Permian-Triassic Research Articles

Ancient deep ocean as a harbor of biotic innovation revealed by Carboniferous ophiuroid microfossils

Fossil-informed molecular phylogenies have emerged as the most powerful tool for correlating biotic evolution and Earth history. The accuracy of these trees, however, depends on the completeness of fossil sampling. For most organismal clades, the available fossil record is insufficiently sampled. This is especially true for groups with a multi-element skeleton, such as echinoderms and vertebrates, where sampling efforts focus largely on rare finds of intact skeletons. For these groups, inconspicuous but informative skeletal fragments are commonly neglected. This sampling bias excludes the numerous paleoenvironments in which preservation of intact skeletons is extremely unlikely, in particular deep-water settings. We describe new finds of brittle-star, or ophiuroid, fossils retrieved from sieving residues of sediments deposited during the Atokan (Upper Carboniferous) on the deep shelf to upper slope of the Ardmore Basin in present-day southern Oklahoma, USA. Although preserved as disarticulated, microscopic ossicles, the pristine preservation of the skeletal microstructure allows for precise identification of the remains. Comparative anatomical and phylogenetic analyses confirm the presence of basal representatives of the extant ophiuroid orders Ophioscolecida and Amphilepidida. Our finds provide the first unambiguous fossil evidence that the early crown-group diversification of the Ophiuroidea was well under way long before the end-Permian mass extinction, and that a significant part of this diversification took place in deep-water settings, as previously predicted by molecular evidence.

Ancient deep ocean as a harbor of biotic innovation revealed by Carboniferous ophiuroid microfossils

Abstract Fossil-informed molecular phylogenies have emerged as the most powerful tool for correlating biotic evolution and Earth history. The accuracy of these trees, however, depends on the completeness of fossil sampling. For most organismal clades, the available fossil record is insufficiently sampled. This is especially true for groups with a multi-element skeleton, such as echinoderms and vertebrates, where sampling efforts focus largely on rare finds of intact skeletons. For these groups, inconspicuous but informative skeletal fragments are commonly neglected. This sampling bias excludes the numerous paleoenvironments in which preservation of intact skeletons is extremely unlikely, in particular deep-water settings. We describe new finds of brittle-star, or ophiuroid, fossils retrieved from sieving residues of sediments deposited during the Atokan (Upper Carboniferous) on the deep shelf to upper slope of the Ardmore Basin in present-day southern Oklahoma, USA. Although preserved as disarticulated, microscopic ossicles, the pristine preservation of the skeletal microstructure allows for precise identification of the remains. Comparative anatomical and phylogenetic analyses confirm the presence of basal representatives of the extant ophiuroid orders Ophioscolecida and Amphilepidida. Our finds provide the first unambiguous fossil evidence that the early crown-group diversification of the Ophiuroidea was well under way long before the end-Permian mass extinction, and that a significant part of this diversification took place in deep-water settings, as previously predicted by molecular evidence.

Mercury evidence from southern Pangea terrestrial sections for end-Permian global volcanic effects

The latest Permian mass extinction (LPME) was triggered by magmatism of the Siberian Traps Large Igneous Province (STLIP), which left an extensive record of sedimentary Hg anomalies at Northern Hemisphere and tropical sites. Here, we present Hg records from terrestrial sites in southern Pangea, nearly antipodal to contemporaneous STLIP activity, providing insights into the global distribution of volcanogenic Hg during this event and its environmental processing. These profiles (two from Karoo Basin, South Africa; two from Sydney Basin, Australia) exhibit significant Hg enrichments within the uppermost Permian extinction interval as well as positive Δ199Hg excursions (to ~0.3‰), providing evidence of long-distance atmospheric transfer of volcanogenic Hg. These results demonstrate the far-reaching effects of the Siberian Traps as well as refine stratigraphic placement of the LPME interval in the Karoo Basin at a temporal resolution of ~105 years based on global isochronism of volcanogenic Hg anomalies.

