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The Kamura section, located in the Chichibu Belt of Kyushu Island in southern Japan, contains a succession of uppermost Permian to Upper Triassic shallow-marine atoll sediments from the mid-Panthalassic Ocean. In the present study, carbonate microfacies, conodont biostratigraphy, and carbonate carbon isotopes were analyzed, making it possible to construct a detailed biochronological framework for the Triassic of the central Panthalassic region. A total of 14 conodont zones are recognized from the uppermost Changhsingian to the upper Norian. The Lower Triassic contains the Hindeodus parvus, Isarcicella isarcica, and H. postparvus zones (Griesbachian), the Neospathodus dieneri Zone (Dienerian), and the Novispathodus ex gr. waageni-Parachirognathus Zone (Smithian), while no evidence of the upper Lower Triassic Spathian substage was recovered at Kamura. The overlying Middle Triassic section consists of the Chiosella ex gr. timorensis-Cratognathus, ‘Paragondolella’ ex gr. alpina-Pg. ex gr. excelsa, Budurovignathus hungaricus, and B. mungoensis zones, followed in the Upper Triassic by the Quadralella tadpole-Gladigondolella malayensis, Q. lobata-Q. carpathica, Primatella cf. orchardi-Pr. permica, Epigondolella rigoi-‘Pg.’ hallstattensis, and E. ex gr. bidentata-Norigondolella steinbergensis zones. The exact stratigraphic intervals present at Kamura were refined through intercalibration of the conodont biozonation data with its δ13Ccarb profile, which shows a characteristic series of negative and positive excursions that correspond to well-established global reference profiles. The Permian–Triassic boundary is placed 0.20 m above the Mitai-Kamura formation contact (a reference datum corresponding to the end-Permian extinction horizon, = 0 m) based on the first appearance of H. parvus, and the Olenekian–Anisian boundary is placed 17.60 m above the reference datum based on the first appearance of Ch. ex gr. timorensis. Kamura carbonates were assigned to six fabric types and 17 microfacies. The microfacies succession records a deepening immediately following the end-Permian mass extinction, a strong shallowing during the mid to late Smithian, development of an unconformity spanning the entire Spathian, and minor sea-level fluctuations during the Middle and Late Triassic. The Spathian unconformity is attributed to a eustatic fall related to a sharp cooling event at or close to the Smithian–Spathian boundary that exposed the Kamura atoll. The subsequent resumption of shallow-marine sedimentation in the earliest Middle Triassic was probably due to continued thermal subsidence of the oceanic crustal basement beneath the atoll. The present work is the most complete analysis to date of the conodont biostratigraphic, carbon isotope chemostratigraphic, and eustatic records of the Triassic System in the central Panthalassic Ocean and should serve as a regional reference standard in the future.

We present recent study results of the Lower Triassic conodont succession from the Ganxi and Jianshi areas of Enshi city, western Hubei Province, South China, which were situated on a carbonate ramp at the northeastern margin of the Upper Yangtze Platform. Therein, the uppermost Permian to Lower Triassic succession is well exposed and yielded abundant conodonts. A total of nine conodont zones are differentiated: (1) Clarkina yini Zone, (2) Clarkina meishanensis Zone, (3) Hindeodus changxingensis Zone, (4) Hindeodus parvus Zone, (5) Hindeodus postparvus Zone, (6) Clarkina planata Zone, (7) Neoclarkina aff. discreta Zone, (8) Neospathodus dieneri Zone, and (9) Novispathodus waageni Zone. The Ns. dieneri M1, Ns. dieneri M2, and Ns. dieneri M3 Subzones have also been distinguished within the Ns. dieneri Zone, and the Nv. waageni eowaageni and Nv. waageni waageni Subzones are recognizable within the Nv. waageni Zone in Jianshi. Most of the zones occur in succession, but the C. planata Zone is a local ecozone reflecting deeper water biofacies during H. postparvus Zone time. In the Jianshi section, the Permian–Triassic boundary is placed at Bed 136-2 based on the appearance of Hindeodus parvus immediately above the disappearance of Changhsingian taxa, while the Induan–Olenekian boundary (IOB) is drawn at Bed 225 + 40 cm based on the first appearance of Nv. waageni eowaageni within the upper range of the Ns. dieneri Zone indices. The Enshi conodont zones overall correlate well with those recognized elsewhere in South China and worldwide.

