late permian changhsingian conodont biozonation and the basal boundary ganxi section western hubei province south china four neogondolellid conodont interval zones were recognized across the changhsingian stage at ganxi section western hubei province south china they are in ascending order the clarkina wangi zone the clarkina changxingensis changxingensis zone the clarkina changxingensis yini zone and the clarkina meishanensis meishanensis zone the present study suggests that the base of the changhsingian can be defined by the first appearance datum fad of clarkina wangi within an evolutionary lineage from clarkina longicuspidata to clarkina wangi the wuchiapingian changhsingian boundary can be placed at the base of bed 104 at ganxi section south china because of the first occurrence of clarkina wangi

revised conodont based integrated high resolution timescale for the changhsingian stage and end permian extinction interval at the meishan sections south china abstract meishan section d with the wuchiapingian changhsingian and permian triassic gssps has become the most intensively studied section because it records the whole process of the largest biological extinction during the phanerozoic numerous data including high precision geochronology multiple isotope chemostratigraphy magnetostratigraphy and high resolution multiple fossil biostratigraphy have been determined during the last decade conodonts are very abundant in the changhsingian stage at the meishan sections and their biostratigraphy together with geochronologic and multiple geochemical data provide a basic temporal framework to calibrate the end permian mass extinction and realize global correlation between sections at meishan and those in other regions of the world however major discrepancies exist in various previous studies of conodonts from the meishan sections many different authors have documented very different species ranges based on different concepts and approaches of taxonomy we here employ a sample population approach to revise and refine the high resolution conodont biostratigraphic framework for the changhsingian stage and end permian mass extinction interval across the permian triassic boundary ptb at the meishan sections eight zones are recognized from the latest wuchiapingian to the basal triassic they are in ascending order the clarkina longicuspidata zone in the uppermost wuchiapingian the clarkina wangi zone clarkina subcarinata zone clarkina changxingensis zone clarkina yini zone clarkina meishanensis zone clarkina zhejiangensis hindeodus changxingensis zone in the changhsingian stage and the hindeodus parvus zone in the basal triassic conodont evolutionary lineages for the whole changhsingian are also tentatively established all species are described in detail and growth series of different specimens for valid species are figured as completely as possible the temporal relationship of each conodont zone with geochemical excursions geochronologic calibration and magnetostratigraphical polarity zones are provided which is critical to understand the tempo of the end permian mass extinction

changhsingian conodont succession and the end permian mass extinction event at the daijiagou section in chongqing southwest china abstract previous studies suggested rapid evolution of conodonts across the permian triassic boundary ptb and the end permian mass extinction pattern varies in different sections in south china here we document a high resolution conodont succession from a carbonate facies of the changhsingian stage and across the ptb at the daijiagou section about 35 km north to chongqing city southwest china two genera and twelve species are identified seven conodont zones are recognized from the uppermost part of the lungtan formation to the lowest feixianguan formation they are the clarkina liangshanensis c wangi c subcarinata c changxingensis c yini c meishanensis and hindeodus parvus zones in ascending order based on the high resolution biostratigraphical framework at daijiagou the end permian mass extinction was rapid and it began in the base of the clarkina meishanensis zone associated with the extinction a negative excursion of 13 c carb started in the middle part of clarkina yini zone with a progressive shift of 1 6 to the middle part of the clarkina meishanensis followed by a sharp shift of 3 51 from the clarkina meishanensis zone to the hindeodus parvus zone our study also suggests that the triassic index species hindeodus parvus co occurred with hindeodus changxingensis and clarkina zhejiangensis and directly overlies the clarkina meishanensis zone at the daijiagou section all these data from the daijiagou section and some previous studies of other sections in sichuan guizhou provinces and chongqing city suggest that the first occurrences of hindeodus parvus are slightly earlier than the sharp negative excursion of 13 c carb and the fad at the meishan gssp section we consider that the slight difference of the end permian mass extinction chemostratigraphy and conodont biostratigraphy at daijiagou and its adjacent areas is most likely subject to different lithofacies fossil preservation and the constraint on the stratigraphic resolution rather than a different tempo of the end permian mass extinction in a global sense the whole changhsingian conodont succession at daijiagou provides a high resolution correlation with other equivalent sections in the palaeotethys the controversial results of biostratigraphy and chemostratigraphy between the sections investigated in this paper and the meishan gssp section also provide some important implications that accurate chronocorrelation requires the evaluation of multiple varied stratigraphcal signals rather than relying solely on the fad of the triassic index species hindeodus parvus for recognizing the permian triassic boundary ptb growth series of abundant specimens for each species are figured the taxonomy of some hindeodus species in the ptb interval is updated

a newly discovered earliest triassic chert at gaimao section guizhou southwestern china abstract the permian triassic ptb boundary section at gaimao huaxi district guiyang guizhou province records a unique lithological transition between the permian and triassic in south china thus bioclastic limestones of the changxing formation are overlain by radiolarian bearing siliceous rocks of the dalong formation and ultimately limestone mudstone alternations of the shabaowan formation conodont sampling of the section revealed well preserved elements that enabled a conodont biostratigraphy to be established the occurrences of hindeodus julfensis and hindeodus typicalis in changxing formation bioclastic limestone indicate a late permian age four conodont zones have been established in dalong and shabaowan formations in ascending order those are the isarcicella isarcica zone neogondolella or clarkina planata zone neogondolella krystyni zone and neospathodus dieneri zone the presence of typical griesbachian conodonts i isarcica and isarcicella staeschei in upper dalong formation indicates that this formation s radiolarian bearing siliceous mudrocks are of earliest triassic age and not restricted to the permian as previously thought thin section analysis reveals that the upper dalong formation contains spheroidal radiolarians but not a diverse assemblage of permian holdover taxa the new data proves that following the end permian mass extinction of radiolarian the abundance of these siliceous planktons was maintained at least locally enabling chert deposition to persist thus the gaimao section provides an exception to the early triassic chert gap the first of its kind in palaeo tethys and indicates that the end of chert deposition does not always mark the end permian mass extinction

conodont biostratigraphic control on transitional marine to non marine permian triassic boundary sequences in yunnan guizhou china the recovery of conodonts associated with ash beds and magnetostratigraphy in the key zhongzhai section near langdai liuzhi guizhou province provides precise and definitive control on the position of the permian triassic boundary in the transition from marine to non marine facies of western guizhou and eastern yunnan provinces of southwestern china in the zhongzhai section the boundary interval consists of a lower limestone 20 cm thick that contains fragments of hindeodus sp and clarkina sp this is overlain by a 50 cm thick black shale bed containing an abundant brachiopod fauna but only a single conodont fragment this bed is in turn overlain by a 23 cm thick limestone that contains clarkina meishanensis merrillina ultima hindeodus changxingensis h praeparvus and h eurypyge directly over this limestone is a 5 cm thick ash bed followed by a 10 cm thick black shale which is overlain by a second upper ash bed that is 3 cm thick on top of the upper ash bed is a 20 cm thick silty limestone containing an abundant dwarf conodont fauna dominated by hindeodus and containing h parvus but also including clarkina tulongensis the permian triassic boundary is placed at the level of the black shale located between the two ash beds 2007 elsevier b v all rights reserved

