bluuebunny/crossref_metadata_2025 huggingface dataset:
An isotopic biogeochemical study of the Oxford Clay Formation (U.K.)
Authors: Kenig Fabien , Hayes John M. , Summons Roger
Published: January 2018

Lipids from a suite of 12 representative samples from the Lower Oxford Clay (LOC) and from the Middle and Upper Oxford Clay (MUOC) were extracted with organic solvent, separated, and analyzed qualitatively and quantitatively using gas chromatography-mass spectrometry (GC-MS) and isotopically using isotope-ratio-monitoring gas chromatography-mass spectrometry (irmGCMS). Determination of molecular structures allowed identification of compounds which retained enough chemical structural information to be recognizable as having a biochemical origin related to a specific organism or group of organisms (biomarkers). By allowing assignment of each compound to a portion of the local carbon cycle (production, sedimentation, and alteration), isotopic analyses of individual compounds provided further information regarding their origins. The 12 samples were chosen to represent the various macrofaunal assemblages define by Duff (1975) and to cover the total range of variability of the bulk geochemical parameters measured on sediments from LOC and MUOC (Kenig et al., this symposium).

A relatively high content of unsaturated hydrocarbons, as well as the abundance of biogenic forms of molecular stereoisomers such as ββ hopanes and ααα steranes and other molecular indicators, confirms the low level of maturity of organic matter in the LOC. Contributions from the two main sources of sedimentary organic matter already identified from bulk geochemical data, marine phytoplankton and terrestrial organic matter, can be recognized in the saturated hydrocarbon fraction of all the samples analyzed. However, contributions from these two sources vary as a function of the TOC content, the HI, and the δ13C of organic matter. Saturated hydrocarbon fractions of high-TOC samples, formed during periods of high marine productivity, are mainly dominated by pristane and phytane and by tetra- and pentacyclic biomarkers. This dominance decreases with the TOC content and the 13C abundance. Conversely, the relative abundance of compounds indicative of terrigenous input increases. In samples with lower TOC, n-alkanes with a strong odd-carbon preference, peaking at C27, are particularly prominent in the saturated hydrocarbon fraction.

Biosynthetic products with n-alkyl carbon skeletons are found in nearly all organisms. Accordingly, sedimentary n-alkanes are likely to derive from multiple sources. These can be partly distinguished by isotopic analysis of individual n-alkanes. In particular, marine and terrestrial sources can be resolved. Considering the variation of their relative abondance and of their isotopic composition as a function of TOC, δ13C of total organic matter and hydrogen index, the origins of n-alkanes, pristane and phytane as well as those of other biomarkers will be discussed. The paleobiological assemblage responsible for the production and alteration of the organic matter will be tentatively reconstructed.
Comparison of Cretaceous and Oligocene endolithic reef communities from Puerto Rico
Authors: Krumm Debra K.
Published: January 2018

The question of the response of endolithic reef communities to changes in primary framework builders that serve as hosts prompted a study to compare two different types of frameworks from two formations, one Cretaceous and the other Oligocene, from Puerto Rico. The primary framework builders from the Cretaceous Cotui Formation of western Puerto Rico are rudistid bivalves, with corals and stromatoporoids also serving as supporting organisms to a lesser extent. Both larger endolithic organisms such as lithophagid bivalves and smaller endoliths such as clionid sponges are common throughout the study area. All three framework types serve as hosts. However, actual densities of endoliths, especially the bivalves, are low per host.

Corals are the primary framework builders in the Upper Oligocene Lares Formation of northwestern Puerto Rico. In the study area, two types of coral frameworks were observed. The main reef was composed of massive coral heads, while facies interpreted as lower-energy patch reef and lagoonal environments were comprised of more delicate branching poritid-like corals. Oysters were common in both facies. Few larger endoliths were found in the branching coral. By contrast, boring bivalves including lithophagids, occurred in high densities in many of the massive coral heads. Some of the oysters were riddled by clionids.

