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Strata of Permian – Early Triassic age that include a record of three major extinction events (Capitanian Crisis, Latest Permian Extinction and the Smithian/Spathian Extinction) were examined at the Festningen section, Spitsbergen. Over the c. 12 Ma record examined, mercury in the sediments shows relatively constant background values of 0.005–0.010 μg g–1. However, there are notable spikes in Hg concentration over an order of magnitude above background associated with the three extinctions. The Hg/total organic carbon (TOC) ratio shows similar large spikes, indicating that they represent a true increase in Hg loading to the environment. We argue that these represent Hg loading events associated with enhanced Hg emissions from large igneous province (LIP) events that are synchronous with the extinctions. The Hg anomalies are consistent across the NW margin of Pangea, indicating that widespread mercury loading occurred. While this provides utility as a chemostratigraphic marker the Hg spikes may also indicate loading of toxic metals to the environment, a contributing cause to the mass extinction events.

Lower Triassic marine strata in Spitsbergen accumulated on a mid-to-high latitude ramp in which high-energy foreshore and shoreface facies passed offshore into sheet sandstones of probable hyperpycnite origin. More distal facies include siltstones, shales and dolomitic limestones. Carbon isotope chemostratigraphy comparison allows improved age dating of the Boreal sections and shows a significant hiatus in the upper Spathian. Two major deepening events, in earliest Griesbachian and late Smithian time, are separated by shallowing-upwards trends that culminated in the Dienerian and Spathian substages. The redox record, revealed by changes in bioturbation, palaeoecology, pyrite framboid content and trace metal concentrations, shows anoxic phases alternating with intervals of better ventilation. Only Dienerian–early Smithian time witnessed persistent oxygenation that was sufficient to support a diverse benthic community. The most intensely anoxic, usually euxinic, conditions are best developed in offshore settings, but at times euxinia also developed in upper offshore settings where it is even recorded in hyperpycnite and storm-origin sandstone beds: an extraordinary facet of Spitsbergen's record. The euxinic phases do not track relative water depth changes. For example, the continuous shallowing upwards from the Griesbachian to lower Dienerian was witness to several euxinic phases separated by intervals of more oxic, bioturbated sediments. It is likely that the euxinia was controlled by climatic oscillations rather than intra-basinal factors. It remains to be seen if all the anoxic phases found in Spitsbergen are seen elsewhere, although the wide spread of anoxic facies in the Smithian/Spathian boundary interval is clearly a global event.

初始巢湖裂齿鱼(Chaohuperleidus primus)产自安徽省巢湖市马家山采石场南陵湖组上段地层(早三叠世奥伦尼克期斯帕斯亚期),由于模式材料保存很差,其骨骼学特征未被完整地记述.依据模式材料及同一层位发现的3件保存完整的新材料,补充描述初始巢湖裂齿鱼的骨骼解剖信息,修正其属征,复原其头骨的骨骼模式.修正后的巢湖裂齿鱼属征支持以往的分类学结论,\"顶骨与膜质翼耳骨愈合形成的骨块具有发育的前、中、后凹线,鳃盖骨与下鳃盖骨高度近等,下鳃盖骨具大的圆形前背突\"是该属可能的近裔性状.巢湖裂齿鱼属与裂齿鱼属(Perleidus)的形态特征最相似,除可能的近裔性状外,与后者不同之处是次眶骨、鳃条骨和轴上鳍条的数量更多.依据巢湖裂齿鱼属头骨的骨骼特征,与以往错误地归入裂齿鱼目的早三叠世类群及裂齿鱼目内最相近的类群进行解剖学比较和讨论,为新鳍鱼类干群的谱系分析提供新的解剖学依据.

The Smithian–Spathian boundary interval is characterised by a positive carbon isotopic excursion in both δ13Ccarb and δ13Corg, concurrent with a major marine ecosystem reorganisation and the resurgence of microbialite facies. While these δ13C records have been traditionally interpreted as capturing global carbon cycle behaviour, recent studies have suggested that at least some excursions in early Triassic δ13C values may incorporate influences from authigenic or early diagenetic processes. To examine the mechanistic drivers of Smithian–Spathian boundary geochemistry, the carbonate geochemistry of a core from Georgetown, Idaho (USA), was analysed using a coupled δ44/40Ca, δ26Mg and trace‐metal framework. While the δ13C record in the Georgetown core is broadly similar to other Smithian–Spathian boundary sections, portions of the record coincide with substantial shifts in δ44/40Ca, δ26Mg and trace‐metal compositions that cannot feasibly be interpreted as primary. Furthermore, these geochemical variations correspond with lithology: The δ13C record is modulated by variations in the extent of dolomitisation, and the diagenetic styles recognised here coincide with individual lithostratigraphic units. A primary shift in local sea water δ13C values is inferred from the most geochemically unaltered strata, from ca 3‰ in the middle Smithian to ca 5‰ in the early Spathian, although the timing and pathway through which this occurs cannot be readily identified nor extrapolated globally. Therefore, the Georgetown core may not directly record exogenic carbon cycle evolution, showing that there is a need for the careful reconsideration of the Smithian–Spathian boundary—and more broadly, Early Triassic—geochemical records to examine potential local and diagenetic influences on sedimentary geochemistry. While the Smithian–Spathian boundary carbon isotopic excursion has been traditionally interpreted as capturing global carbon cycle behaviour, recent studies have suggested that at least some Early Triassic carbon isotopic excursions may incorporate influences from authigenic or early diagenetic processes. Using a coupled calcium isotope, magnesium isotope and trace‐metal framework, we identify that the carbon isotopic record in Georgetown, Idaho (USA), is driven by several styles of diagenesis, rather than reflecting global sea water evolution. Despite previous interpretations, we suggest that the Georgetown core does not directly record exogenic carbon cycle evolution and argue that there is a need for the careful reconsideration of Smithian–Spathian boundary geochemical records to examine potential local and diagenetic influences.