Lower Triassic conodont biostratigraphy has been well studied around the world in the past decades, but the Induan-Olenekian boundary (IOB) remains undecided. The Novispathodus waageni group has been taxonomically re-assessed based on abundant new materials from the Jianshi and Chaohu sections, South China. New study shows that Nv. waageni typically possesses: (1) an approximately equi-dimentional P1 blade element, (2) an accurate upper profile with denticle height descending in both directions, (3) a denticulated posterior edge (lower denticles posterior of the highest denticle), and (4) a round basal cavity outline. Of the three proposed subspecies of the waageni species, both Nv. waageni waageni (Sweet, 1970) and Nv. w. eowaageni (Zhao and Orchard, 2005) are valid, and the former differs clearly from Nv. w. eowaageni in having (1) a slightly higher length/height ratio (holotype=1.30 : 1.23), (2) a thicker blade, sometimes with medial thickening, (3) fewer (broader) denticles per unit length, (4) generally recurved denticles, not straight and upright, (5) highest denticles closer to posterior, (6) common differentiation of a posterior cusp, and (7) more sinuous basal profile, with increased posterior upturning. A third subspecies illustrated as Nv. waageni n. subsp. A sensu Goudemand, 2014 is not conspecific with older individuals of Nv. w. eowaageni, and also cannot be assigned to the Nv. waageni group. Abundant new materials demonstrate a clear ontogenic process for Nv. w. eowaageni, indicating that Nv. w. eowaageni occurring in the Induan−Olenekian boundary (IOB) succession is rather stable. Small, earlier individuals (i.e., those from Bed 225 in Jianshi) are referred to as Nv. w. eowaageni Morphotype A, and are thought to have likely evolved from Ns. dieneri Morphotype 3, and to be the precursor of mature elements of Nv. w. eowaageni. The first appearance datum of Nv. w. eowaageni therefore is an ideal mark defining the IOB.

As one of the most important intervals in Earth life evolution, the latest Permian to earliest Triassic witnessed the greatest mass extinction and most profound recovery of marine biotas. In this period, gondolellid conodonts went through a major faunal turnover and morphologic change marked by platform reduction during the late Griesbachian to Dienerian. However, the details of this morphologic change process remain poorly known. The resultant Dienerian segminate conodonts also display remarkable morphologic variations related to growth, which has caused a great deal of confusion in taxonomy. Ontogenetic and phylogenetic studies are believed to be essential in understanding the developmental process and evolution of organisms and thus will be helpful for improving taxonomic definitions and revealing temporal changes of morphology. Here, based on abundant and well-preserved specimens from the Salt Range and Surghar Range of northwestern Pakistan, we described in detail the morphologic variants and reconstructed the ontogenetic series for seven stratigraphically important Griesbachian-Dienerian conodonts belonging to Clarkina, Neoclarkina, Neospathodus, and Sweetospathodus. A further Dienerian key species Eurygnathodus costatus is also included in discussion based on the work of Lyu et al. (2020) . The phylogenetic relationships among these taxa were reconstructed by means of cladistic approach. Some important evolutionary trends were recognized. Morphometric data including element length, platform width and denticle number were collected based on global occurrences and were plotted to illustrate the ontogenetic trajectory. Comparisons of ontogenetic trajectories revealed complex heterochronic patterns for platform growth. The reduction of platform may result from progenesis and neoteny in late Griesbachian Neoclarkina species and further from postdisplacement of the flange in Dienerian segminate conodonts. The Dienerian Neospathodus lineage may represent a paedomorphosis of the flange, whereas the lineage of Sw. kummeli–Eu. costatus was probably characterized by a peramorphosis of the platform through acceleration.