The comparison revealed that while the composition of the two endolithic communities was similar, the abundances and differences in density of the individual endolithic organisms was markedly different. This is attributed primarily to differences in the host substrates themselves. Hosts were abundant in both the Cotui and the Lares. However, the exoskeletons of rudistids differ considerably from corals, as do stromatoporoids. External influences such as environment, may have had some impact as well.
Paleobiogeographic significance of Famennian echinoderm faunas from northwestern China
Authors: Maples C.G. , Waters J.A. , Lane N.G. , Hong-Fei Hou
Published: January 2018

A diverse (>200 specimens representing more than 20 taxa) Famennian echinoderm fauna has been collected from the Hongguleleng Formation, Junggar Basin, Xinjiang, Uygur Autonomous Region, Peoples Republic of China. Famennian faunas are relatively poorly known on a global basis, Famennian echinoderm faunas in general are very poorly known, and echinoderm faunas of any age from China are virtually unstudied. Echinoderms are highly endemic, which makes them relatively poor for global biostratigraphy, but excellent for use in biogeographic studies. Because Frasnian and Famennian faunas are noted for their general lack of endemism, echinoderms may be critical, sensitive indicators of Famennian biogeographic provinces. Preliminary analysis indicates that this Chinese Famennian echinoderm fauna is dominated by blastoids and inadunate, small-calyx camerate, and flexible crinoids, many of which show morphological characters that are intermediate in nature at higher classificatory levels between older Devonian and younger Carboniferous taxa. The taxonomic composition of this fauna clearly indicates that diversification and re-radiation in the aftermath of the Frasnian-Famennian extinction event was well underway before the close of the Famennian. The most similar faunas are from Famennian rocks of England and, possibly, Germany. Brachiopods, corals, and trilobites of this age also show similarities between northwestern China and western Europe. These two areas were high latitudinal and tropical, respectively, during deposition, therefore their similar composition may represent latitudinal contraction associated with global cooling or a nearshore migratory pathway between the two areas via Kazahkstan and Poland.
Biological and evolutionary responses to transgressive-regressive cycles
Authors: McGhee George R.
Published: January 2018

Transgressive-regressive cycles involve environmental change and therefore, under the predictions of the theory of natural selection, biological response is expected. The nature, magnitude, and instrumentation of that response is, however, less well understood and difficult to predict. Generally the magnitude of biological response would be expected to be a direct function of the magnitude of the environmental change produced by alterations in sea level. However, this may not be the case. Moreover, the magnitude of environmental perturbation seen may itself not be a direct function of the magnitude, range, or even rate of sea level rise or fall.

Biological responses to transgressive-regressive cycles are highly variable, yet may be empirically demonstrated. Although the reality of faunal changes can be observed, the precise forcing mechanism or mechanisms driving those changes may be hypothetical at best. The observed iterative morphological series seen in shallow water Jurassic ammonites, for example, appear to be produced by a complex interplay of species adaptation to changes in local habitat and response to immigration from oceanic realms, both of which are ultimately driven by relative sea level. Likewise, changes in diversity and species composition in Devonian shallow marine communities appear to be produced by the effect of variable sedimentation rates and shifts in the oxygen minimum zone, both of which also are related to changes in relative sea level.

Published onlap-offlap sequence curves, as such, may offer very little to the paleobiologist interested in the evolutionary behavior of marine organisms. Additional geographic and areal data are required if any rigorous quantitative relationship between relative sea level and evolutionary biology is to be formulated. In the Devonian, for example, it can be demonstrated that a total lack of correlation exists between the evolutionary biology of major benthic marine organisms (brachiopods) and relative sea level as projected from onlap-offlap curves. It could be hypothesized that the rate of change of sea level is more important to organisms than relative sea level itself, though most hypotheses concerning the biological effect of sea level are explicitly framed in terms of relative sea level (usually invoking the species-area effect). Again, onlap-offlap curves alone offer little in testing such a rate hypothesis, as it can also be demonstrated that no correlation exists between the derivative of the Devonian relative sea level curve and the evolutionary biology of the Brachiopoda.
Onshore-offshore patterns during the Ordovician radiations: a worldwide assessment
Authors: Miller Arnold I.
Published: January 2018

To understand the evolutionary significance of apparent temporal trends in global biotic diversity, it is important to delve beneath the umbrella of synoptic, global-scale compilations. Specifically, when evaluating a measurable increase or decrease on a global diversity curve, we must determine whether it reflects a transition that was truly global in scope and space-transcendent, or, alternatively, whether it is the manifestation of change associated with particular geographic or environmental regime(s).