Permian-Triassic insect diversity revealed by fossils from China

Most of the research on Paleoentomology focuses on describing morphology and classification of one species of fossil insects. However, there is little information on the temporal diversity of insects during the Permian and Triassic periods. The end-Permian mass extinction (EPME) was the greatest biological and ecological crisis of the Phanerozoic Eon on Earth, while the pattern of recovery of terrestrial ecosystem is still unclear. In this paper, the population and distribution of insects in various regions of China before and after the fifth mass extinction were studied by counting the fossil literature data of insects from the Permian to Triassic. We found the genus diversity of the proto-orthoptera decreased after the mass extinction. The Blattoidea (cockroach) showed a brief trend of extinction after the mass extinction, but soon returned to prosperity; Hemiptera’s population was less affected by mass extinctions, with only minor fluctuations in diversity and subsequent prosperity beyond the Permian; The order Mecoptera is speculated to be an emerging species of the Triassic. Specific trend changes for the above four purposes may be affected by volcanic activity. Insect diversification can reflect changes in terrestrial ecology, providing a reliable example of changes in our current climate environment: scientists can predict the possible ecological impact of global warming through previous records, and take preventive measures to prevent the mass extinction of species again.

An expanded Smithian–Spathian (Lower Triassic) boundary from a reefal build‐up record in Oman: implications for conodont taxonomy, high‐resolution biochronology and the carbon isotope record

AbstractSome 2.7 myr after the Permian–Triassic boundary mass extinction, a stepwise extinction of the nekton (ammonoids and conodonts) ended at the Smithian–Spathian boundary (SSB) during an episode of climate cooling. SSB records from continental shelves are usually affected by an unconformity, suggesting a forced regression of glacio‐eustatic origin. Here, we document a new 30‐m‐thick SSB section from Jebel Aweri (Batain Plain, Oman) that provides an exceptionally complete and expanded record preserved in an exotic block. Most of this SSB section consists of microbial boundstone build‐ups with a framework of metazoan bioclasts that formed in shallow water on an offshore seamount. In Wadi Musjah (Hawasina nappes, Oman), another exotic block records the SSB in a deeper water setting represented by Hallstatt‐type facies. These two sections provide a unique perspective on the early Spathian rapid re‐diversification of conodonts. They led to a thorough revision of conodont taxonomy around the SSB and to the construction of the highest resolution biochronological scheme for this time interval in the Tethys. A total of five SSB sections from Oman representing both offshore seamounts and lower slope deposits were included in a high‐resolution, quantitative unitary associations (UA) analysis. The resulting 8 conodont biozones are intercalibrated with ammonoid zones and with the carbonate carbon isotope record ultimately placing the SSB in the interval of separation between UAZ3and UAZ4. Only the association ofNovispathodus pingdingshanensiswithIcriospathodus crassatuscan be used to unambiguously characterize the base of the Spathian.

On Triassic Murchisonia-like gastropods – surviving the end-Permian extinction to become extinct in the Late Triassic

On Triassic Murchisonia-like gastropods – surviving the end-Permian extinction to become extinct in the Late Triassic

Palaeoecology of the Hiraiso Formation (Miyagi Prefecture, Japan) and implications for the recovery following the end-Permian mass extinction.

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.

Increased bivalve cosmopolitanism during the mid-Phanerozoic mass extinctions

The impact of mass extinctions on biogeographic patterns remains unclear. Analysis of large-scale biogeographic patterns can provide insights into macroevolutionary processes. Here, we aim to trace the biogeographic dynamics of bivalves from the Middle Permian to the Early Jurassic based on an updated dataset, including 25,891 bivalve occurrence data, by using biogeographic connectedness (BC) and multiple-site β-diversity measures. The results reveal a significant bivalve cosmopolitanism event following the Permian–Triassic mass extinction (PTME) and a possible cosmopolitanism event after the Triassic–Jurassic mass extinction (TJME). Analysis of the BC of survivors and newcomers in each event reveals that both potential cosmopolitanism events were related to the selective extinction of endemic taxa, suggesting that endemics are more vulnerable during mass extinctions. The geographic expansion of survivors also possibly contributed to the cosmopolitanism in the aftermath of the PTME, supporting the ecological release hypothesis following the PTME. Finally, we found that the spatial sampling heterogeneity can bias biogeographic patterns, for instance, bivalve cosmopolitanism after the TJME.

