volume imaging lidar observations of the convective structure surrounding the flight path of a flux measuring aircraft the university of wisconsin volume imaging lidar has been used to portray images of the three dimensional structure of clear air convective plumes in the atmosphere surrounding the flight path of the instrumented twin otter aircraft operated by the national aeronautical establishment nae of canada lidar images provide a context for interpretation of the aircraft measurements the position of data points within a convective element can be determined and the temporal development of the plume can be observed to time the observation with respect to the life cycle of the plume plots of the vertical flux of water vapor q w superimposed on lidar images clearly demonstrate the well known sampling difficulties encountered when attempting to measure fluxes near the top of the convective layer when loran was used to determine average aircraft velocity flight leg averaged horizontal winds measured by the aircraft and area averaged winds measured by lidar agree to within 0 2 m s 1 in speed and 1 in direction

calculation of area averaged vertical profiles of the horizontal wind velocity from volume imaging lidar data area averaged horizontal wind measurements are derived from the motion of spatial inhomogeneities in aerosol backscattering observed with a volume imaging lidar spatial averaging provides high precision reducing sample variations of wind measurements well below the level of turbulent fluctuations even under conditions of very light mean winds and strong convection or under the difficult conditions represented by roll convection wind velocities are measured using the two dimensional spatial cross correlation computed between successive horizontal plane maps of aerosol backscattering assembled from three dimensional lidar scans prior to calculation of the correlation function three crucial steps are performed 1 the scans are corrected for image distortion by the wind during a finite scan time 2 a temporal high pass median filtering is applied to eliminate structures that do not move with the wind and 3 a histogram equalization is employed to reduce biases to the brightest features

lithospheric evolution in the wake of the mendocino triple junction structure of the san andreas fault system at 2 ma as the mendocino triple junction mtj moves northwards up the north american margin the tectonic regime changes from subduction to strike slip for the first few million years following triple junction migration the san andreas fault system consists of several strike slip faults distributing deformation over a region 150 km wide this same region is expected to be affected by a slab gap beneath north america created by the northward removal of the subducting gorda plate and into which asthenospheric mantle is thought to rise to crustal depths the onshore and offshore mendocino triple junction seismic experiment mtjse provides a continuous seismic velocity reflectivity cross section across the deforming zone from the pacific ocean basin to the eastern edge of the california coast ranges the accretionary complex rocks that make up most of the crustal thickness are underlain by a 5 10 km thick high velocity 6 4 7 2 km s 1 layer at the base of the crust that extends from the pacific to at least 50 km and probably 90 km east of the san andreas fault the top of the lower crustal layer deepens from 7 km beneath the pacific ocean basin at the west end of the profile to 23 km at the east end by a gentle 5 10 eastward dip punctuated by abrupt offsets at the san andreas and maacama fault zones at each fault the top of the lower crust is offset by up to 4 km down to the east the moho is similarly deformed beneath the faults although by only 2 km such localized deformation of the moho implies that these two strike slip faults penetrate through the entire crust to the upper mantle good agreement between seismic velocity and seismic reflectivity in the vicinity of the faults gives confidence in these results although details of the offset beneath the san andreas fault are better resolved than those under the maacama fault seismic velocities in the upper mantle show only a small change along the profile from 8 1 km s 1 beneath the pacific to about 7 9 km s 1 beneath the coast ranges we infer that upwelling of asthenosphere into the slab gap is limited laterally or a lithospheric lid is present in the slab gap by 2 ma gravity data and crustal density structure show that most of the margin width is in local airy isostasy with the changes in crustal thickness near the strike slip faults corresponding closely to changes in surface topography the crustal blocks defined by the strike slip faults appear to be independently in isostatic equilibrium provided that the mantle beneath the coast ranges has a somewhat lower density than that beneath the pacific plate the densities in the coast range upper mantle are consistent with limited temperature elevation suggesting that the asthenospheric mantle is present beneath the depth of seismic energy penetration from our survey