The Guryul Ravine section in Kashmir, northern India is an important reference section for global Lower Triassic stratigraphy. Once a candidate Global Stratotype Section and Point (GSSP) for the Permian-Triassic Boundary (PTB), the section has attracted intense attention for the PTB beds, but few studies have concerned the entire Lower Triassic stratigraphy. As one of the most continuous marine Lower Triassic successions on the northern margins of Gondwana, the Guryul Ravine section provides an important conodont biostratigraphic yardstick for worldwide correlations. This study presents recent results of the Lower Triassic conodont zonation from the Guryul Ravine section. A total of 6500 elements including 1600 P1 elements were recovered. Ten conodont zones were recognized from the Griesbachian to Spathian: Hindeodus parvus, Isarcicella staeschei, Clarkina planata, Neoclarkina krystyni, Neospathodus dieneri, Ns. pakistanensis, Novispathodus waageni, Scythogondolella mosheri, Nv. pingdingshanensis, and Nv. abruptus – Nv. brevissimus zones. The PTB is placed within Bed 52 in Unit E2, 80 cm above the base of Unit E2, based on the first occurrence (FO) of H. parvus. The Induan–Olenekian boundary (IOB) is tentatively placed at the base of Member G according to the positive maximum δ13Ccarb values, but it could be slightly higher based on conodonts. The Smithian-Spathian boundary (SSB) is drawn at the top of Member H based on the FO of Nv. pingdingshanensis and the carbon mdpt(N3-P3). Several conodont taxa are newly recognized near the top of the study section where the conodont fauna is dominated by segminiplanate elements of the Neogondolellinae. Many of these age-diagnostic species have been identified in other sections around the world, and their occurrence in Guryul Ravine supports their potential for worldwide correlation. The conodont sequence erected from the study section corresponds well to those of South China (e.g. Meishan) and elsewhere worldwide. The newly established conodont zonation from Kashmir provides a high precision time-frame to consider biotic evolution and environmental change during the Early Triassic, a crucial period of Earth history.

Investigation of the end-Permian mass extinction (EPME) has been greatly facilitated by high-resolution conodont biostratigraphic studies. To date, however, a detailed biostratigraphic framework has been lacking for shallow-marine successions of the Tethys region. In the present study, we analyzed carbonate microfacies, conodont biostratigraphy, and carbonate carbon isotopes of the Yangou Quarry section, a shallow-marine EPME succession that accumulated on an isolated carbonate bank on the northern margin of the Yangtze Platform. Microfacies analysis yielded four facies and 8 microfacies that record a seawater deepening immediately following the EPME. Ooids were abundantly produced during the EPME and earliest Triassic mass extinction (ETME) but were replaced by microbial mats, algae, bivalves, and brachiopods during an earliest Triassic transgression. A total of three conodont zones are recognized from the uppermost Changhsingian to the lowermost Griesbachian, in ascending order, the Hindeodus praeparvus Zone, H. parvus Zone, and Isarcicella staeschei Zone. The EPME and PTB (Permian-Triassic boundary) horizons are marked by the first occurrences of H. praeparvus at 6.18 m and H. parvus at 6.57 m, respectively, above the base of the section. The conodont biostratigraphic framework of the Yangou Quarry section was refined through intercalibration with its δ13Ccarb profile. This section records two discrete negative carbon isotope excursions (CIEs) that are correlative with the EPME and ETME horizons, and that can be correlated with similar CIEs at Meishan D and other PTB sections globally. Our study provides the first integrated, high-resolution biochemostratigraphic framework for a shallow-marine PTB succession in the eastern Tethys region, which will facilitate paleoenvironmental studies of similar facies elsewhere as well as correlations with deeper-water facies.

