paleoaltimetry from stable isotope compositions of fossils stable isotope systematics of phosphatic vertebrate and carbonate invertebrate fossils are reviewed emphasizing external vs biological controls on isotope compositions and their variation external controls include elevation and isotopic lapse rates temperature atmospheric circulation patterns aridity and changes to precipitation seasonality e g development of monsoons biological controls include temperature regulation and temperature dependent biological activity water balance behavior and rates of hard part secretion and maturation some key factors include what sources of water an animal samples how those sources respond isotopically to elevation and the isotopic sensitivity of a biologic tissue to environmental changes general research design criteria are enumerated including numbers of fossils and analyses required as well as uncertainties in the interpretability of isotopic shifts isotope zoning from fossil teeth and shells from the indian foreland demonstrate comparable seasonal monsoon signals at 11 ma vs today implying a high and broad plateau at that time mean isotope compositions of fossil teeth from the lee of the cascade range central oregon show a pronounced decrease in 18 o initiating 7 ma signaling topographic rise associated with impingement of basin and range extension on the arc mean compositions and zoning in fossil shells from the northern rocky mountains indicate high elevations and topographic relief in the late cretaceous and early paleogene paleoaltimetry will principally benefit from better estimates of temperature because temperature lapse rates are less variable than isotopic lapse rates and because the combination of temperature and isotopic studies may help distinguish between local isotopic changes and distal ones caused by catchment or rain shadow effects

evidence for increased latent heat transport during the cretaceous albian greenhouse warming quantitative estimates of increased heat transfer by atmospheric h2o vapor during the albian greenhouse warming suggest that the intensified hydrologic cycle played a greater role in warming high latitudes than at present and thus represents a viable alternative to oceanic heat transport sphaerosiderite d 18 o values in paleosols of the north american cretaceous western interior basin are a proxy for meteoric d 18 o values and massbalance modeling results suggest that albian precipitation rates exceeded modern rates at both mid and high latitudes comparison of modeled albian and modern precipitation minus evaporation values suggests amplification of the albian moisture deficit in the tropics and moisture surplus in the mid to high latitudes the tropical moisture deficit represents an average heat loss of 75 w m 2 at 108n paleolatitude at present 21 w m 2 the increased precipitation at higher latitudes implies an average heat gain of 83 w m 2 at 458n at present 23 w m 2 and of 19 w m 2 at 758n at present 4 w m 2 these estimates of increased poleward heat transfer by h2o vapor during the albian may help to explain the reduced equator to pole temperature gradients

multi taxa isotopic investigation of paleohydrology in the lower cretaceous cedar mountain formation eastern utah u s a deciphering effects of the nevadaplano plateau on regional climate we investigate the regional climatic effects of the formation of the nevadaplano plateau during the sevier orogeny in an overall warming world paleohydrology was reconstructed from 590 individual measurements of phosphate o isotopes in continental faunas of the lower cretaceous cedar mountain formation utah u s a semi aquatic turtles crocodiles and terrestrial dinosaurs taxa are compared to coeval pedogenic carbonates to interpret changing water sources over time samples were grouped into four stratigraphic faunas lower yellow cat upper yellow cat ruby ranch and mussentuchit members resulting isotopic values were converted to d18 ow values using established d 18 op d 18 ow and d 18 oc d 18 ow relationships at a formation scale turtles d 18 op 14 1 to 15 7 v smow and crocodiles d 18 op 15 0 to 19 2 document water compositions of 28 1 to 26 1 and 27 7 to 24 2 respectively within the zonal range for formation scale meteoric water at 34u n paleolatitude 27 1 to 24 8 established by pedogenic carbonates d18 oc 22 0 to 23 5 v smow these data suggest that like soil carbonates turtle and crocodile phosphate isotopes can be used as proxies for meteoric water isotopic composition dinosaurd18 op sauropods 19 7 to 21 9 ornithischians 16 6to 21 7 small theropods 16 9to 18 2 andlarge allosauroids 19 1 to 20 3 values generally exceed those of semi aquatic taxa using mass balance equations for modern terrestrial animals adjusted for size and inferred dinosaur physiology ingested water is calculated for the above dinosaur groups on a member scale when meteoric water values are compared with calculated dinosaur drinking water values are equal to or lighter than meteoric water for most herbivorous groups as low as 215 5 for ornithischians and equal to or heavier than meteoric water for most carnivorous groups as high as 22 0 for allosauroids changes in d18 ometeoric water d 18 odinosaur ingested water faunal assemblages and sedimentology from member to member correlate to thrusting events of the sevier orogeny high elevations in the orogeny attenuated the influences of pacific moisture causing rainshadow induced aridity on the leeward foreland basin during upper yellow cat time and hosted seasonal snow accumulation by the end of ruby ranch time as suggested by 18 o enriched water e g up to an average of 22 0 from an allosauroid tooth and extremely 18 o depleted water e g 215 5 for ornithischians in the ruby ranch member by mussentuchit time delivery of the western interior seaway dominated moisture to the region despite continued rise of the sevier mountains

dalton wells geology and significance of debris flow hosted dinosaur bonebeds in the cedar mountain formation lower cretaceous of eastern utah usa the lower cretaceous dalton wells dinosaur locality north of moab utah consists of a 2 m thick stacked succession of four fossil rich bonebeds with an estimated collective lateral extent of more than 4000 m2 to date 215 m2 of the bonebeds have been excavated and more than 4200 vertebrate fossil field specimens have been collected the site occurs at the base of the yellow cat member of the cedar mountain formation and lies unconformably on upper jurassic strata of the morrison formation the age of the assemblage is tentatively accepted as barremian nine dinosaur taxa are recognized making dalton wells one of the richest abundance and diversity lower cretaceous dinosaur localities in the world the bonebeds are rare examples of fossiliferous subaerial debris flow deposits at least four flows originated an undetermined distance up slope from an early cretaceous site of dinosaur bone concentration and flowed through the site carrying bones short distances toward an adjacent area of lakes ponds and wetlands host sediments most likely accumulated on the eastward dipping slopes of a backbulge in a foreland basin the overall depositional setting was alluvial lacustrine in a warm to hot and seasonally wet and dry climate the consistent expression and location of lacustrine facies in both the brushy basin member of the morrison formation and the yellow cat member of the cedar mountain formation indicate that high rates of subsidence typified the dalton wells area both before and after the j k transition and further suggest that there was some form of long term to episodic and localized influence on subsidence the depositional slope required to generate debris flows may have been established by forebulge crustal flexure but could also have been established or amplified by the high rates of subsidence that maintained the lacustrine paleoenvironments in the field area concretionary deposits in the yellow cat member at dalton wells are diagenetic and apparently resulted from groundwater precipitation likely enhanced by the presence of organics bones and lacustrine carbonates the regional and cross facies expression of calcretes in the yellow cat member combined with the rarity of pedogenic indicators confirms that they are not paleosols mineral precipitation likely occurred as groundwater flow was established in response to foreland basin development it remains unknown under what specific circumstances animals died and carcasses accumulated prior to being reworked by debris flows however the stratigraphic association of seasonally wet and dry facies throughout the yellow cat member suggests that drought induced mortality events were probably common in a seasonally wet and dry environment debris flows may have been triggered by intense rainfall or seismic events