pterosaur diversity untangling the influence of sampling biases lagerstatten and genuine biodiversity signals abstract pterosaurs were a diverse and successful group of mesozoic reptiles with an evolutionary history that extended for approximately 145 myr recent attempts to understand species richness trajectories for pterosaurs have led to them becoming a focal group for ongoing debate about the importance of sampling biases in determining observed species richness patterns in the vertebrate fossil record here we reanalyse pterosaur species richness through time and make statistical comparisons to proxies for pterosaur fossil record sampling and global terrestrial tetrapod sampling using several approaches including generalised least squares multiple regression models moreover we make quantitative comparisons between species richness and morphological diversity disparity sampling of the pterosaur fossil record shows substantial temporal heterogeneity with cretaceous pterosaur records more commonly recovered from terrestrial environments and with sampling proxies for cretaceous pterosaurs closely tracking global sampling proxies for terrestrial tetrapods the similarities between pterosaur based and global sampling proxies for cretaceous data call into question the hypothesis that observed correlations between pterosaur sampling proxies and pterosaur species richness result from mere redundancy multiple regression modelling supports the hypothesis that much of the variation present in pterosaur palaeobiodiversity curves results from a combination of the presence or absence of lagerstatten sites of exceptional preservation and a background sampling signal that may reflect temporal variation in fossiliferous sedimentary rock despite these evident strong biases in the pterosaur record it seems plausible that both species richness and disparity peaked relatively late in the evolutionary history of pterosaurs during the late jurassic early cretaceous although an absence of pterosaur bearing terrestrial lagerstatten in the late triassic early jurassic fossil record means that caution is required it is possible that a late peak in diversity may reflect the ecological radiation of pterodactyloid pterosaurs from the late jurassic onwards which has been linked to increased terrestrial locomotory abilities and ecological niche occupancy and relaxed constraints upon body size evolution

early triassic conodont palynological biostratigraphy of the meishan d section in changxing zhejiang province south china the lower triassic consisting of the yinkeng fm helongshan fm and the lower part of the nanlinghu fm is well developed at the meishan d section of changxing county zhejiang province south china based on detailed study of the conodont biostratigraphy from the interval of the permian triassic boundary and the lower triassic in the meishan d section 8 conodont zones are recognized in ascending order as follows the neogondolella changxingensis yini hindeodus praeparvus zone beds 24a 24e top of the changxing fm the neogondolella meishanensis meishanensis hindeodus eurypyge zone beds 25 27b base of the yinkeng fm the hindeodus parvus zone beds 27c 27d first conodont zone of triassic the global index for the base of triassic the isarcicella staeschei zone beds 28 29a lower part of the yinkeng fm i isarcica zone beds 29b 51 lower part of the yinkeng fm the neogondolella tulongensis n planata zone beds 52 72 from upper part of the yinkeng fm to lower part of the helongshan fm the neospathodus kummeli zone beds 73 92 middle part of the helongshan fm and the neospathodus cristagalli n dieneri zone beds 93 111 from upper part of the helongshan fm to the base of the nanlinghu fm at the meishan d section the palynological biostratigraphy is also studied herein the palynological assemblage of lundbladispora taeniaesporites equisetosporites is found in the intervals which contain the conodont isarcicella isarcica zone and the lower part of the neogondolella tulongensis n planata zone

a delayed end permian extinction in deep water locations and its relationship to temperature trends bianyang guizhou province south china new collecting at a biostratigraphically highly resolved deep water section in south china reveals a brief a few tens of thousands of years but measurable delay in extinction timing relative to contemporaneous shallower water sections foraminifers and conodonts in the bianyang section show a sharp extinction at the top of hindeodus changxingensis zone whilst in shallower sections such as the well known meishan gssp location these taxa have a major extinction pulse at the top of the preceding clarkina yini zone the main end permian extinction coincides with the onset of a negative carbon isotope excursion whilst the deep water extinctions occur around the lowpoint of the carbon isotope curve rapidly increasing surface water temperatures and the effects of deep water anoxia were all important during the crisis although it is noteworthy that regression and extinction also show a close temporal link

new species of the conodont genus hindeodus and the conodont biostratigraphy of the permian triassic boundary interval abstract four new species of the conodont genus hindeodus hindeodus eurypyge sp nov hindeodus inflatus sp nov hindeodus sp nov a and hindeodus sp nov b are described from the permian triassic transition in south china our study confirms the first appearance of hindeodus parvus at the gssp level base of bed 27c at meishan however at shangsi the first occurrence of h parvus is about 4 5 m above the event boundary analysis of conodont biostratigraphy of the meishan d section and the shangsi section suggest significant differences between the two sections these include the absence of h changxingensis wang from the shangsi section and the approximately 4 5 m of the shangsi section that contains h priscus kozur h latidentatus kozur and h eurypyge n sp below the first occurrence of h parvus these differences may be accounted for most easily by suggesting that there is a minor depositional hiatus at the permian triassic boundary gssp level as based on the first appearance of the conodont hindeodus parvus in meishan section d taxonomic re evaluation of hindeodus pa elements indicates that species of the genus can be broadly separated into two groups based on the morphology of the posterior portion of the element and on growth patterns the stable pa element morphology of hindeodus first developed in the carboniferous was replaced by a complex of rapid evolutionary change in the latest permian and early triassic with as many as 11 valid species of the genus in the permian triassic boundary interval which are probably descendants of only two species h typicalis and h n sp b we suggest that the dramatic change in conodont biofacies observed at the p t boundary in south china from neogondolella dominated faunas to hindeodus dominated faunas was caused by the introduction of a high component of silt beginning in bed 27 at meishan and bed 28 at shangsi that tipped the environmental balance in favor of hindeodus and isarcicella over neogondolella clarkina species we contend that hindeodus species were adaptable to higher levels of turbidity than neogondolella clarkina species and hence at meishan and shangsi it was not a matter of a drastic increase in the abundance of hindeodus but an exclusion of neogondolella

lower triassic carbonate δ238u record demonstrates expanded oceanic anoxia during smithian thermal maximum and improved ventilation during smithian spathian boundary cooling event abstract the smithian spathian boundary ssb transition was recently identified as a major biocrisis on the road to marine ecosystem recovery following the end permian mass extinction marine anoxia is hypothesized to have played an important role in the ssb biocrisis however an understanding of the relationship of this biocrisis to contemporaneous marine redox conditions has been hampered by limited knowledge of the timing duration and extent of anoxia during the smithian spathian s s transition here we present a high resolution carbonate u isotope record from the jiarong section of south china that spans the mid smithian to mid spathian interval this record shows persistent negative 238u values averaging 0 56 in the late smithian followed by a rapid positive shift from 0 78 to 0 10 across the ssb and then a more gradual shift back to lower 238u values in the early to mid spathian u isotope mass balance modeling suggests that the global area of anoxic seafloor expanded strongly during the late smithian and the early to mid spathian but contracted sharply during the s s transition this redox pattern shows an excellent correspondence to previously published tropical sea surface temperature sst records with peak oceanic anoxia coinciding with the smithian thermal maximum stm and diminished anoxia during a pronounced global cooling event at the ssb although paleontological records commonly do not distinguish between terminations during the late smithian and ssb we hypothesize that the ssb biocrisis which was marked by sharp diversity losses among conodonts ammonoids and other marine invertebrates was primarily associated with the stm in which case oceanic anoxia is likely to have been a major stressor of mid olenekian marine biotas