The new conodont genusMagnigondolellais recognized based on specimens recovered from the Anisian (Middle Triassic) of British Columbia in Canada, and Nevada in the USA. This new genus encompasses problematic specimens with high carinas, which have recently been collectively referred to asNeogondolellaex gr.regalisMosher. Ten species from North America are herein assigned toMagnigondolellan. gen., including the eight new speciesM.alexanderi,M.cyri,M.julii,M.nebuchadnezzari,M.salomae,M. n. sp. A,M. n. sp. B, andM. n. sp. C, as well as the two existing speciesM.regalis(Mosher) andM.dilacerata(Golding and Orchard). Other species from the Tethys region are also tentatively assigned toMagnigondolellan. gen. Based on published records, the genus appears to range from the Spathian to the upper Anisian in North America. The recognition of eight new species from the Anisian significantly increases the conodont biodiversity of this period, which has previously been regarded as a time of low diversity. Although some of the species included withinMagnigondolellan. sp. have relatively long stratigraphic ranges, many have been identified in both British Columbia and Nevada, and therefore show potential for biostratigraphic correlation on a regional scale.

30 pages; International audience; The transition from the Smithian substage to the Spathian substage of the Olenekian stage of the late Early Triassic was a critical time marked by a series of biological and environmental changes during the multimillion-year recovery interval following the end-Permian mass extinction. However, the Smithian/Spathian boundary (SSB) does not yet have an agreed definition, a shortcoming that complicates high-resolution analysis of events during the Smithian-Spathian transition. Here, we review key biostratigraphic (i.e., ammonoid and conodont) studies of the Smithian and Spathian substages in historically important regions (e.g., the Canadian Arctic for the Boreal realm, western North America for the eastern Panthalassic Ocean) and more recently re-studied locations (e.g., Pakistan and India in the southern Tethys, South China in the eastern Tethys) as well as the carbon isotope chemostratigraphy of 29 major Smithian-Spathian sections globally. Key ammonoid genera (e.g., Wasatchites, Anasibirites, Glyptophiceras and Xenoceltites of the late Smithian, and Bajarunia, Tirolites and Columbites of the early Spathian), conodont species (e.g., Scythogondolella milleri, Novispathodus waageni, and Borinella buurensis of the late Smithian, and ‘Triassospathodus’ hungaricus, Neogondolella aff. sweeti, and Icriospathodus spp. of the early Spathian), and carbonate carbon isotope excursions provide appropriate markers for constraining the SSB. Use of the first occurrence of the conodont Novispathodus pingdingshanensis as a potential marker of the SSB is also discussed. Based on correlations of biostratigraphic and carbon isotope data globally, we propose to revise previous placements of the SSB transition in some sections. Finally, we show that the Smithian Thermal Maximum (STM; herein named) was middle Smithian in age and not correlative with the SSB, as inferred in some earlier studies, and that the SSB coincided with a subsequent major global cooling event.

Eight new species of the conodontNeogondolellaare described from the Anisian (Middle Triassic) of northeastern British Columbia. The subtlety of morphological variation in this conodont genus has hampered biostratigraphical correlation, but large, often independently dated collections have enabled the description ofN.cuneiforme,N.curva,N.hastata,N.dilacerata,N.indicta,N.panlaurentia,N.tenera, andN.vellicatan. spp. Several of these species are widespread, as specimens ofN.curva,N.hastata,N.indicta,N.panlaurentia,N.tenera, andN.vellicataare found in contemporary collections from Nevada, whereasN.panlaurentiahas also been recovered from the Canadian Arctic. This distribution promises to significantly improve correlation among Anisian sections in North America.