taphonomy and palaeoenvironment of the middle eocene rodent localities of northwestern himalaya india abstract in northwestern himalaya the middle eocene rodents are known from the upper subathu group in jammu and kashmir and himachal pradesh india and from the coeval kuldana formation in pakistan most of the localities in these areas represent more or less the same timeframe but their faunal compositions differ considerably and also some of them are lithologically dissimilar the bone assemblages from some of the productive middle eocene rodent localities of jammu and kashmir were analysed applying the standard techniques of taphonomic data collection and interpretation to reconstruct their taphonomic histories and palaeoenvironment the petrography of the rodent bearing matrix was also studied and used in the taphonomic analysis the analysis has revealed markedly different taphonomic histories for two of the most prolific localities thereby partly explaining the differences in their faunal composition and demonstrating that taphonomy can be an important aid to biostratigraphic interpretations the east babbian gala ebgl rodent assemblage was initially accumulated in the mammalian predator scats for the accumulation of sindkhatuti skl bone assemblage the nonpredator agents are held responsible and a catastrophic mortality is indicated the taphonomic data from west babbian gala wbgl chenpur cpl tattapani ttpl and triyath barakh road tbrl localities is inadequate to identify with certainty mode of accumulation of their assemblages which is best ascribed at present to an attritional mortality and fluvial accumulation the palaeoenvironmental reconstructions suggest fluvio deltaic conditions at the time of deposition of the rodent yielding uppermost part of the subathu group they further indicate that the shoreline of the tethys sea was close to the site of deposition of the middle eocene rodents and other land mammals these interpretations are supported by other associated vertebrate groups which also include marine mammals cetacea

taphonomy of vertebrate assemblages from the paleogene of northwestern wyoming and the neogene of northern pakistan abstract we compare the taphonomy of vertebrate assemblages from two long continental records the early paleogene of the bighorn basin wyoming and the neogene siwalik sequence of northern pakistan both sequences contain a similar array of fluvial facies and the abundance of these facies differs among formations we document environments of preservation of vertebrate localities over time to determine comparability of fossil assemblages within and between sequences changes in sample size and species richness are noted to reveal potential sampling effects on patterns of faunal turnover preservational history determined the environment sample size quality of specimens taxonomic composition and spatial and temporal resolution of fossil assemblages and thereby the quality of the fossil record and its suitability for further analyses in both sequences changes in prevailing taphonomic processes reflect changes in lithofacies and habitat distribution correlated changes are found in fossil productivity species richness and faunal composition both sequences contain some episodes of apparent faunal change in which appearances and disappearances of rare taxa can be attributed principally to changes in sample size the paleogene record has high taxonomic resolution i e to genus or species for most mammalian fossil remains temporal and spatial averaging of paleogene fossil assemblages changes with lithofacies the neogene record has higher taxonomic resolution for remains of small mammals different preservational circumstances impose different constraints on paleocological and evolutionary analyses the best opportunities for paleocommunity reconstruction are provided by high taxonomic resolution large samples nd varied environments of preservation these circumstances are found in limited portions of each record the best opportunities for documenting evolution within lineages and species replacement patterns are provided by high taxonomic resolution high temporal resolution and consistent preservational context these taphonomic attributes pertain to the more common paleogene mammals particularly from the rich paleosol localities of the willwood formation and to the more common neogene small mammals from abandoned channel fills of the siwalik record