exceptional vertebrate biotas from the triassic of china and the expansion of marine ecosystems after the permo triassic mass extinction abstract the triassic was a time of turmoil as life recovered from the most devastating of all mass extinctions the permo triassic event 252 million years ago the triassic marine rock succession of southwest china provides unique documentation of the recovery of marine life through a series of well dated exceptionally preserved fossil assemblages in the daye guanling zhuganpo and xiaowa formations new work shows the richness of the faunas of fishes and reptiles and that recovery of vertebrate faunas was delayed by harsh environmental conditions and then occurred rapidly in the anisian the key faunas of fishes and reptiles come from a limited area in eastern yunnan and western guizhou provinces and these may be dated relative to shared stratigraphic units and their palaeoenvironments reconstructed the luoping and panxian biotas both from the guanling formation are dated as anisian pelsonian on the basis of conodonts and radiometric dates the former being slightly older than the latter the xingyi biota is from the zhuganpo formation and is ladinian or early carnian while the guanling biota is from the overlying xiaowa formation dated as carnian the first three biotas include extensive benthos and burrowing in the sediments and they were located in restricted basins close to shore further even though the luoping and panxian biotas are of similar age their faunas differ significantly reflecting perhaps palaeogeographically isolated basins between the time of the xingyi and guanling biotas there was a major transgression and the guanling biota is entirely different in character from the other three being dominated by pelagic forms such as large floating crinoids attached to logs very large ichthyosaurs and thalattosaurs and pseudoplanktonic bivalves with no benthos and no burrowing phylogenetic study of the fishes and marine reptiles shows apparently explosive diversification among 20 actinopterygian lineages very early in the early triassic but a later expansion of marine reptile groups in the late olenekian and early anisian this offset in diversification patterns is matched by comparisons of feeding guild categories and body size data new research tools will shed considerable light on the phylogenetic and ecological implications of recovery of mairne vertebrates in the triassic

conodont biostratigraphy of a new permo triassic boundary section at wenbudangsang north tibet abstract the wenbudangsang section is a newly discovered continuous succession of marine carbonates that straddles the permian triassic boundary ptb extending from the late permian to the earliest triassic induan the section is located in the wenbudangsang area of geji county northern tibet and tectonically sits within the northern gangdise stratigraphic division conodonts are abundant throughout this section except being comparatively rare and less diverse in the permian strata below the distinctive ptb clay bed the conodonts are mainly represented by hindeodus isarcicella pa elements neogondolella pa elements and ramiform elements with few neospathodus pa elements present at the top of the section two conodont zonal successions have thus been determined based on hindeodus isarcicella and neogondolella species the hindeodus isarcicella succession includes the uppermost permian hindeodus julfensis zone hindeodus praeparvus zone and the lowermost triassic hindeodus parvus zone isarcicella staeschei zone isarcicella isarcica zone and hindeodus postparvus zone the neogondolella succession consists of the upper permian neogondolella changxingensis neogondolella deflecta neogondolella postwangi zone neogondolella yini neogondolella zhangi zone neogondolella meishanensis zone the neogondolella taylorae zone that crosses the ptb and the lowermost triassic neogondolella krystyni zone and neogondolella prediscreta n sp zone the top of the section is defined by the neospathodus kummeli zone and neospathodus cristagalli zone two new species hindeodus microdentatus n sp and n prediscreta n sp are established and described in this paper the ptb conodont successions recognised in the new wenbudangsang section have been closely correlated herein with other well known ptb sections the gssp meishan section of south china sections in abadeh in iran and sections at spiti in india importantly the conodont faunas from wenbudangsang now provide an opportunity to effectively correlate the ptb hindeodid and gondolellid zonal schemes given the high abundance of both assemblages which is unique to this section

uppermost permian to lower triassic conodont successions from the enshi area western hubei province south china abstract 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

controls on regional marine redox evolution during permian triassic transition in south china abstract although oceanic anoxia is regarded as a leading cause of the permian triassic boundary ptb mass extinction its timing extent and underlying causes remain unclear here we conducted a high resolution fe s c mo geochemical study of the entire changhsingian and lowermost induan succession in a carbonate ramp setting at ganxi western hubei province south china six stratigraphic units representing discrete redox intervals were identified based on integrated fe s c mo data units i iii are of latest wuchiapingian to early changhsingian age with units i and iii characterized by euxinia and unit ii by uncertain redox conditions unit iv of mid changhsingian age records a gradual transition from euxinic to ferruginous conditions units v and vi spanning the latest permian mass extinction lpme to earliest triassic interval were deposited under dominantly ferruginous conditions punctuated by both euxinic and oxic episodes redox variations at ganxi were controlled by contemporaneous oceanographic changes in the upper oceanic thermocline region i euxinia in units i and iii may record elevated marine productivity as suggested by mean organic carbon accumulation rates or ocar of 6 5 and 5 1 mg cm2 kyr respectively that was possibly related to upwelling ii the euxinic to ferruginous transition from unit iv to units v vi can be attributed to a combination of reduced sulfate availability and rising terrigenous iron inputs mean fe of 1 7 and 3 9 respectively for units v iv and vi compared to 1 0 for units i iii and iii transient intervals of euxinia in units v and vi were facilitated by enhanced sulfate fluxes related to episodic volcanism during this interval an integration of the redox data from ganxi with previously published data from the shangsi and xiakou sections suggests that enhanced weathering fluxes were most likely the key factor controlling the marine redox transition from euxinic to ferruginous conditions during the latest permian across the south china region

controls on facies architecture of a large triassic carbonate platform the great bank of guizhou nanpanjiang basin south china abstract the great bank of guizhou gbg is an exceptionally well exposed isolated triassic platform in the nanpanjiang basin of south china the platform is exhumed with its depositional profile preserved and is dissected by a faulted syncline that exposes a complete and uncomplicated cross section providing a unique opportunity to evaluate mechanisms involved in its birth evolution and demise the gbg formed near the southern margin of the yangtze platform during a deepening event that expanded the nanpanjiang basin and drowned the region surrounding the gbg in the latest permian initial accumulation of the gbg began in the latest permian with small reef mounds and open marine skeletal packstones following the end permian extinction cyanobacterial boundstones grew over the bank top during the early triassic the gbg developed a low relief bank profile with mobile oolite shoals at the margin shallow subtidal and peritidal deposits in the interior and gentle slopes dominated by pelagics debris flow deposits and turbidites at the basin margin in the middle triassic anisian the gbg developed a progressively steepening profile rimmed with massive tubiphytes reefs the platform was flat topped with tidal flat deposits across the interior basin margin deposition was dominated by turbidites and debris flow deposits but eventually shifted to avalanche and rock fall deposits as the slopes steepened to the angle of repose in the middle triassic ladinian an erosional escarpment up to 1700 m high developed at the margin platform margin strata are bedded packstones similar to interior strata whereas breccias at the basin margin contain coral boundstone clasts suggesting erosion of reefs from the escarpment a restricted subtidal lagoon formed in the interior producing an atoll like morphology later a flat topped profile was restored as tidal flats spread across the interior in the beginning of the late triassic deepening contributed to termination of the gbg before siliciclastic turbidites and shales were deposited over the platform in contrast with the well known platforms of the dolomites of northern italy the gbg contains abundant muddy carbonates and a progressively steepening bank to reef rimmed and escarpment architecture the italian platforms contain little mud and have angle of repose pinnacle geometries the gbg s larger size increased mud production and protected it from extensive winnowing of mud which in turn resulted in off bank shedding of muddy sediments that were stable on relatively gentle basin margin slopes which progressively steepened and ultimately led to avalanche deposits and a high relief erosional escarpment in contrast the lesser mud content of the dolomites platforms forced avalanche and talus deposition to dominate throughout deposition of basin margins which in turn produced their angle of repose geometries