identifying soft sediment deformation in rocks abstract the correct identification of sedimentary folds and fabrics created during gravity driven deformation of unlithified successions from those tectonic structures formed during regional deformation is essential when interpreting geological histories preserved within the rock record this topic has become increasingly relevant over the past 40 years as improved seismic resolution and coverage have led to the realisation that significant portions of unlithified sediments along the continental margins undergo gravity driven deformation to create mass transport deposits mtd s the late pleistocene lisan formation exposed in the dead sea basin was chosen as a case study because it remains poorly lithified and structures developed within it are unequivocally related to soft sediment deformation ssd created when the succession underwent downslope directed movement this work tests various assertions previously used to deduce if structures were formed in unlithified sediments or during hard rock deformation hrd associated with subsequent tectonism within the lisan formation we describe veins developed along fractures and cleavage forming axial planar to folds that are structures previously assumed to be restricted to hrd in addition truncated folds incorporation of deformed fragile fragments into overlying sediment and cross cutting clastic dykes are all indicative of ssd the key diagnostic feature in establishing ssd is the sedimentary infill of irregular erosive surfaces that truncate underlying structures although compaction and diagenesis have not played a significant role in the case study caution should be exercised when examining structures preserved in the rock record as folds and fabrics originally created by ssd may be considerably enhanced and altered where significant overburden exists

constraints on palaeoenvironments in the lower cretaceous wealden of southern england from the geochemistry of sphaerosiderites abstract sphaerosiderites are millimetre scale concretions of feco 3 that form predominantly in waterlogged environments and are of use in palaeoenvironmental and palaeohydrological studies we present petrographic elemental and stable isotopic 13 c 18 o data from sphaerosiderites collected from the lower cretaceous wealden sediments of southern england the sphaerosiderites are composed of very pure feco 3 with only small amounts of ca mg and mn present suggesting that they are well preserved and were precipitated from fresh groundwater 13 c values display a relatively large range from about 5 to 30 vpdb in contrast 18 o values are relatively invariant 1 0 83 with an average of 3 01 vpdb the relationship between carbon and oxygen suggests that the sphaerosiderites faithfully record palaeo groundwater 18 o likely 18 o values for groundwater were calculated using a published experimentally derived siderite water fractionation equation and plausible assumed values for palaeotemperature the average estimate was 4 9 smow the wealden sphaerosiderite oxygen isotope values are comparable with other early cretaceous data from similar palaeolatitudes but lower than estimated holocene values for equivalent latitudes this observation may indicate greater rainfall at 30 n during the cretaceous relative to the holocene and also suggests relative stability of palaeoclimatic conditions during the early cretaceous at this palaeolatitude

high resolution carbon isotope records of the aptian to lower albian from se france and the mazagan plateau dsdp site 545 a stratigraphic tool for paleoceanographic and paleobiologic reconstruction high resolution carbon isotope stratigraphy is established for the aptian to lower albian of the vocontian basin se france and correlated to the carbon isotope record of the mazagan plateau dsdp site 545 the carbon isotope stratigraphy of the vocontian basin is proposed as a standard reference curve for the aptian to lower albian due to the completeness and high temporal resolution of the stratigraphic succession the good biostratigraphical time control and the frequent occurrence of regional to global black shale horizons including oceanic anoxic events 1a oae 1a of the lower aptian and oae 1b of the lower albian the carbon isotope record appears better suited for long distance short term correlation of different marine and terrestrial environments than biostratigraphy because of the synchroneity of carbon isotope signals in a range of sediment types however the combination of both biostratigraphy and carbon isotope stratigraphy provides an effective tool to reconstruct biotic change and paleoceanography and to correlate regional to global black shale horizons in different marine environments this combined approach allows us to ascertain the synchroneities or diachroneities of first and last appearances of biostratigraphic marker species based on the demonstrated diachroneity of important biostratigraphic markers of the aptian albian boundary the globally observed break point between the end of the uppermost aptian positive carbon isotope excursion and the onset of the pronounced negative shift of 13c values is an alternative criterion the distinctive structure and amplitudes of the carbon isotope record are observed in both the inorganic and organic carbon and can therefore be recognized in all marine and terrestrial environments of the aptian to lower albian

deep sea surface dwelling enteropneusts from the mid atlantic ridge their ecology distribution and mode of life the ecology distribution and mode of life of three species of surface dwelling enteropneusts is described based on rov observations and samples on the flanks of the northern mid atlantic ridge mar at comparative stations north and south of the sub polar front tergivelum cinnabarinum was most abundant in the north mean 4 56 ind 1000 m 2 3 50 s d and occurred at low densities in the south mean 1 19 1 68 s d yoda purpurata was dominant in the south mean 17 00 ind 1000 m 2 12 32 s d but only one individual was found in the north the within station distribution of all enteropneust species encountered was generally random t cinnabarinum was larger mean total length 142 mm than y purpurata mean total length 70 mm size distributions suggested smaller individuals of both species on the western side of the mar size and density of enteropneusts were generally higher in areas with higher carbon flux to the seafloor a single individual of allapasus isidis was observed drifting and settling to the seafloor at the sw site traces on the seafloor made by t cinnabarinum covered a much higher percentage of the total seabed area surveyed mean 0 323 0 155 s d than those of y purpurata mean 0 034 0 037 s d stable isotope values for t cinnabarinum suggested that it was a typical surficial deposit feeder enteropneusts appear to be abundant and an important bioturbator on the sedimented seafloor of the mar at around 2500 m depth

preservation of primary stable isotope signals in dinosaur remains and environmental gradients of the late cretaceous of montana and alberta abstract although the use of stable isotope data from vertebrate remains is becoming common for the cenozoic their application to mesozoic environments has been rare in part due to the perception that diagenesis has obfuscated all potential primary signal in this paper we illustrate how stable isotope data collected from dinosaur and other vertebrate remains can in fact be used to reconstruct paleoenvironmental conditions during the mesozoic carbon and oxygen isotope ratios were measured from tooth enamel of hadrosaur dinosaurs and from scales of freshwater fish that were collected from sites in the two medicine judith river and dinosaur park formations of montana and alberta these formations represent a coastal to upland gradient along the western margin of the late cretaceous inland seaway isotopic comparisons among skeletal components and among taxa are used as evidence that primary paleoenvironmental information as recorded by isotope data is preserved in tooth enamel and freshwater fish scales a comparison of carbon isotope ratios between hadrosaur tooth enamel and sedimentary organic matter indicates that these animals had a larger isotopic offset compared to bulk diet than modern mammals and that all hadrosaurian isotope data are consistent with the existence of c3 only ecosystems higher and more variable carbon and oxygen isotope ratios from animals occupying the coastal judith river region are interpreted to reflect a range of freshwater to brackish water conditions and plants that were undergoing water stress lower and less variable carbon and oxygen isotope ratios from the upland two medicine and intermediate dinosaur park areas are interpreted to reflect a gradual rainout of moisture from air masses moving inland and more uniform environmental conditions overall these results indicate that stable isotopes from dinosaur and other vertebrate remains have the potential to expand our understanding of terrestrial environments and ecosystems during the mesozoic

instability in tropical pacific sea surface temperatures during the early aptian the cretaceous has long been recognized as a time when greenhouse conditions were fueled by elevated atmospheric co2 and accompanied by perturbations of the global carbon cycle described as oceanic anoxic events oaes yet the magnitude and frequency of temperature change during this interval of warm and equable climate are poorly constrained here we present a ighresolution record of sea surface temperatures ssts reconstructed using the tex86 paleothermometer for a sequence of early aptian organic rich sediments deposited during the first cretaceous oae oae1a at shatsky rise in the tropical pacific ssts range from 30 to 36 0c and include two prominent cooling episodes of 4 0c the cooler temperatures reflect significant temperature instability in the tropics likely triggered by changes in carbon cycling induced by enhanced burial of organic matter sst instability recorded during the early aptian in the pacific is comparable to that reported for the late albian early cenomanian in the atlantic suggesting that such climate perturbations may have recurred during the cretaceous with concomitant consequences for biota and the marine environment