mammalian generic diversity and turnover in the late paleocene and early eocene of the bighorn and crazy mountains basins wyoming and montana usa abstract patterns of mammalian generic turnover richness and faunal composition were investigated for faunas from 17 biostratigraphic zones in middle paleocene through early eocene deposits of the bighorn and clarks fork basins of northern wyoming and the crazy mountains basin of south central montana significance of turnover was evaluated 1 by comparison of observed turnover to expected turnover calculated from the multiple regression of turnover on zone duration and generic richness and 2 by comparison of observed turnover to a bootstrapped turnover distribution patterns of turnover and richness also were assessed in light of relative sampling quality of each faunal zone the analysis identified four intervals of significant faunal change the torrejonian tiffanian transition the late tiffanian the earliest wasatchian and the middle to late wasatchian the first interval was characterized by a high number of last occurrences in the latest torrejonian resulting in a decrease in standing generic richness in the earliest tiffanian but no major changes in ordinal composition during the next interval of significant turnover the late tiffanian higher than expected first occurrences resulted in an increase in standing richness and a change in faunal composition most probably reflecting the immigration of taxa from outside north america the third and most dramatic interval of significant generic turnover took place in the earliest wasatchian and was distinguished by a high number of first occurrences but relatively few last occurrences this led to a marked increase in generic richness a pattern similar to that for the early wasatchian of north america as a whole the major change in faunal composition as in the late tiffanian was largely composed of immigrants from other continents the pattern of faunal change during the early wasatchian of the bighorn basin along with evidence for global warming at the paleocene eocene boundary supports previous interpretations associating this episode in mammalian evolution with the opening of high latitude intercontinental dispersal routes during the fourth interval of interest the middle to late wasatchian the bighorn basin fossil record shows a drop in generic richness this differs from the overall north american pattern and may be in part an artifact of still inadequate sampling for the latest part of the stratigraphic sequence in the bighorn basin

lower eocene alluvial paleosols willwood formation northwest wyoming u s a and their significance for paleoecology paleoclimatology and basin analysis abstract the lower eocene willwood formation of northwest wyoming is a 700 m thick accumulation of alluvial floodplain and channel mudstones and sandstones nearly all of which show paleopedogenic modifications pedogenesis of willwood sandstones is indicated by taproot and vertebrate and invertebrate bioturbation early local cementation by calcium carbonate and thin illuviation cutans on clastic grains pedogenesis in willwood mudstones is indicated by plant bioturbation insect and other invertebrate burrow casts and lebensspuren free iron aluminum and manganese mobilization including hydromorphic gleying sesquioxide and calcareous glaebule formation in lower parts of the solum presence of clay rich and organic carbon rich zones and well differentiated epipedons and albic and spodic horizons probable a horizons are also locally well developed occurrence of variegated paleosol units in thick floodplain mudstone deposits and their association with thin lenticular and unconnected fluvial sandstones in the willwood formation of the central and southeast bighorn basin suggest that these soils formed during times of rapid sediment accumulation the tabular geometry and lateral persistence of soil units as well as the absence of catenization indicate that willwood floodplains were broad and essentially featureless all willwood paleosols were developed on alluvial parent materials and are complex in that b horizons of younger paleosols were commonly superimposed upon and mask properties of suspected a and b horizons of the next older paleosols the soils appear to be wet varieties of the spodosol and entisol groups aquods and ferrods and aquents respectively though thick superposed and less mottled red purple and yellow paleosols resemble some ultisols most willwood paleosols resemble warm temperate to subtropical alluvial soils that form today under alternating wet and dry conditions and or fluctuating water tables the up section decrease in frequency of gley mottles increase in numerical proportion and thickness of red versus orange coloration and increase in abundance of calcrete glaebules indicate better drained soils and probably drier climate in late willwood time this drying is believed to be related to creation of rain shadows and spacing of rainfall but not necessarily decrease in absolute rainfall due to progressive tectonic structural elevation of the mountainous margins of the bighorn basin

wind retrieval from multiangle backscatter lidar profiles through anisotropic aerosol structures this is the accepted version of the following article tomas s and f rocadenbosch 2015 wind retrieval from multiangle backscatter lidar profiles through anisotropic aerosol structures j geophys res atmos 120 7758 7776 doi 10 1002 2014jd022858 which has been published in final form at http onlinelibrary wiley com wol1 doi 10 1002 2014jd022858 full

