first report of wiwaxia from the cambrian chengjiang lagerstatte research was supported by the chinese academy of sciences kzzd ew 02 2 the national basic research program of china 2013cb835006 the national natural science foundation of china 41472012 the natural science foundation of jiangsu province bk2012893 and clare college cambridge

ordovician faunas of burgess shale type the renowned soft bodied faunas of the cambrian period which include the burgess shale disappear from the fossil record in the late middle cambrian after which the palaeozoic fauna dominates the disappearance of faunas of burgess shale type curtails the stratigraphic record of a number of iconic cambrian taxa one possible explanation for this loss is a major extinction but more probably it reflects the absence of preservation of similar soft bodied faunas in later periods here we report the discovery of numerous diverse soft bodied assemblages in the lower and upper fezouata formations lower ordovician of morocco which include a range of remarkable stem group morphologies normally considered characteristic of the cambrian it is clear that biotas of burgess shale type persisted after the cambrian and are preserved where suitable facies occur the fezouata biota provides a link between the burgess shale communities and the early stages of the great ordovician biodiversification event

vertical cyclic loading response of shallow skirted foundation in soft normally consolidated clay skirted foundations are a potential foundation solution for a range of offshore structures including hydrocarbon and renewable energy platforms and subsea structures offshore foundations can be s

a new early cambrian konservat lagerstatte expands the occurrence of burgess shale type deposits on the yangtze platform abstract we report the fandian biota a new konservat lagerstatte from the cambrian stage 3 yuxiansi and jiulaodong formations in sichuan south china with close faunal links to the chengjiang biota in yunnan the biodiversity of the fandian biota includes total group euarthropods radiodonts bivalved forms acercostracans trilobites non biomineralized trilobitomorphs armoured lobopodians palaeoscolecids pedunculate brachiopods hyoliths chancelloriids sponges and filamentous algae benthic dwellers dominate the fossil community e g trilobitomorphs brachiopods sponges with rare instances of nektonic radiodonts bivalved euarthropods and infaunal palaeoscolecids organisms the fandian biota contains soft bodied taxa that were only known from chengjiang and xiaoshiba until now namely primicaris acercostracan xandarella non trilobite trilobitomorph and mafangscolex palaeoscolecid expanding the distribution of these previously endemic taxa beyond yunnan to the northern yangtze platform during the cambrian stage 3 our findings provide a more comprehensive understanding of early cambrian biodiversity that inhabited the yangtze platform over a substantially greater palaeobiogeographic distribution than previously considered

effects of preloading and consolidation on the uplift capacity of skirted foundations centrifuge tests investigating the effect of compressive preloading and consolidation on the subsequent uplift capacity of shallow skirted foundations that rest on lightly over consolidated kaolin clay are reported the uplift resistance total and pore pressures at the foundation invert were monitored during the installation consolidation and uplift the results show that uplift performed immediately after the preloading generates a lower capacity due to the remoulding of the clay and reduction in soil strengths that result from the application of preloading the soil strength can be recovered and eventually enhanced by the subsequent consolidation process a theoretical framework where the variation of the soil operative strength with preloading and consolidation is interpreted using the critical state concept is proposed to explain and justify the experimental observations the framework is validated through retrospective prediction of the uplift resistance of the centrifuge model tests with good ag

early cambrian priapulid worms buried with their lined burrows five specimens of the priapulid maotianshania cylindrica preserved inside their lined burrows were described from the lower cambrian chengjiang deposits near kunming southern china the exceptional preservation suggests that this worm made a dwelling tube by lining within the uppermost sediment layers this seems to be unique among priapulids in comparison with the cambrian selkirkia and paraselkirkia as well as some modern priapulid larvae and loriciferans taphonomic evidence indicates that the burrow and worm specimens are not buried in situ but were moved by storm tsunami or turbidity generated currents that are thought to have brought sedimentary material intermittently

skeletal faunas of the lower cambrian yu anshan formation eastern yunnan china metazoan diversity and community structure during the cambrian age 3 abstract the lower cambrian stage 3 yu anshan formation in yunnan province south china hosts the chengjiang lagerstatte an exceptional window on the cambrian explosion however skeletal microfossils from this formation have long been neglected owing to the dominance of siliciclastics over carbonates here we characterize a new assemblage of small shelly fossils from the maotianshan shale member of the yu anshan formation the assemblage consists of univalved mollusc hyolith and brachiopod shells trilobite and bradoriid carapaces chancelloriid sclerites sponge spicules and echinoderm ossicles combining this information with taxonomic data previously tabulated for fossil assemblages from three other facies we performed quantitative comparisons of the genus level taxonomic diversity and modes of life and nutrition of four mutually equivalent early cambrian age 3 paleocommunities 1 skeletal faunas of the inner shelf 2 predominantly soft bodied faunas of the intra shelf basin 3 archaeocyathan faunas of the carbonate shelf and 4 sponge dominated faunas of the slope to basin areas the taxonomic and paleoecological distinctness of these four paleocommunities indicate possible low levels of competition within the communities and rapid expansion of habitat ecospace ranges though with similarities in the taxonomic composition of poriferans and arthropods reflecting the rapid migration of these two groups into new habitats the present integrative study provides a more comprehensive portrait of metazoan diversification and paleocommunity evolution during the peak phase of the cambrian explosion than do investigations based on single communities

science and empiricism in pile foundation design scientific approaches to pile design have advanced enormously in recent decades and yet still the most fundamental aspect of pile design that of estimating the axial capacity relies heavily upon empirical correlations improvements have been made in identifying the processes that occur within the critical zone of soil immediately surrounding the pile but quantification of the changes in stress and fabric is not straightforward this paper addresses the degree of confidence we can now place a on the conceptual and analytical frameworks for estimating pile capacity and b on the quantitative parameters required to achieve a design the discussion is restricted to driven piles in clays and siliceous sands with particular attention given to extrapolating from design approaches derived for closed ended piles of relatively small diameter to the large diameter open ended piles that are used routinely in the offshore industry from a practical viewpoint we need design approaches that minimise sensitivity

experimental investigation of reverse end bearing of offshore shallow foundations shallow skirted foundations can mobilize uplift resistance from end bearing in the short to medium term however uncertainty exists over the magnitude of reverse end bearing resistance compared wi

lower cambrian burgess shale type fossil associations of south china abstract burgess shale type preservation has been reported from numerous qiongzhusian and canglangpuian sections of southern china during the last few decades the early cambrian chengjiang type faunas of east yunnan were of particular interest due to their excellent preservation and taxonomic diversity a new definition and revision of the chengjiang type faunas is given which indicates that distinct ecological variations occurred between the chengjiang and haikou faunas on a smaller scale and between the arthropod dominated faunas of shallow shelf and the sponge dominated faunas of deeper shelf e g hunan on a larger scale recent finds from the yuanshan formation of deze east yunnan and the niutitang formation of zhongnan zunyi county guizhou indicate a much wider distribution of burgess shale type fauna during this period than was previously known the present investigations of the latter fauna revealed the presence of tsunyidiscus niutitangensis naraoia spinosa n cf longicaudata isoxys curvirostratus i paradoxus skioldia aldna amplectobelua trispinata cf tsunyiella diandongensis scenella sp cambrorhytium elongatum hyalosinica archaica and choiaella radiata the occurrence of burgess shale type preservation on the yangtze platform is not restricted to a small area as in the burgess shale but known from a ca 80 km wide geographic stripe extending for more than 500 km along the rim of proterozoic platform core this wide distribution of burgess shale type preservation is interpreted to be triggered by the coincidence of specific palaeoecological conditions including the rapid sedimentation of finest siliciclastic particles and the partial influence of suboxic water masses