Previous analyses of the Ordovician faunal radiations have suggested that an onshore-offshore environmental overprint was associated with the diversity increase: trilobite-dominated biotas, which were ubiquitous during the Cambrian, became progressively restricted to deepwater through the Ordovician as diversifying, articulate brachipod-dominated faunas came to dominate shallower, open marine settings. At the same time, a less rapid proliferation of mollusc-rich biotas enabled them to become particularly diverse in nearshore settings. Additional analyses of diversification conducted for post-Paleozoic biotas have yielded onshore-offshore signals associated with diversification of a variety of taxa, suggesting the existence of a general evolutionary pattern associated with marine diversification that transcends taxonomy and time.

However, to date, evaluations of Ordovician onshore-offshore patterns have been based on data limited primarily to North America, and, thus, to the Paleozoic continent of Laurentia. Thus, it is reasonable to ask whether this pattern was unique to Laurentia, or whether diversification proceeded similarly in Ordovician seas around the world.

To analyze possible patterns of environmental and geographic selectivity associated with episodes of Ordovician diversification and extinction, I am currently compiling a database on the paleogeographic and paleoenvironmental distributions of Ordovician genera. Although this compilation is still in its infancy, preliminary analyses suggest that, in aggregate, paleoenvironmental patterns exhibited elsewhere are comparable to those recognized for Laurentia. However, the data remain scanty for many parts of the world; as the database grows, a province-by-province analysis of diversification patterns will be conducted. This analysis will not only permit determination of the degree to which onshore-onshore patterns transcended paleogeographic boundaries, but, more generally, will enable exploration of the relationship between local diversity trends and global-scale trends already documented for the Ordovician with synoptic data.
Actuopaleontological investigations of shallow water Red Sea echinoids
Authors: Nebelsick James H.
Published: January 2018

The regular and irregular echinoid fauna of the Northern Bay of Safaga (Red Sea, Egypt) has been investigated within the framework of an actuopaleontological study of the flora, fauna, sediments and facies. The distribution of echinoids has been compared to grain size parameters as well as to the distribution of other organisms.

The study area (ca. 10 × 7 km) was investigated using SCUBA-diving techniques along 55 transects with a total length of 126 km. Echinoid presence was quantified using weights of fragments (2 mm) originating from 67 standardized bulk samples distributed throughout the Bay. The complex morphology of the echinoid test and the spines allow the identification of fragmented material upon comparison to complete specimens. The resulting data was analyzed using correlation techniques as well as Q and R-mode multivariate statistical analysis. This method counters the difficulties originating from the cryptic habitats and patchy distributions.

The results of the analysis show that echinoid distribution can be analyzed for both regular and irregular wchinoid taxa despite taphonomic bias and restrictions imposed by the analytic method. Time averaging in fact counters the difficulties arising from the patchy distributions of echinoids. There is a close correlation of echinoid distribution to sedimentary and bottom facies as well as to grain size parameters and other environmental factors. The distribution of irregular echinoids is highly differentiated with coarse coastal sand dominated by Clypeaster sp., Echinodiscus auritus, Fibularia ovulum, and Lovenia elongata; muddy sands by Laganum depressum, Clypeaster sp. and Echinocyamus crispus; and muds by members of the Schizasteridae. Regular echinoids, mostly Eucidaris metularia, Echinometra mathaei, Tripneustes gratilla, Heterocentrotus mammillatus and Diadema setosum, dominate the sediments found within, or near reefs, coral carpets and patch reefs.

The methodology used in this actuopaleontological investigation should be useful in recognizing the distribution patterns of ancient echinoid faunas, especially in light of the significance of regular echinoids in the bioerosion of reefs and irregular echinoids in the bioturbation of sediments.
Palaeontology and palaeoecology of the Lower Cambrian Emu Bay Shale Lagerstätten, Kangaroo Island, South Australia
Authors: Nedin Christopher
Published: January 2018

The last two decades have seen the status of deposits containing soft bodied Cambrian fossils rise from geological curios into one of the foundations of modern thinking on early metazoan evolution and ecology. Some thirty of these soft bodied assemblages or Lagerstätten, resembling the Burgess Shale fauna are now known. One of these is the Lower Cambrian Emu Bay Shale fauna from Kangaroo Island, South Australia.

The Emu Bay Shale has been mapped in two localities approx. 8 km (5 miles) apart on the northern coast of Kangaroo Island, at Emu Bay and at Big Gully. Previous investigations into the numerically abundant Lagerstätten fauna at Big Gully have highlighted its unusually pauperate diversity, with only some seven species described. The preservation is also unusual, comprising replacement by iron stained calcite. The fauna is confined to a 10 m thick basal siltstone. The age of the deposit is believed to be mid to upper Botomian and is thus marginally older than Early Cambrian soft bodied assemblages found on the North American continent and predating the better known Middle Cambrian Burgess Shale.