paleoecology of an early eocene mammalian fauna from paleosols in the clarks fork basin northwestern wyoming u s a winkler d a 1983 paleoecology of an early eocene mammalian fauna from paleosols in the clarks fork basin northwestern wyoming u s a palaeogeogr palaeoclimmatol palaeoecol 43 261 298 the paleoecology and depositional history of an early eocene vertebrate assemblage dominated by small mammals is analyzed at a richly fossiliferous locality in the willwood formation northwestern wyoming systematic surface sampling using a quadrat net screen washing and quarrying of fresh sediment show that all vertebrate material in these fluvial deposits is contained in dark gray mudstones representing the a horizons of paleosols seven such paleosols occur in 22 m of stratigraphic section the fauna includes 34 species of mammals and also birds reptiles amphibians fishes and gastropods all vertebrate fossil material is fragmented but it shows no evidence of transportation or current sorting surface weathering and possibly carnivore activity are responsible for the fragmentation and for an overabundance of dense and compact skeletal elements detailed surface collections were made to obtain multiple samples from the different bone beds paleosols principle component analysis shows that differences in the type and abundance of fossils from the various collecting areas are related to differences between contained bone beds not differences along single bone beds one paleosol has a red b horizon and six have an orange b horizon the gray over red colored paleosol is faunally distinct from gray over orange paleosols it contains the only specimens of two large archaic mammals and no very small mammalian taxa cluster analysis on the occurrence of vertebrate taxa is used to define subsets of the fauna that may represent animals living in different habitats separate clusters are formed by a group of the most common terrestrial herbivorous mammals and the crocodilian allognathosuchus and by a group of small possibly arboreal herbivores and carnivores the relative abundance of each mammalian species was initially calculated from a sample representing a minimum of 300 individual animals collected from the surface the surface sample is dominated by mammals that are medium sized for the fauna screen washing yields a greater relative abundance of very small mammals than was found on the surface this indicates that the surface sample is biased against small forms corrected relative abundances based on both surface and washing samples show that the fauna is dominated numerically by very small mammals one multituberculate species and several insectivores screen washing of fresh matrix is the best means of sampling a locality for paleoecological purposes

plant and mammal diversity in the paleocene to early eocene of the bighorn basin abstract abundant plant and vertebrate fossils have been recovered from fluvial sediments deposited in the bighorn basin wyoming during the first 13 m y of the tertiary here we outline and discuss changes in the composition and diversity of floras and faunas during this period which includes the recovery of terrestrial ecosystems from the k t boundary extinctions and later during the paleocene eocene transition the greatest global warming of the cenozoic floral diversity has been studied at three levels of spatial resolution sub local at individual collecting sites local along a single bed or stratigraphic horizon and basin wide regional sub local diversity shows a moderate increase from the early to late paleocene followed by a decrease across the paleocene eocene boundary then an increase into the later early eocene local heterogeneity was lower in paleocene backswamp floras although distinct groups of species dominated in different local fluvial settings such as backswamps and alluvial ridges heterogeneity of backswamp forests increased by about 65 from the early to late wasatchian early eocene the number of plant species inferred from the bighorn basin dataset rose gradually from the puercan to an early clarkforkian peak of about 40 species declined sharply to about 25 species by the clarkforkian wasatchian boundary then rose through the wasatchian to about 50 species a regional analysis of mammalian genera shows high turnover and a rapidly increasing number of genera within a million years of the k t boundary 10 50 genera a slight decline to 40 genera by the early clarkforkian then an increase from 40 to 75 genera by the late wasatchian our analyses found no major extinctions in mammals during the paleocene and early eocene in the bighorn basin but a one third decrease in the number of plant species at about the paleocene eocene boundary rates of taxonomic turnover were much higher for mammals than plants the diversity trends for plants and mammals show little congruence implying that the two groups responded in a very different manner to post k t extinction opportunities there is also little congruence between plant diversity levels and change in mean annual temperature mat as inferred from foliar physiognomy