palaeohydrology vegetation and climate since the late illinois episode 130 ka in south central illinois abstract our interpretation of pollen and ostracode successions from four basins in south central illinois provides a new synthesis of palaeovegetation palaeohydrology and palaeoclimate for the period from the late illinois episode about 130 000 years ago to near the end of the wisconsin episode about 25 000 years ago correlations of pollen biozones between raymond pittsburg and bald knob basins are the basis for identifying the late illinois glacial sangamon interglacial wisconsin glacial and hudson interglacial episodes glacial episodes were identified primarily by the presence of picea pollen and the ostracode limnocythere friabilis whereas interglacial episodes were identified by quercus pollen and by the ostracodes candona caudata and heterocypris punctata within interglacial and glacial episodes pollen and ostracode assemblages varied with changes in moisture balance local palaeohydrology was assessed primarily on the basis of environmental tolerance indices of ostracodes and the stable isotope c o stratigraphy of ostracodal calcite regional moisture balance was assessed from multivariate analyses of the pollen successions three climatic regimes occurred during the sangamon episode 1 one regime was characterised by precipitation exceeding evaporation that promoted basin overflow this climate was inferred from the high percentages generally 80 of deciduous forest pollen peaks in the abundance of liquidambar and fagus pollen indicate that winters may have been slightly warmer and effective moisture slightly greater than at present 2 the second climatic regime was continental similar to the present climate of illinois in which precipitation is equal to or just less than evaporation this climate is inferred from abundant ambrosia pollen 40 to 60 and abundant nektic swimming ostracode valves which suggest a shallow lake these conditions probably developed in association with a heat low over the interior of north america during marine oxygen isotope stages 5e and 5c associated with the transition between the first two climates are fossils of the subtropical ostracode heterocypris punctata and the giant tortoise geochelone crassiscutata that suggest short periods in winter when polar low pressure systems did not extend into illinois as they do today 3 the third climatic regime occurred during the transition from the sangamon interglacial episode to the wisconsin glacial episode a severely continental climate is indicated by the heat tolerant ostracode pelocypris tuberculatum variable 18o values of ostracode valves and high environmental tolerance index values for the ostracode assemblages the weedy chenopodiaceae and amaranthaceae families grew on exposed mudflats the tree pollen associated with this type of climate included low percentages of picea and liquidambar an assemblage that has no modern analogue we suggest that this transitional climatic regime was associated with the large scale changes in the climate system during marine oxygen isotope stage 4

a bat guano deposit in jamaica recorded agricultural changes and metal exposure over the last 4300 years abstract bats are excellent ecological indicators because they are long lived globally distributed and show predictable responses to environmental stressors unaltered bat guano deposits although rare can serve as environmental archives to reveal changes in dietary patterns over millennial time scales we inferred changes in agricultural and industrial practices using a continuous 4300 year old bat guano deposit from jamaica cadmium mercury lead and zinc increased during the industrial revolution which began in ca 1760 a period characterized by elevated emissions of metals to the atmosphere beginning in the early 20th century decreases in 206pb 207pb isotopes tracked the history of leaded gasoline use metal concentrations in the bat guano deposit exceeded those recorded in two nearby lake sediment cores from jamaica carbon nitrogen and sulfur stable isotope profiles in bat guano tracked the agricultural history of jamaica specifically the introduction of nitrogen fertilizers sugarcane and possibly fungicides bat populations are under stress globally and such intact guano deposits provide potentially critical information on long term changes in their food source and exposure to metals

k o ocr relationships in soil the relationships between k o and ocr are investigated for primary loading unloading reloading conditions the study reviews laboratory data from over 170 different soils and presents an approach common to clays silts and sands simple empirical methods for predicting k o for normally consolidated and overconsolidated soils are evaluated the validity of the methods is supported by statistical analyses on the basis of the findings only the effective stress friction angle o and prior stress history ocr and ocrmax are needed to predict approximate values of k o

sponge dominated offshore benthic ecosystems across south china in the aftermath of the end ordovician mass extinction abstract offshore benthic communities were sparse after the end ordovician mass extinction the recent discovery of diverse abundant sponges in south eastern china anhui and zhejiang provinces that flourished during the hirnantian late ordovician post extinction interval raises questions over the extent and ecological significance of the sponge community at that time this paper dramatically expands the scale of the hirnantian sponge fauna within south china with seven new occurrences across 2000 km these occurrences cross the ordovician silurian boundary interval in the marginal and submerged platform areas of the yangtze sea in jiangsu hubei hunan chongqing and sichuan provinces in condensed sections platform margin facies the occurrences are normally represented by extensive spiculite layers but several sites yield entire exceptionally preserved body fossils at ganggangshan near nanjing jiangsu province such preservation is abundant the new occurrences are combined with palaeogeographic and tectonic reconstructions to produce a model for the distribution and preservation of the sponge fauna we argue that the exceptional preservation was due largely to nepheloid layers that were generated during rapid post glacial transgression that flooded the weathered land surface of the uplifted cathaysia block nepheloid layer collapse led to rapid deposition of suspended sediment within the deeper parts of the intra plate restricted basin and on adjacent platform margins and slopes the suspended sediment influx also introduced abundant nutrients to the water column as indicated by a significant 13c excursion during the sponge bearing mudstone interval at ganggangshan the combined sponge assemblage was dominant over large areas of the hirnantian offshore sea floor across south china we predict that similar occurrences with exceptional preservation will also be found in other continental blocks abundant articulated sponges may be encountered particularly in restricted basin successions containing rapidly deposited graptolitic mudstones near the ordovician silurian boundary

lower ordovician graptolite biozonation and lithofacies of southern bolivia relevance for palaeogeographic interpretations the interpretation of the lithofacies and basin evolution of the early ordovician of southern bolivia is based on a number of sections on an e w transect lithostratigraphic units are extremely diachronous and only the available data on the graptolite biostratigraphy enabled an interpretation of the basin evolution the newly proposed graptolite biozonation includes the biozones of rhabdinopora flabelliformis adelograptus sp araneograptus murrayi hunnegraptus copiosus tetragraptus phyllograptoides expansograptus protobalticus expansograptus holmi baltograptus minutus azygograptus lapworthi and isograptus victoriae isograptus victoriae is the first isograptid identified from gondwanan south america the early ordovician succession of southern bolivia is the most complete one documented from south america and can be used as a standard for this continent the faunas are most easily correlated with the faunal succession of scandinavia and without doubt belong to the atlantic graptolite faunal province they show distinct differences from coeval faunas of the argentine precordillera referable to the pacific faunal province

stable carbon and hydrogen isotopes from bat guano in the grand canyon usa reveal younger dryas and 8 2 ka events we inferred climate change through the pleistocene holocene transition from 13 c and d values of bat guano deposited from 14 5 to 6 5 ka calendar ka in bat cave grand canyon arizona the 13 c and d values generally covaried indicating that regional late pleistocene climate was relatively cool and wet and early holocene climate gradually became warmer with increased summer precipitation until ca 9 ka at which time the onset of modern north american monsoon like conditions occurred during the younger dryas event 13 c values decreased whereas d values increased indicating a cool and possibly drier period we also observed a distinct isotopic anomaly during the 8 2 ka event at which time both 13 c and d values decreased the 13 c values abruptly increased at 8 0 ka suggesting a rapid change in atmospheric circulation and greater infl uence from convective storms originating from the south deposits of bat guano represent a largely untapped source of paleoenvironmental information that can provide continuous and long term continental archives of environmental change

palaeoecology of the graptoloidea abstract graptoloids class graptolithina were colonial pterobranch hemichordates and formed a major component of the early paleozoic macrozooplankton by analogy with modern pterobranchs they filtered food particles from the water mass in which they lived by means of ciliated lophophores they are inferred to have been able to migrate vertically through the water column for feeding efficiency and predator avoidance as by modern euphausiids but their means of locomotion is still highly conjectural the rhabdosomes which housed the colonies grew by distal accretion and large examples are inferred to have taken up to several years to have reached full size the few studies of survivorship suggest a relatively constant mortality of individuals within the community tubular and blister like outgrowths of cortical tissue are seen rarely and are inferred to be a response to parasitism and rare faecal packages with crumpled rhabdosomes suggest ingestion by predators the function of the monospecific aggradations of conjoined colonies synrhabdosomes seen on rare bedding planes is uncertain but is unlikely to have been part of their normal life history and ecology monospecific assemblages of unconnected colonies on single bedding planes are not rare however and suggest localised populations of single species in the overlying water column in life other bedding planes have a range of species resulting from mass mortality from volcanic eruptions and suggest a diversity of species in the water column the onshore offshore and depth facies preference of some 200 ordovician species has led to an ecological model in which the graptoloid habitat is partitioned vertically and horizontally in waters of the neritic and pelagic realms one group of species group 1 is largely confined to a deep water biotope mesopelagic zone characterised by dysaerobic water where they are thought to have exploited high bioproductivity denitrification zones a second group group 2 occupies an epipelagic biotope and is confined to waters of the epipelagic zone aerobic water a third and less well defined group group 3 occupies the inner shelf waters of the epipelagic zone only the median duration of species in the deep water biotope is significantly shorter than that of species in the epipelagic biotope suggesting greater environmental stress and instability in the dysaerobic zone over geological time consistent with models of disruption of the density structure and circulation patterns of the oceans from climatic instability the diversity and abundance of species were enhanced in both the epipelagic and deep water biotopes in regions of marginal upwelling where nutrients were brought from the deep to the shallow water zones it was in these regions that the classical graptolitic shale developed