water utilization of the cretaceous mussentuchit member local vertebrate fauna cedar mountain formation utah usa using oxygen isotopic composition of phosphate abstract while the oxygen isotopic composition of pedogenic carbonate has successfully been used to address the effects of global climate change on the hydrologic cycle detailed regional paleohydrologic studies are lacking since the hydrologic cycle can vary extensively on local or regional scales due to events such as such as mountain building and since pedogenic carbonates calcite form in a narrow moisture regime other proxies such as vertebrate remains must be used to decipher local versus regional variations in paleohydrology in this study the oxygen isotopic composition 18op of phosphatic remains from a diverse set of vertebrate fossils fish turtles crocodiles dinosaurs and micro mammals from the mussentuchit member mm of the cedar mountain formation utah usa aptian to cenomanian are analyzed in order to determine differences among the available water reservoirs and water utilization of each taxon calculated changes in water reservoir 18ow over time are then used to determine the effects of the incursion of the western interior seaway wis and the sevier mountains on paleohydrology during the mm time calculation of 18ow from the results of isotopic analysis of phosphate oxygen suggests that turtles and crocodiles serve as another proxy for meteoric water 18o that can be used as a measure of average local precipitation 18ow similar to pedogenic calcite pedogenic calcites can be slightly biased toward higher values however due to their formation during evaporative conditions turtles and crocodiles can be used in place of pedogenic calcite in environments that are not conducive to pedogenic carbonate formation remains of fish with rounded tooth morphology have 18op values that predict temperatures consistent with other estimates of mean annual temperature for this latitude and time the 18op of ganoid scales and teeth with pointed morphology however indicates that these skeletal materials were precipitated from water that is 18o enriched due to migration to either evaporatively enriched water or 18o enriched estuarine waters of the western interior seaway wis another possibility that cannot be discounted and assuming all morphological remains are from the same taxon is that the pointed teeth and ganoid scales precipitated at different temperatures than rounded teeth mammal and herbivorous dinosaur 18op suggests they primarily drank isotopically depleted river water co existence of crocodiles turtles and mammals allows for calculation of relative humidity from site to site and these calculations suggest humidity averaged 58 and ranged between 42 and 76 the 18ow values estimated from semi aquatic taxa and pedogenic calcite suggest dominance of wis derived moisture during their growth herbivorous dinosaurs particularly indicate that altitude and catchment effects from the sevier mountains are seemingly important for river water 18ow in the fall through early spring these data suggest that temporal changes in the isotopic composition of the mm fauna are produced by the small scale regressive transgressive cycles of the wis

the ecology and biogeography of discospirina tenuissima foraminifera in the atlantic and indian oceans the large 1 cm diameter miliolid foraminifera discospirina tenuissima carpenter and jeffreys 1870 is common at four sites nw ne sw and se located on either side of the mid atlantic ridge to the north 54 n and south 49 n of the charlie gibbs fracture zone the white discoidal tests of this epifaunal species were visible in video surveys of flat and gently 10 sloping sediment covered areas of seafloor replicate 500 m long transects 1000 m2 surface area obtained using the remote operated vehicle isis average densities varied from 0 07 se site to 1 12 nw ind m 2 for sloped transects and 0 02 nw to 1 75 sw ind m 2 for flat transects considerable variation was also evident between individual transects 0 2 25 ind m 2 the tests displayed no consistent dispersion pattern both significantly random and clumped patterns were observed in some cases within a single site isis was also used to make detailed in situ observations of d tenuissima and to collect individual specimens the delicate test margin sometimes exhibited angular notches and other signs of damage presumably a result of megafaunal activity in some cases the damage had been repaired specimens perforated by a large central hole occurred at the se site smaller sessile organisms including agglutinated foraminifera and occasional brachiopods use d tenuissima tests as a substratum for attachment in all areas some tests were surrounded by a ring of sediment presumably surface material collected by pseudopodia we interpret these features as being comparable to the feeding cysts created by other foraminiferal species they were particularly common at the se site where one or two abandoned rings indicated that some tests had moved distances of several centimetres across the seafloor most previous records of d tenuissima are from well oxygenated sites in the ne atlantic we provide the first records from the indian ocean here this species occurs at bathyal depths in the northwest 1980 m and northeast 938 m arabian sea where bottom water oxygen concentrations are depressed

the mid cretaceous water bearer isotope mass balance quantification of the albian hydrologic cycle a latitudinal gradient in meteoric n 18 o compositions compiled from paleosol sphaerosiderites throughout the cretaceous western interior basin kwib 34 75 n paleolatitude exhibits a steeper more depleted trend than modern predicted values 3 0x 34 n latitude to 9 7x 75 n lighter furthermore the sphaerosiderite meteoric n 18 o latitudinal gradient is significantly steeper and more depleted 5 8x 34 n to 13 8x 75 n lighter than a predicted gradient for the warm mid cretaceous using modern empirical temperature n 18 o precipitation relationships we have suggested that the steeper and more depleted relative to the modern theoretical gradient meteoric sphaerosiderite n 18 o latitudinal gradient resulted from increased air mass rainout effects in coastal areas of the kwib during the mid cretaceous the sphaerosiderite isotopic data have been used to constrain a mass balance model of the hydrologic cycle in the northern hemisphere and to quantify precipitation rates of the equable greenhouse albian stage in the kwib the mass balance model tracks the evolving isotopic composition of an air mass and its precipitation and is driven by latitudinal temperature gradients our simulations indicate that significant increases in albian precipitation 34 52 and evaporation fluxes 76 96 are required to reproduce the difference between modern and albian meteoric siderite n 18 o latitudinal gradients calculations of precipitation rates from model outputs suggest mid high latitude precipitation rates greatly exceeded modern rates 156 220 greater in mid latitudes 2600 3300 mm yr 99 greater at high latitudes 550 mm yr the calculated precipitation rates are significantly different from the precipitation rates predicted by some recent general circulation models gcms for the warm cretaceous particularly in the mid to high latitudes our mass balance model by no means replaces gcms however it is a simple and effective means of obtaining quantitative data regarding the mid cretaceous hydrologic cycle in the kwib our goal is to encourage the incorporation of isotopic tracers into gcm simulations of the midcretaceous and to show how our empirical data and mass balance model estimates help constrain the boundary conditions

the ecosystem of the mid atlantic ridge at the sub polar front and charlie gibbs fracture zone eco mar project strategy and description of the sampling programme 2007 2010 the work was supported by the uk natural environment research council consortium grant no ne c512961 1 and the census of marine life

oxygen isotopes from biogenic apatites suggest widespread endothermy in cretaceous dinosaurs the much debated question of dinosaur thermophysiology has not yet been conclusively solved despite numerous attempts we used the temperature dependent oxygen isotope fractionation between vertebrate body water 18obody water and phosphatic tissues 18op to compare the thermophysiology of dinosaurs with that of non dinosaurian ectothermic reptiles present day 18op values of vertebrate apatites show that ectotherms have higher 18op values than endotherms at high latitudes due to their lower body temperature and conversely lower 18op values than endotherms at low latitudes using a data set of 80 new and 49 published 18op values we observed similar and systematic differences in 18op values 18o between four groups of cretaceous dinosaurs theropods sauropods ornithopods and ceratopsians and associated fresh water crocodiles and turtles expressed in terms of body temperatures tb these 18o values indicate that dinosaurs maintained rather constant tb in the range of endotherms whatever ambient temperatures were this implies that high metabolic rates were widespread among cretaceous dinosaurs belonging to widely different taxonomic groups and suggest that endothermy may be a synapomorphy of dinosaurs or may have been acquired convergently in the studied taxa