mallee model for mammal communities of the early cenozoic and mesozoic abstract mallee is an endemic australian woodland and shrubland of semi arid summer dry regions between dry woodland and desert shrubland in other parts of the world such as africa and the americas such climatic regions support grassland ecosystems using australian and african climofunctions and models gives very different reconstructions of paleoclimate subhumid versus perhumid and paleovegetation woodland versus rainforest for north american fossil mammal faunas before cenozoic evolution of grassland ecosystems modern mammal faunas of africa and australia have different ecological spectra of taxonomic units body size feeding and locomotion of species of mammals on precipitation gradients gradients in proportions of such categories yield transfer functions for mean annual precipitation from percent species of artiodactyla or macropodidae percent species of moderately large animals 45 180 kg percent species of arboreal mammals and percent species of grazers these transfer functions can be applied to fossil mammal faunas to estimate paleoprecipitation in africa australia and north america modern transfer functions match well paleoprecipitation estimates based on depth to calcic horizons in paleosols at the same localities in kenya and inland australia back through the miocene for fossil mammal faunas of the rocky mountain region of north america african transfer functions fail but australian transfer functions predict paleoprecipitation back to the cretaceous tertiary boundary 66 ma furthermore modern mallee soils investigated in this study closely match cretaceous to eocene paleosols of the rocky mountains extinct mallee like vegetation such as pori woodlands of kenya and cunhaka woodlands newly defined of the rocky mountains better explains the dominance of small nocturnal insectivorous arboreal mammals of paleogene and mesozoic mammal faunas than comparisons with african grassland or rainforest faunas

petrography and geochemistry of floodplain limestones from the clarks fork basin wyoming u s a carbonate deposition and fossil accumulation on a paleocene eocene floodplain abstract floodplain limestones are increasingly important sources of fossil vertebrates from the clarks fork basin the northern extension of wyoming s bighorn basin despite their importance for understanding paleogene floodplain faunas little work has addressed the depositional history of these carbonates or evaluated potential taphonomic biases affecting the assemblages they produce recent studies of bighorn basin paleosols have increased our understanding of parameters affecting the paleo floodplain and large collections of limestones now exist this has allowed detailed investigation of limestone petrography and geochemistry and the proposal of a new model for their formation floodplain limestones record a complex depositional and diagenetic history precipitation of micritic low mg calcite and accumulation of bone occurred in low energy ponded water at the earth s surface pedogenic overprinting obscured primary textures and produced diagenetic grainstones packstones and wackestones biological and chemical pedogenic processes formed most carbonate allochems including micrite grains and calcified plant cells microbial fermentation occurred at shallow burial depths and methane production migration and oxidation affected the carbon isotope composition of diagenetic carbonate and primary micrite pore space was fully occluded by phreatic calcite cements during late stage diagenesis fossil assemblages contained within the limestones likely represent fauna derived from rarely sampled floodplain microenvironments hydraulic transport of bones was minimal accumulation of fossil material occurred episodically and bones were rapidly encased in micrite the uncommon body size distribution characteristic of limestone faunas is attributed in part to buffering of chemical and physical processes normally effecting bone decomposition during surface exposure and pedogenesis

sampling and faunal turnover in early eocene mammals badgley c and gingerich p d 1988 sampling and faunal turnover in early eocene mammals palaeogeogr palaeoclimatol palaeoecol 63 141 157 faunal turnovers in the fossil record are episodes of synchronous appearance and disappearance of species from a community often resulting in net change in species richness we studied the biostratigraphic record of faunal turnover involving early wasatchian early eocene mammals from the clark s fork basin wyoming u s a two faunal turnovers occur in this record one at the base of the wasatchian comprised mainly of appearances of taxonomically and ecologically distinctive species and a later one biohorizon a of schankler 1980 comprised mainly of disappearances especially of carnivorous species this study focuses on biohorizon a in the record of the clark s fork basin biohorizon a may be an artifact of sampling sample size and species richness are highly correlated r 0 95 throughout this record moreover sample size and species richness fluctuate markedly between successive stratigraphic intervals peaks of appearances coincide with large sample sizes and peaks of disappearances with low sample sizes the peaks and valleys in fossil productivity over time mask the real timing of appearances and disappearances of species changes in fossil productivity in the stratigraphic section may result from changes in exposure area taphonomic factors or ecological factors evaluation of the effects of sampling is a necessary prerequisite for investigating the chronological and ecological significance of faunal turnovers

