middle late permian mass extinction on land the end permian mass extinction has been envisaged as the nadir of biodiversity decline due to increasing volcanic gas emissions over some 9 million years we propose a different tempo and mechanism of extinction because we recognize two separate but geologically abrupt mass extinctions on land one terminating the middle permian guadalupian at 260 4 ma and a later one ending the permian period at 251 ma our evidence comes from new paleobotanical paleopedological and carbon isotopic studies of portal mountain antarctica and comparable studies in the karoo basin south africa extinctions have long been apparent among marine invertebrates at both the end of the guadalupian and end of the permian which were also times of warm wet greenhouse climatic transients marked soil erosion transition from high to low sinuosity and braided streams soil stagnation in wetlands and profound negative carbon isotope anomalies both mass extinctions may have resulted from catastrophic methane outbursts to the atmosphere from coal intruded by feeder dikes to flood basalts such as the end guadalupian emeishan basalt and end permian siberian traps

significant changes in land vegetation and oceanic redox across the cretaceous paleogene boundary abstract the impact of an extraterrestrial body 65 5 ma caused the so called cretaceous paleogene k pg event that resulted in a mass extinction and rapid changes in the surface environment on earth here we report changes in land vegetation and oceanic redox across the k pg boundary at caravaca southeastern spain using biomarkers the results reveal that the basal 3 mm thick layer of the k pg boundary clay is marked by a rapid increase in the concentration of terrestrial long chain n alkanes and dibenzofuran indicating the destruction of land vegetation and an increase in the supply of terrestrial organic matter into the marine environment during the deposition of the k pg boundary clay this layer also records a rapid increase in the concentration of dibenzothiophenes which indicates a change in redox conditions from oxic to anoxic euxinic conditions in the intermediate water over the seafloor the low oxygen conditions could have been caused by an increase in the influx of terrestrial organic matter into the ocean a rapid increase in the concentration of retene and retene cadalene occurred during the deposition of the upper part of the boundary clay 10 kyr after the mass extinction indicating the recovery of conifers which greatly decreased at the k pg boundary

late cretaceous restructuring of terrestrial communities facilitated the end cretaceous mass extinction in north america the sudden environmental catastrophe in the wake of the end cretaceous asteroid impact had drastic effects that rippled through animal communities to explore how these effects may have been exacerbated by prior ecological changes we used a food web model to simulate the effects of primary productivity disruptions such as those predicted to result from an asteroid impact on ten campanian and seven maastrichtian terrestrial localities in north america our analysis documents that a shift in trophic structure between campanian and maastrichtian communities in north america led maastrichtian communities to experience more secondary extinction at lower levels of primary production shutdown and possess a lower collapse threshold than campanian communities of particular note is the fact that changes in dinosaur richness had a negative impact on the robustness of maastrichtian ecosystems against environmental perturbations therefore earlier ecological restructuring may have exacerbated the impact and severity of the end cretaceous extinction at least in north america

an upper permian permineralized plant assemblage in volcaniclastic tuff from the xuanwei formation guizhou province southern china and its palaeofloristic significance a new permineralized fossil plant assemblage is described from volcaniclastic tuff collected in the upper permian wuchiapigian to changhsingian xuanwei formation at shanjiaoshu mine guizhou province china the assemblage is fragmentary but contains a small sphenopsid strobilus a partial strobilus of a lepidodendralean lycopsid pinnae of the filicalean fern anachoropteris and a filicalean non laminate fertile pinna rachis the marattialean ferns eoangiopteris scolecopteris and psaronius hooked stems of probable gigantopterid affinity and two kinds of cardiocarpalean ovules this represents the first indisputable evidence of anachoropteris from the permian of china and contrasts with previous evidence from europe and north america that indicates this genus became extinct during earliest permian times the assemblage highlights the persistence of plants from wetland communities and mire ecosystems into the upper permian of southern china and adds further support to the presence of the ameriosinian phytogeographical realm this represents the first record of a plant assemblage preserved in volcaniclastic sediments from the upper permian of southern china and in combination with other recently discovered plant assemblages in similar deposits in southern china suggests volcanism to be an important factor in facilitating permineralized plant preservation in this realm although the source of the volcanism that produced the tuff is unknown its age and location are consistent with the emishan large igneous province lip of southwest china