structural configuration of the early cretaceous cordilleran foreland basin system and sevier thrust belt utah and colorado abstract stratigraphic and provenance data from lower cretaceous rocks in utah and colorado and structural evidence from the sevier belt in west central utah allow recognition of the ties between early thrust belt evolution and foreland basin system development regional isopach patterns of lower cretaceous strata define foreland basin system depozones lower cretaceous strata in west central utah that thicken westward from 100 m to 1 2 km were deposited within the flexurally subsiding foredeep depozone correlative units in eastern utah and western colorado 100 m thick were deposited in the back bulge depozone these thickness trends indicate the lower cretaceous foreland basin system consisted of a foredeep 100 180 km wide and forebulge 260 460 km wide a computer generated flexural model of the foreland basin system produces a reasonable match of the observed basin geometry using a 400 km wide l

variability of particulate flux over the mid atlantic ridge abstract the magnitude and composition of the sinking particle flux were studied over the northern mid atlantic ridge mar from june 2007 to july 2010 four moorings equipped with dual sediment traps 100 m and 1000 m above the sea floor sampled regions north and south of the charlie gibbs fracture zone between 49 n and 54 n and east and west of the mar biogenic data were coupled with satellite estimates of primary production and modelled particle source to assess the variability in export flux large variations were found in the seasonality chemical composition magnitude and source of sinking particulate material between mooring sites the northern moorings recorded both greater mean primary production and greater particle mass flux than the southern moorings although the large inter annual variability within the sites exceeded inter site differences while estimates of primary production and organic carbon fluxes are comparable to other investigations of this type they are notably lower than previous estimates for the abyssal plain of the north atlantic the deeper traps consistently recorded a higher mass flux compared to the shallower traps however we suggest that the overall flux recorded by the shallower traps was reduced by trapping inefficiency which in the light of the low current velocities may largely be due to the physical nature of the sinking material although deep trap flux estimates may be more susceptible to errors due to re suspended and advected material from nearby topography mass flux and current velocity are not linked in addition the relatively low aluminium concentration of the deep trap material indicates that this contribution is relatively small the organic carbon flux to the ne nw se and sw station was 0 8 1 2 1 1 and 1 1 g m 2 y 1 respectively corresponding to an export flux of 0 6 over this region of the mar

abyssal hills hidden source of increased habitat heterogeneity benthic megafaunal biomass and diversity in the deep sea abyssal hills are the most abundant landform on earth yet the ecological impact of the resulting habitat heterogeneity on the wider abyss is largely unexplored topographic features are known to influence food availability and the sedimentary environment in other deep sea habitats in turn affecting the species assemblage and biomass to assess this spatial variation benthic assemblages and environmental conditions were compared at four hill and four plain sites at the porcupine abyssal plain here we show that differences in megabenthic communities on abyssal hills and the adjacent plain are related to environmental conditions which may be caused by local topography and hydrodynamics although these hills may receive similar particulate organic carbon flux food supply from the surface ocean to the adjacent plain they differ significantly in depth slope and sediment particle size distribution we found that megafaunal biomass was significantly greater on the hills mean 13 45 g m 2 95 confidence interval 9 25 19 36 g m 2 than the plain 4 34 g m 2 95 ci 2 08 8 27 g m 2 anova f 1 6 23 8 p 0 01 assemblage and trophic compositions by both density and biomass measures were significantly different between the hill and plain and correlated with sediment particle size distributions hydrodynamic conditions responsible for the local sedimentary environment may be the mechanism driving these assemblage differences since the ecological heterogeneity provided by hills in the abyss has been underappreciated regional assessments of abyssal biological heterogeneity and diversity may be considerably higher than previously thought

dinosaur bones fossils or pseudomorphs the pitfalls of physiology reconstruction from apatitic fossils abstract a prerequisite to any attempt to reconstruct thermophysiology of ancient animals through analysis of stable isotopes of oxygen is the assumption that apatitic fossils are isotopically unaltered parts of their original skeletons we suggest that sufficient evidence is available to seriously question this assumption because living bones contain about 1 3 by weight of organic matrix mass balance considerations show that at least half of an apatitic fossil must be new material added post mortem furthermore living apatitic skeletons contain almost no rare earth elements and uranium whereas apatitic fossils bear high concentrations of these elements additionally we found that while in living fish correlation between 18o of oxygen in the phosphate and that in the carbonate of apatite is poor these two values are linearly correlated in fossil fish this suggests diagenetic recrystallization has taken place perfect preservation of micro textures such as haversian canals does not prove the pristine condition of a fossil some of the most beautifully preserved fossils are highly silicified most apatitic fossils probably are pseudomorphs replacing original skeletal elements whereas distribution of stable isotopes of oxygen in fossils might provide information about their burial environment it could be misleading in attempts to interpret the organisms physiology this cautionary note is supported by the similarity of 18op in bones of coexisting fossil fish dinosaurs and various other reptiles at different latitudes the overlap of predicted 18op values in fish and mammals living in contact with the same environmental water also weakens the hope that ectotherms can be distinguished from endotherms by the isotopic composition of oxygen in their bones and teeth

oxygen isotope compositions of late jurassic vertebrate remains from lithographic limestones of western europe implications for the ecology of fish turtles and crocodilians oxygen isotopes can be used to reconstruct the palaeoenvironmental conditions in which vertebrates lived and thereby give an indication of their ecology this has been done for faunas from the famous late jurassic lithographic limestones of western urope oxygen isotope compositions of phosphate from apatite were measured in aquatic or semiaquatic vertebrate remains fish turtles and crocodilians deposited in these protected coastal marine environments the unknown water composition in the oxygen isotope fractionation equations between phosphate and water was solved for turtles by assuming that modern relationship between environmental water and turtle bone isotope compositions applies to the past the results show that 1 coastal marine waters were thermally homogenous at the regional scale of western europe 2 oxygen isotope data discriminate between coastal marine and freshwater to brackish water inhabitants 3 the plesiochelyid turtles were coastal marine inhabitants their 18o values allow the calculation of the oxygen isotope compositions of marine waters thus refining the estimate of water temperatures by combining 18o values from fish and 4 the marine isotopic signature and the cranial anatomy of plesiochelyid turtles lead us to propose that they had a salt excreting system i e the fundamental physiological feature that controls osmoregulation in the marine environment these late jurassic turtles are proposed to be the first know marine turtles several tens of million years before the chelonioids or sea turtles