lower middle triassic conodont biostratigraphy of the mingtang section nanpanjiang basin south china abstract the well exposed stratigraphic sequences on the great bank of guizhou gbg in south china provide important information for the understanding of various environmental settings during the permian triassic mass extinction and the subsequent recovery including one of the oldest triassic marginal reef complexes which is viewed as an important indicator of biotic recovery following the end permian mass extinction here we report a systematic conodont study on a newly exposed lower middle triassic section the mingtang section at the margin of the gbg to provide more data for the time scale of the post extinction recovery twenty four species in 11 conodont genera are identified and assigned to hindeodus parvus neoclarkina discreta neospathodus dieneri novispathodus waageni neospathodus triangularis triassospathodus homeri chiosella timorensis nicoraella germanica and nicoraella kockeli zones in ascending order these zones correlate well with the conodont successions in south china and over the world the induan olenekian boundary can be well defined by the first occurrence of novispathodus waageni in the lower middle part of the luolou formation while the early middle triassic boundary was placed at 0 2 m below the top of the luolou formation according to the first occurrence of chiosella timorensis these conodont data suggest that the tubiphytes reef began to recover in the bithynian early middle triassic later than benthonic organisms such as foraminifers and calcareous algae

conodont diversity and evolution through the latest permian and early triassic upheavals abstract a study of latest permian and early triassic multielement conodonts identifies eight steps in their evolutionary history during an interval when earth s biosphere was highly stressed these steps are 1 gradual decline of families and genera through the changhsingian up to the late griesbachian 2 conodont biofacies change and extinction of tethyan endemic species close to the permian triassic boundary ptb 3 faunal turnover with extinction and origination in the late griesbachian 4 initial radiation in gondolellids and diversification in apparatuses during the dienerian 5 explosive radiation in the early middle smithian 6 major extinction in the late smithian 7 major radiation early in the spathian 8 gradual turnover and decline in the late spathian through early anisian conodontophorids were reduced from five families at the beginning of the changhsingian to three by the ptb and to two late in the griesbachian from the changhsingian to the late griesbachian there was a single multielement apparatus represented in the gondolellidae whereas by the olenekian there were at least twelve given absolute age constraints the conodont recovery in the aftermath of the ptb was extraordinary conodont evolution during the dienerian remains obscure but was very significant in terms of changes in multielement apparatuses in spite of induan extinctions generic diversity generally increased from the ptb up to the late smithian in terms of species genera and multielement apparatuses the acme of triassic conodonts was in the middle smithian and the biggest extinction was in the late smithian after this extinction generic and apparatus diversity quickly returned to high levels marking a significant spathian recovery gradual decline characterized the late spathian and persisted into the early anisian a synthetic summary of the temporal distribution and proposed relationships amongst all known lower triassic conodonts provide an improved foundation for biostratigraphic and biochronologic studies extinction and radiation trends correlate well with sea level changes and sequence boundaries faunal turnovers correspond to lowstands in the late griesbachian late smithian and late spathian and radiations correspond to transgressions in the early griesbachian early smithian and early spathian the trends also correlate with perturbations in the carbon cycle with lower triassic 13c minima corresponding to extinction and faunal turnover and positive values generally occurring during radiations however middle triassic recovery of marine benthos follows a positive maxima and an overall decline in conodont diversity new taxa borinella chowadensis b megacuspa neogondolella griesbachensis and n mongeri are described

a refined succession of changhsingian and griesbachian neogondolellid conodonts from the meishan section candidate of the global stratotype section and point of the permian triassic boundary abstract a detailed study of new conodont collections from the changxing formation at the meishan section has resulted in taxonomic refinement of several important neogondolellid species most of the previously erected species are much more strictly redefined mainly based on the denticulation of the holotypes and the stratigraphic ranges attributed to key conodont taxa are modified three new species and two new subspecies all of which are form species are tentatively erected and described mainly for the purpose of taxonomic explanation as a result of the taxonomic refinement six neogondolellid conodont zones are recognized for the changxing formation and the permian triassic boundary interval

the smithian spathian boundary late early triassic a review of ammonoid conodont and carbon isotopic criteria abstract 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

quantitative stratigraphic correlation of the lower triassic in south china based on conodont unitary associations abstract unitary association method uam analyses of conodont faunas from 28 sections spanning the biggest phanerozoic end permian mass extinction and significant global environmental and ecosystem perturbations during the succeeding early triassic are presented based on 72 conodont species 26 unitary association zones uazs are established for the latest permian to earliest middle triassic of south china these uazs provide quantitative high resolution tools to correlate sequences in the early triassic of south china and to compare and test high resolution conodont biostratigraphy based on interval conodont zones developed over the past three decades our quantitative analyses provide insights on ongoing debates relating to the first appearance datum fad of the conodont hindeodus parvus which is used to place and subsequently correlate the golden spike defining the base of the triassic permian triassic boundary at the base of bed 27c at the gssp meishan d section previous proposals that suggested potential earlier occurrences of h parvus below its fad at meishan section are not supported by our results in deep water sections the first occurrence fo of h parvus lies at the base of uaz 5 at the bianyang section while it lies within uaz 6 at the meishan section this indicates that the earliest occurrence of h parvus in south china is in the bianyang section but this conclusion needs further testing due to the reliance on spot data by the uam anomalously high occurrences of hindeodus in the mingtang section close to the bianyang section further suggests that the bianyang mingtang area may have provided a temporally extended habitable zone for anchignathodontid conodonts stage boundaries currently proposed or established using interval conodont zones locate within or between uazs and are difficult to correlate with carbon isotope curves uazs are useful in helping to define gssps by recognizing which correlations are most robust and in the selection of the most appropriate species and level for gssps

lower triassic conodont sequence in chaohu anhui province china and its global correlation abstract the early triassic paleogeographical setting of the chaohu section in china was in a deep part of the yangtze platform and this has resulted in a rather complete lower triassic sequence with rich ammonoid and conodont successions three lower triassic sections west pingdingshan north pingdingshan and south majiashan have been sampled in detail for a systematic conodont study eight conodont zones are recognized in ascending order these are the zones of hindeodus typicalis neogondolella krystyni neospathodus kummeli neospathodus dieneri neospathodus waageni neospathodus pingdingshanensis neospathodus homeri and neospathodus anhuinensis these are correlated with the sequences in north america and other areas of the world the succession provides a good basis for the definition of the global stratotype of the induan olenekian boundary gssp which has been proposed at the base of the neospathodus waageni zone in west pingdingshan seven new species are introduced neospathodus chaohuensis n chii n concavus n eotriangularis n pingdingshanensis n posterolongatus n tongi a new subspecies n waageni eowaageni and three morphotypes of n dieneri