transitional changes in arborescent lignophytes at the devonian carboniferous boundary abstract it is usually considered that after the extinction of the devonian tree archaeopteri s no new arborescent lignophytes were established before the late tournaisian a reassessment of this pattern is presented here based on a three fold approach a re evaluation of the taxic diversity of tournaisian lignophyte trees based on descriptions of new plants from palaeotropical latitudes a study of the patterns of phenotypic changes occurring among early lignophytes using a principal coordinate analysis and a phylogenetic analysis of the affinities of the arborescent taxa the best supported results indicate that a substantial taxonomic and phenotypic diversity of arborescent lignophytes was already established in the first part of the tournaisian including some taxa that persisted until the serpukhovian two genera may have originated in the late devonian and crossed the devonian carboniferous boundary fewer originations and a decrease in phenotypic diversity occurred in the visean the phenotypic distinctiveness of tree stems compared with those of other growth forms in the lignophytes is assessed we propose a scenario in which the presence of lignophyte trees is continuous across the devonian carboniferous boundary with arborescent taxa distinct from archaeopteris already present in the latest devonian possibly in upland floras and diversifying significantly soon after the devonian carboniferous boundary supplementary material a list of taxa characters and matrices used in the principal coordinate analysis and phylogenetic analysis is available at http www geolsoc org uk sup18447

the chicxulub asteroid impact and mass extinction at the cretaceous paleogene boundary the cretaceous paleogene boundary similar to 65 5 million years ago marks one of the three largest mass extinctions in the past 500 million years the extinction event coincided with a large asteroid impact at chicxulub mexico and occurred within the time of deccan flood basalt volcanism in india here we synthesize records of the global stratigraphy across this boundary to assess the proposed causes of the mass extinction notably a single ejecta rich deposit compositionally linked to the chicxulub impact is globally distributed at the cretaceous paleogene boundary the temporal match between the ejecta layer and the onset of the extinctions and the agreement of ecological patterns in the fossil record with modeled environmental perturbations for example darkness and cooling lead us to conclude that the chicxulub impact triggered the mass extinction

radiation and extinction patterns in permian floras from north china as indicators for environmental and climate change abstract permian continental sequences from north china contain previously unrecognized episodes of plant radiation and elevated extinction the earliest extinction in the lower shihhotse formation roadian guadalupian records a 45 floral species loss and is tentatively correlated with global extinctions amongst dinocephalian reptiles two younger extinctions are dated by correlating the illawara reversal and palaeomagnetic polarity sequences from shanxi province against global palaeomagnetic history missing data from the shanxi sequence are evaluated using a novel approach estimating likely maximum and minimum sequence changes that provide age estimates for post illawara events in north china the second extinction in the middle upper shihhotse formation is more significant and is dated to the mid capitanian with a loss of 56 of plant species coinciding with two phases of volcanism of the emeishan large igneous province in south china previously linked to the mid capitanian marine mass extinction the youngest extinction in the upper upper shihhotse formation late capitanian to mid wuchapingian is catastrophic and represents the end of range in the sequence changes in sedimentary facies suggest it to be related to global climatic warming and drying other viable causal mechanisms for the extinction episodes include plate motion and collision global climate change volcanism and biological competition