north american nonmarine climates and vegetation during the late cretaceous abstract analyses of physiognomy of late cretaceous leaf assemblages and of structural adaptations of late cretaceous dicotyledonous woods indicate that megathermal vegetation was an open canopy broad leaved evergreen woodland that existed under low to moderate amounts of rainfall evenly distributed through the year with a moderate increase at about 40 45 n many dicotyledons were probably large massive trees but the tallest trees were evergreen conifers megathermal climate extended up to paleolatitude 45 50 n mesothermal vegetation was at least partially an open broad leaved evergreen woodland perhaps a mosaic of woodland and forest but the evapotranspirational stress was less than in megathermal climate some dicotyledons were large trees but most were shrubs or small trees evergreen conifers were the major tree element some mild seasonality is evidenced in mesothermal woods precipitational levels probably varied markedly from year to year northward of approximately paleolatitude 65 n evergreen vegetation was replaced by predominantly deciduous vegetation this replacement is presumably related primarily to seasonality of light the southern part of the deciduous vegetation probably existed under mesothermal climate comparisons to leaf and wood assemblages from other continents are generally consistent with the vegetational climatic patterns suggested from north american data limited data from equatorial regions suggest low rainfall late cretaceous climates except probably those of the cenomanian had only moderate change through time temperatures generally appear to have warmed into the santonian cooled slightly into the campanian and more markedly into the maastrichtian and then returned to santonian values by the late maastrichtian the early eocene was probably warmer than any period of the late cretaceous latitudinal temperature gradients were lower than at present for the campanian and maastrichtian a gradient of about 0 3 c 1 latitude is inferred equability was high a mean annual range of temperature of about 8 c is inferred for paleolatitude 51 56 n during the campanian most late cretaceous plants evolved in a climate characterized by absence of freezing and low to moderate amounts of precipitation a brief low temperature excursion and a major long lasting increase in precipitation occurred at the cretaceous tertiary boundary in megathermal climates these events selected for plants that could exist in rainforest environments in mesothermal climates deciduousness and contamitant structural adaptations were selected the events at the cretaceous tertiary boundary had a major and long lasting impact on the evolution of land plants and their ecosystems low precipitation at low to middle late cretaceous latitudes is suggested to be the result of high levels of atmospheric co2 which in turn are probably related to inability of warm saline oceans to store large amounts of carbon conditions appear to have rapidly changed at the cretaceous tertiary boundary when oceanic circulation and stratification may have been fundamentally altered after the boundary the oceans were apparently able to store much greater amounts of carbon and the oceans withdrew large amounts of co2 from the atmosphere in turn more precipitation fell at low to middle latitudes the resulting high biomass vegetation formed a second major carbon reservoir to keep atmospheric co2 low relative to the late cretaceous changes in oceanic and atmospheric circulation probably resulted from some factor external to the ocean atmosphere system

isotopic reconstruction of past continental environments abstract vertebrate fossils and continental sediments provide a rich record of variations in the isotopic composition of surface environments to interpret these records a greater understanding of isotopic sources as well as fractionations associated with animal physiology soil geochemistry and diagenesis has been essential tooth enamel and fish otoliths yield subannual records of surface environments whereas soil minerals may integrate signals over many thousands of years carbon isotope variations in fossil vertebrates and soils record changes in the structure of vegetation and the isotope composition and concentration of atmospheric co2 oxygen isotope variations may be indirectly related to climate through reconstruction of the oxygen isotope composition of meteoric water or directly related to temperature through application of oxygen isotope paleothermometry to soil minerals or otoliths in africa nitrogen isotope variations show promise as a proxy for rainfall abundance though the gen

trawled megafaunal invertebrate assemblages from bathyal depth of the mid atlantic ridge 48 54 n we investigated the effects of contrasting surface primary production on the benthic invertebrate megafauna at four sites on the mid atlantic ridge the sites designated nw ne sw and se were located to the west and east of the ridge axis and to the north and south of the charlie gibbs fracture zone benthic megafauna were sampled in 2007 and 2009 with a semi balloon otter trawl at a target depth of 2 500 m the total biomass and density of major taxonomic groups did not differ significantly between sites despite those to the north being characterised by greater surface productivity than those to the south however the density and biomass of individual taxonomic groups as well as diversity and body size all showed significant differences between sites diversity was highest at the se and lowest at the ne site most species were larger to the north community composition was significantly different between all sites with the greatest number of unique species found at the se and noticeably fewer unique species at the northern sites there was no clear correlation between the surface productivity and community structure suggesting complex ecological controls on the communities it is speculated that in addition to the energy supply drivers such as strong currents and sediment characteristics play an important role in shaping the communities at the different sites to what extent the ridge acts as a dispersal barrier for benthic invertebrate fauna remains unclear however high numbers of species unique to the southern site suggest a limited dispersal between the northern and southern areas

tectonically induced climate and its control on the distribution of depositional systems in a continental foreland basin cloverly and lakota formations lower cretaceous of wyoming u s a abstract continental sediments of the cloverly and lakota formations lower cretaceous in wyoming are subdivided into three depositional systems perennial to intermittent alluvial intermittent to ephemeral alluvial and playa chert bearing sandstones conglomerates carbonaceous mudrocks blocky mudrocks and skeletal limestones were deposited by perennial to intermittent alluvial systems carbonaceous mudrocks contain abundant wood fragments cuticle and cortical debris and other vascular plant remains representing deposition in oxbow lakes abandoned channels and on floodplains under humid to seasonal conditions intraformational conglomerates sandstones bioturbated and blocky mudrocks with caliche nodules and bioturbated limestones characterize deposition in intermittent to ephemeral alluvial systems bioturbated limestones are encased in bioturbated mudrocks with abundant pseudo slickensides the presence of caliche nodules in some of the blocky to bioturbated mudrocks is consistent with supersaturation and precipitation of calcium carbonate from groundwater under semi arid conditions caliche nodules pseudo slickensides and carbonate rich floodplain sediments are interpreted to have been deposited by intermittent to ephemeral alluvial systems under seasonal to semi arid climatic conditions laminated mudrocks siltstones vuggy carbonates bedded to nodular evaporites pebbly mudrocks and diamictites were deposited in evaporative alkaline lakes or playas pebbly mudrocks and diamictites are interpreted to represent deposition from channelized and unchannelized hyperconcentrated flows on a playa resulting from intense rain events within the basin the areal abundance and distribution of these depositional systems change systematically across the overfilled portion of the early cretaceous cordilleran foreland basin in wyoming the lower part a interval of the cloverly and lakota formations is characterized by deposits of perennial to intermittent rivers that existed 300 to 1000 km east of the sevier fold and thrust belt proximal to the sevier fold and thrust belt the a interval of the cloverly formation and upper ephraim formation of the gannett group are typified by deposits of intermittent to ephemeral rivers and their associated floodplains in the middle part b interval of the cloverly formation intermittent to ephemeral alluvial systems expand to 600 km into the basin the upper part c interval of the cloverly formation is characterized by playa deposits in the bighorn and wind river basins and intermittent to ephemeral alluvial deposits along the front of the ancestral sevier mountains deposits of perennial to intermittent alluvial systems in the c interval of the cloverly and lakota formations are restricted to the black hills region almost 900 km to the east of the sevier mountains the change in the areal distribution of depositional systems through time within this continental foreland basin may be attributed to the development of a rain shadow associated with the uplift of the sevier mountains in the early cretaceous

palaeoceanographic significance of the tethyan livello selli early aptian from the hybla formation northwestern sicily biostratigraphy and high resolution chemostratigraphic records high resolution micropalaeontological and chemostratigraphic records for the hauterivian aptian succession outcropping at calabianca nw sicily provide new insight into the palaeoclimatic and palaeoceanographic evolution of the tethys ocean calcareous nannofossil and planktonic foraminiferal biostratigraphy together with 13c chemostratigraphy allowed the identification of a hiatus in the barremian and a major one including most of the upper aptian the entire lower albian and part of the middle albian the livello selli equivalent was identified on the basis of lithology and well constrained by calcareous plankton biostratigraphy as well as by the 13c curve the multi proxy record from the calabianca section is consistent with previous documentation of tethyan sections and others worldwide early aptian global events such as black shale deposition nannoconid crisis c isotopic negative spike and positive excursion associated with the oae1a increase in abundance of leupoldinids and clavate hedbergellids are superimposed on local regional events being strictly related to climate changes and increased run off based on micropalaeontological results and geochemical proxies ba p v ni the livello selli equivalent is interpreted as a high productivity event associated with variable but overall anoxic dysoxic conditions in the lower water column the onset of new physical chemical and biological conditions in the oceans and of the mid cretaceous greenhouse climate are interpreted as consequences of the superplume episode

