Early Triassic). Round#2/Reviewer#1

Author response of: A database of conodont occurrences between the Changhsingian (Late Permian) and the Spathian (Olenekian, Early Triassic). Round#1

Probnis sauvanyaensissp. nov., the first representative of the ‘grylloblattodean’ family Probnidae from the Iberian Peninsula, is described from the middle to ?upper Permian outcrop of Sauvanyà in the Catalan Pyrenees. The family is otherwise represented by two additional species of Probnis from the ?middle Permian of the USA and by a single genus and species from the ?Lower Triassic of Ukraine. As is known from outcrops with rather extreme climates, the family may have survived the global warming of the Permian–Triassic crisis. We also describe a roachoid of the family Spiloblattidae from the same outcrop as the second representative of this family from the Iberian Peninsula.

Decision Revise: A database of conodont occurrences between the Changhsingian (Late Permian) and the Spathian (Olenekian, Early Triassic). Round#1

The Early–Middle Triassic actinopterygian genus Pteronisculus is part of the Triassic Early Fish Fauna (TEFF) – a cosmopolitan group of taxa that thrived in the aftermath of the end-Permian mass extinction. Pteronisculus is considered an important non-neopterygian outgroup taxon in many works dealing with the interrelationships of early crown actinopterygians, but the phylogenetic relationships of many TEFF genera are debated, with the topology of the lineages giving rise to crown actinopterygians consequently unclear. This is despite exceptional, three-dimensional preservation of an abundance of fossils associated with TEFF fishes. Pteronisculus gunnari from the Induan (Early Triassic) Kap Stosch Formation, East Greenland, is known in less detail than other species of the genus. Here, we use X-ray micro-computed tomography to comprehensively redescribe the three-dimensionally preserved holotype of P. gunnari, including a detailed description of the internal anatomy, including the braincase, hyoid arch and gill arches. The specimen shows morphological features previously undescribed for the genus, including paired premaxillae, medially directed teeth on the palate, canals for the buccohypophysial canal and internal carotids piercing the parasphenoid, and numerous parotic toothplates. Its body scale covering is complete, but the braincase and palatoquadrate are ossified as multiple elements, indicating that the specimen was not fully mature and allowing new insights into ossification patterns and ontogenetic development of the skeleton of non-neopterygian actinopterygians. These new anatomical data enrich our understanding of both the morphological complexity and the interrelationships of actinopterygians from the TEFF.

Review of: A database of conodont occurrences between the Changhsingian (Late Permian) and the Spathian (Olenekian, Early Triassic). Round#1/Reviewer#2

Review of: A database of conodont occurrences between the Changhsingian (Late Permian) and the Spathian (Olenekian, Early Triassic). Round#1/Reviewer#1

Review of: A database of conodont occurrences between the Changhsingian (Late Permian) and the Spathian (Olenekian, Early Triassic). Round#1/Reviewer#3

The tectonic evolution of Hainan Island during the Late Permian–Early Triassic period is still unclear. This study identified two types of basalts on the island and presented detailed geochronology, whole-rock geochemistry, and Hf isotope data of the Late Permian–Early Triassic basalts. U-Pb dating results indicated that baddeleyites and zircons of one sample from Group 1 basalts had formation ages of 256 ± 3 Ma and 255 ± 3 Ma, respectively, and two samples from Group 2 gave formation ages of 241 ± 2 Ma and 240 ± 3 Ma, respectively. Both groups are characterized by negative anomalies of Nb, Ta, and Ti, and enrichment in Ba, Th, U, and K. Group 1 belongs to sub-alkaline basalt and exhibited SiO2 contents ranging from 50.50% to 51.05%, with ΣREE concentration of 136–148 ppm. Hf isotope analysis showed that the εHf(t) values of baddeleyites and zircons were −10.56 to −4.70 and −14.94 to −6.95, respectively. Group 2 belongs to alkaline basalt and had a higher SiO2 content of 52.48%–55.49% and ΣREE concentration of 168–298 ppm. They showed more depleted Hf isotopic composition with εHf(t) values ranging from −2.82 to +4.74. These data indicate that the source area of Group 1 was an enriched mantle, likely derived from partial melting of spinel lherzolite mantle, and was modified by subduction-derived fluids. Group 2 was derived from depleted mantle, most likely originating from partial melting of garnet + spinel lherzolite mantle. They were contaminated by crustal materials and metasomatized by subduction-derived fluids with a certain degree of fractional crystallization. Comprehensive analysis suggests that Group 1 samples likely formed in an island arc tectonic setting, while Group 2 formed in a continental intraplate extensional (or initial rift) tectonic setting. Their formation was mainly controlled by the Paleo-Tethys tectonic domain. Group 1 basalts implied that subduction of the Paleo-Tethys oceanic crust lasted at least in the late Permian (ca. 255 Ma). Group 2 basalts revealed that the intra-plate extensional (or initial rift) stage occurred in the middle Triassic (ca. 240 Ma).