wave equation based reflection tomography of the 1992 landers earthquake area in the framework of a recent wave equation based traveltime seismic tomography we show that incorporating moho reflected phases pmp and sms in addition to the direct p and s phases can significantly increase tomography resolution in the lower crust and this may provide additional evidence to resolve important tectonic issues to highlight the resolving power of the new strategy we apply it in the region around the 1992 landers earthquake mw 7 3 in southern california using seismic arrivals from local earthquakes obtaining 3 d high resolution p and s wave crustal velocity models and poisson s ratio structures in the upper crust our method confirmed features that had been previously found however in the middle to lower crust we found low velocity anomalies on the southeastern section of the san jacinto fault and high vp and low vs structures to the west of the big bear earthquake which may be related to upwelling of partial melt from the mantle

late paleozoic macrofloral assemblages from weibei coalfield with reference to vegetational change through the late paleozoic ice age in the north china block abstract based on investigations of seven stratigraphic sections in the weibei coalfield a typical coal basin in the north china block the succession of late paleozoic plant macrofossil assemblages from the benxi or penchi in old spelling taiyuan shanxi lower shihhotse and upper shihhotse formations were redefined these zones are the paripteris spp linopteris spp conchophyllum richthofenii assemblage benxi fm neuropteris pseudovata lepidodendron posthumii assemblage taiyuan and lower shanxi fms emplectopteridium alatum emplectopteris triangularis cathaysiopteris whitei assemblage upper shanxi and lower shihhotse fms gigantonoclea lagrelii fascipteris hallei lobatannularia heianensis assemblage upper shihhotse fm as a result of this biostratigraphic reanalysis it has become clear that biostratigraphic boundaries do not exactly correlate to lithostratigraphic boundaries as has been thought the biostratigraphy of the terrestrial deposits in the north china block were correlated to the iugs global chronostratigraphy the more precise chronostratigraphic constraints that were obtained as a result of this study make it possible to more precisely correlate the vegetational successions to the concurrent waxing and waning of the late paleozoic ice sheets

vertebrate diversity across the end permian mass extinction separating biological and geological signals abstract this study examines regional diversity patterns of permian triassic terrestrial vertebrates of the south african karoo basin and the russian fore ural region previous studies clearly established that the diversity patterns of synapsids the dominant terrestrial tetrapods of their time are significantly biased by heterogeneity in the permian triassic terrestrial rock record this conclusion was based on a positive correlation between taxonomic diversity estimates tdes and varying sampling proxies 1 number of formations and 2 outcrop area recently these proxies have been criticized to be non independent variables or problematic for other reasons and 3 number of localities or 4 number of specimens have been suggest as more reliable proxies in the present study i test the relevance of the latter proxies 2 4 with respect to vertebrate diversity in south africa and russia on these regional scales log transformed and generalized differenced tdes of vertebrates at varying taxonomic levels are with few exceptions not significantly correlated with the various sampling proxies 2 4 for the complete time series after eliminating the impact of the end permian extinction event by excluding the earliest triassic time intervals selected vertebrate tdes in south africa and russia show statistically significant strong positive correlations with outcrop area number of localities and number of specimens diversity residuals resulting from modeled diversity estimates exhibit clade specific patterns with little support for a mid permian end guadalupian event but strong support for a severe end permian extinction the results imply that although vertebrate diversity patterns in south africa and russia are at least partially biased by the permian triassic terrestrial rock record they still preserve genuine biological signals finally it is important to note that outcrop area represents a valid and useful sampling proxy at the regional scale of the south african karoo basin and that it should be used in concert with other sampling proxies such as the number of localities and specimens that accurately capture various aspects of sampling in a given study area as it has been performed in the present study