gecko global events impacting conodont evolution abstract with a record that spans approximately 300 million years late cambrian through the triassic jurassic transition i e the conodontozoic conodonts witnessed all principal events in the evolution of life on earth from the invasion of the land to the exploration of the air from the explosion of biomineralization in the oceans to the rise of dinosaurs and mammals including three of the major extinction events that occurred in the phanerozoic mainly used for biostratigraphic or geochemical studies the potential of conodonts to help unravel changes perceived to be of global extent rarely has been explored while specialists have identified rapid changes in conodont element morphology throughout their history the conodont animal has often been perceived to have been a static entity in a constantly evolving world when biological equilibrium in the oceans was undergoing profound alteration and faunal recoveries took place in phases that seem to have had recurrent patterns it is now essential that we begin to further investigate how conodonts as biologic entities responded to or were impacted by palaeogeographic changes eustatic and climatic fluctuations shifting redox conditions and major faunal turnovers and reorganizations that took place during the conodontozoic

the lower triassic sulphur mountain formation in the wapiti lake area lithostratigraphy conodont biostratigraphy and a new biozonation for the lower olenekian smithian earth science sector ess contribution 20080714 the sulphur mountain formation in the wapiti area is subdivided into the phroso meosin mountain new and vega members which collectively span much of the lower triassic the smithian conodont faunas are particularly well developed and form the basis of three partly new conodont zones and two new subzones the lachrymiformis zone meeki zone and mosheri zone with the last subdivided into the phryna and milleri subzones an informal lowermost smithian nepalensis interval is introduced although it has yet to be found in the area the phroso member is latest griesbachian dienerian and in its uppermost part smithian specifically the lachrymiformis and meeki zones these are shown to be equivalent to the euflemingites romunduri ammonoid zone the meosin mountain member is assigned to the meeki zone in its lower part and the phryna subzone of the mosheri zone in its upper part at least the upper part of the mosheri zone is equivalent to the anawasatchites tardus ammonoid zone the mackenzie dolomit

conodont zonation across the permian triassic boundary at the xiakou section yichang city hubei province and its correlation with the global stratotype section and point of the ptb xiakou section is situated north of the central yangtze platform with successive late permian to early triassic strata thicker than the global stratotype section and point gssp of the permian triassic boundary ptb we recognized three conodont zones across the ptb in this section by high precision biostratigraphy they are the hindeodus latidentatus clarkina meishanensis zone hindeodus parvus zone and isarcicella isarcica zone in ascending order which correspond well with the gssp the present biostratigraphic work on xiakou section certainly confirmed the conodont zonation through the ptb at the gssp and also testified to the correctness of the ptb demarcation in xiakou section based on this precise demarcation of the ptb the appearance of a clay layer bed zsji266 just beneath the ptb should be an important advantage over the gssp because this clay layer approaches to the ptb much in contrast with those two clay layers bed 26 and bed 28 in the gssp therefore the radiometric isotopic da

multidisciplinary high resolution correlation of the permian triassic boundary abstract biostratigraphic correlation of the ten most important permian triassic boundary sections throughout tethys enables establishment of four conodont and ammonoid subdivisions within a stratigraphic interval one to a few metres thick representing less than 1 ma in ascending order they are conodonts clarkina changxingensis c deflecta zone hindeodus typicalis interval isarcicella parva zone and i isarcica zone and ammonoids pseudotirolites pleuronodoceras zone lower otoceras zone upper otoceras zone and ophiceras zone most of them can be traced to north america and the arctic region carbon isotope investigations of 24 sections along tethys and in greenland and spitzbergen confirm the consistency of 13c negative excursions at the permian triassic boundary together with an inconsistent ir anomaly eight sections show that in most cases there is a succession of ir anomaly denoting the end permian catastrophic environment 13c excursion biomass loss extinction p t boundary origination of newcomers potentially capable of intercontinental correlation within that short time interval there is an intercontinental sequence boundary at the top of the permian and a transgressive surface at the p t boundary followed shortly by a maximum flooding surface an intercontinental anoxia event accompanied the transgression three delineations of the mass extinction phases and three population explosions have been recognized and can be more or less correlated in south china and the southern alps radiometric dating of the volcanogenic boundary clays of meishan shangsi and the main stage siberian tunguss traps give an almost identical age of 250 ma thus implying a synchronous interregional volcanic event there are a few palaeomagnetic transforms within the ptb strata thus multidisciplinary research of the p t boundary strata allows subdivision of this short interval into more than ten intercontinentally correlatable parts each subdivision averages less than 100 ka in duration this may be the highest resolution obtained so far in pre cretaceous rocks high frequency milankovitch type cyclic deposits within the p t boundary beds enable correlation of even higher resolution in the lower yangtze area this high resolution is made possible because the p t transition is a time of saltation and catastrophy in geological history causality of the aggregation of events merits further investigation

conodont biostratigraphy across the permian triassic boundary at the dawen section great bank of guizhou guizhou province south china implications for the late permian extinction and correlation with meishan several continuous permian triassic boundary ptb sections are well exposed in the interior of the great bank of guizhou gbg on the east limb of the bianyang syncline luodian county guizhou province south china fourteen conodont taxa are identified including clarkina kazi clarkina lehrmanni n sp clarkina taylorae clarkina zhejiangensis hindeodus eurypyge hindeodus inflatus hindeodus sxlatidentatus hindeodus parvus erectus hindeodus parvus parvus hindeodus postparvus hindeodus praeparvus hindeodus typicalis isarcicella staeschei and merrillina ultima based on a detailed study of the permian triassic interval at the dawen section the first occurrence fo of h parvus parvus in the lower daye formation at about 7 45 m above the contact surface between the upper permian skeletal packstone and a calcimicrobial framestone unit is correlated with the permian triassic boundary the occurrence of h eurypyge h praeparvus and m ultima immediately below and h postparvus above the interval supports this interpretation a morphometric analysis of 31 hindeodus specimens helped distinguish h parvus erectus from h parvus parvus and h postparvus correlation with the meishan section ptb gssp using both conodont biostratigraphy and carbon isotopes indicates that the major extinction at the two localities is simultaneous and coincides with the top of the skeletal packstone at dawen the contact between the skeletal packstone and the calcimicrobialite is very irregular and has previously been interpreted as a dissolution surface and correlated with a surface in the lower part of bed 27 at meishan our results confirm this interpretation and reveal that the dissolution event postdated the extinction

early triassic induan olenekian conodont biostratigraphy global anoxia carbon isotope excursions and environmental perturbations new data from western australian gondwana the early triassic induan olenekian stage boundary dienerian smithian sub stage boundary has been identified at a depth of 2719 25m in the petroleum exploration well senecio 1 located in the northern perth basin western australia conodont faunas represent three conodont zones in ascending order the neospathodus dieneri zone the neospathodus waageni eowaageni zone and the neospathodus waageni waageni zone the induan olenekian dienerian smithian boundary is placed at the base of the neospathodus waageni eowaageni zone equivalent to the first appearance of neospathodus ex gr waageni utilised elsewhere and adopted by the iugs ics triassic subcommission to define the base of the olenekian bulk kerogen 13c carbon isotopes define a positive peak of c 4 per mille that essentially coincides with the induan olenekian boundary as seen in proposed global stratotype sections and points gssps in south china and spiti india demonstrating the global utility of this level for correlation an anoxic zone is recognised in the lower part of the senecio 1 core and the upper limit of this zone is dated as late induan late dienerian temporal and spatial mapping of marine anoxia and dysoxia globally demonstrates that pulses of dysoxia anoxia affected shallow marine zones at different times in different locations dysoxia anoxia in the shallow marine environment appeared in the latest permian at the extinction level later than in the deep marine environment and appears to be largely restricted to the induan griesbachian and dienerian and early olenekian smithian temporally and geographically restricted upwelling of an oxygen minimum zone into the ocean surface layer due to environmental perturbations including extreme global warming increased terrestrial chemical weathering intensity and continental erosion sea level rise and changes in marine nutrient inventories and productivity rates is interpreted as a likely cause of observed variation in shallow marine dysoxia anoxia in the early triassic