assessing relative abundances in fossil assemblages abstract the relative abundances of taxa or skeletal elements in a fossil assemblage can provide important information concerning the palaeoecology and taphonomy of the assemblage however these relative abundances must be estimated from samples of the assemblage rather than measured directly the sampling error this produces decreases the accuracy with which relative abundances can be estimated from the fossil record using the multinomial distribution it is possible to place constraints on the accuracy of estimation of relative abundance provided that two out of three key parameters sample size required degree of similarity and confidence level are known applying this methodology to the fossil record it can be shown that in order to be 95 confident the taxon relative abundances of a fossil assemblage lie within 5 of those found in a sample 534 individuals must be collected this methodology enables the assessment of published relative abundance estimates and the development of sampling protocols for future studies

lithospheric structure of northern california from teleseismic images of the upper mantle teleseismic p wave travel time residuals from 120 earthquakes recorded across the u s geological survey california seismic network were used to determine the lithosphere p wave velocity structure beneath northern california a region characterized by complex interactions between the pacific north american and gorda plates lateral p wave velocity variations beneath the array were determined by inversion of 9383 travel time residuals inversion results for the crust show strong correlations to volcanic features the active volcanic fields shasta medicine lake lassen and clear lake are characterized by crustal low velocity anomalies that average approximately 6 possibly identifying partially molten magma bodies cooled solidified magma bodies beneath the extinct volcanic fields sonoma southern clear lake and sutler buttes are denoted by relative velocity highs averaging 3 the largest upper mantle velocity variations occur in the depth range 30 110 km where velocities vary from 5 5 to 9 5 these velocity variations reflect changes in the thickness and geometry of the pacific north american and gorda plates where they interact at the mendocino triple junction north of the mendocino triple junction the steep 70 east dipping portion of the gorda plate is imaged as a 5 velocity high to depths near 270 km a presumed segment of the gorda plate observed beneath the northern great valley and south of the inferred edge of the plate is characterized by a 9 velocity high in the depth range 30 70 km beneath the northern coast ranges shallow asthenosphere is imaged in the depth range 30 100 km as a pronounced southward tapering 4 low velocity zone which we interpret as the slab window results from this study provide improved constraints on gorda plate subduction evolution of the san andreas fault system and development of the lithosphere beneath western north america

taphonomy of the microvertebrate fauna from the early miocene thomas farm locality florida u s a abstract in a taphonomic analysis of the microvertebrate component of the early miocene thomas farm locality north central florida fossils from four sedimentary layers are analyzed and compared to determine the taphonomic factors that were involved in the formation of the bone accumulations found in the various levels of the site the lowest layers sampled were deposited under seasonal aquatic conditions and the primary agent of bone sorting was apparently moving water the abundant microvertebrates in the uppermost sand layer resulted from a combination of both a relatively unmodified coprocoenosis and an attritional assemblage of microvertebrates that frequented cave habitats or lived in the immediate area deposition within the sinkhole occurred in a relatively short span of time and the fauna is comprised primarily of those vertebrates that were living in close proximity to the sinkhole

taphonomy of a late cretaceous mammal bearing microvertebrate assemblage from the deccan inter trappean beds of naskal peninsular india abstract taphonomic analysis of a microvertebrate assemblage from the late cretaceous deccan inter trappean sequence of naskal peninsular india is undertaken to infer the taphonomic factors involved in the accumulation of bones at a time predaceous avians and large mammals were non existent approximately 1 ton of matrix was screen washed and a large number 9100 of isolated skeletal remains of fish amphibians turtles lizards snakes crocodiles mammals and dinosaurs in addition to pelecypods ostracodes gastropods and charophytes were recovered different mechanisms are postulated for the initial accumulation of the fauna whereas scavenging activity played no significant role in the accumulations hydraulic sorting was responsible for accumulation of the terrestrial and semi aquatic component of the fauna the wide distribution of bone fragments presence of pre burial fractures on some of the bones and the occurrence of the assemblage in a thin calcareous palaeosol unit indicate that the vertebrate remains accumulated rapidly as a consequence of a prolonged drought induced mass mortality event and were subjected to subaerial exposure the study concludes that the naskal assemblage accumulated in a distal floodplain lake which served as a natural death trap on whose banks terrestrial and other animals might have gathered in search of food and water during a prolonged drought and perished subsequently due to the desiccation of the lake