the relationship between euramerican and cathaysian tropical floras in the late palaeozoic palaeobiogeographical and palaeogeographical implications abstract wetland plant communities persisted though much of the pennsylvanian in euramerica and are the dominant coal forming vegetation in this region distribution of these floras show a dramatic decline at the end of the carboniferous with many of the plant genera and species becoming extinct by the onset of the permian this has been correlated with climate change and in particular aridification associated with northwards plate motion and euramerica moving into the doldrums but is also associated with the variscan orogeny and forefront destroying large areas of formerly lowland basinal settings other factors may include pennsylvanian glaciations as evidenced by cyclothem and rhythmical deposition in lowlying wetland settings and change in eustatic base level evidence from euramerica demonstrates extinction of this kind of wetland biota by the earliest permian and the development of drier floras including conifer dominated assemblages however new data from other parts of the world most notably north china confirm this model and highlight the presence of similar coal swamps ranging from the late pennsylvanian through the permian in this paper we summarise and synthesize recent taxonomic and systematic investigations undertaken on the plant fossils from the pennsylvanian benxi formation the oldest recognised wetland plant community in china and the early permian taiyuan formation the best preserved wetland plant community from china results indicate a remarkable similarity of the pennsylvanian early permian floras of north china with the older assemblages in the pennsylvanian of euramerica and the presence of typical euramerican coal swamp plant families genera and in some cases species in china conclusions include the presence of the ameriosinian phytogeographical realm uniting euramerica and northern cathaysia at this time coal swamps in the permian of north china evolving from a euramerican origin and the dramatic floral turnover at the end of the carboniferous representing a regional event rather than a global extinction episode patterns of plant distribution through this interval have profound implications on established palaeogeographical models and support continental connection between euramerica and cathaysia before the end of the carboniferous contradicting ideas of cathaysian island biogeography and biotic distinction continental connection appears to be related to glacial eustatic low stand and previously shallow marine environments becoming vegetated also important is the fact that in both euramerica and north china the pattern of floristic demise within wetland plant communities are similar to each other implying the same causal mechanisms with plants occupying waterlogged positions being the most severely devastated however ecosystem demise occurred at the end of the carboniferous in euramerica and in the middle permian in north china but in both cases the primary cause was climate change

land plant diversity and the end permian mass extinction the permian and triassic represent a time of major global climate change from icehouse to hothouse conditions and significant 25 northward motion of landmasses amalgamated in essentially one supercontinent pangea the greatest of all mass extinctions occurred around the permian triassic boundary 251 ma although there is no consensus regarding the cause s recent studies have suggested a meteor impact and worldwide die off of vegetation on the basis of sparse local observations however new analyses of global permian and triassic plant data in a paleogeographic context show that the scale and timing of effects varied markedly between regions the patterns are best explained by differences in geography climate and fossil preservation not by catastrophic events caution should be exercised when extrapolating local observations to global scale interpretations at the other extreme global compilations of biotic change through time can be misleading if the effects of geography climate and preservation bias are not considered

the terminal triassic catastrophic extinction event in perspective a review of carboniferous through early jurassic terrestrial vertebrate extinction patterns abstract a catastrophic terminal triassic extinction event among terrestrial vertebrates is not supported by available evidence the current model for such an extinction is based on at least eight weak or untenable assumptions 1 a terminal triassic extinction inducing asteroid impact occurred 2 a terminal triassic synchronous mass extinction of terrestrial vertebrates occurred 3 a concurrent terminal triassic marine extinction occurred 4 all terrestrial vertebrate families have similar diversities and ecologies 5 changes in familial diversity can be gauged accurately from the known fossil record 6 extinction of families can be compared through time without normalizing for changes in familial diversity through time 7 extinction rates can be compared without normalizing for differing lengths of geologic stages and 8 catastrophic mass extinctions do not select for small size these assumptions have resulted in unsupportable and or erroneous conclusions carboniferous through early jurassic terrestrial vertebrate families mostly have evolution and extinction patterns unlike the vertebrate evolution and extinction patterns during the terminal cretaceous event only the serpukhovian mid carboniferous extinction event shows strong analogy to the terminal cretaceous event available data suggest no terminal triassic extinction anomaly but rather a prolonged and nearly steady decline in the global terrestrial vertebrate extinction rate throughout the triassic and earliest jurassic