stable isotope composition of cave guano from eastern borneo reveals tropical environments over the past 15 000 cal yr bp abstract insular southeast asia is a key driver for global atmospheric and oceanic circulation is a hotspot for biodiversity and conservation and is likely to have played a unique and important role in early human dispersals despite this partially due to its vast size and remote tropical location very few continuous palaeoenvironmental records exist especially in eastern borneo therefore we investigated 13 c and 15 n values and geochemistry of two cave guano deposits to reconstruct palaeoenvironments in eastern borneo firstly a profile was recovered from gomantong caves sabah reflecting a continuous deposit over 15 cal kyr bp secondly a profile was recovered from bau bau cave east kalimantan that ranged from 15 5 cal kyr bp the geochemical signature of each deposit confirmed the material to be ancient guano 13 c values revealed that a continuous dense rainforest persisted over at least the last 15 cal kyr bp around the gomantong site that was relatively insensitive to regional climate change by contrast 13 c values at bau bau indicate that although rainforest remained dominant in the record a significant drying occurred between 7 7 and 6 3 cal kyr bp with up to 25 grasses present although most regional models suggest that sea level rise and increased holocene insolation led to an increase in monsoonal moisture we find some evidence of more regional variability and that a reduction in monsoonal precipitation could have occurred however we cannot discount the implementation of an anthropogenic fire regime that opened the canopy allowing more grasses to occur

a new lagerstatte from the middle ordovician st peter formation in northeast iowa usa a new fossil fauna has been discovered from a recently recognized shale unit within the middle ordovician st peter formation in northeast iowa it contains a variety of invertebrates and vertebrates including soft body tissues impressions and 3 dimensionalpreservations the exceptional preservation reveals a new konservat lagerstatte the winneshiek lagerstatte and opens a unique window into the community that inhabited the margins of the laurentian cratonic seaway during middle ordovician transgression among the fossils several conodont assemblages including the apparatus of enigmatic coleodontids are preserved some conodont assemblages associated with soft body tissues are particularly noteworthy

did cooling oceans trigger ordovician biodiversification evidence from conodont thermometry the ordovician period long considered a supergreenhouse state saw one of the greatest radiations of life in earth9s history previous temperature estimates of up to 70 c have spawned controversial speculation that the oxygen isotopic composition of seawater must have evolved over geological time we present a very different global climate record determined by ion microprobe oxygen isotope analyses of early ordovician silurian conodonts this record shows a steady cooling trend through the early ordovician reaching modern equatorial temperatures that were sustained throughout the middle and late ordovician this favorable climate regime implies not only that the oxygen isotopic composition of ordovician seawater was similar to that of today but also that climate played an overarching role in promoting the unprecedented increases in biodiversity that characterized this period

preservation of early cambrian animals of the chengjiang biota the chengjiang biota of yunnan china documents the earliest extensive radiation of the metazoa recorded in the fossil record gauging preservational bias is crucial in providing an assessment of the completeness of this biota and thereby elucidating whether it represents a comprehensive depiction of early cambrian life we here present a model to explain the nature of the exceptional preservation of the chengjiang biota and details of the decay process this study indicates that chengjiang fossils were preserved through two taphonomic pathways that may have captured tissues of distinct compositions and this finding should provide a foundation for the interpretation of chengjiang fossils many chengjiang fossils are preserved by pyrite later pseudomorphed by iron oxides the clay rich host sediment was deficient in organic carbon but replete in available fe and this composition ensured that a decaying carcass acted as a local substrate for fe and s reducing bacteria pyrite morphology probably reflects contrasts in the decay rate and hence the h 2 s production rate of different tissues in a carcass reactive rapidly decaying tissues would have quickly supplied h 2 s producing many pyrite nuclei resulting in framboidal habits more recalcitrant tissues would have produced h 2 s more slowly so that crystal growth operated on fewer nuclei resulting in larger euhedral pyrite crystals reflective films especially common on chengjiang arthropods represent the remains of degraded carbon

the link between metazoan diversity and paleo oxygenation in the early cambrian an integrated palaeontological and geochemical record from the eastern three gorges region of south china abstract the link between environmental perturbations especially oceanic redox conditions and evolution during the cambrian biodiversification event is still highly controversial although this issue has attracted considerable attention for decades we here report on the fossil record of the early cambrian biota discovered in the uppermost yanjiahe and shuijingtuo formations that crop out in the luojiacun and qiaojiaping sections eastern three gorges area south china the uppermost member of the yanjiahe formation contains abundant benthic algae based on the fossil record four distinct intervals were recognized in the shuijingtuo formation i few sessile suspension feeders such as sponges were recovered from interval i ii interval ii is dominated by bivalved arthropods living in the water column in this interval are also found a few sponges and eodiscoid trilobites iii no fossils other than few sponge spicules were recovered from interval iii iv diverse benthic communities composed of sponges cnidarians brachiopods as well as bradoriids dominate interval iv comprehensive research on framboidal pyrite morphology whole rock geochemistry as well as in situ la icp ms analyses were carried out on samples from the luojiacun section in order to assess paleo redox conditions the results show that the overall evolution of the paleo redox conditions was characterized by a double episode of sharp anoxic events ae observed at the base of intervals i and iii followed by a gradual oxygenation event oe evidence of oxygenation fluctuations were detected especially within interval iv a case study is presented herein which brings together early cambrian changes in metazoan diversity and changes in environmental conditions it is suggested that periodical oxygenation of the water column increased the biological diversity in the restricted basins of the eastern three gorges thus four intervals of habitat succession can be tentatively reconstructed in the studied area for the cambrian age 2 age 3 interval indicating a transition from uninhabited sediments to well populated habitats finally both the temporal and spatial characteristics of the cambrian aes oes and the fossil record in south china are compared and links between them are discussed in the context of their specific paleo geographical setting

reinterpretation of middle cambrian stratigraphy of the rifted western laurentian margin burgess shale formation and contiguous units sauk ii megasequence rocky mountains canada abstract until recently research on the renowned fossil animals of the burgess shale has advanced to a greater degree than an understanding of the rocks in which they are found studies addressing lithostratigraphy and hydrothermal petrography of the so called inner carbonate belt and adjacent chancellor group however have begun to re evaluate long standing hypotheses on the middle cambrian of western canada tectonic activity along the kicking horse rim buried remnants of neoproterozoic rifting during the cambrian period had more influence on local sedimentation than previously thought notably large scale collapse of the cathedral carbonate platform margin at 509 ma bp is evidence of reactivated basement faults these failures produced listric megatruncation surfaces having near vertical escarpments 150 m in height where they terminate against the platform the majority of what have been interpreted as shed olistoliths from the cathedral platform margin is herein shown instead to be carbonate mud mounds these grew in situ along the face of the cathedral escarpment and are associated with fossiliferous intervals in overlying basinal mudstones at three distinct stratigraphic horizons two within the burgess shale during the delamaran and marjuman stages the mounds nucleated where deep seated normal faults intersected the seafloor building primarily during periods of relative sea level transgression mound growth is associated with syndepositional exhalative activity inferred from stratigraphic relations sedimentology and geochemistry the new name monarch formation is proposed for the initial post collapse beds and mounds deposited against the cathedral escarpment early glossopleura zone the variably defined term takakkaw tongue is thereby confined to pre collapse slope deposits coeval to and correlative with the cathedral formation