New isotopic ages have been obtained from euhedral, first-cycle zircon grains recovered from Rhaetian strata preserved at the Black Bear Ridge section in northeastern British Columbia. Two statistically significant populations are present: an older population ca. 224 Ma, and a dominant younger population ca. 205 Ma. The younger population includes a group of grains with a weighted average 206 Pb/ 238 U age of 205.2 ± 0.9 Ma, which is interpreted to represent the maximum depositional age of the sediment. Potential sources for the two populations are found in the Quesnel terrane in central British Columbia, implying close proximity between this terrane and the autoch­thonous North American margin during the Late Triassic. This is supported by geochemical and structural evidence. The implication that the Quesnel terrane was close to its present-day latitude during the Late Triassic is in conflict with older estimates of paleolatitude based on paleomagnetic and paleontological evidence. The age of 205.2 ± 0.9 Ma obtained from the youngest population of zircons is also consistent with recently published estimates for the age of the Norian-Rhaetian boundary.

Triassic rocks of the Western Canada Sedimentary Basin (WCSB) have previously been interpreted as being deposited on the passive margin of North America. Recent detrital zircon provenance studies on equivalent Triassic rocks in the Yukon have suggested that these rocks were in part derived from the pericratonic Yukon–Tanana terrane and were deposited in a foreland basin related to the Late Permian Klondike orogeny. Detrital zircons within a number of samples collected from Triassic sediments of the WCSB throughout northeastern British Columbia and western Alberta suggest that the bulk of the sediment was derived from recycled sediments of the miogeocline along western North America, with a smaller but significant proportion coming from the Innuitian orogenic wedge in the Arctic and from local plutonic and volcanic rocks. There is also evidence of sediment being derived from the Yukon–Tanana terrane, supporting the model of terrane accretion occurring prior to the Triassic. The age distribution of detrital zircons from the WCSB in British Columbia is similar to those of the Selwyn and Earn sub-basins in the Yukon and is in agreement with previous observations that sediment deposited along the margin of North America during the Triassic was derived from similar source areas. Together these findings support the model of deposition within a foreland basin, similar to the one inferred in the Yukon. Only a small proportion of zircon derived from the Yukon–Tanana terrane is present within Triassic strata in northeastern British Columbia, which may be due to post-Triassic erosion of the rocks containing these zircons.

The Early Triassic is a critical interval recording episodic climatic, environmental, and biotic events after the end-Permian mass extinction. A precise global timescale for this epoch is essential to understand the sequence of events during this crisis. The undefined Induan–Olenekian stage boundary (IOB), long disputed, is a crucial element in providing a high-resolution chronostratigraphic framework for the Lower Triassic. Here we report new conodont lineages from the Jianshi section, South China that may contribute to the definition of the IOB. In Jianshi, within a succession of nine conodont zones, a possible IOB is placed at Bed 225 + 40 cm based on the first occurrence (FO) of conodont subspecies Novispathodus waageni eowaageni. New collections include a total of 99 well-preserved Eurygnathodus costatus specimens from Bed 225 to Bed 241, and a single occurrence of Eu. hamadai? from Bed 226. The FO of Eu. costatus occurs in Bed 225 + 10 cm, 30 cm below N. w. eowaageni. The reconstructed ontogenetic series of Eurygnathodus costatus involves four growth stages (A → B → C → D) based on characteristics of the denticles (nodes or ridges), platform, basal cavity, margin profile, and crimp. These preserve ancestral characters that suggest a novel origin for the evolutionary lineage of the genus, namely from Sweetospathodus kummeli →Eurygnathodus costatus→Eu. sp. D → Eurygnathodus hamadai. Seven additional informal species of Eurygnathodus are differentiated as potential biostratigraphic markers. The FO of Eu. costatus may serve as an auxiliary marker for the IOB.