age constraint for an earliest famennian forest and its implications for frasnian famennian boundary in west junggar northwest china abstract as one of the five major extinction events in earth history the frasnian famennian boundary ffb crisis caused dramatic reductions in marine and terrestrial diversity the effects of this event on terrestrial ecosystems are not well understood due to the limited preservation of terrestrial sedimentary rocks and the relative scarcity of plant fossils this study generates a robust zircon u pb age 371 5 0 9 ma earliest famennian for a new fossil assemblage containing lycopsida archaeopteridales and cladoxylopsida from the upper zhulumute formation of the west junggar basin nw china these taxa are typical arborescent plants of the late devonian and represent the oldest known forest in china documenting afforestation in west junggar coevally with or just after the upper kellwasser event 372 ma the new u pb ages generated in this study refine the placement of the ffb in west junggar to within the zhulumute formation instead of the hongguleleng formation as previously thought

the plant fossil record reflects just two great extinction events five great taxonomic extinctions the so called big five mass extinctions are widely recognized in life history at the end of the ordovician frasnian late devonian permian triassic and cretaceous all of them were originally identified in the marine fossil record and have been interpreted as the result of abrupt global environmental changes previous evidence has suggested that terrestrial biota were also subjected to ecological disruption during these events but it is unknown whether they suffered the same level of large scale taxonomic disruption as marine organisms here we show that the plant fossil record in fact only provides evidence of two mass taxonomic extinction events one through the carboniferous permian transition the other during middle late permian times this differs significantly from the mass extinctions recognized in the marine realm and suggests that vascular plants have a special capacity for surviving abrupt environmental changes

ecological ranking of phanerozoic biodiversity crises the serpukhovian early carboniferous crisis had a greater ecological impact than the end ordovician we propose a new ecological ranking of the major phanerozoic biodiversity crises in which the serpukhovian biodiversity crisis is ranked fifth in ecological impact lesser than the late devonian but greater than the end ordovician and the end ordovician mass extinction is ranked sixth it is interesting that both the end ordovician mass extinction and the serpukhovian biodiversity crisis were triggered by glaciations other than that common trigger the two events were very different glaciation in the ordovician triggered an enormous jump in the extinction rate of marine organisms and was taxonomically very severe yet the ecological impact of those extinctions was minimal glaciation in the serpukhovian triggered a precipitous drop in the speciation rate but only moderate diversity losses yet the ecological impact of those diversity losses and ecosystem restructuring was an ecological level of magnitude larger than that seen in the end ordovician mass extinction

microbial mats in the terrestrial lower triassic of north china and implications for the permian triassic mass extinction abstract evidence for microbial mats has been reported repeatedly from marine lower triassic rocks but scarcely mentioned in post mass extinction terrestrial facies here we report from the terrestrial lower triassic liujiagou formation in north china the presence of five kinds of microbially induced sedimentary structures miss or sedimentary surface textures including old elephant skin textures wrinkle structures palimpsest ripples manchuriophycus structures and sand cracks terrestrial microbial communities that produced these miss adapted not only to periodically desiccated conditions but also to the storm dominated palaeoenvironments in the liujiagou formation the permian triassic mass extinction ptme in north china is marked by the die off of plants disappearance of coal beds extinction of pareiasaurs among tetrapods decreased bioturbation levels and a dramatic change of sedimentary systems through the sunjiagou formation the sunjiagou formation recorded the turnover from an ever wet to a progressively drier and hotter climate and it spans the ptme in north china following this mass extinction miss became much more common and widespread suggesting that the mass extinction provided favourable biological and environmental conditions for the development of the miss in terrestrial ecosystems especially the decreased bioturbation intensity and grazing pressure associated with increased temperature and climatic drying in the upper part of the liujiagou formation and overlying heshanggou formation the disappearance of miss coupled with increased bioturbation might indicate an improvement of terrestrial ecosystems and the beginning of the triassic biotic recovery however as the investigation of miss in space and time through the geological record is in its early stages further geobiologic and geochemical studies as well as high precision isotopic dating from permian triassic terrestrial successions are needed to fully reveal the timing and pattern of the early triassic terrestrial ecosystem reconstruction