accuracy analysis of wind profiles calculated from volume imaging lidar data this paper presents a study of the vertical profiles of horizontal mean winds calculated from data obtained with the university of wisconsin volume imaging lidar vil during the 1989 first international satellite land surface climatology project islscp field experiment program wind profiles are determined from cross correlation functions between subsequent constant altitude plan position indicator planes calculated from volume scans of the convective boundary layer an objective technique to identify unreliable measurements is developed an error analysis based on determining the errors due to random noise in the data is performed the vil wind profiles are compared with radiosonde aircraft based and ground based measurements on the basis of internal consistency tests we estimate that in the convective boundary layer the hourly averaged vil wind estimates which have passed the reliability analysis have root mean square errors of 0 03 0 1 ms 1 in speed and 0 4 2 0 in direction

calculation of divergence and vertical motion from volume imaging lidar data boundary layer divergences are calculated from a sequence of images of the inhomogeneities in aerosol backscattering observed with volume imaging lidar two dimensional spatial cross correlations are calculated between successive horizontal plane images 10 km 5 km which are interpolated from the lidar returns the image at the first time represents the actual aerosol pattern an assumed divergence is included in the interpolation of the second image the divergence is determined by calculating correlations for a matrix of assumed divergences and selecting that value which optimizes the correlation the results from this process are consistent with predictions for divergence over the spatial scale measured and the apparent resolution of the results agrees with the image resolution a higher pulse rate volume imaging lidar system would allow for increased image resolution and increased image area both of which should improve the resolution in the divergence measurements

a rayleigh wave dispersion study between el paso texas and albuquerque new mexico the recent installation of a wwssn station at el paso texas ept makes it possible to analyze rayleigh wave dispersion along the axis of the rio grande rift analysis of dispersion along the path extending from el paso texas to albuquerque new mexico ept alq indicates an average crustal thickness of approximately 32 km and an upper mantle shear wave velocity of approximately 4 25 km s this result is in agreement with recent seismic refraction studies in the area combined analysis of the dispersion and refraction data yields poisson s ratios of 0 24 0 27 and 0 29 in the upper crust lower crust and upper mantle respectively the observed phase velocities are very similar to those reported for the east african rift

comparative paleoecology of paleogene and neogene mammalian faunas trophic structure and composition abstract trophic structure and composition are examined in two important biotic records one the paleogene of wyoming and montana and the other from the neogene of pakistan the paleogene sequence spans approximately 10 million years and encompasses four north american land mammal ages torrejonian tiffanian clarkforkian and wasatchian the neogene sequence spans approximately 17 m y and includes most of the miocene and pliocene with the best documented interval spanning from 16 to 7 ma five basic trophic categories primary consumers herbivores frugivores omnivores secondary consumers insectivores carnivores are recognized for paleogene and neogene mammals based on tooth morphology body size and analogy with modern mammalian groups the paleogene mammalian biota is characterized as one in which both trophic structure and taxonomic composition change through the history of the record the neogene mammalian biota maintains a relatively consistent trophic structure through most of the record although taxonomic composition changes substantially through time based on comparisons of trophic structure from the paleogene and neogene records with that of selected modern mammalian faunas paleogene habitats fluctuated between closed humid forests and more open drier woodlands neogene trophic structure indicates that savanna woodlands were the typical habitat present through most of the sequence only after 7 ma did these woodlands give way to more open grasslands in pakistan