terrestrial marine teleconnections in the collapse and rebuilding of early triassic marine ecosystems abstract the latest permian mass extinction lpe just prior to the permian triassic boundary at 252 ma resulted in the disappearance of 90 of skeletonized marine taxa and the replacement of the paleozoic fauna by the modern fauna in the immediate aftermath of the extinction shallow marine ecosystems were dominated by microbial communities and diminutive disaster taxa lilliput faunas and the post crisis period in general was characterized by high abundance low diversity marine communities occupying a reduced ecological space the recovery of marine ecosystems was a protracted process lasting throughout the 5 myr long early triassic some clades failed to recover and subsequently went extinct dead clades walking while others recovered only to suffer secondary crises during the early triassic profound environmental changes accompanied these biotic developments deep oceans experienced sustained hypoxia or anoxia for at least several million years following the boundary event anoxia was also widespread in shallow marine areas especially at the time of the lpe but it was more episodic and abated more rapidly than in the deep ocean making it an unlikely factor in the delayed recovery of early triassic marine ecosystems the development of anoxia was due at least in part to a sharp temperature rise following the lpe but may have been stimulated by changes in marine nutrient inventories and productivity rates as well these conditions may have been the result of a concurrent increase in subaerial weathering rates that was sustained into the early triassic in addition to increasing nutrient fluxes to marine areas rapid weathering caused a massive influx of sediment to shallow marine systems subjecting marine biotas to siltation stress this scenario implies close teleconnections between terrestrial and marine environments during the permian triassic boundary crisis with perturbations of the terrestrial realm contributing to the marine crisis

quantitative biochronology of the permian triassic boundary in south china based on conodont unitary associations abstract the biochronological characterization of the permian triassic boundary ptb is here improved by means of conodont unitary associations zones uazs the selected data set comprises the six best documented sections in south china including the meishan global stratotype section and point of the ptb this new biochronological zonation has a much higher accuracy than previous schemes which were based on continuous interval zones we show how traditional interval zones around the ptb in south china suffer from diachronous boundaries that cross each other as the result of sampling effort intensity and density and of geographical or ecological exclusion of zonal index taxa inclusive of the first occurrence of the base triassic index species hindeodus parvus our quantitative and robust approach produces a discrete sequence comprising six uazs in the closest agreement with the position of the ptb in meishan the ptb falls here in the interval of separation between uaz 2 and uaz 3 in meishan this interval of separation corresponds to the stratigraphic interval above bed 25 and below bed 27 which also includes the formational boundary between the changhsing and the yinkeng formations we provide a new and independent support for this placement by showing that it correlates with the main turnover of conodont species within the analysed time interval as previously documented the main extinction interval ranged from bed 25 to bed 28 in meishan which are here assigned to uaz 2 and to uaz 4 respectively therefore the main extinction episode is not of end permian age but straddles the ptb previous claims for two distinct extinction pulses bracketing the ptb in south china were based on traditional conodont interval zones and are not supported by the new ua zonation the oldest triassic uaz 3 is identified by the characteristic species hindeodus pisai and by any of the ten characteristic pairs of species neogondolella zhejiangensis or neogondolella tulongensis associated with hindeodus changxingensis hindeodus parvus neogondolella planata neogondolella taylorae or isarcicella huckriedei separate analyses of anchignathodontids and neogondolellids sub data sets show that the base of the triassic is unambiguously defined by the occurrences of the characteristic species h changxingensis isarcicella prisca and i huckriedei in shallow water settings and of two characteristic species n planata and n taylorae in deep water settings moreover we document uncoupled diversity trends across the ptb for each of these two clades a substantial diversification phase of anchignathodontids spans the interval from uaz 3 to uaz 5 it is followed by a drastic 50 reduction of the number of species between uaz 5 and uaz 6 on the other hand neogondolellids show a protracted extinction from uaz 4 to uaz 6 in south china correlations are proposed for the microbialite bearing sections and deeper water ptb sections the ua method also highlights which parts of the conodont record are still insufficiently documented for reliable correlations biochronological correlations with meishan and its u pb radio isotopic ages allow inferring a maximal duration of 61 48 ka for the gap at the base of the triassic microbial limestone at dajiang a time interval that also corresponds to the duration of the main extinction episode in meishan

gps velocity field for the tien shan and surrounding regions 1 measurements at 400 campaign style gps points and another 14 continuously recording stations in central asia define variations in their velocities both along and across the kyrgyz and neighboring parts of tien shan they show that at the longitude of kyrgyzstan the tarim basin converges with eurasia at 20 2 mm yr nearly two thirds of the total convergence rate between india and eurasia at this longitude this high rate suggests that the tien shan has grown into a major mountain range only late in the evolution of the india eurasia collision most of the convergence between tarim and eurasia within the upper crust of the tien shan presumably occurs by slip on faults on the edges of and within the belt but 1 3 mm yr of convergence is absorbed farther north at the dzungarian alatau and at a lower rate with the kazakh platform to the west the tarim basin is thrust beneath the tien shan at 4 7 mm yr with respect to eurasia the ferghana valley rotates counterclockwise at 0 7 myr 1 about an axis at the southwest end of the valley thus gps data place a bound of 4 mm yr on the rate of crustal shortening across the chatkal and neighboring ranges on the northwest margin of the ferghana valley and they limit the present day slip rate on the right lateral talas ferghana fault to less than 2 mm yr gps measurements corroborate geologic evidence indicating that the northern margin of the pamir overthrusts the alay valley and require a rate of at least 10 and possibly 15 mm yr

the giant shakhdara migmatitic gneiss dome pamir india asia collision zone 1 geometry and kinematics 1 cenozoic gneiss domes comprise one third of the surface exposure of the pamir and provide a window into the deep crustal processes of the india asia collision the largest of these are the doubly vergent composite shakhdara alichur domes of the southwestern pamir tajikistan and afghanistan they are separated by a low strain horst top to sse noncoaxial pervasive flow over the up to 4 km thick south pamir shear zone exhumed crust from 30 40 km depth in the 250 80 km shakhdara dome the top to nne alichur shear zone exposed upper crustal rocks in the 125 25 km alichur dome the gunt shear zone bounds the shakhdara dome in the north and records alternations of normal shear and dextral transpression it contributed little to bulk exhumation footwall exhumation along two low angle normal sense detachments resulted in up to 90 km syn orogenic n s extension extension in the southwestern pamir opposes shortening in a fold thrust belt north of the domes and in particular in the tajik depression where an evaporitic decollement facilitated upper crustal shortening gravitational collapse of the pamir plateau margin drove core complex formation in the southwestern pamir and shortening of the weak foreland adjacent to the plateau overall this geometry defines a vertical extrusion scenario comprising frontal and basal underthrusting and thickening and hanging gravitationally driven normal shear in contrast to the himalayan vertical extrusion scenario erosion in the pamir was minor preserving most of the extruded deep crust including the top of the south pamir shear zone at peak elevations throughout the dome