a high resolution temporal record of environmental changes in the eastern caribbean guadeloupe from 40 to 10 ka bp abstract in neotropical regions fossil bat guano accumulated over time as laminated layers in caves hence providing a high resolution temporal record of terrestrial environmental changes additionally cave settings have the property to preserve such organic sediments from processes triggered by winds deflation abrasion and sandblasting and intense rainfall leaching away this study reports both stable carbon and nitrogen isotope compositions of frugivorous bat guano deposited in a well preserved stratigraphic succession of blanchard cave on marie galante guadeloupe these isotopic data are discussed with regard to climate changes and its specific impact on eastern caribbean vegetation during the late pleistocene from 40 to 10 ka cal bp guano 13 c values are higher than modern ones suggesting noticeable vegetation changes this provides also evidence for overall drier environmental conditions during the pleistocene compared to today meanwhile within this generally drier climate shifts between wetter and drier conditions can be observed large temporal amplitudes in both 13 c and 15 n variations reaching up to 5 9 and 16 8 respectively also indicate these oceanic tropical environments have been highly sensitive to regional or global climatic forcing stable isotope compositions of bat guano deposited from 40 to 35 ka bp the last glacial maximum and the younger dryas reveal relatively wet environmental conditions whereas at least from the end of the heinrich event 1 and the bolling period the region experienced drier environmental conditions nevertheless when considering uncertainties in the model age the isotopic record of blanchard cave show relatively similar variations with known proxy records from the northern south america and central america suggesting thus that the blanchard cave record is a robust proxy of past itcz migration teleconnections through global atmospheric pattern suggest that islands of the eastern caribbean basin could be also under the influence of a bipolar temperature gradients that impact the mean location of the itcz with a southern hemisphere imprint during the glacial period and a more significant role of northern hemisphere during the last deglaciation

a new hypothesis for organic preservation of burgess shale taxa in the middle cambrian wheeler formation house range utah cambrian konservat lagerstatten are the most significant fossil deposits for our understanding of the initiation of phanerozoic life although many modes of preservation may occur these deposits most frequently contain nonmineralized fossils preserved in the form of kerogenized carbon films a rare yet important taphonomic pathway that has not previously been explained for any unit by a comprehensive model the middle cambrian wheeler formation of utah one of these lagerstatten contains abundant kerogenized preservation of nonmineralized tissues which occurs within a distinctive taphofacies that accumulated under the following conditions 1 domination of the siliciclastic fraction by clay sized particles 2 close proximity to a carbonate platform which resulted in mixed carbonate clay sediments 3 a well developed oxygen minimum precluding benthic colonization and burrowing and 4 relative proximity to oxic bottom waters facilitating transport of organisms from a habitable environment to one that favored their preservation we propose that preservation of nonmineralized tissues in the wheeler formation may have resulted from a combination of influences that reduced permeability and thus lowered oxidant flux which in turn may have restricted microbial decomposition of some nonmineralized tissues those influences include near bottom anoxia preventing sediment irrigation by restriction of bioturbation reducing conditions near the sediment water interface that may have acted to deflocculate aggregations of clay minerals resulting in low permeability face to face contacts early diagenetic pore occluding carbonate cements and an absence of coarse grains such as silt skeletonized microfossils fecal pellets or bioclasts this model may be applicable to kerogenized preservation of macrofossils in other fossil lagerstatten

the great ordovician biodiversification event gobe the palaeoecological dimension abstract the great ordovician biodiversification event gobe saw a spectacular increase in marine biodiversity at all taxonomic levels largely within the phyla established much earlier during the so called cambrian explosion the diversification was probably the result of a combination of several geological and biological processes and the positive feedbacks resulting from them the present paper reviews the palaeoecological dimension of the gobe it involved major increases in s and biodiversity largely associated with the rise of the paleozoic evolutionary fauna dominated by suspension feeders and involving a greater occupation of ecospace and more complex ecological structures in the ecological evolutionary units p1 and p2 in the benthos these include more complex food webs than those of the cambrian greater tiering especially above the sediment water interface and the development of guild structures indicating increased competition between taxa for particular resources the ordovician is characterized by a profound change in reef composition with a switch from microbial dominated reefs in the early and middle ordovician to metazoan dominated reefs in the late ordovician increases in complexity of deep water trace fossil assemblages began in the early ordovician and mark the increasing exploitation in that environment and the development of hardgrounds permitted bioerosion and encrusting strategies together with the appearance of cryptic communities within the water column the gobe involved a significant increase in the diversity of the phytoplankton and the development of a diverse zooplankton including planktotrophic larvae from a range of invertebrate clades this revolution in the plankton enabled the establishment of a diverse fauna of pelagic vertebrates molluscs and arthropods and promoted the rise of suspension feeders in the benthos an escalation amongst predators and thus community evolution may also have been a major driver of biodiversification

the messaoudensis trifidum acritarch assemblage and correlation of the base of ordovician stage 2 floian the global stratotype section and point gssp for stage 2 of the ordovician system now the floian stage and approximately equivalent to the lower and middle arenig of england and wales is defined by the first appearance datum fad of the graptolite tetragraptus approximatus in the diabasbrottet quarry section at mount hunneberg sweden one of the issues this raises is how to correlate the base of stage 2 at the gssp with areas and successions that do not contain a correlative graptolite fauna the distinctive cymatiogalea messaoudensis stelliferidium trifidum acritarch assemblage is present in the upper tremadocian araneograptus murrayi graptolite biozone of nw england and ranges across the tremadocian stage 2 boundary there the tremadoc arenig boundary of anglo welsh nomenclature it also occurs widely at other high southern ordovician palaeolatitudes around the margin of gondwana being reported from ireland wales the isle of man belgium germany spain and turkey and may also be present in bohemia and argentina eastern cordillera it therefore has the potential to contribute towards the recognition and correlation of the base of stage 2 in those areas of particular interest are the first appearance datums of various taxa within the stratigraphical range of the messaoudensis trifidum assemblage notably that of aureotesta clathrata simplex which is considered to be close to the base of stage 2 in nw england elements of the messaoudensis trifidum assemblage also occur in baltica the palaeoplate on which the gssp for the base of stage 2 is located however many of the taxa used to subdivide the messaoudensis trifidum assemblage around gondwana have not been recorded from baltica and may be restricted palaeobiogeographically to the gondwanan margin furthermore acritarch microfloras have not been reported from the diabasbrottet quarry section itself and there are hiatuses across the base of stage 2 in the two sections from baltica considered in this paper hence direct correlation of the base of stage 2 between the gssp and other sections using acritarchs is not yet possible nevertheless some taxa for example the genera peteinosphaeridium and rhopaliophora are shown to have fads at similar stratigraphical levels in the late tremadocian stage of both baltica and gondwana and therefore have the potential to correlate time slices in the late tremadocian stage between palaeoplates

base stability of multi propped excavations in soft clay subjected to hydraulic uplift excavations in soft clay underlain with an aquifer may be destabilized by hydraulic uplift previous studies on this subject are based mainly on field observations dewatering from the aquifer is a

high resolution early paleozoic ordovician silurian time scales for much of the geologic time scale resolving power appears to be limited by the duration of biostratigraphic zones and subzones yet these zones exploit the appearance and disappearance events of only a small fraction of the species they span computer algorithms can sequence an order of magnitude more events and make explicit the uncertainties that arise when calibrating the resulting time line an illustrative case history builds an ordovician and silurian time scale from the geologic record of the entire graptolite clade over 1900 species from more than 400 localities and sections worldwide the same approach can be applied to any stratigraphic interval with detailed biostratigraphic observations it provides the foundation for time scales and paleobiologic time lines using logic similar to graphic correlation optimizing algorithms search for a composite sequence of species first and last appearance events that minimizes the implied shortcomings of all the field observations the algorithms minimize the number of species coexistences that are implied but never observed and the net adjustments needed to bring local range charts into agreement with a single composite sequence of events after total section thicknesses have been rescaled to help normalize for variation in depositional rate mean stratigraphic thicknesses are used to scale the intervals between adjacent events in the composite sequence the resulting scaled composite sequence is converted to a relative geologic time scale by identifying stage and zone boundaries within the sequence of graptolite events this relative scale is in turn calibrated by dated volcanic ash beds that were incorporated in the search for the optimal sequence these dated events are also used to test for linearity of the scaled composite the final time scale has a potential resolving power of 0 02 0 1 m y more than ten times better than can be achieved by traditional zones graptolite zones vary widely in duration from as short as 0 1 m y to nearly 5 0 m y the mean duration of zones or zonal groupings calibrated here is 1 44 m y in the ordovician and 0 91 m y in the silurian the average uncertainty in locating zone boundaries in a single composite sequence is about one fourth of the mean zone duration the variance resulting from differences in time scales developed from differing numbers of field observations and in response to changes in the optimization criteria gives a very conservative measure of the overall robustness of the method these differences indicate an average uncertainty in the age of graptolite zone boundaries that is more nearly equal to the mean zone duration for zone duration the mean uncertainty amounts to about one half of the length of an average zone