Guttigomphus avilionis gen. et sp. nov., a trirachodontid cynodont from the upper Cynognathus Assemblage Zone, Burgersdorp Formation of South Africa.

The Burgersdorp Formation of South Africa is a richly fossiliferous rock sequence at the top of the Permian-Triassic Beaufort Group and is known for its abundance of Early-Middle Triassic vertebrate remains, particularly cynodonts. Fossils from the Burgersdorp Formation are referred biostratigraphically to the Cynognathus Assemblage Zone (CAZ), which is further divided into three subzones: Langbergia-Garjainia, Trirachodon-Kannemeyeria, and Cricodon-Ufudocyclops. Each subzone is characterised by the presence of a distinct species of trirachodontid, a group of gomphodont cynodonts found relatively abundantly throughout the CAZ, with the lower two subzones characterised by the medium-sized trirachodontids Langbergia and Trirachodon. The uppermost part of the formation, the Cricodon-Ufudocyclops subzone, yields trirachodontids of larger size. The majority of these trirachodontid specimens have previously been referred to Cricodon metabolus, a taxon also known from the Manda Beds of Tanzania and the Ntawere Formation of Zambia. Here we identify one of the specimens (BP/1/5538) previously referred to Cricodon as a new taxon, Guttigomphus avilionis. Guttigomphus can be distinguished from other gomphodont cynodonts by features of the upper postcanine teeth, such as an asymmetric crown in occlusal view (crown narrower along the lingual margin than the labial). Our phylogenetic analysis recovers Guttigomphus as a basal member of Trirachodontidae, outside of the clade including Cricodon, Langbergia and Trirachodon.

Composition, environment, and economic value of the Permian to Cretaceous coated grains from Zagros and the Persian Gulf

Ooid grainstone/packstone carbonate facies of the Dalan, Kangan, and Arab formations are the main hydrocarbon reservoirs in the Persian Gulf. Based on detailed petrographic and petrophysical analyses, sedimentological and mineralogical features of the Permian to Late Cretaceous carbonate and iron-rich coated grains from Zagros and the Persian Gulf were investigated. Frequent ooids in these formations indicate a high-energy environment and a wave-dominated shallow carbonate platform. Because of wide-spread Permian–Triassic epiric seas and long-lasting periods of arid and hot climate, Permian–Triassic carbonate ooids have more vertical and lateral distribution in comparison with Late Jurassic carbonate ooids. Dolomite, calcite, and anhydrite are the major minerals of carbonate ooid grains. Early Cretaceous iron-rich ooids have been deposited above a major Late Aptian disconformity during the highstand systems tract. Ooid ironstone bulk sample X-ray diffraction (XRD) analysis shows that goethite, siderite, fluorapatite, calcite, quartz, and pyrite are the major phases of ooid ironstone deposits. This layer of iron bearing ooids could have economic importance in its outcrops in the Zagros area. Late Cretaceous iron-rich coated grains (pisoid–oncoids) were deposited above the Sarvak exposure surface during the Late Cretaceous, long-lasting sea-level fall on the Arabian Plate. Boehmite, diaspore, hematite, and goethite are the main minerals of these kind of iron-rich deposits. Late Cretaceous karst-type bauxite deposits have also been reported from different sections of the Zagros area and have economic value for mining.

Permian−Middle Triassic floral succession in North China and implications for the great transition of continental ecosystems

The global pattern of plant evolution through the Permian−Triassic mass extinction is uncertain, and the extent to which land plants were affected is debated. Detailed studies undertaken at a regional scale can help evaluate this floral transition, and thus we provide a detailed account of floral evolution from the Permian to Middle Triassic of North China based on new paleobotanical data and a refined biostratigraphy. Five floral transition events are identified from before, during, and after the Permian−Triassic crisis, including the disappearance of the gigantopterid flora (associated with loss of coal deposits), the end-Permian mass extinction of Paleophytic taxa, and gradual recovery in the Triassic with the stepwise appearance of the Mesophytic vegetation. The record begins with a Cisuralian gigantopterid-dominated rainforest community, and then a Lopingian walchian Voltziales conifer-ginkgophyte community that evolved into a voltzialean conifer-pteridosperm forest community. The last is associated with a change amongst terrestrial vertebrates from the Jiyuan fauna to a pareiasaur-dominated fauna, found in red beds that lack coal deposits due to arid conditions. The disappearance of the voltzialean conifer forest community may represents the end-Permian mass extinction of plants although it could also be a consequence of the non-preservation of plants in sedimentary red-beds. The first post-crisis plants are an Induan herbaceous lycopsid community, succeeded by the Pleuromeia-Neocalamites shrub marsh community. A pteridosperm shrub woodland community dominated for a short time in the late Early Triassic along with the reappearance of insect herbivory. Finally, in the Middle Triassic, gymnosperm forest communities gradually rose to dominance in both uplands and lowlands along with other diverse plant communities, indicating the establishment of the Mesophytic Flora.