The taxonomy, diversity, evolutionary lineages, and stratigraphical distributions of Middle and early Late Triassic conodonts are reviewed and re-evaluated. Twenty-five genera are recognized in the Middle and early Late Triassic, including a new genus cited in open nomenclature. Of these, 24 genera are assigned to two families and seven subfamilies. The family Gondolellidae consists of the subfamilies Cornudininae, Epigondolellinae, Neogondolellinae, Novispathodinae, Paragondolellinae and Pseudofurnishiinae. The family Gladigondolellidae is monotypic, consisting of the subfamily Gladigondolellinae. The genus Neostrachanognathus is not assigned to any family or subfamily as its origin is unclear. Conodont provincialism was low in the early Anisian, but from the late Anisian faunistic differences started to increase and became stronger during the early Ladinian, reaching a peak around the mid-Ladinian. Provincialism remained strong until the earliest Carnian and changed to an all-Triassic low in the early Tuvalian. The provincialism between North America and Tethys rebounded on the specific level during the late Tuvalian. Diversities on generic and specific levels have been established, and two major conodont diversity cycles are recognized: the first ranges from the Bithynian (early Anisian) to the Julian (late early Carnian), and the second is restricted to the Tuvalian (late Carnian).

The chronostratigraphy of Guandao section has served as the foundation for numerous studies of the end-Permian extinction and biotic recovery in south China. Guandao section is continuous from the Permian–Triassic boundary to the Upper Triassic. Conodonts enable broad delineation of stage and substage boundaries and calibration of foraminifer biostratigraphy as follows. Changhsingian–Griesbachian: first Hindeodus parvus, and first appearance of foraminifers Postcladella kalhori and Earlandia sp. Griesbachian–Dienerian: first Neospathodus dieneri, and last appearance of foraminifer P. grandis. Dienerian–Smithian: first Novispathodus waageni and late Dienerian first appearance of foraminifer Hoyenella ex gr. sinensis. Smithian–Spathian: first Nv? crassatus and last appearance of foraminifers Arenovidalina n. sp. and Glomospirella cf. vulgaris. Spathian–Aegean: first Chiosella timorensis and first appearance of foraminifer Meandrospira dinarica. Aegean–Bithynian: first Nicoraella germanica and first appearance of foraminifer Pilammina densa. Bithynian–Pelsonian: after last Neogondolella regalis, prior to first Paragondolella bulgarica and first appearance of foraminifer Aulotortus eotriasicus. Pelsonian–Illyrian: first Pg. excelsa and last appearance of foraminifers Meandrospira? deformata and Pilamminella grandis. Illyrian–Fassanian: first Budurovignathus truempyi, and first appearance of foraminifers Abriolina mediterranea and Paleolituonella meridionalis. Fassanian–Longobardian: first Bv. mungoensis and last appearance of foraminifer A. mediterranea. Longobardian–Cordevolian: first Quadralella polygnathiformis and last appearance of foraminifers Turriglomina mesotriasica and Endotriadella wirzi. The section contains primary magnetic signature with frequent reversals occurring around the Permian–Triassic, Olenekian–Anisian, and Anisian–Ladinian boundaries. Predominantly normal polarity occurs in the lower Smithian, Bithynian, and Longobardian–Cordevolian. Predominantly reversed polarity occurs in the upper Griesbachian, Induan–Olenekian, Pelsonian and lower Illyrian. Reversals match well with the GPTS. Large amplitude carbon isotope excursions, attaining values as low as −2.9‰ δ13C and high as +5.7‰ δ13C, characterize the Lower Triassic and basal Anisian. Values stabilize around +2‰ δ13C through the Anisian to Carnian. Similar signatures have been reported globally. Magnetic susceptibility and synthetic gamma ray logs show large fluctuations in the Lower Triassic and an overall decline in magnitude of fluctuation through the Middle and Upper Triassic. The largest spikes in magnetic susceptibility and gamma ray, indicating greater terrestrial lithogenic flux, correspond to positive δ13C excursions. High precision U–Pb analysis of zircons from volcanic ash beds provide a robust age of 247.28 ± 0.12 Ma for the Olenekian–Anisian boundary at Guandao and an age of 251.985 ± 0.097 Ma for the Permian–Triassic boundary at Taiping. Together, the new U–Pb geochronology from the Guandao and Taiping sections suggest an estimated duration of 4.71 ± 0.15 Ma for the Early Triassic Epoch.