new sites of chengjiang fossils crucial windows on the cambrian explosion soft bodied and lightly sclerotized chengjiang fossils have been found at more than ten new localities in the lower cambrian qiongzhusi and canglangpu formations of east central yunnan at the same time three different fossil assemblages have been recognized i e kunmingella isoxys naraoia assemblage at chengjiang kunmingella cricocosmia assemblage at haikou and kunmingella wutingaspis obolus assemblage at anning and wuding these sites yield new and striking specimens such as a new tentacular animal brachiopods with pedicles preserved and the enigmatic xidazoon having mixed phyla characters which are significant in our understanding of animal phylogeny above all the appearance of diverse chordates and agnathans vertebrates greatly expands our knowledge of the cambrian explosion the discovery of soft bodied fossils at many new localities and the very wide distribution of the qiongzhusi formation suggest that many more localities remain to be discovered here a new early form of tentaculate cambrotentacus sanwuia gen et sp nov perhaps related to lophophorates and entoprocts is described

spatial variation in the diversity and composition of the lower cambrian series 2 stage 3 chengjiang biota southwest china abstract strata hosting the lower cambrian series 2 stage 3 chengjiang biota maotianshan shale member yu anshan formation occur throughout the eastern part of yunnan province southwest china in this study literature based faunal inventories from 10 areas representing 34 localities together with 22 038 new specimens collected at three localities from three of the 10 areas were analyzed quantitatively to assess large scale spatial variation in taxonomic diversity and composition our analyses show substantial co variation between local paleoenvironmental settings and species diversity and suggest the presence of three general taphofacies in the maotianshan shale member from west to east low diversity 26 species characterizes the wuding area where fossiliferous strata have undergone extensive bioturbation high diversity 215 species characterizes the chengjiang haikou anning areas where fossiliferous strata consist of stacked couplets of thin event and background mudstone layers moderate diversity 55 species characterizes the malong area where fossiliferous strata consist of indistinctly bedded shale showing fewer single event layers but abundant background layers in spite of variations in sampling effort between sites spatial patterns in species diversity and community composition were controlled primarily by variation in depositional environments along a proximal offshore to lower shoreface gradient which influenced both ecological and taphonomic factors the offshore settings haikou chengjiang anning areas show relatively high species diversity and exceptional preservation of soft bodied fossils reflecting rapid burial in distal tempestites relatively high degrees of bioturbation time averaging and hydrodynamic disturbance caused a substantial decrease in the quality of preservation and number of soft bodied species in the wuding and malong areas arthropods are the most diverse group in most localities followed by priapulids poriferans brachiopods lobopods and hyoliths this study shows that the chengjiang biota lends itself very well to high resolution characterization of spatial variation in taxonomic diversity faunal composition and fossil preservation furthermore the chengjiang biota may provide a unique opportunity to assess the roles of environmental factors taphonomy and ecological controls on species diversity at local to regional spatial scales

shift in limiting nutrients in the late ediacaran early cambrian marine systems of south china abstract the ediacaran to cambrian periods are characterized by the diversification and extinction of metazoans carbon cycle perturbation and ocean oxygenation ocean nutrient cycles play a major role in the primary production and productivity driven shallow water anoxia that was responsible for mass extinction in some phanerozoic intervals however the relationships between these cycles and primary production and biological events during the ediacaran to cambrian periods have not previously been well explored this study presents stratigraphic profiles of nitrogen and organic carbon isotopes for sections belonging to the shelf and deep basin regions of the yangtze platform south china the nitrogen isotope profiles for these two regions share a similar trend showing 1 relatively stable 15n values of 5 6 in the early middle ediacaran 635 ma ca 560 ma and 2 a shift towards lower 15n values 3 4 since the shuram 13ccarb excursion the 15n values in the shelf section experienced a two stage decrease from the late ediacaran to cambrian stage 2 of the terreneuvian series down to 1 and then an increase from 1 to 4 across the cambrian stage 2 3 boundary i e the terreneuvian cambrian series 2 boundary at 521 ma these data in combination with previously reported nutrient profiles 15n p and mo allow the following new conclusions to be drawn 1 the early middle ediacaran ocean was characterized by n mo colimitation of primary production on a geological timescale that is different from the p limitation on long term primary production in the modern ocean 2 a shift in the ultimate limiting nutrient from n and mo to p likely occurred in late ediacaran early cambrian marine systems this shift may have been a prerequisite for the extinction of small shelly fossils in response to the development of photic zone anoxia for several million years in cambrian stage 2 which was followed by the third and most prominent phase of metazoan diversification

centrifuge modelling of uplift response of suction caisson groups in soft clay this paper describes a program of centrifuge model tests on the uplift behaviour of suction caisson foundations the parameters considered were the loading rate caisson diameter d soil strength

geochronological constraint on the cambrian chengjiang biota south china the cambrian chengjiang biota of south china provides compelling fossil evidence for the rapid appearance of metazoan phyla in earth history the cambrian explosion however the timing of the chengjiang biota is poorly constrained owing to lack of datable rock materials within the maotianshan shale that yields the fossils here we integrate secondary ion mass spectrometry sims and chemical ablation isotope dilution thermal ionization mass spectrometry ca id tims u pb analyses of detrital zircons from the maotianshan shale to provide high precision geochronological constraint on the chengjiang biota the youngest group of sims u pb detrital zircon dates yields an age peak at 520 ma six zircons from this group are further dated by the ca id tims u pb technique but suggesting that they were not formed from a single zircon growth event thereby neither the age peak nor the weighted mean age defined by the youngest sims u pb dates could represent the maximum depositional age of the maotianshan shale instead the youngest ca id tims u pb date 518 03 0 69 0 71 ma 2 analytical uncertainty incorporates u pb tracer calibration uncertainty provides the first robust maximum age of the chengjiang biota this new geochronological constraint on the chengjiang biota indicates that the cambrian explosion reached its major phase around 518 03 0 69 0 71 ma demonstrating a protracted process 22 myr for the cambrian explosion supplementary material sims and ca id tims zircon u pb data are available at https doi org 10 6084 m9 figshare c 4024849

the spence shale lagerstatte an important window into cambrian biodiversity the spence shale member of the langston formation is a cambrian miaolingian wuliuan lagerstatte in northeastern utah and southeastern idaho it is older than the more well known wheeler and marjum lagerstatten from western utah and the burgess shale from canada the spence shale shares several species with these younger deposits yet it also contains a remarkable number of unique species because of its relatively broad geographical distribution and the variety of palaeoenvironments and taphonomy the fossil composition and likelihood of recovering weakly skeletonized or soft bodied taxa varies across localities the spence shale is widely acknowledged not only for its soft bodied taxa but also for its abundant trilobites and hyoliths recent discoveries from the spence shale include problematic taxa and provide insights about the nature of palaeoenvironmental and taphonomic variation between different localities supplementary material a generic presence absence matrix of the spence shale fauna and a list of the spence shale localities are available at https doi org 10 6084 m9 figshare c 4423145

paleontology and paleoecology of guano deposits in mammoth cave kentucky usa article i nfo article history received 9 january 2014 available online xxxx bat guano deposits are common in the mammoth cave system kentucky usa paleontological remains associated with these deposits are important records of local landscape changes recent excavations in the cave suggest that vertebrate remains in most of these deposits are dominated by chiroptera although no extinct fauna were identi fied the presence of a large roost oftadarida brasiliensis in the chief city section is beyond the northern extent of its current range suggesting that this deposit dates to an undetermined interglacial period stable isotope analyses of tadarida associated guano indicate a c3 prey signature characteristic of forested habitat this was unexpected since this speciesis typically associatedwith openenvironments further ecomorphological analysisof wing shape trends in interglacial holocene and historic aged assemblages indicate that interglacial faunas are dominated by fast flying open space taxa t brasiliensis while late holocene and historic assemblages contain more taxa that utilized closed forest or forest gaps