investigation of a shallow slope failure on expansive clay in texas abstract highway slopes constructed with highly plastic clay soils undergo shrink swell cycles during the wet dry season which usually soften the soil and may cause failure a few years following construction there are two major wet dry cycles in texas where summer to early fall is categorized as the dry period and late fall to spring is categorized as the wet period during this study the failure of a highway slope located in fort worth texas was investigated and the effect of rainfall on the slope failure was evaluated the failure of the slope was investigated using soil test borings geophysical testing laboratory testing slope stability analysis and unsaturated flow analysis the site investigation included sample collections from different depths of borings determination of the soil index properties and various shear strength testing to determine soil strength parameters the obtained test results were further utilized in slope stability and flow analyses using the finite element method fem in plaxis the study indicated that both a fully softened condition and rainfall were responsible for the slope failure the fully softened condition provided a factor of safety of 1 46 whereas the perched water condition after rainfall provided a nearly failing factor of safety of 1 05

paleoecology of the late pennsylvanian age calhoun coal bed and implications for long term dynamics of wetland ecosystems quantitative plant assemblage data from coal balls miospores megaspores and compression floras from the calhoun coal bed missourian of the illinois basin usa are used to interpret spatial and temporal changes in plant communities in the paleo peat swamp coal ball and miospore floras from the calhoun coal bed are dominated strongly by tree ferns and pteridosperms and sigillarian lycopsids are subdominant depending on geographic location within the coal bed although the overall composition of calhoun peat swamp assemblages is consistent both temporally and spatially site to site differences and short term shifts in species dominance indicate local topographic and hydrologic control on species composition within the broader context of the swamp statistical comparison of the calhoun miospore assemblages with those from other late pennsylvanian coal beds suggests that the same basic species pool was represented in each peat swamp landscape and that the relative patterns of dominance and diversity were persistent from site to site therefore it appears that the relative patterns of proportional dominance stayed roughly the same from one coal bed to the next during late pennsylvanian glacially driven climatic oscillations

the mid carboniferous eustatic event stratigraphic and paleontologic evidence from mid carboniferous namurian basin and shelf successions in widely scattered parts of the world indicates that a major eustatic event occurred about 330 ma the event began with a regression that is recorded in most shelf sequences the regression was followed by a brief transgression about 328 ma and the event ended with a transgression that flooded large shelf areas about 325 ma the mississippian pennsylvanian unconformity in north america is a well known product of this event but equally prominent and contemporaneous unconformity surfaces are also present in europe north africa and elsewhere the event is believed to have caused numerous extinctions and it resulted in marked fluctuations in faunal diversity 94 references 2 figures