Ecosystem responses of two Permian biocrises modulated by CO2 emission rates

Carbon dioxide (CO2) emissions and associated climate change are thought to have caused a number of widespread marine anoxia and mass extinction events in the geologic past. However, how marine ecosystems respond to different CO2 emission patterns remains an important unresolved question. The geologic records of the Permian Period, which witnessed two mass extinctions associated with volcanic eruption (thus CO2 emissions) but with vastly different biological responses, provide a unique window to address this issue. Here, we present a long-term uranium isotope (δ238U) record using marine limestones covering the latest Early Permian through Middle to Late Permian. The δ238U values show two episodes of low values in the middle Capitanian and late Changhsingian, indicating two periods of expansion of marine anoxia during the Permian Period. We use a uranium isotope mass balance model to quantify the anoxic seafloor areas, and we further use a carbon cycle model (LOSCAR, Long-term Ocean Sediment Carbon Reservoir) based on observed δ13C of marine carbonates, sea surface temperature records, and ocean surface pH data to quantify the carbon emission rates across the two biocrises. The uranium isotope mass balance model reveals that the anoxic seafloor area is three times larger during the end-Permian mass extinction (EPME, covering ∼35% of the seafloor areas) than that during the end-Guadalupian event (EGE, covering ∼10% of the seafloor areas). The CO2 emission rates across the two biocrises modeled from the LOSCAR model show that the carbon emission rate across the EPME was at least five times faster than that during the EGE, with the best-fit δ13C values of the input sources ranging from −8 to −12‰, indicating a predominant volcanic CO2 source during the EPME, and close to −25‰ during the EGE. Comparing model results and observed proxy data led to the suggestion that the more severe ecosystem responses during the EPME, including higher extinction rate and larger extent of seafloor anoxia, are closely linked to the faster carbon emission rates compared to the EGE.

Clay mineralogy mediated by pH and chemical weathering intensity of Permian–Triassic boundary K-bentonites at Dongpan (Guangxi, South China)

Volcanic ash deposits of the Permian-Triassic (P-T) transition in South China, in addition to being associated with the Permian-Triassic boundary mass extinction, are useful marker beds for regional correlation of sedimentary strata. This study investigates the source(s) of P-T volcanic ash layers in South China by studying their clay mineralogy and geochemical characteristics in deep-marine facies at Dongpan. Mineralogically, the Dongpan deposits consist mainly of clay minerals and quartz, with small amounts of anatase and feldspar. C lay minerals in the volcanic ash layer are mainly composed of R1 mixed-layer illite/smectite (I/S) (56.2–74.8%), smectite (14–22.8%), kaolinite (5.4–27.3%) and illite (1.2–5.3%). The relatively high content of kaolinite and weak illitization of smectite at Dongpan differ from the features of clay-mineral assemblages in other contemporaneous deep-water facies. Our results indicate that strong chemical weathering in an acidic and oxidizing environment characterized by low K+/H+ ratios inhibited uptake of K+ in the interlayers of I/S clay minerals and, thus, illitization of smectite. We infer that weathering intensity rather than redox state was the primary influence on the rate of kaolinization of clay minerals in these deep-marine facies. The Dongpan section exhibits a uniform REE pattern, indicating a single and stable source of volcanic ash during the P-T transition. Trace-element and REE distribution patterns and mixed-layer I/S clay-mineral morphologies are consistent with the source of the volcanic ash at Dongpan being a nearby continent-margin volcanism.