Conodonts, as a biotic group, next to ammonoids, pollen and spores, crustaceans and vertebrates, provide proxy clues for environment and age assessments of the rocks in which they occur. Conodonts are widely used for Triassic marine biostratigraphy. However, there are various discussions about their multielement taxonomy and evolutionary lineages (e.g., generation, speciation). Although first studies reported that most Triassic conodont species were unimembrate, studies carried out in the following years maintained that all Triassic conodonts were multimembrate. Although statistical reconstructions of a number of Triassic apparatuses were attempted, the discovery of fused clusters and natural assemblages has subsequently demonstrated that Triassic conodonts are indeed multimembrate, and all of the elements exist together in the same apparatus. The present paper aims to clarify the evolutionary relationship and array of some Lower Triassic conodonts. Columbitella dagisi n. sp. is described.

Minute fossils from a variety of different metazoan clades, collectively referred to as small shelly fossils, represent a distinctive taphonomic mode that is most commonly reported from the Cambrian Period. Lower Triassic successions of the western United States, deposited in the aftermath of the end-Permian mass extinction, provide an example of small shelly style preservation that significantly post-dates Cambrian occurrences. Glauconitized and phosphatized echinoderms and gastropods are preserved in the insoluble residues of carbonates from the Virgin Limestone Member of the Moenkopi Formation. Echinoderm plates, spines and other skeletal elements are preserved as stereomic molds; gastropods are preserved as steinkerns. All small shelly style fossils are preserved in the small size fractions of the residues (177 to 420 μm), which is consistent with the size selection of small shelly fossils in the Cambrian. Energy-dispersive X-ray spectra of individual fossils coupled with X-ray diffraction of residues confirm that the fossils are dominantly preserved by apatite and glauconite, and sometimes a combination of the two minerals. The nucleation of both of these minerals requires that pore water redox oscillated between oxic and anoxic conditions, which, in turn, implies that Lower Triassic carbonates periodically experienced oxygen depletion after deposition and during early diagenesis. Long-term oxygen depletion persisted through the Early Triassic, creating diagenetic conditions that were instrumental in the preservation of small shelly fossils in Triassic and, likely, Paleozoic examples.

The Hiraiso Formation of northeast Japan represents an important and under-explored archive of Early Triassic marine ecosystems. Here, we present a palaeoecological analysis of its benthic faunas in order to explore the temporal and spatial variations of diversity, ecological structure and taxonomic composition. In addition, we utilise redox proxies to make inferences about the redox state of the depositional environments. We then use this data to explore the pace of recovery in the Early Triassic, and the habitable zone hypothesis, where wave aerated marine environments are thought to represent an oxygenated refuge. The age of the Hiraiso Formation is equivocal due to the lack of key biostratigraphical index fossils, but new ammonoid finds in this study support an early Spathian age. The ichnofossils from the Hiraiso Formation show an onshore-offshore trend with high diversity and relatively large faunas in offshore transition settings and a low diversity of small ichnofossils in basinal settings. The body fossils do not, however, record either spatial or temporal changes, because the shell beds represent allochthonous assemblages due to wave reworking. The dominance of small burrow sizes, presence of key taxa including Thalassinoides , Rhizocorallium and Holocrinus , presence of complex trace fossils, and both erect and deep infaunal tiering organisms suggests that the benthic fauna represents an advanced stage of ecological recovery for the Early Triassic, but not full recovery. The ecological state suggests a similar level of ecological complexity to late Griesbachian and Spathian communities elsewhere, with the Spathian marking a globally important stage of recovery following the mass extinction. The onshore-offshore distribution of the benthic faunas supports the habitable zone hypothesis. This gradient is, however, also consistent with onshore-offshore ecological gradients known to be controlled by oxygen gradients in modern tropical and subtropical settings. This suggests that the habitable zone is not an oxygenated refuge that is only restricted to anoxic events. The lack of observed full recovery is likely a consequence of a persistent oxygen-limitation (dysoxic conditions), hot Early Triassic temperatures and the lack of a steep temperature/water-depth gradient within the habitable zone.