oxygen isotope fractionation between crocodilian phosphate and water oxygen isotope compositions of phosphate 18op were measured in tooth enamel from captive and wild individuals of 8 crocodilian species a rough linear correlation is observed between the 18op of all the studied species and the oxygen isotope composition of ambient water 18ow differences in mean air temperature diet and physiology could contribute significantly to the large scatter of 18op values the combination of these parameters results in a fractionation equation for which the slope 0 82 is lower than that expected 1 from predictive model equations that assume temperature and diet as fixed parameters taking into account large uncertainties the observed oxygen isotope fractionation between phosphate and ambient water does not statistically differ from that formerly established for aquatic turtles case studies show that 18op values of fossil crocodile tooth enamel can be used to discriminate between marine and freshwater living environments within a precision of about 2 only

general circulation model simulation of the δ18o content of continental precipitation in the middle cretaceous a model proxy comparison we use the genesis atmospheric general circulation model gcm with water isotopic transport and fractionation capabilities to quantify the influence of atmospheric co 2 sea level and elevation of the western cordillera on the 18 o of middle cretaceous precipitation the model predicts a systematic increase of nearly 3 in the 18 o of north american precipitation due to warming associated with an increase in co 2 from 2 to 12 times pre industrial levels in contrast the specification of lowstand conditions and a high ancestral western cordillera reduces the 18 o of north american precipitation locally by as much as 6 and 8 we compare the simulated 18 o of precipitation with the 18 o of paleosol siderite spherules and find good agreement only when the model includes lowstand conditions and a high ancestral western cordillera our results imply either that cretaceous high latitude paleosol 18 o was influenced by orographic precipitation and the western interior seaway or that the gcm9s hydrological cycle is deficient at high p co 2 additional paleosol data are needed to resolve this issue

upper jurassic lower cretaceous morrison and cedar mountain formations ne utah nw colorado relationships between nonmarine deposition and early cordilleran foreland basin development abstract sedimentologic stratigraphic and petrologic analysis of the upper jurassic lower cretaceous morrison and cedar mountain formations of utah and colorado provides information on the timing and nature of early cordilleran foreland basin development the morrison formation can be subdivided into three depositional facies assemblages 1 lower progradational shallow marine lacustrine fluvial and eolian facies deposited during oxfordian kimmeridgian retreat of the stump sundance sea 2 a middle assemblage containing sandy gravelly braided fluvial deposits which are overlain by meandering fluvial channel and overbank facies and 3 an upper assemblage of laterally stable low sinuosity fluvial channel facies deposited during tithonian early neocomian time the upper part of this assemblage shows evidence of alteration and early diagenesis related to development of an early cretaceous unconformity the overlying cedar mountain formation is subdivided into two facies assemblages 1 the neocomian buckhorn conglomerate was deposited by northeast trending sandy gravelly braided rivers that were incised into the underlying morrison formation 2 an upper assemblage containing laterally stable low sinuosity fluvial channel facies deposited during late neocomian albian time the base of the unit contains a thick calcrete zone that formed during an unconformity following buckhorn deposition morrison and cedar mountain formation sandstones contain three petrofacies a feldspar rich lower morrison petrofacies qmflt 70 19 11 and chert rich upper morrison and buckhorn cedar mountain petrofacies qmflt 54 5 41 and 69 4 27 respectively sandstone composition and paleocurrent data indicate a cordilleran source area composed of proterozoic paleozoic and mesozoic sedimentary rocks the morrison formation and buckhorn conglomerate were deposited in the back bulge depozone of the late jurassic cordilleran foreland basin system and onlapped a flexural forebulge located in central utah late neocomian eastward migration of the forebulge uplifted areas in eastern utah producing an unconformity while the foredeep in central utah underwent flexural subsidence the upper part of the cedar mountain formation represents overfilling of the foredeep and deposition above the forebulge

taphonomy of debris flow hosted dinosaur bonebeds at dalton wells utah lower cretaceous cedar mountain formation usa abstract a taphonomic study of the lower cretaceous dalton wells dw dinosaur bonebeds near moab utah provides insight into the origins preservational biases and paleobiological significance of one of the richest and most diverse early cretaceous dinosaur sites known the bonebeds occur in a stacked succession of debris flows at the base of the yellow cat member of the cedar mountain formation which was deposited in a seasonally dry alluvial lacustrine setting although only 5 of the locality has been collected more than 4200 bones were recovered representing an assemblage overwhelmingly dominated by dinosaurs with a minimum of 67 individuals that represent at least eight genera the assemblage also includes eight elements from four non dinosaurian reptiles the dinosaur fauna is sauropod dominated mni minimum number of individuals 41 a basal macronarian mni 15 venenosaurus mni 3 a camarasaurid mni 2 and a large number mni 21 of generically unassigned sauropod elements other dinosaurs include the theropods utahraptor mni 9 nedcolbertia mni 2 a possible ornithomimid mni 2 plus a large iguanodontid mni 4 and the ankylosaurid gastonia mni 9 patterns of skeletal articulation and clustering ontogenetic representation and bone surface modification indicate that the assemblage accumulated and was exposed for more than a year as the result one or more multiple mass mortality events likely droughts that culled large numbers of subadults from the biocoenose carcasses and disarticulated elements were reworked then later transported a short distance and buried by a succession of debris flows skeletal representation data patterns of sorting breakage burrows abrasion and scratch marks provide evidence for sorting trampling and scavenging prior to debris flow reworking pre debris flow sorting is attributed to earlier hydraulic winnowing of easily transported elements the intensity and thoroughness of breakage involving 97 of the elements suggest highly focused high load impacts compatible with trampling by sauropods and iguanodontids lightly abraded and vertically displaced elements indicate episodes of trampling in soft mud trampling occurred before and after debris flow transport theropod tooth marks are uncommon but bone scavenging by osteophagous insects was common and severe resulting in substantial damage to articular surfaces comparisons of dw and other debris flow hosted bonebeds indicate that there are few consistent patterns among fossil assemblage and bone modification data however there are numerous similarities in the geological and spatial taphonomy datasets from these sites resulting from the similar physico hydraulic conditions under which elements were transported reworked and buried geologically and taphonomically dalton wells is similar to the blagoveshchensk monodominant hadrosaur bonebed in the udurchukan formation of eastern russia which also is interpreted as a debris flow hyperconcentrated flow deposit dalton wells also shares geologic and taphonomic characteristics with four bonebeds southeast of the town of green river utah and all occur at the base of the yellow cat member the uniform stratigraphic occurrences of the dalton wells blagoveshchensk and the green river sites resting on an unconformity and their shared sedimentologic and taphonomic features indicate that these sites originated in response to similar tectonic depositional and biostratinomic factors