Recovery from persistent nutrient-N limitation following the Permian–Triassic mass extinction

Global warming, widespread oceanic anoxia and stagnation, and large perturbations of the global carbon cycle characterized the end-Permian to Middle Triassic interval. Nitrogen isotopes of marine sediments (δ15Nbulk) decreased through the Permian–Triassic transition, implying development of nitrate-limited and ammonium-dominated conditions (i.e., anaerobic marine N cycle) in Early Triassic oceans, which may have contributed to the delay in marine biotic recovery following the end-Permian mass extinction. However, the temporal evolution of the nitrogen cycle and the role of nutrient supply in marine ecosystem recovery during this interval remain poorly understand. Here, we present a new high-resolution Permian–Triassic nitrogen isotope curve from the Nanpanjiang Basin of South China. Low δ15N (−2‰ to +2‰) during the Griesbachian-to-Smithian substages (i.e., first ∼2 Myr of Early Triassic) reflects enhanced nitrogen fixation concurrently with climatic hyperwarming and expansion of oceanic anoxia. A large rise in δ15N (to +8‰) followed by a decline (to −2‰) reflects an aborted recovery of the marine N cycle during the Spathian substage of the Early Triassic. During the Middle Triassic, δ15N fluctuations between +1‰ and +4‰ during the Anisian Stage, followed by stabilization around +4‰ in the Ladinian Stage, suggest a slow stepwise re-establishment of the aerobic marine N cycle. Although both South China and northwestern Pangea experienced a transition to anaerobic N cycling during the Early Triassic, South China experienced an earlier and more rapid onset of this event as well as larger N-cycle fluctuations during the recovery interval than northwestern Pangea. Overall, N cycle changes coincided with those in paleotemperature and ocean-redox state, demonstrating an integrated response of the marine system to the extreme environmental perturbations of the Early Triassic. In summary, our results support persistence of nutrient-N-limited conditions and strong microbial N-fixation throughout the Early Triassic, with a full return to the aerobic N cycle only after stabilization of oceanic environmental conditions during the Middle Triassic.

Multiple drivers and lineage-specific insect extinctions during the Permo–Triassic

The Permo–Triassic interval encompasses three extinction events including the most dramatic biological crisis of the Phanerozoic, the latest Permian mass extinction. However, their drivers and outcomes are poorly quantified and understood for terrestrial invertebrates, which we assess here for insects. We find a pattern with three extinctions: the Roadian/Wordian (≈266.9 Ma; extinction of 64.5% insect genera), the Permian/Triassic (≈252 Ma; extinction of 82.6% insect genera), and the Ladinian/Carnian boundaries (≈237 Ma; extinction of 74.8% insect genera). We also unveil a heterogeneous effect of these extinction events across the major insect clades. Because extinction events have impacted Permo–Triassic ecosystems, we investigate the influence of abiotic and biotic factors on insect diversification dynamics and find that changes in floral assemblages are likely the strongest drivers of insects’ responses throughout the Permo–Triassic. We also assess the effect of diversity dependence between three insect guilds; an effect ubiquitously found in current ecosystems. We find that herbivores held a central position in the Permo–Triassic interaction network. Our study reveals high levels of insect extinction that profoundly shaped the evolutionary history of the most diverse non-microbial lineage.

A late Permian archosauriform from Xinjiang shows evidence of parasagittal posture.

Archosaurs diversified and became dominant during the Mesozoic Era, but their earliest relatives (non-archosaurian archosauromorphs) were already scarcely present in the late Permian. Here we describe a new species of non-archosaurian archosauriform from the upper Permian of Xinjiang, China. Preserved as a partial hindlimb, it possesses a few derived features shared with other archosauriforms, including a much stouter tibia than fibula, a longer metatarsal III than metatarsal IV, and a hooked metatarsal V. Phylogenetic analysis confirmed the new taxon to be a non-archosaurian archosauriform. The morphology of the knee, crus, and pes shows traits that are commonly related with a parasagittal posture, including an entirely proximo-distal articulation of the femur and fibula, the slender and closely spaced tibia and fibula, and a mesaxonic foot with a reduced fifth toe. The new taxon shows that the parasagittal posture evolved before the end-Permian Mass Extinction.