Seawater viscosity is influenced by temperature as well as through excretion of exopolymers by some plankton. We examined the role of viscosity on the movement patterns and sensory abilities of the dinoflagellate Heterocapsa triquetra, manipulating the viscosity of seawater to simulate a 10+1.58C temperature change. In a second treatment, we seeded the water with microbeads to examine swimming behaviours in the presence of a mechanical stimulus. Increased viscosity reduced distances between conspecifics 4.7-fold and increased distances between protists and microbeads by 3.4-fold. Increased viscosity also affected other aspects of motility, with an overall reduction in swimming speed of 2.0- and 7.0-fold for treatments with and without mechanical stimuli. Higher viscosities were associated with upward vertical migration, in both the presence and absence of microbeads. Cells were highly sensitive to disturbances to the velocity field, by as little as 1.5%, and different approach distances of H. triquetra to conspecifics over mechanical stimuli suggest sensory capacity to distinguish types of particles. Mediation of motility and migratory behaviours through viscosity implies ramifications for the distribution of protists and their encounters with resources, predators and conspecifics triggered by events such as temperature changes and phytoplankton bloom events.

We report a new ichthyopterygian assemblage from Lower Triassic horizons of the Prida Formation at Fossil Hill in central Nevada. Although fragmentary, the specimens collected so far document a diverse fauna. One partial jaw exhibits isodont dentition with blunt tipped, mesiodistally compressed crowns and striated enamel. These features are shared with the Early Triassic genusUtatsusaurusknown from coeval deposits in Japan and British Columbia. An additional specimen exhibits a different dentition characterized by relatively small, rounded posterior teeth resembling other Early Triassic ichthyopterygians, particularlyGrippia.This Nevada assemblage marks a southward latitudinal extension for Early Triassic ichthyopterygians along the eastern margin of Panthalassa and indicates repeated trans-hemispheric dispersal events in Early Triassic ichthyopterygians.

Elasmobranchs are reported for the first time from Lower Triassic deposits in Oman. The well-preserved remains consist of isolated teeth, dermal denticles and fin spines, recovered from conodont residues. The low-palaeolatitude sections consist of Lopingian–Olenekian shallow and pelagic carbonates in exotics, olistoliths and breccia blocks that have been redeposited in younger allochthonous strata of the Hawasina Basin throughout the Oman Mountains at Jabal Safra (olistoliths within the Jurassic Guwayza Formation, Olenekian), as well as at Wadi Alwa (exotic Alwa Formation, Lopingian–Olenekian) and Wadi Wasit Block (slope breccia in the Al Jil Formation, Induan), both of which occur in the Ba'id region. The recovered fauna contains a small number of pre-existing genera, but is mainly composed of new hybodont and neoselachian taxa. They are identified as: Omanoselache halli Koot & Cuny sp. nov., cf. Omanoselache sp., Safrodus tozeri Koot & Cuny gen. et sp. nov. and Polyfaciodus pandus Koot & Cuny gen. et sp. nov., based on the majority of the recovered dental remains. Spine fragments are identified as cf. Amelacanthus sp. This fauna represents the second published record of neoselachian teeth from the Induan and the most extensive record from the Lower Triassic in terms of abundance and diversity. The fauna is dominated by Neoselachii, whereas other Early Triassic faunas are hybodont-dominated, and histological study of the neoselachian enameloid significantly adds to our knowledge of the early stages of their evolution. All described taxa are new to the Oman fossil record and that of western Neotethys, apart from Omanoselache and Amelacanthus, which have been recognized from Wordian deposits, and Omanoselache is the second genus from Oman known to have survived the late Permian mass extinction. The level of faunal diversity recognized here is comparable to other Early Triassic faunas but is much reduced compared to the Wordian pre-extinctions fauna.http://zoobank.org/urn:lsid:zoobank.org:pub:E82E8BC2-1743-4883-B27B-3564DAAF2DF1