fossil crocodilians as indicators of late cretaceous and cenozoic climates implications for using palaeontological data in reconstructing palaeoclimate abstract that the earth s climate has cooled over the last 100 million years has been recognized since the early nineteenth century the transition from the hot house world of the cretaceous a time interval without significant polar icesheets to the ice house world in which we now live today the dynamics process responsible for this change are being examined using computer models especially general circulation models gcm s through such work our understanding of the dynamics of the earth system improves and our ability to predict future trends is enhanced but the success of modelling experiments can only be assessed by comparing results with observations the pattern which for palaeoclimate are drawn exclusively from the geological record palaeoclimate interpreted from geological data is invariably based on analogy with the recent the validity of which depends on corroboration from multiple lines of evidence this requires the compilation and investigation of large global datasets of well constrained geological climate proxies this study uses the palaeodistribution of fossil crocodilians to examine the spatial distribution of palaeoclimate during this transition fossil crocodilians have a relatively good fossil record and are climatically limited in the recent they also provide a manageable global dataset with which to investigate other issues that impinge on the use of geologic data for reconstructing palaeoclimate taphonomy sampling effects time averaging tectonics and for fossils palaeobiogeography and evolution as such this study provides a possible template for examining other climate proxies in order to validate and hone palaeoclimatic interpretations an analysis of modern crocodilians indicates that temperature is the principal influence on their global distribution with the coldest month mean temperature cmm of 5 5 c marking the minimum thermal limit for the group corresponding today to a minimum mean annual temperature mat of 14 2 c the duration of warmth during the year partly indicated by the mean annual range of temperature mart is also important as this affects early juvenile development and survival the presence of standing water provides an essential thermal buffer against temperature extremes by analogy the palaeodistribution of fossil crocodilians suggests the following during the late cretaceous and early palaeogene mat s in excess of 14 2 c cmm s 5 5 c permeated throughout mid latitudes and coastal regions in high latitudes during the oligocene the restriction of fossil crocodilians to low latitudes suggests high latitude cooling as indicated by numerous other lines of evidence coeval restriction of crocodilians to coastal regions in mid latitude north america and much of asia consistent with increased seasonality and aridification in continental interiors may reflect local orographic changes as well as global climate change during the miocene fossil crocodilians return to the great plains of north america but do not reoccupy the continental interior of asia by the pliocene crocodilians are again restricted to low latitudes and coastal regions in mid latitudes coincident with further high latitude cooling and aridification and cooling of mid latitude continental interiors minor distributional changes during the holocene may reflect human effects

high elevation of the nevadaplano during the late cretaceous during the late cretaceous central nevada may have been a high elevation plateau the nevadaplano some geodynamic models of the western us require thickened crust and high elevations during the mesozoic to drive the subsequent tectonic events of the cenozoic while other models do not to test the hypothesis of high elevations during the late mesozoic we used carbonate clumped isotope thermometry to determine the temperature contrast between late cretaceous to paleocene carbonates atop the putative plateau in nevada versus carbonates from relatively low paleoelevation central utah site lacustrine carbonates from the nevada site preserve summer temperatures 13 c cooler than summer temperatures from paleosol carbonates from the utah site after correcting for 1 2 c of secular climatic cooling between the times of carbonate deposition at the two sites this 13 c temperature difference implies an elevation difference between the two sites of 2 2 3 1 km including uncertainties from age estimation and climate change broadens this estimate to 2 km our findings support crustal thickness estimates and cenozoic tectonic models that imply thickened crust and high elevation in nevada during the mesozoic

testing the foodbancs hypothesis seasonal variations in near bottom particle flux bioturbation intensity and deposit feeding based on 234th measurements abstract naturally occurring 234th 24 d half life was used on the west antarctic continental shelf to evaluate temporal variations in the flux of particulate material reaching the seabed bioturbation intensity the seasonal continuity of feeding by benthic fauna and trends in particle selection during ingestion for six common detritivores four surface deposit feeders and two subsurface deposit feeders these measurements were made at three stations during the five foodbancs cruises december 1999 march june and october 2000 and march 2001 to assess the nature of pelagic benthic coupling on the shelf and to evaluate the seabed as a potential food bank for deposit feeders when surface primary production is minimal two summer regimes were sampled march 2000 and march 2001 with the latter exhibiting a distinct 1 2 cm thick phytodetritus layer in nearly all sediment core samples at site b the 234th fluxes into the near bottom 150 170 mab sediment traps were indistinguishable for the december march 2000 march june 2000 and june october 2000 sampling intervals fluxes ranging from 170 to 280 dpm m 2 d 1 however the sediment trap 234th flux measured for the october 2000 march 2001 interval 1000 dpm m 2 d 1 was 5 fold greater than during the other three sampling periods consistent with the deposition of a phytodetritus layer the steady state 234th fluxes derived from seabed inventories at site b were 2 4 2 7 times greater than the sediment trap 234th fluxes indicating substantial scavenging of this particle reactive radiotracer in the bottom 150 m of the water column and or lateral transport near the seabed the seabed 234th inventories at the three stations showed no variation during the first four cruises but were significantly greater during cruise fb v march 2001 when the phytodetritus layer occurred based on 234th distributions in the seabed bioturbation intensities quantified using the diffusive mixing coefficient db varied from 0 5 to 97 cm2 yr 1 mixing coefficients were significantly lower during fb ii than during fb iii but no other time comparisons were statistically significant p 0 05 234th dbs showed no distinct seasonality and no correlation with either organic carbon flux into the sediment traps or 234th inventory in the seabed the four surface deposit feeders examined an echiuran worm and three holothurians protelpidia murrayi bathyplotes fuscivinculum and peniagone vignoni exhibited greater particle selection for recently deposited sediment during ingestion than the two subsurface deposit feeders studied a head down deposit feeding holothurian molpadia musculus and an irregular urchin amphipneustes lorioli all six deposit feeders contained excess 234th activity in gut sediments during all five cruises indicating sediment ingestion year round even during the austral winter the lack of seasonal variation in bioturbation intensity and the demonstration of year round feeding in deposit feeders are consistent with the hypothesis that the seafloor sediments accumulate labile organic matter produced during periods of high primary production and that deposit feeders utilize this food source as a food bank on a year round basis

stable isotope chemistry of fossil bone as a new paleoclimate indicator abstract during fossilization bone is thought to recrystallize and alter chemically on timescales of kyr to a few tens of kyr i e similar to the timescale for formation of soils therefore c and o isotope compositions of bone apatite should correlate with trends in soil water composition and aridity and serve as paleoclimate indicators this hypothesis was tested by analyzing c and o isotope compositions of the co 3 component of fossil bone apatite from mid oligocene through late pleistocene units in oregon and western idaho including the john day 19 4 30 0 ma mascall 15 2 15 8 ma and rattlesnake 7 2 7 8 ma formations whose paleosol sequences have been studied in detail and the juntura 10 11 ma hagerman 3 2 ma and fossil lake 18 o values provide a baseline of meteoric water compositions stable isotope compositions of bone co 3 do change in response to broad climatic trends but show poor correlation with compositions of corresponding paleosol co 3 at specific horizons instead compositional deviations between bone and paleosol co 3 correlate with compositional deviations with the next higher paleosol this suggests that the timescale for fossilization exceeds one paleosol cycle based on stratigraphic evidence and simple alteration models fossilization timescales are estimated at 20 50 kyr indicating that bone co 3 will prove most useful for sequences spanning 100 kyr c isotopes show negative and strong positive deviations during wet and dry climates respectively and short term trends correspond well with changes in aridity within the mascall and rattlesnake formations as inferred from paleosols a proposed correction to 18 o values based on 13 c anomalies implies a small 1 5 increase in meteoric water 18 o during the late oligocene global warming event consistent with a minimum temperature increase of 4 c a strong inferred decrease in 18 o of 4 5 after 7 ma closely parallels compositional changes in tooth enamel and reflects a doubling in the height of the cascade range

carbon isotope composition of lower cretaceous fossil wood ocean atmosphere chemistry and relation to sea level change the carbon isotope composition of fossil wood fragments collected through a biostratigraphically well constructed aptian lower cretaceous shallow marine siliciclastic succession on the isle of wight southern britain shows distinct variations with time the results indicate that the stratigraphic signature of delta sup 13 c sub wood through the aptian was influenced primarily by fluctuations in the isotopic composition of co sub 2 in the global ocean atmosphere system as registered in marine carbonates elsewhere and was not governed by local paleoenvironmental and or paleoecological factors negative and positive excursions in delta sup 13 c sub wood through the lower aptian occur in phase with inferred transgressions and regressions respectively a pattern that contrasts with that observed in many previous studies for different time intervals the relationship between delta sup 13 c variations and relative sea level change is tentatively interpreted as a response to various climatic and eustatic factors relating to rapid sea floor spreading thermal uplift of ocean floor emplacement of plateaus volcanic co sub 2 emissions weathering and sedimentary rate