The variations of terrestrial trace fossils and sedimentary substrates after the end‐Permian extinction in the Dengfeng area, North China

Evolution of terrestrial infauna in the Early Triassic enables to understand terrestrial biotic recovery after the end‐Permian mass extinction (EPME). Six ichnospecies in two ichnogenera, including Skolithos linearis, S. verticalis, S. annulatus, S. isp., Planolites montanus, and P. beverleyensis, were recognized from the Lower Triassic Liujiagou Formation (Induan Stage) and Heshanggou Formation (Olenekian Stage) in the Baiping section of the Dengfeng area, North China. The ichno‐ecological analyses of ichno‐taxonomic abundance, ichnodiversity, bioturbation index, burrow size, and tiering level revealed that terrestrial infauna expanded from epibenthic to endobenthic through the Early Triassic. The tiering deepening suggested that tracemakers gradually began to excavate into the sediments instead of moving on the microbial mats, indicating that the burrowing capability of trace‐making animals has recovered in the Olenekian. Four types of sedimentary substrates were summarized: non‐bioturbated matground, matground with bioturbated patches, weakly bioturbated mixed ground, and moderately bioturbated mixed ground. Occurrence of the substrate of mixed ground may be a sign of the initial recovery of the terrestrial ecosystem after the EPME.

Ancestral body plan and adaptive radiation of sauropterygian marine reptiles.

Sauropterygia is the most diversified and dominant clade among marine reptiles, but their early evolution is scarcely understood. Here we report the earliest known complete specimen related to sauropterygians from the Early Triassic. It is referred to Hanosaurus hupehensis by an exclusive combination of features and shows mosaic morphology integrating the characters of multiple sauropterygian sub-lineages. In phylogenetic results from both parsimony and Bayesian analyses employing our reconstructed dataset, Hanosaurus is stably resolved as the basal-most member of Sauropterygiformes, a clade comprising all sauropterygians and saurosphargids. This skeleton reveals an unexpected ancestral body plan for sauropterygiforms with an elongate trunk and four short limbs, differing from many of its immediate descendants but more similar to non-sauropterygiform marine reptiles at their early aquatic stage as axial swimmers. After this convergence on body plan, we quantitatively confirm the rapid divergence of sauropterygiform reptiles following the end-Permian mass extinction.

Changes in the Family Composition of Eoblattid Insects (Insecta: Eoblattida) near the Permian–Triassic Boundary

Changes in the Family Composition of Eoblattid Insects (Insecta: Eoblattida) near the Permian–Triassic Boundary

Mapping monstrosity: Malformed sporomorphs across the Smithian/Spathian boundary interval and beyond (Salt Range, Pakistan)

In the last 500 million years, Earth's biota experienced periods of crises with extinctions on a large scale and significant turnover events, one of them being the Permian-Triassic extinction event. The following Early Triassic was a critical time marked by a series of biological and environmental changes with a complex recovery pattern of marine faunas and ecosystems. Generally, animals and plants respond to stress by using different strategies that help them tolerate or recover from unfavourable environmental conditions. In this contribution, we quantitatively and qualitatively describe a variety of malformations of spores and pollen grains from the extensively studied Nammal section (Salt Range, Pakistan) across the Smithian/Spathian boundary interval (Early Triassic). High dominance of malformed sporomorphs is recorded throughout the studied interval, indicating stressful conditions for plants on the Indian margin during the Early Triassic. One of the highest abundances of malformed sporomorphs coincides with the spore spike and the negative carbon isotope excursion during the middle Smithian, emphasising this intense biotic stress. Either a cocktail of volcanic gases, acid rains, soil acidification, and heavy metal pollution as a consequence of a late pulse of the Siberian Trap large igneous province or climatic extremes might have been responsible for these malformations. Here teratology is used as a tool/means to assess the severity of biotic crises in the plant kingdom, indicating its potential value as a signal of ecological disturbance. • Fossil spores and pollen morphology as a proxy for ancient environmental pollution. • Sporomorphs identification schemes to quantify morphological change. • Evaluation of possible causes triggering morphological variation in sporomorphs.