The explosive ammonoid rediversification after the Permian-Triassic mass extinction is now well understood in terms of taxonomic richness and biogeography. Using an updated dataset of Early Triassic ammonoids, we compare morphological disparity and taxonomic richness patterns at the regional and global scales. Disparity evolved similarly at both scales, suggesting a global influence of abiotic factors. Morphological diversification occurred early in the Smithian and a marked contraction of the morphospace took place during the end-Smithian extinction. We confirm that trends in disparity and richness were decoupled during the Griesbachian and Dienerian. Three macroevolutionary processes may be involved: (1) a nonselective extinction at the Permian-Triassic boundary; (2) a Dienerian constrained radiation with several homeomorphic genera; (3) a potential deterministic extinction during the end-Smithian crisis. We also demonstrate a superfamily imprint upon disparity for the Spathian when most superfamilies occupied a restricted part of the morphospace. Sphaerocones were the most affected by the Dienerian and end-Smithian extinction, but explanations remain elusive. On the one hand, this may be linked to widespread harsh conditions at those times. On the other hand, as the sphaerocones occurred episodically during the Early Triassic, this might be explained by a relaxing of ecological constraints or simply by convergent evolution.

The Early Triassic was a period of ecological restoration for the earth’s system after the end-Permian mass extinction.Geochemical records linked to the variations in marine ecosystems during this period have attracted the interest of geologists for many years.Based on petrographic analysis of samples and evaluations of their reliability as proxies for original seawater,this study investigated the carbon and oxygen isotopic compositions of 350 carbonate rock samples from the Lower Triassic（and adjacent strata）in the southern Longmenxia section of Guang’an,eastern Sichuan Basin.The results indicate that the Triassic carbonate rocks from the southern Longmenxia section favorably preserved the original seawater’sδ13C signal.Furthermore,carbon and oxygen isotopic compositions are found to be poorly correlated,with a determination coefficient as low as 0.0205 and only 44 rock samples show results of Mn/Sr>2 and/orδ180<-6.5‰.The complete carbon isotopic curve for the Lower Triassic is established using the data from the remaining 306 samples with Mn/Sr<2 and/orδ18O>-6.5‰.This curve presents favorable comparability on a global scale,specifically in theδ13C minima near the Permian-Triassic boundary,at the top of the Jia1 and within the the Jia3,as well as in theδ13C maxima at the tops of the Ye1 and Ye4,at the base of the Jia2 and at the top of the Ye3.The peaks and troughs corresponding to these maxima and minima all reflect global signals.By comparing these results to previous research on coeval carbon isotopic curves established within the chronostratigraphic framework,the ages of these critical evolution points are determined.The results show that the Ye1 roughly corresponds to the Griesbachian substage;the Ye2 through Ye4 correspond to the Dienerian substage;Jial corresponds to the Smithian substage;from the Jia2 to the lower part of the Jia4 correspond to the Spathian substage;and the middle and upper parts of the Jia4 belongs to the Aegean Substage of the Middle Triassic.Around the boundary between the Jial and Jia2（which represents the Smithian-Spathian boundary（SSB））,the value ofδ13C increases rapidly from-0.911‰to 3.679‰.The span during which the seawater’s carbon isotope experiences this drastic change may be less than36 kyr.The oxygen isotope,which is more sensitive to sedimentary environmental changes,exhibits changes prior to the carbon isotope near the SSB,indicating a significant increase in the salinity of the seawater before a sharp rise in the carbon isotope;this event leads to the formation of evaporites and dolomites.

Anachronistic and unusual carbonate facies (AUCFs) are identified in four localities with exposed Spathian strata in the western Balkanides. These include thin-bedded micritic limestone, flat-pebble breccia/conglomerate, mud-chip conglomerate, limestone-marl ribbon rock, vermicular limestone, and microbial oolite. Their depositional and/or early diagenetic origin is interpreted on the basis of petrographic characteristics, results from previous studies, and comparison with analogues from the geological record. Various controlling factors are distinguished in the context of their relative influence on global, regional, or local scale, i.e., environmental conditions (high degree of CaCO 3 supersaturation, fluctuations in oxygen levels and salinity), biological controls (bioturbation, microbial blooms, scarcity or abundance of metazoans), and uniformitarian sedimentary processes (wave agitation, storm action, terrigenous input, seismic shocks). Most of the AUCFs are assigned to features associated with enhanced CaCO 3 precipitation, while the vermicular limestones belong to fabrics that formed due to limited biologic activity. The thin-bedded micritic limestones, flat-pebble breccias/conglomerates, and limestone-marl ribbon rocks represent anachronistic facies, while the remaining AUCFs are regarded as unusual sedimentary features and fabrics. This study reports a new occurrence of diverse Spathian AUCFs formed in subtidal settings besides those described from the southwestern USA and south China. The results show that anomalous paleoceanographic conditions for carbonate sedimentation persisted locally in the shallow Western Tethys until late Early Triassic time.