a burgess shale like fauna from the lower cambrian of north greenland the cambrian explosion refers to the major adaptive radiation of the metazoans during the earliest phanerozoic an event that is best known by the abrupt appearance of hard parts near to the precambrian cambrian boundary 550 myr bp 1 deciphering this important evolutionary episode depends largely on the study of these skeletal remains2 3 together with trace fossils that include burrows and trackways4 5 many of these latter fossils evidently represent the activities of soft bodied organisms such as worms and lightly sclerotized arthropods whose exact identity is seldom known not least because they can be fossilized only in exceptional circumstances6 however documenting the soft bodied representatives of early metazoan communities cannot be neglected if they accounted for a substantial fraction of these early biotas7 here we report a new soft bodied fauna from the lower cambrian of north greenland this assemblage has highly significant similarities with the younger burgess shale and provides additional evidence for the geological longevity of this faunal type and its widespread distribution in deeper waters of cambrian oceans

using gis to study palaeobiogeographic and macroevolutionary patterns in soft bodied cambrian arthropods abstract soft bodied cambrian arthropods from burgess shale type deposits are some of the most famous and extensively studied fossil invertebrates but global species level assessments of their biogeographic patterns have not previously been explored quantitatively here we use a newly developed occurrence database in conjunction with geographic information systems gis analysis and paleogis which allows fossil locality positions to be viewed in the context of cambrian palaeogeography to quantitatively reconstruct geographic distribution patterns of primarily soft bodied arthropod species further we compare these patterns with those of co occurring trilobite taxa soft bodied cambrian arthropods show both statistically larger geographic ranges and greater stratigraphic longevities than co occurring trilobites many of the most widely distributed soft bodied arthropods were likely capable of swimming and this may in part explain their extensive distributions

taphonomy and palaeoecology of a late ordovician caryocaridid from the soom shale lagerstatte south africa abstract a new species of caryocaridid is reported from the late ordovician of south africa the fossils show a complex multi layered structure that may represent exceptional preservation of the original arthropod exo endo and epicuticle alternatively the layered structure may comprise the carapace with a mineralized cast of the internal void and a layer of fibrous illite external to the carapace the genesis of the fibrous illite is important as it demonstrates that not all fibrous textures associated with fossils in the soom shale and perhaps other lagerstatten can be interpreted as mineralized muscle tissue caryocaris cedarbergensis n sp extends the geographical ecological and temporal range of the family and provides the first evidence of a zooplanktonic constituent to the soom shale biota the genus most likely represents a cool adapted mesopelagic group during the early middle ordovician which inhabited an epipelagic cold water shelf environment during the late ordovician

local scale proxy evidence for the presence of closed canopy forest in north western borneo in the late pleistocene bones of strategy i bats from the archaeological record of the great cave of niah sarawak abstract the limits of the distribution of closed canopy forest in southeast asia during the glacial cycles of the pleistocene are the subject of continuing debate in this context this paper reports the results of an analysis of a novel line of evidence as a local scale case study 22 dated assemblages of bat bones that were recovered from the archaeological sequences of the great cave of niah in sarawak malaysian borneo were examined by examination of the morphological characteristics of the distal articulation of the humerus seven families and nine genera were identified five species level attributions could be made these assemblages formed a time series of 14 chronological intervals 48 0 35 ky bp ky bp 103 calibrated years before present 1950 incorporating samples from the high glacial interval 26 18 ky bp and last glacial maximum 23 19 ky bp bones of bat taxa that are adapted to forage in the cluttered environments in the interior of closed canopy forest strategy i bats were employed as proxy evidence for the presence of closed canopy forested habitats in the vicinity bones of strategy i bats principally small hipposideros spp were identified in all examined assemblages and intervals in the time series statistical testing indicated no evidence of differences in the absolute frequency of distal humeri from strategy i bats in the pleistocene samples 48 11 8 ky bp or in the entire time series 48 0 35 ky bp and no significant linear trend was found in the time series to suggest an increase of the bones strategy i bat taxa with the onset of the holocene these findings suggest that closed canopy forest habitats have been a persistent component in the landscape around the great cave of niah since 48 ky bp a taphonomic hypothesis is proposed to explain the dichotomy between the findings of this study and the pollen record of the site

the lower ordovician fezouata konservat lagerstatte from morocco age environment and evolutionary perspectives abstract the lower ordovician fezouata konservat lagerstatte from southern morocco has been one of the major palaeontological discoveries of the last decade it provides a unique insight into one of the most critical periods in the evolution of marine life the cambrian ordovician transition however its potential for deciphering key trends in animal diversification was hitherto largely limited by major uncertainties concerning its stratigraphic position age and environmental setting based on extensive fieldwork fossil evidence and facies recognition our study provides clarification on these three crucial issues exceptional preservation is limited to two intervals within the fezouata shale graptolites indicate a late tremadocian age for the fezouata konservat lagerstatte as a whole which is supported by biostratigraphical evidence provided by acritarchs sedimentological features and reconstructed patterns of relative sea level changes indicate relatively shallow water environmental conditions under distal storm influence in an offshore to lower shoreface siliciclastic ramp setting the fezouata biota represents a unique and exceptional window into the palaeobiodiversity in open marine conditions thus contrasting with the other ordovician konservat lagerstatten presently known in our analyses of this new set of data we pave the way for accurate temporal faunal and environmental comparisons with other lower palaeozoic konservat lagerstatten and unlock the full potential of the fezouata biota to better understand the processes and scenarios of early animal radiations

experimental study of uplift resistance of shallow skirted foundations in clay under transient and sustained concentric loading wind wave and current forces cause significant overturning loads to be transmitted to foundation systems of fixed bottom offshore structures while buoyancy forces in conjunction with environmental loading impart direct tensile loads to foundations of floating facilities shallow skirted foundations are a potentially attractive foundation solution when overturning or tension loading is significant as suctions mobilised within the soil plug provide tensile resistance while passive suctions are maintained undrained reverse end bearing will govern failure providing enhanced uplift resistance compared with vented pull out of the foundation unit with or without the soil plug governed by skirt soil friction currently uncertainty exists over the limiting ratio of skirt depth to foundation diameter to mobilise undrained reverse end bearing and the duration over which passive suctions can be sustained this paper reports results from beam centrifuge tests investigating the response of shallow skirted fou

paleoecology of benthic metazoans in the early cambrian maotianshan shale biota and the middle cambrian burgess shale biota evidence for the cambrian substrate revolution abstract as the depth and intensity of bioturbation increased through the proterozoic phanerozoic transition the substrates on which marine benthos lived changed from being relatively firm with a sharp sediment water interface to having a high water content and blurry sediment water interface microbial mats once dominant on normal marine proterozoic seafloors were relegated to stressed settings lacking intense metazoan activity this change in substrates has been termed the agronomic revolution seilacher a pfluger f 1994 from biomats to benthic agriculture a biohistoric revolution in krumbein w e ed biostabilization of sediments bibliotheks and informationsystem del carl von ossietzky universitat oldenburg 97 105 and the impact of the subsequent development of the mixed layer on benthic metazoans has been termed the cambrian substrate revolution bottjer d j hagadorn j w dornbos s q 2000 the cambrian substrate revolution gsa today 10 9 1 7 because the early cambrian was a transitional time in this substrate revolution it is hypothesized that benthic metazoans adapted to typical proterozoic style soft substrates co existed with benthic metazoans adapted to more typical phanerozoic style soft substrates paleoecological examination of the benthic metazoans of the early cambrian maotianshan shale chengjiang biota and middle cambrian burgess shale biota combined with examination of core samples from the rocks in which the maotianshan shale biota is preserved was performed in order to test this hypothesis results of the core analysis reveal that the rocks in which the maotianshan shale biota was preserved and therefore the substrate on which it lived contains almost no evidence for bioturbation of any kind while the immediately underlying rocks of similar lithology are dominated by intermediate levels of horizontal bioturbation and contain some evidence for the beginning of mixed layer development these results suggest that benthic metazoans of the maotianshan shale biota lived on a typical proterozoic style soft substrate and that environmental conditions associated with the exceptional preservation of the maotianshan shale biota may have also suppressed bioturbation levels results of the paleoecological analysis indicate that the maotianshan shale and burgess shale biotas contain mobile and sessile benthic metazoans adapted to typical proterozoic style soft substrates and others adapted to typical phanerozoic style soft substrates in addition the maotianshan shale biota is dominated by benthic suspension feeding genera adapted to typical proterozoic style soft substrates indicating that this biota lived during the early stages of the cambrian substrate revolution the burgess shale biota however contains more benthic suspension feeding genera adapted to typical phanerozoic style soft substrates than the maotianshan shale biota which suggests that the soft substrate on which they lived had more advanced levels of mixed layer development this research suggests that the adaptive radiation of benthic metazoans during the cambrian explosion was driven in part by the cambrian substrate revolution as benthic metazoans were forced to adapt to the development of the mixed layer in subtidal siliciclastic soft substrate environments during the cambrian