early triassic conodonts of jiarong nanpanjiang basin southern guizhou province south china abstract jiarong huishui county guizhou province south china is a key locality for the study of the early triassic recovery after the end permian mass extinction the size reduction of conodonts at the smithian spathian transition was first documented in jiarong and it is also a locality that contributes to the documentation of the early triassic paleo seawater temperatures in the jiarong sections thirteen conodont zones were identified for the early triassic in ascending order they are hindeodus parvus zone hindeodus sosioensis zone clarkina krystyni zone neoclarkina discreta zone neospathodus cristagalli eurygnathodus costatus assemblage zone novispathodus waageni eowaageni zone novispathodus waageni waageni zone discretella discreta zone pachycladina parachirognathus assemblage zone novispathodus pingdingshanensis zone icriospathodus collinsoni zone triassospathodus homeri zone triassospathodus triangularis zone these conodont zones in the jiarong sections improve the global correlation of early triassic sections and also provide better regional age constraints in an area that is important for studies of recovery from the extinction based on the first appearance of nv waageni eowaageni the induan olenekian boundary is recognized at 3 6 m above the base of the jiarong iii section the dominance of blade shaped segminate conodonts was replaced by gondola shaped segminiplanate conodonts twice the first time was in the late griesbachian and the second time was in the early spathian the dominance of segminiplanate conodonts probably indicates that the deeper seawater environment became more oxygenated during the late griesbachian and early spathian for short time intervals as it is believed that the griesbachian segminiplanate conodonts favored deeper oxygenated water habitats a new genus spathogondolella gen nov and a new species spathogondolella jiarongensis sp nov have been recognized

a unique permian triassic boundary section from the neotethyan hawasina basin central oman mountains in the wadi wasit area central oman mountains dienerian breccias are widespread these breccias consist mostly of guadalupian reefal blocks often dolomitised and some rare small sized blocks of lowermost triassic bivalve bearing limestones a unique block with a size of about 200 m3 including permian and earliest triassic faunas has been studied in detail the so called wadi wasit block consists of three major lithological units a basal unstratified grey limestone is rich in various reef building organisms rugose corals calcareous sponges stromatoporoids and has been dated as middle permian it is disconformably overlain by well and thin bedded light grey to yellowish coloured limestones rich in molluscs two major lithologies coquina limestone respectively bioclastic limestone unit characterise the shelly limestones their contact seems gradual these two units are well dated they are of griesbachian age and contain three conodont zones the parvus zone the staeschei zone and the sosioensis zone and two ammonoid zones the ophiceras tibeticum zone and an unnamed interval the third unit consists of a grey marly limestone containing neospathodus kummeli basal dienerian it is the first record of well dated basal triassic sediments in the arabian peninsula the coquina limestone is dominated by the bivalve promyalina with some claraia and eumorphotis this bivalve association is interpreted as a pioneering opportunistic assemblage towards the top of the bioclastic limestone unit the faunal diversity increases and contains probably more than 20 taxa of bivalves microgastropods crinoids brachiopods ammonoids echinoid spines ostracods and conodonts the generic diversity of this biofacies exceeds by far any other griesbachian assemblage known our data give new evidence for the geodynamical history for the distal carbonate shelf bordering the hawasina basin a break in the sedimentation characterises the late permian the basal triassic shows a steady transgression and the breccias may record a distinct gravitational collapse of platform margins linked with sea level low stand at the end of induan time late dienerian basal smithian 13ccarb isotopic analyses were performed and yield typical permian values of around 4 for the reefal limestone with a strong negative shift across the permian triassic boundary during the griesbachian values shift positively from 0 5 to 3 1 parallel to an increase in faunal diversity and probably primary productivity the detailed faunal analysis and the discovery of an unexpected diversity give us a new understanding of the recovery of the early triassic marine ecosystem

stable carbon isotope stratigraphy across the permian triassic boundary in shallow marine carbonate platforms nanpanjiang basin south china a distinct negative 13c excursion is documented in two permian triassic sections heping and taiping in shallow marine carbonate platform deposits in the nanpanjiang basin south china these sections span from the changhsingian to the dienerian and are characterized by a distinct marine boundary facies change from massive skeletal lime packstone in the changhsingian to distinctive calcimicrobial framestone in the griesbachian hindeodus parvus zone the 13corg and 13ccarb excursions occur directly after the onset of the calcimicrobial framestone herein termed the permian triassic boundary event and before the first occurrence of h parvus the isotope shifts are associated with a sharp drop in species abundance and diversity and coincide with a decrease in total organic carbon toc content the shift towards depleted values in 13corg and 13ccarb at the permian triassic boundary event together with low toc contents persists throughout the griesbachian h parvus zone these data document a corresponding negative shift of 13corg and 13ccarb values and low toc contents with the onset of growth of calcified microbial framestones a postextinction disaster facies immediately below the base of the griesbachian h parvus zone based on paleontological evidence the first occurrence of the disaster facies follows the extinction event which implies that the 13c depleted values above this facies postdate the event this suggests that two separate events had to account for the initiation of the extinction and the 13c excursion however the consequences that led to the negative isotopic shift might be linked to the intriguing recovery lag of early triassic ecosystems based on data from ptb sections worldwide of a greater 13c offset in high compared with low latitudes we propose that methane eruptions from thermal destabilization of high latitude clathrate deposits may have led to the negative 13c shift and may have caused long term adverse ecological conditions

the timing and pattern of biotic recovery following the end permian mass extinction the aftermath of the great end permian period mass extinction 252 myr ago shows how life can recover from the loss of 90 species globally the crisis was triggered by a number of physical environmental shocks global warming acid rain ocean acidification and ocean anoxia and some of these were repeated over the next 5 6 myr ammonoids and some other groups diversified rapidly within 1 3 myr but extinctions continued through the early triassic period triassic ecosystems were rebuilt stepwise from low to high trophic levels through the early to middle triassic and a stable complex ecosystem did not re emerge until the beginning of the middle triassic 8 9 myr after the crisis a positive aspect of the recovery was the emergence of entirely new groups such as marine reptiles and decapod crustaceans as well as new tetrapods on land including eventually dinosaurs the stepwise recovery of life in the triassic could have been delayed either by biotic drivers complex multispecies interactions or physical perturbations or a combination of both this is an example of the wider debate about the relative roles of intrinsic and extrinsic drivers of large scale evolution from a much more devastated planet and biota than the others with only some 10 of species surviving the epme was much harsher than the other mass extinctions during which global species diversity reduced to only about 50 of the pre extinction total 1 2 24 26 this means that the triassic recovery has two profound implications first it may show qualitative as well as quantitative differences from the other post extinction recoveries and second it can act as an exemplar of what to expect at its most extreme when global biodiversity is pushed to the brink there are obvious implications for current concerns about biodiversity loss and recovery resulting from human impacts 27 28 in the past ten years attention has focused on the sedimentary successions in south china these are enormously laterally extensive with some formations extending more than 2 000 km from the zhejiang to yunnan provinces the huge exposures length of the sections and improving dating open up the opportunity to explore physical environmental and biotic changes through the extinction and recovery times in varied marine habitats and compare these with patterns elsewhere in the world fig 1 a fine scale forensic analysis of this extraordinary time in earth s history now becomes possible the end permian mass extinction the epme killed 80 96 of marine animal species and 70 of terrestrial vertebrate species