Abstract The timing and tectonic evolution of the closure of the Paleo-Tethys Ocean remain controversial, with dates ranging from Late Permian time to the Jurassic. Field mapping shows that the regional Kaixinling unconformity lies between the Upper Permian–Middle Triassic Nayixiong Formation and Middle–Upper Triassic Jiapila Formation in the North Qiangtang terrane of China. It is characterized by ~50-cm-thick weathering crust and abrupt changes in stratigraphy, lithofacies, and biological realms in the Kaixinling area. Zircon U-Pb dating of interlayered tuffs and siliceous dolomite accurately constrained formation of the Kaixinling unconformity to 243–239 Ma (Anisian–Ladinian). Detrital zircon grains from the Nayixiong and Jiapila formations show unimodal peak ages of 256 Ma and 302 Ma, respectively, which indicate provenance mainly from the northern magmatic arc. The absence of Pan-African ages rules out the basement source of the North Qiangtang terrane. These data, integrated with contemporaneous paleolatitude data from the North Qiangtang terrane, suggest that the development of the Kaixinling unconformity was associated with the tectonic transition from the Jinshajiang oceanic subduction-related retroarc foreland basin to the collision-related intracontinental foreland basin in the North Qiangtang. Thus, development of the unconformity marked the closure of the Jinshajiang Ocean at 243 Ma. Our results further highlight diachronous suturing of the Paleo-Tethys Ocean from the Ailaoshan Ocean in Early Triassic time to the Jinshajiang Ocean in Middle Triassic time, which signified the broader-scale reconstruction of the Pangea supercontinent.

The West Junggar area in the southwestern part of the Central Asian Orogenic Belt (CAOB), is one of the largest areas of growth of the Phanerozoic crust in the world that has experienced intense Late Paleozoic magmatic activity, where crust-mantle interaction is significant. The issue of crustal growth has long been regarded as one of the most fundamental in earth sciences. In light of the challenges posed by the composition of deep materials and the Late Paleozoic crustal growth in the West Junggar area, there is a continued need to systematically determine the spatial distribution characteristics of deep materials in the crust, analysis the growth pattern and growth volume of the crust, and enhance the Late Paleozoic tectonic evolution of the region. Focusing on granite type Sr-Nd-Pb-Hf isotopic mapping, this study found that the West Junggar area has the isotopic characteristics of high positive εHf (t) and εNd (t), low (87 Sr/86 Sr)i, and young crustal mode age, there is almost no old crystalline basement in the deep crust. During the Late Paleozoic, about 85% of West Junggar had 75%–95% crustal growth, dominated by lateral crustal growth and material recirculation; about 15% of the area (connected to the Jietebudiao area) had 50%–75% crustal growth, dominated by vertical crustal growth. The West Junggar area mainly experienced four orogenic stages in the Late Paleozoic. In the Early Carboniferous period (360–320 Ma), there was significant intra-oceanic subduction, involving a substantial amount of juvenile material in lateral crustal accretion. The Late Carboniferous-Early Permian period (320–294 Ma) is the post-orogenic extension stage, during which a massive amount of juvenile mantle source was added. This resulted in the most intense magmatism and crustal growth, which could have the growth of the crust potentially more than 75%. In the Early Permian period (294–272 Ma), there was an intracontinental evolution stage and a decrease in the participation of juvenile material. During the Early Permian-Early Triassic period (272–250 Ma), magmatic activity decreased significantly, where the southwestern region experienced high-temperature, low-pressure, crustal thinning extension. Despite this, the crust received juvenile material, and plutonic magma intrusion occurred.