permian tetrapod extinction events abstract four substantial tetrapod extinctions have been identified during the permian but only one of these is an apparent mass extinction analyses of global compilations of the family level diversity of permian tetrapods have been confounded by incorrect and compiled correlations instead analyzing diversity patterns at the genus level in best sections identifies only one apparent mass extinction of permian tetrapods much evolutionary turnover took place among tetrapods during the latter part of the early permian and had been identified as a single mass extinction at the artinskian kungurian boundary however the only stratigraphically dense tetrapod record of the late early permian from the southwestern usa indicates a succession of extinctions spread out from redtankian through littlecrontonian kungurian time not a single mass extinction olson s gap remains a hiatus in the global record of permian tetrapods equivalent to part of the kungurian roadian across the gap eupelycosaur dominated assemblages were replaced by therapsid dominated assemblages but the claim that this is associated with a mass extinction olson s extinction has been based on compressing all of the extinctions of the redtankian littlecrotonian and olson s gap into one event recognition of olson s gap does not preclude the possibility of an extinction at the early middle permian boundary olson s extinction however the gap in the tetrapod fossil record makes it impossible to establish the magnitude precise timing and structure of the extinctions that took place across olson s gap the only permian mass extinction of tetrapods is the dinocephalian extinction event during the gamkan near the end of the guadalupian which saw the total extinction of dinocephalians and major diversity drop in therocephalians in the karoo basin of south africa this extinction is the loss of at least 64 of generic diversity the changeover from dinocephalian assemblages to assemblages without dinocephalians in other parts of permian pangea suggests that the dinocephalian extinction event was a global event the late permian tetrapod extinctions are older than the end permian marine extinctions furthermore the magnitude of the diversity drop and ecological severity of the end permian tetrapod extinctions have been greatly overstated best sections analysis in the karoo basin indicates a stepwise late permian tetrapod extinction during deposition of the upper dicynodon assemblage zone that took at least 250 000 and perhaps more than a million years the culmination of this stepwise extinction across the highest occurrence of dicynodon boundary of platbergian and lootsbergian land vertebrate faunachrons is a loss of genera not much above an inferred background extinction rate of permian tetrapod genera and resembles the amount of turnover seen at several other boundaries of permian and triassic land vertebrate faunachrons the case for coeval land plant insect and tetrapod extinctions during the permian is a weak one the first coeval marine and nonmarine mass extinctions of the phanerozoic were likely the end guadalupian extinction climate change notably greenhouse climates may have driven permian tetrapod extinctions but that hypothesized relationship needs better documentation

stratigraphic imprint of the late palaeozoic ice age in eastern australia a record of alternating glacial and nonglacial climate regime stratigraphic and sedimentological data from new south wales and queensland eastern australia indicate that the late palaeozoic ice age comprised at least eight discrete glacial intervals each 1 8 ma in duration here termed glaciations separated by nonglacial intervals of comparable duration these events spanned an interval from mid carboniferous c 327 ma to the early late permian c 260 ma and illustrate a pattern of increasing climatic austerity and increasingly widespread glacial ice from initial onset until an acme in the late early permian followed by an opposite trend towards the final demise of glaciation in the late permian the alternating glacial nonglacial motif suggests that the late palaeozoic ice age was considerably more dynamic than previously thought these patterns are remarkably consistent with recent interpretations of palaeofloral change eustatic sea level fluctuations and co 2 climate glaciation relationships for this interval of time the detailed record of alternating glacial and nonglacial climate mode disclosed herein may facilitate more closely resolved evaluations of stratigraphic records elsewhere notably in far field ice distal northern hemisphere successions

a drowned lycopsid forest above the mahoning coal conemaugh group upper pennsylvanian in eastern ohio u s a over 800 mud filled casts of upright lycopsid tree stumps have been documented immediately above the mahoning coal in an active underground mine located in northwestern jefferson county ohio the coal body originated as a pod shaped peat body of 60 km2 trees are rooted at several levels within a thin 15 40 cm bone coal directly above the banded coal they extend upward up to 15 cm into overlying flat bedded carbonaceous mudstones that coarsen up from a maximum basal diameter of 1 2 m stumps taper upward to diameters no less than 0 3 m within single entry transects 6 m wide that total 2585 m in length stumps are randomly distributed the trees are identified as lepidodenrids on the basis of gross morphology external stem patterns and attached stigmarian root systems and provisionally as lepidophloios or lepidodendron by associated palynology of the enclosing matrix palynological analyses of incremental seam samples indicate an initial dominance of lycopsid spores with lepidodendracean affinities lycospora granulata from lepidophloios hallii replaced upwards by tree fern spores with a reoccurrence of lepidodendracean spores in the upper benches spores of sigillaria crassispora are abundant only at the base of the coal petrographic analyses indicate a prallel trend from vitrinite rich to inertinite and liptinite rich upward in the coal body all data indicate that the peat represented by the mahoning coal was drowned slowly during the earliest stages of inundation a lycopsid forest was re established only to be subsequently drowned