a proposed ontogenesis and evolutionary lineage of conodont eurygnathodus costatus and its role in defining the base of the olenekian lower triassic abstract 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

convergent continental margin volcanic source for ash beds at the permian triassic boundary south china constraints from trace elements and hf isotopes abstract volcanic activity around the time of the permian triassic boundary ptb has been proposed as a trigger for the associated biocrisis multiple claystone beds are prominent near the ptb sections in south china twenty one ptb ash beds from three sections at shangsi jianshi and meishan in south china were sampled and analyzed volcanic ash geochemistry indicate dacite and rhyolite compositions zircons from the ash layers yield comparatively low nb hf and high th nb ratios falling in the range of arc orogenic related settings zircon hf isotope compositions show that ehf t values vary from 11 7 to 1 8 indicating involvement of both juvenile and ancient crustal components the ash beds ss27a js129 js130 js133 ms25 ms26 near the biotic extinction horizon display a large variation in ehf t and relatively positive average values indicating input of juvenile mantle or crust and implying rapid transit through the older basement of the south china craton spatial and temporal distribution of ash beds from thirty one ptb sections worldwide reveal that volcanic ash beds occur mainly in or proximal to the tethys region and were sourced locally integration of hf isotope and trace element compositions from magmatic zircons suggests that the ptb volcanism occurred along the convergent continent margin in or near southwestern south china as a result of the closure of the paleo tethys ocean

complete biotic and sedimentary records of the permian triassic transition from meishan section south china ecologically assessing mass extinction and its aftermath abstract the meishan section south china is the global stratotype section and point gssp for the permian triassic boundary ptb and is also well known for the best record demonstrating the permian triassic mass extinction ptme all over the world this section has also been studied using multidisciplinary approaches to reveal the possible causes for the greatest phanerozoic biocrisis of life on earth many important scenarios interpreting the great dying have been proposed on the basis of data from meishan nevertheless debates on biotic extinction patterns and possible killers still continue this paper reviews all fossil and sedimentary records from the permo triassic p tr transition based on previously published data and our newly obtained data from meishan and assesses ecologically the ptme and its aftermath to determine the biotic response to climatic and environmental extremes associated with the biocrisis eight updated conodont zones clarkina yini clarkina meishanensis hindeodus changxingensis clarkina taylorae hindeodus parvus isarcicella staeschei isarcicella isarcica and clarkina planata zones are proposed for the ptb beds at meishan major turnover in fossil fragment contents and ichnodiversity occurs across the boundary between bed 24e 5 and bed 24e 6 suggesting an extinction horizon in a thin stratigraphic interval the irregular surface in the middle of bed 27 is re interpreted as a firmground of glossifungites ichnofacies rather than the previously proposed submarine dissolution surface or hardground surface both fossil fragment contents and ichnodiversity underwent dramatic declines in beds 25 26a coinciding with metazoan mass extinction fossil fragment content ichnodiversity and all ichnofabric proxies including burrow size tiering level bioturbation level indicate that the p tr ecologic crisis comprises two discrete stages coinciding with the first and second phases of the ptme in meishan ecologic crisis lagged behind biodiversity decline during the ptme pyrite framboid size variations suggest that depositional redox condition was anoxic to euxinic in the latest changhsingian became euxinic in beds 25 26a turned dysoxic in bed 27 then varied from euxinic to anoxic through most of the griesbachian the 9 c increase in seawater surface temperature from bed 24e to bed 27 at meishan seems to result in dramatic declines in biodiversity and fossil fragment contents in beds 25 26a but had little effect on all ecologic proxies both metazoans and infauna seem not to have been affected by the pre extinction anoxic euxinic condition the anoxic event associated with the ptme may have occurred in a much shorter period than previously thought and is only recorded in beds 25 26a at meishan fossil fragment contents ichnofaunas ichnofabrics and pyrite framboid size all show that no signs of oceanic acidification and anoxia existed in bed 27 the early griesbachian anoxia may have resulted in rarity of ichnofauna and metazoans in the lower yinkeng formation in which the ichnofauna is characterized by small simple horizontal burrows of planolites and metazoan faunas are characterized by low diversity high abundance opportunist dominated communities the rapid increase of 9 c in sea surface temperature and a short anoxia or acidification coincided with the first pulse biocrisis while a prolonged and widespread anoxia probably due to a long period of high seawater temperate condition may be crucial in mortality of most organisms in the second pulse ptme marine ecosystems started to recover coupled with environmental amelioration in the late griesbachian

lower middle triassic conodont biostratigraphy of the qingyan section guizhou province southwest china abstract the middle triassic qingyan formation at its type section the qingyan section of guizhou southwest china yields more than 300 species belonging to 17 fossil groups which mark the radiation of benthic organisms following the end permian mass extinction this study intends to establish a primary conodont biostratigraphical succession through the lower and middle triassic sequence at qingyan to provide a time framework for the understanding of the recovery and radiation process from the mass extinction a total of 30 species in 8 conodont genera are stratigraphically significant and assigned to the neospathodus dieneri neospathodus cristagalli neospathodus waageni neospathodus homeri chiosella timorensis and neogondolella cf bulgarica zones in ascending order most conodont zones correlate well with their counterparts recognized from elsewhere in china and even worldwide the first appearance of ns waageni marks the induan olenekian boundary which is placed at the lower middle part of the luolou formation 121 47 m above the permian triassic boundary the olenekian anisian early middle triassic boundary is here defined by the first occurrence of chiosella timorensis at the base of the qingyan formation although no conodonts retrieved from the upper qingyan formation containing the extraordinarily diverse biota i e the qingyan biota stratigraphical correlation with the neighbouring conodont bearing sections in guizhou and the ammonoid zones suggest that the qingyan biota has an age of early late anisian early middle triassic

recurrent biotic rebounds during the early triassic biostratigraphy and temporal size variation of conodonts from the nanpanjiang basin south china eleven conodont zones are established for the lower triassic of the motianling section in the nanpanjiang basin south china detailed size measurements on 2244 p1 conodont elements demonstrate dynamic size variation patterns during the early triassic that are calibrated to the early triassic timescale and conodont zonation correlation of conodont size variation with various environmental indicators shows that these size changes are primarily controlled by rapidly changing and episodic environmental conditions and ecological recovery in the aftermath of the end permian mass extinction decreasing size trends occur in the early griesbachian late griesbachian and at the smithian spathian boundary episodes of size increase rebounds occur in the middle griesbachian induan olenekian boundary and middle late spathian the observed temporal size variations indicate that conodont animals were significantly affected by rapidly changing environmental conditions mainly temperature and redox conditions during the early triassic and recurrent size increases rebounds occurred during periods of environmental and climatic amelioration climatic cooling and oxygenation demonstrating a complicated recovery history of marine ecosystems in the aftermath of the largest phanerozoic biotic crisis supplementary material data for all species are available at https doi org 10 6084 m9 figshare c 4528616