a poorly preserved fish like animal from the chengjiang lagerstatte cambrian series 2 stage 3 abstract specimens of a poorly preserved animal including individuals and body parts have been discovered from the chengjiang lagerstatte these specimens are interpreted to be a fish like animal and are described as an unnamed myllokunmingiid the morphologies and preservation of individuals and body parts are described and the relative decay patterns are briefly discussed these specimens are from the event mudstone beds of the maotianshan shale member but exhibit the classic preservation of organisms in the background mudstone beds slow accumulation and this might indicate that different preservation modes of organisms co exist in the event mudstone beds based on the facts that lenses cannot be discerned on all the specimens of myllokunmingiids their visual organs may have been more like eyespots than true eyes

stratigraphic controls of soft bodied fossil occurrences in the cambrian chengjiang biota lagerstatte maotianshan shale yunnan province china abstract the early cambrian maotianshan shale exposed near kunming china is one of the oldest and best preserved konservat lagerstatten containing the chengjiang biota although the fossils have been well studied the depositional processes and stratigraphic relationships amongst the fossil bearing localities are poorly understood largely due to limited continuous exposures and structural complexity in this area in this study we use a detailed facies and stacking pattern analysis to delineate the depositional history and stratigraphic relationship of the maotianshan sedimentologic observations from five prolific fossil localities of the chengjiang biota have yielded six distinct facies within the maotianshan shale the three coarse grained facies composed of siltstones and very fine sandstones f1 f3 contain sedimentary structures including hummocky cross stratification and combined flow ripples that are consistent with deposition within storm wave base the fine grained facies composed of interbedded silty mudstones and clay rich mudstones f4 f6 were deposited below the wave base and represent episodes of lower storm frequency and pelagic sedimentation these six facies have specific stacking patterns indicating the presence of five distinct depositional units each of those depositional units is bound on its upper and lower contact by a flooding surface fining upward successions near the base of each stratigraphic unit are interpreted as short lived marine transgressions these are overlain by coarsening upward stacked facies interpreted as a period of shoreline progradation the fossils of the chengjiang fauna are exclusively found in the coarsening upward part of the depositional units the oldest fossil bearing intervals are associated with the most westerns sections in the study area in contrast the youngest fossil bearing intervals are found in the most eastern sections this time transgressive relationship is interpreted to reflect a genetic relation between distinct sedimentary processes and environments and the burial and preservation of the chengjiang biota

exceptionally preserved late ordovician biotas from manitoba canada there are few body fossil biotas known from early paleozoic accretionary shorelines and very few examples of ordovician soft bodied assemblages this study documents two recently discovered biotas from separate sedimentary basins in manitoba canada that provide unique information about tropical shoreline communities shortly before the late ordovician extinction event each site represents a distinct depositional environment but they share biotic elements including eurypterids xiphosurids and large problematic tubes the william lake biota representing more restricted conditions includes jellyfish that are among the best hydromedusan body fossils known rocks at the airport cove site deposited under more open circulation contain scolecodonts and noncalcified algae these biotas have some parallels with the recently described middle ordovician winneshiek lagerstatte but are also similar to some late silurian assemblages considered together early paleozoic marginal marine deposits are a rich but as yet poorly known source of paleobiodiversity data

ground truthing late ordovician climate models using the paleobiogeography of graptolites 1 the 18o records obtained from conodonts suggest that during the mid ordovician equatorial temperatures stabilized at close to the present day a hypothesis broadly supported by published climate models however the degree to which equatorial temperatures represent global climate state and varied between different climatic modes greenhouse icehouse interglacial glacial and to what extent ordovician 18o and climate models truly reflect the global climate remain to be tested here we present paleobiogeographical data for the planktonic graptolites from the gracilis time slice i e early sandbian stage that just postdates the postulated onset of climate stabilization twinspan analysis and constrained seriation provide robust ecological groupings in paleobiogeographical presence absence data the highest level groups reflect tropical subtropical assemblages and a high southerly latitude assemblage constrained seriation defines latitude distinct biotopes that are considered equivalent to modern zooplanktonic provinces the distribution pattern of graptolite biotopes in the gracilis time slice show 1 that models explaining local graptolite ecological assemblages using lateral differentiation e g upwelling are to be favored above those using depth stratification and 2 a steep faunal gradient from equator to pole which is typical of a cool nongreenhouse world and comparable to the modern situation we therefore broadly support the climate stabilization hypothesis paradoxically the climate of the early late ordovician appears similar to that of the present day despite the higher atmospheric pco2 levels graptolite species were indicative of temperature controlled ocean water masses in much the same way as the modern zooplankton

estimating palaeo water depth from the physical rock record abstract palaeo water depth and its change with time is a key factor in environmental analysis and in sedimentology in general the literature published on this topic and on related subjects however is substantial albeit scattered within and between different communities geologists oceanographers engineers physicists etc here i focus on proxies for palaeo bathymetry as obtained from the physical rock record floral faunal and chemical evidence for palaeo water depth being equally important must be dealt with elsewhere an assessment of the main depth related parameters in actualistic settings is presented and their applicability to the fossil sedimentary record discussed the outcome reveals the full complexity of this topic there is for example no such thing as an average wave base depth applicable to a wide range of fossil case settings this because wave and current climates in general and particularly so in neritic and coastal settings are intriguingly complex furthermore observations from modern oceans are not a priori applicable to fossil ones acknowledging these problems and limitations critically evaluated quantitative proposals for depth indicative facies and features in the sedimentary record are presented and error bars discussed

effect of perforations on uplift capacity of skirted foundations on clay the retrieval of deep water subsea installations resting on soft soil such as mudmat shallow foundations can be a difficult and costly operation if significant resistance to uplift is experienc

taphonomy and depositional circumstances of exceptionally preserved fossils from the kinzers formation cambrian southeastern pennsylvania abstract the emigsville member of the kinzers formation cambrian southeastern pennsylvania is a deposit of exceptional preservation containing three main lithofacies that were part of a mixed siliciclastic carbonate debris fan developed seaward of a carbonate shelf along the appalachian margin of laurentia fossils were exceptionally preserved in a shelf environment subject to tempestite deposition most remains are fragmentary which emphasizes the importance of predation as a taphonomic process where emigsville sediments were deposited remains are preserved mostly as organic carbon films pyrite crusts and aluminosilicate films these preservation styles apparently depended upon the development of microbial consortia in isolated microenvironments and some of the microbes were autolithified sedimentary and biological evidence suggests that anoxia salinity fluctuations and sedimentary obrution played relatively minor roles in the emigsville member of the kinzers formation the abundance of exceptionally preserved remains suggests that exceptional sedimentary conditions were not necessary in the cambrian in order for exceptional preservation to occur the abundance of predation evidence in a deposit of exceptional preservation reinforces the concept that predation was the primary taphonomic filter during cambrian time

using gis to unlock the interactions between biogeography environment and evolution in middle and late devonian brachiopods and bivalves abstract the late devonian was a time of profound evolutionary and environmental change associated with the frasnian famennian biodiversity crisis one way to unravel the faunal dynamics of this complex crisis is to document the spatial and temporal patterns associated with biodiversity decline this analysis investigates the relationship between biogeography relative sea level and environmental changes in laurentian brachiopod and bivalve species during the givetian through famennian stages upper middle to terminal devonian representatives from all major brachiopod and bivalve clades and paleocommunities were examined to provide a cross faunal comparison species ranges were reconstructed both spatially and temporally at the level of conodont zones using gis to understand the timing and extent of species invasions and the importance of geographic range during the crisis interval species geographic ranges were linked closely with both relative sea level change and depositional environment and expanded as relative sea level rose in addition times of interbasinal species invasions corresponded closely with sea level rises that breached tectonic barriers species with larger geographic ranges were more resistant to extinction during the late devonian this relationship is reflected partly in a general trend towards increased extinction resistance in taxa that are found farther offshore in environments that potentially included more area for example there is an increased survival advantage for species that inhabited the middle and outer platform environments though not for species inhabiting the open shelf additionally species whose givetian to frasnian history includes at least one interbasinal invasion event were more likely to survive the late devonian biodiversity crisis than noninvasive species this may have relevance for our understanding of the current biodiversity crisis given the role that invasive species are playing in mediating modern extinctions