the flux of overflow water through the charlie gibbs fracture zone we report the results of a set of measurements made within the charlie gibbs fracture zone in 1988 1989 the principal data sources are year long current meter records 16 in number and 23 conductivity temperature depth stations the aim was to determine the flux of overflow water passing westward out of the iceland basin in the eastern north atlantic within the fracture zone overflow water is defined either as having salinity greater than 34 94 at the present time or more generally as having a potential density 0 27 8 kg m3 in 1988 1989 the core salinity had a value equal to that reported in 1981 and 1983 but was fresher by about 0 02 than was found in 1964 the flux was estimated twice per day and was found to fluctuate strongly with energy spread in a broad band of periods ranging from 10 to 400 days no annual signal could be detected the mean value was 2 4 0 5 sv less than all previous estimates based on hydrography alone it is suggested that hydrography may systematically overestimate transport because diffusion is neglected flux estimates from current meter arrays are rarely used in initializing numerical ocean models consequently measurements like those reported here are an independent and important means for assessing the performance of such models at the deepest levels water enters the two transform valleys of the fracture zone from the west in the northern valley the flow is periodically flushed out by energetic bursts of overflow water a critical value of an inverse froude number is shown to define the flushing threshold

determination of oxygen isotope fractionation between water and phosphate from living lingulids potential application to palaeoenvironmental studies abstract lingulids are inarticulate brachiopods with phosphatic shells which live exclusively in marine waters their distribution is generally restricted to the continental shelf within the 40 belt from temperate to equatorial areas they show a range of morphological physiological and behavioral features that have remained remarkably constant since the cambrian the oxygen isotope fractionation between water and phosphate from living lingulids was determined as a tool to investigate the temperature and or salinity of past coastal seawater oxygen isotope measurements were performed according to the silver phosphate method on a collection of lingulids coming from well known and varied marine environments a global 18o variation of 3 5 was found for these lingulids which proves their good sensitivity to environmental factors namely the oxygen isotope composition and the temperature of seawater oceanographic data provided average temperature and salinity values in the living sites of the studied specimens least squares treatment of the data gave the following fractionation equation t c 112 2 15 3 4 20 0 71 18o po4 18o h2o which is similar to the equations determined by longinelli and nuti 1973a and kolodny et al 1983 for other phosphate bearing invertebrates and fishes all these results suggest that a unique equation describes the phosphate water fractionation of many marine organisms except for mammals

middle cretaceous greenhouse hydrologic cycle of north america we present a paleolatitudinal precipitation reconstruction for the greenhouse setting of mid latitude north america based on the oxygen isotopic composition of sphaerosiderites found in middle cretaceous wetland paleosols our reconstructed middle cretaceous d 18 o values of precipitation are 4 less than values from comparable modern low elevation coastal settings free of monsoons the data fit a conceptual model in which the precipitation source for the eastern margin of the cretaceous western interior seaway of north america is an 18 o enriched oceanic coastal jet in this subtropical tropical setting midcretaceous precipitation rates are interpreted to range from 2500 to 4100 mm yr

bathyal demersal fishes of charlie gibbs fracture zone region 49 54 n of the mid atlantic ridge i results from trawl surveys abstract demersal fishes were sampled by single warp otter trawl otsb at three sites on the mid atlantic ridge mar to the northeast ne northwest nw and southeast se of the charlie gibbs fracture zone at approximately 2500 m depth the mean abundance was 4109 fish km 2 sd 3714 and biomass 897 1 kg km 2 sd 842 9 compared with 1996 fish km 2 sd 1497 and 721 2 kg km 2 sd 387 at the same depth on the porcupine seabight psb segment of the ne atlantic ocean margin from previous studies there was no significant difference in biomass or abundance between the three sites on the mar nor in comparison with the ocean margin a total of fish 22 species were recorded at the three mar sites with evidence of highest species richness at the se site no unique species were found on the ridge but there were differences in species composition between the psb and the mar coryphaenoides brevibarbis and antimora rostrata were important at both the ne and nw trawl sites on the mar whereas halosauropsis macrochir was most important in the se we conclude that the mar is an important habitat for species otherwise confined to narrow strips of appropriate depth around the north atlantic ocean margins the mar supports similar population densities to ocean margin settings but with differences in relative importance of different species between regions

stable isotope composition and rare earth element content of vertebrate remains from the late cretaceous of northern spain lano did the environmental record survive abstract oxygen and carbon isotope measurements have been performed on phosphatic remains from faunal associations dinosaurs crocodiles turtles and fish of the late cretaceous continental and marine sediments from northern spain basque country the environmental meaning of the oxygen isotope record in fossil reptiles is discussed on the basis of known paleoecology modern fauna analogs and apatite chemistry rare earth elements ree co32 and po43 contents fossil remains in sandstones and argillites from two localities urria and cuezva have low down to 16 and scattered 18o po4 co3 and 13c values with ree patterns characterized by strong middle ree enrichments these geochemical compositions of the biogenic apatites have most likely been acquired during a multi stage late diagenesis involving complete recrystallization of the apatite in the presence of aqueous fluids ree contents of fossils preserved in the clayey sands from the site of lano suggest that samples have only been affected by early diagenesis despite the diversity of analyzed taxa and the close association of marine sharks and rays and freshwater species crocodiles and turtles evolving in a littoral environment the narrow range of phosphate 18o values is interpreted as reflecting the temperature and isotopic composition of groundwaters that prevailed in the burial environment the potential information relative to the physiology and thermal regime of the vertebrates has been erased during the process of early diagenesis if all oxygen in the phosphate has exchanged with groundwaters the oxygen isotope composition of vertebrate remains suggests that a warm climate t 20 25 c prevailed in northern spain during the late cretaceous

correlation of aptian albian carbon isotope excursions in continental strata of the cretaceous foreland basin eastern utah u s a abstract nodular carbonates calcretes in continental foreland basin strata of the early cretaceous cedar mountain formation cmf in eastern utah yield 13c and 18o records of changes in the exogenic carbon cycle related to oceanic anoxic events oaes and terrestrial paleoclimate chemostratigraphic profiles of both forebulge and foredeep sections show two prominent positive 13c excursions each with a peak value of 3 0 vpdb and having background 13c values of about 6 0 vpdb these excursions correlate with the global early aptian ap7 and late aptian early albian ap12 al1 carbon isotope excursions aptian albian positive 13c excursions in the cmf also correspond to 3 4 per mil increases in carbonate 18o these phenomena record local aridification events the chemostratigraphic profile on the thinner forebulge section of the cmf is calibrated for the first time by a radiogenic u pb date of 119 4 2 6 ma on a carbonate bed and by detrital zircon u pb dates on two bounding sandstone units maximum depositional ages of 146 ma and 112 ma petrographic observations and diagenetic analyses of micritic to microsparitic carbonates from nodules indicate palustrine origins and demonstrate that they crystallized in shallow early meteoric phreatic environments meteoric calcite lines derived from cmf carbonates have 18o values ranging between 8 1 to 7 5 0 vpdb supporting an estimate of zonal mean groundwater 18o of 6 0 vsmow for an aptian albian paleolatitude of 34 n furthermore our two chemostratigraphic profiles exhibit a generally proportionate thinning of correlative strata from the foredeep on to the forebulge suggesting that there were consistently lower rates of accumulation on the forebulge during the aptian albian identification of the global aptian albian 13c excursions in purely continental strata as demonstrated in this paper opens a new avenue of research by identifying specific stratigraphic intervals that record the terrestrial paleoclimatic impacts of perturbations of the global carbon cycle