vertebrate fossil bearing paleosol units willwood formation lower eocene northwest wyoming u s a implications for taphonomy biostratigraphy and assemblage analysis abstract in the lower 300 m of the fluvial willwood formation of northwest wyoming most large concentrations of vertebrate fossils consist of disarticulated and broken skeletal remains that occur in widespread tubular thin 2 cm 1 m greenish and bluish gray mudstones that are low in percentage of free iron aluminum and manganese relatively high in percentages of organic carbon and often show evidence of clay eluviation these units lie atop sesquioxide rich sometimes clay illuviated variegated unit red yellow purple and mottled variants and are relicts of the a horizons of podzolic spodosols aquods the wide distribution of bone fragments the numerical proportions of bone elements weathering of the fragments and biogenic evidence indicate the vertebrate remains accumulated gradually as litter on the surface of the soils and became incorporated into the a horizon the bones were disarticulated broken and otherwise disturbed by the action of scavengers prior to burial occurrence of abundant vertebrate remains in discrete readily identifiable and widespread paleosol units makes these units valuable biostratigraphic markers zonules faunules evidence of geologically short term lag accumulation of the bones is important to assemblage analysis the paleosol concentrations result from attritional mortalities that more closely reflect composition of the life assemblage than do remains concentrated by fluvial transport or predators

taphonomy of a late eocene microvertebrate locality wind river basin wyoming u s a abstract the taphonomic history of a late eocene micromammal assemblage badwater locality 20 wind river basin wyoming is examined using methods of data collection and analysis designed to elucidate three taphonomic processes death and initial accumulation transport and burial and postburial alteration the disarticulated fragmentary nature of the fossils and the low percentage of teeth and jaws in the taphonomic sample suggests that much of the assemblage was initially accumulated in predator scats or pellets nonpredator agents of mortality were responsible for an additional attritional component there is evidence that the bones were exposed for a short period of time before burial and that the assemblage represents a time lag soil accumulation there is no evidence either from orientation and surface characteristics of the bones or from the sediments that the fossils were hydraulically transported and deposited postburial alteration included breakage of small bones due to mechanical stress the greatest information loss occurred during initial accumulation little additional information was lost during burial or through postburial alteration this information loss primarily concerned the relative abundance structure of the mammalian community in contrast information concerning species richness appears to be only slightly altered

paleoenvironmental controls on vertebrate bearing abandoned channels in the upper carboniferous abstract a paleoenvironmental study of the vertebrate bearing sapropelic coal that underlies the upper freeport coal westphalian d upper carboniferous at linton ohio identifies a hierarchy of physical and chemical controls that influenced the formation of this deposit surface and subsurface data from previous work and field study of extensive exposures show that the fossiliferous cannel occurs at the bottom of an approximately 15 m deep abandoned river meander within a sandstone dominated multistorey sediment body storeys of this sediment body fine upward and consist of varying proportions of sandstones and siltstones within lateral accretion beds that are interpreted as point bar deposits associated channel fills are generally organic rich and composed of coals such as the linton cannel or carbonaceous mudstones maximum observed channel depth is approximately 18 m and the maximum thickness of the multistorey sediment body reaches nearly 40 m the sandstone dominated sediment body that contains the linton cannel trends northwestwardly and contrasts with mudstone dominated coarsening upward sequences that were deposited contemporaneously in adjoining areas this lithic pattern suggests that fluvial activity was restricted to a persistent topographic low that may have resulted from movement along the transylvania fault zone a previously documented basement controlled feature rapid subsidence on the southern side of this structure confined the fluvial system and favored the preservation of deposits within the meander belt including the fossil bearing sapropelic channel fill at linton the low inorganic content and oxbow like outline of the linton fossil deposit and its lateral relationship to other storeys in the multistorey channel sequence indicate that the abandoned meander was closed rapidly by neck cutoff and in the absence of clastic influx filled by sapropelic peat remains of aquatic to terrestrial animals that lived in or near the oxbow lake slowly rotted in this scavenger free anaerobic setting because of the substantial depth of the original meander and a lack of coarse grained fill materials a prolonged period of sapropelic filling insured the preservation of an abundant and diverse autochthonous vertebrate assemblage most westphalian tetrapod deposits represent sapropelic peats and muds and share some of the taphonomic attributes of the linton deposit the high degree of autochthony evidenced by westphalian vertebrate accumulations indicates that taphonomic controls of low lying peat forming alluvial and delta plain systems differ significantly from those of well drained alluvial valley settings