tectonic framework and phanerozoic evolution of sundaland abstract sundaland comprises a heterogeneous collage of continental blocks derived from the india australian margin of eastern gondwana and assembled by the closure of multiple tethyan and back arc ocean basins now represented by suture zones the continental core of sundaland comprises a western sibumasu block and an eastern indochina east malaya block with an island arc terrane the sukhothai island arc system comprising the linchang sukhothai and chanthaburi blocks sandwiched between this island arc formed on the margin of indochina east malaya and then separated by back arc spreading in the permian the jinghong nan uttaradit and sra kaeo sutures represent this closed back arc basin the palaeo tethys is represented to the west by the changning menglian chiang mai inthanon and bentong raub suture zones the west sumatra block and possibly the west burma block rifted and separated from gondwana along with indochina and east malaya in the devonian and were accreted to the sundaland core in the triassic west burma is now considered to be probably cathaysian in nature and similar to west sumatra from which it was separated by opening of the andaman sea basin south west borneo and or east java west sulawesi are now tentatively identified as the missing argoland which must have separated from nw australia in the jurassic and these were accreted to se sundaland in the cretaceous revised palaeogeographic reconstructions illustrating the tectonic and palaeogeographic evolution of sundaland and adjacent regions are presented

a new macroalgal assemblage from the xiaoshiba biota cambrian series 2 stage 3 of southern china abstract exquisitely preserved burgess shale type fossils from the xiaoshiba lagerstatte in the cambrian series 2 hongjingshao formation of southern china provide remarkable perspective on early metazoans but have never been reported with plants here we first recognize a new assemblage of highly mineralized macroalgae from this biota based on morphological differences there are three new genera and four new species identified doulia rara gen et sp nov eolaminaria simigladiola sp nov singulariphyca ramosa gen et sp nov and rugophyca longa gen et sp nov relative to the other three species s ramosa is widely distributed among the beds which may indicate a dominat species in this community this new discovery fills part of the long gap in the detailed record of macroalgae between the chengjiang biota and the kaili biota representing a localized macroalgal flourish at the end of cambrian stage 3 the assemblage that shows morphological characters similar to some macroalgae found in the precambrian and primitive to those of the cambrian stage 5 lays the basis for revealing the evolutionary biology of early macroalgae and understanding the precambrian cambrian transition questions taphonomic study of this fossiliferous bed indicates that some well preserved macroalgae are preserved within their original habitats through analyzing the depositional environments of the known cambrian macroalgae we suggest that macroalgae tend to be preserved in relatively deep marine environments with less disturbance

the emu bay shale konservat lagerstatte a view of cambrian life from east gondwana recent fossil discoveries from the lower cambrian emu bay shale ebs on kangaroo island south australia have provided critical insights into the tempo of the cambrian explosion of animals such as the origin and seemingly rapid evolution of arthropod compound eyes as well as extending the geographical ranges of several groups to the east gondwanan margin supporting close faunal affinities with south china the ebs also holds great potential for broadening knowledge on taphonomic pathways involved in the exceptional preservation of fossils in cambrian konservat lagerstatten ebs fossils display a range of taphonomic modes for a variety of soft tissues especially phosphatization and pyritization in some cases recording a level of anatomical detail that is absent from most cambrian konservat lagerstatten

large deformation numerical modeling of short term compression and uplift capacity of offshore shallow foundations abstractlarge deformation finite element analysis has been used to model the undrained response of skirted shallow foundations in uplift and compression large deformation effects involve changes in embedment ratio and operative local soil shear strength with increasing foundation displacement either in tension or compression centrifuge model testing has shown that these changes in geometry affect the mobilized bearing capacity and the kinematic mechanisms governing failure in undrained uplift and compression small strain finite element analysis cannot by definition capture the effects of changing foundation embedment ratio and variation in local soil strength with foundation displacement in this paper load displacement relationships ultimate capacities and kinematic mechanisms governing failure from large deformation finite element analyses are compared with centrifuge model test results for circular skirted foundations with a range of embedment between 10 and 50 of the foundation diameter the re

the great appendage arthropod tanglangia biogeographic connections between early cambrian biotas of australia and south china abstract the cambrian great appendage arthropod tanglangia luo and hu in luo et al 1999 has until now been known from a single species from the chengjiang biota of southwest china cambrian series 2 stage 3 a new species from the emu bay shale konservat lagerstatte on kangaroo island south australia cambrian series 2 stage 4 tanglangia rangatanga sp nov extends the geographic and stratigraphic ranges of this genus and amplifies the biogeographic links between non biomineralised faunas from the early cambrian of australian east gondwana and the south china plate

undrained bearing capacity factors for conical footings on clay introduction the bearing capacity of circular foundations on undrained clay is of fundamental importance in many geotechnical problems in particular there are a number of designs of offshore foundations where the foundation can be treated approximately as a large circular footing for instance some gravity bases the spudcan foundations of jack up units and the more recently developed caisson foundations in most cases the footing is not placed at the ground surface and it is important to take into account the depth of embedment furthermore the base of a spudcan is generally not flat but approximates a shallow cone for foundations on soft clays the effect of the increase of strength of the soil with depth needs to be taken into account and this is particularly important for large foundations the purpose of this note is to present calculations of bearing capacity factors for shallow circular foundations accounting for embedment cone angle rate of increase of strength with depth and surface roughness of the foundation the results have widespread application particularly in the offshore industry the soil is assumed to be rigid plastic with yield determined by the tresca condition with an undrained strength su the method of characteristics is used for the bearing capacity calculation as described by shield 1955 eason shield 1960 houlsby 1982 and houlsby wroth 1982a for application to undrained axisymmetric problems some previous results have been published for this problem using similar numerical techniques e g houlsby wroth 1982b salencon matar 1982 houlsby wroth 1983 tani craig 1995 martin 2001 but the study presented here involves a much more comprehensive coverage of the parameters where comparisons can be made with the previous solutions the factors differ by up to about 0 5 which gives some indication of the level of accuracy attainable with this numerical technique exceptionally the rough footing results given by tani craig 1995 are higher by up to about 5 but this may be due to a problem with their numerical integration procedures see martin randolph 2001

primordial storms an overview of depositional environments in mid late proterozoic platforms of india abstract a large part of the central and southern indian shield is covered by mid late proterozoic platformal sediments these widely separated platformal covers display a kinship in respect of lithology and sedimentary structures another possible feature of commonality may emerge from recognition of storm sequence along with hummocky cross stratification because of the following attributes that characterise the platformal covers 1 slow sedimentation rate spanning from mid proterozoic to end of proterozoic along with facies persistence over a large distance imply deposition on a level basement which would have allowed unimpeded passage to storms 2 this slow sedimentation was affected frequently by intense mid latitude winter storm activity 3 absence of vegetal cover during proterozoic further reinforces the notion of unimpeded passage of winds storms the possibility of a single vast master basin subsequently separated during the phanerozoic unroofing cannot be ruled out in comparison with the vastness of mid late proterozoic platformal provinces hummocky cross stratification and storm sequences reported so far seem paltry possibly due to poor preservation and the consequent difficulty in recognising such forms rather than due to their actual rarity

graptolite biozone correlation charts charts are presented showing the correlation of graptolite biozonations for the lower ordovician to lower devonian i e for the entire stratigraphical range of the planktonic graptoloid graptolites regions chosen are those for which the most detailed biostratigraphical studies have been undertaken for baltica average graptolite zone chron duration appears to vary from c 300000 years ludlow epoch to 2 4 ma lochkovian epoch

external radial stress changes and axial capacity for suction caissons in soft clay a series of centrifuge tests was performed on instrumented model caissons in normally consolidated lightly overconsolidated and sensitive clays to investigate the external radial stress changes around suction caissons during installation consolidation and pullout and axial capacity after consolidation total pressure transducers embedded at different elevations of the caisson wall showed external radial total stresses that varied almost linearly with depth during both penetration and extraction of the caisson with smaller gradients during post consolidation pullout only slight differences were found in the measured external radial total stress when pressure transducers entered the suction affected zone from the jacking affected zone comparisons are presented between measurements and two theoretical predictions for both the external radial total stress during caisson installation and the radial effective stress after consolidation a simple cavity expansion approach was found to give reasonable pr