Abstract The location and timing of the development of the suture zone between the Siberian and North China paleoplates in the northern part of the East Asian continent are controversial. This work involved petrological, geochronological, and geochemical analyses of the Xingshuwa ophiolitic mélange to determine the tectonic affinity of the Xar Moron River ophiolite belt and place further constraints on the late Paleozoic tectonic evolution of the northern part of the East Asian continent. Geological mapping and petrological analyses revealed various sizes of serpentinite, gabbro, basalt, chert, and oceanic-island/seamount and sandstone blocks, which represent a dismembered ophiolite and oceanic plate stratigraphy (OPS) above the ophiolite, in the matrix of deformed sandstones and siltstones. Geochemical analysis revealed multiple types of ophiolites and chert blocks in the mélange. The diversity of ophiolite and OPS components suggests that they represent fragments of a broad oceanic basin like today’s Pacific Ocean. Zircon U-Pb dating revealed that some ophiolite blocks formed in the Early Permian, and the youngest zircons in the matrix formed in the middle—Late Permian. Based on zircon U-Pb dating and regional geological data, the emplacement of the Xingshuwa ophiolitic mélange occurred in the Late Permian—Early Triassic. Compared with the other ophiolite belts in the southeastern Central Asian Orogenic Belt (CAOB), the Xar Moron River ophiolite belt has the youngest formation age, which is similar to that of the Solonker ophiolite belt. The Solonker—Xar Moron River ophiolite belt is suggested to represent the final suture zone between the Siberian and North China paleoplates, and indicates that the Paleo-Asian Ocean closed in the Late Permian–Early Triassic.

The Early Triassic is pivotal for understanding the recovery and diversification of post-extinction biotas, marking the initial emergence or early diversification of many modern life forms. This phase holds dual significance as it establishes the groundwork for contemporary biodiversity evolution and provides crucial insights into managing present ecological challenges. Focused efforts on the Sanga do Cabral Formation in the Paraná Basin unveil a critical opportunity for studying Early Triassic vertebrates in South America, offering a unique perspective on Western Gondwana's biotic recovery after the End-Permian Mass Extinction. Here, we review the geology and fossil record of the most important fossiliferous outcrop of the Sanga do Cabral Formation, the Bica São Tomé Fossil Site. Prospections at the outcrop have already recovered over two hundred specimens, including holotypes and representative materials of important Early Triassic taxa. Our review aims to demonstrate the relevance of the site and highlight strategies for its preservation. The site includes an unusual representation of archosauromorphs, although its content is dominated by procolophonids. Among the known localities of the Sanga do Cabral Formation, the Bica São Tomé Fossil Site stands out for the unique presence of well-preserved specimens in articulation, such as the nearly complete skeleton of the archosauromorph Teyujagua paradoxa. Even so, most of the record is dominated by fragmentary and reworked specimens. The Bica São Tomé site stands as a beacon for understanding Lower Triassic ecosystems in Latin America, presenting an unparalleled opportunity for Mesozoic exploration in Brazil. The Sanga do Cabral Formation, with its wealth of fossil evidence, promises to enrich our understanding of the Early Triassic period and its significance in shaping modern biodiversity.

Facies architecture, pedogenesis and palynology of the Olenekian dryland setting – A sedimentary record of Early Triassic climate oscillations in the SE Germanic Basin

Elevated temperatures persisted for an anomalously protracted interval following pulsed volcanic carbon release associated with the end-Permian mass extinction, deviating from the expected timescale of climate recovery following a carbon injection event. Here, we present evidence for enhanced reverse weathering-a CO2 source-following the end-Permian mass extinction based on the lithium isotopic composition of marine shales and cherts. We find that the average lithium isotopic composition of Lower Triassic marine shales is significantly elevated relative to that of all other previously measured Phanerozoic marine shales. Notably, the record generated here conflicts with carbonate-based interpretations of the lithium isotopic composition of Early Triassic seawater, forcing a re-evaluation of the existing framework used to interpret lithium isotopes in sedimentary archives. Using a stochastic forward lithium cycle model, we demonstrate that elevated reverse weathering is required to reproduce the lithium isotopic values and trends observed in Lower Triassic marine shales and cherts. Collectively, this work provides direct geochemical evidence for enhanced reverse weathering in the aftermath of Earth's most severe mass extinction.