In late 1991, a study of the Emu Bay Shale was undertaken to document the palaeontology and palaeoecology of the fauna. Preliminary findings, whilst increasing the number of species, confirm the pauperate diversity of the fauna. The new forms include several specimens of anomalocarid appendages. These not only represent the first occurrence of this form in Australia, but also the first occurrence outside the Burgess Shale of anomalocarid appendages with 11 segments, as compared with the more common and widespread 14 segment appendages. This connection may be important in the light of recent palaeoreconstructions which show the west coast of Canada and eastern Australia in close proximity during the early Cambrian. Also the spatial arrangement of the appendages indicates that anomalocarids may have shoaled and hunted in groups. They appear to have fed on the sea bottom, possibly using their appendages to probe the muddy bottom for shallowly buried prey as well as for capturing and transporting prey to the mouth.

The assemblage appears to be dominated by the preservation of hard or permineralized body parts. However, abundant calcified ribbon-like structures concentrated on some bedding planes have yet to be classified. Several exceptionally preserved specimens of Myoscolex appear to have a series of metamerically repeated ‘paddle-like’ appendages, similar to some forms from the Burgess Shale, thus casting doubt on an annelid affinity.

The assemblage appears representative of a deep water, low oxygen environment prone to periodic anoxia, possibly similar to the accretionary environment of the Burgess Shale.

The Emu Bay Shale at Emu Bay exhibits a shelly assemblage, mostly comprised of disarticulated Hsuaspis exuvia with occasional small Redlichia exuvia and hyolithids. No calcite replacement is evident. The location represents current swept, probably shallow water environment.
A gradual morphological transition during a rapid speciation event in marginellid gastropods (Neogene; Dominican Republic)
Authors: Nehm Ross H. , Geary Dana H.
Published: January 2018

Paleontological studies can bring to light two important aspects of the speciation process: long term patterns of morphological change, and the paleoenvironmental context of such changes. We examined the temporal patterns of morphological change and their geographic and paleoenvironmental context in species of Prunum (Marginellidae; Gastropoda) from the Neogene of the northern Dominican Republic. We document a speciation event from P. coniforme (Sowerby 1849) to P. christineladdae (Maury 1917) which is unusual in both its temporal expression, and in the relative clarity of the ecological setting for speciation.

We believe that the changes in morphology from P. coniforme to P. christineladdae represent a speciation event. The two species are distinguished by several shell features, including overall shape, spire height, relative height of the top of the lip, and apertural denticulations. The nature and magnitude of these differences, compared with morphological differences among extant species of Prunum, indicate that separate species designations are warranted for P. coniforme and P. christineladdae. A sequence of stratigraphic and morphological intermediates between these species provides strong stratophenetic evidence for speciation.

The stratigraphic interval characterized by intermediate morphologies includes approximately 22 m of section. Sedimentation rates yield estimates of approximately 73,000–275,000 years for our interval of morphologic change. This transitional interval represents between 0.6–2.5 % of the total duration of the ancestral species.

The patterns of morphological change exhibited by the two species generally fit the predictions of punctuated equilibrium; change from ancestor to descendent is relatively rapid, outside the transitional interval species exhibit no directional morphologic trends, and the ancestral species persists after speciation.

Our data reveal some information on the mode of speciation. Prunum species from our study area exhibit well-defined depth ranges. P. christineladdae occurs only in deep water deposits, whereas P. coniforme is common in shallow water deposits. Based on distributional data, we suggest that depth, or one or more of its associated variables, was critical to the isolation and evolution of P. christineladdae.
Shell matrix proteins - a potential tool for investigating the phylogenetic relationships of the Echinodermata
Authors: Polson Emma S. , Lawrence J. , Robbins L. L.
Published: January 2018

The phylogenetic relationships of the echinoderms remains controversial due to the traditional use of morphological characters which do not reflect convergent evolution. While biochemical techniques and DNA analysis may be used in addition to morphological characters for analysis of living echinoderms, these tools cannot be extended to fossils. Shell matrix proteins - of echinoderms may be trapped and preserved for millions of years in fossil genera.

Analysis of shell matrix protein from Astropectin irregularis, Luidia clathrata and Mellita tenuis, reveal the presence of at least three major proteins of approximate molecular weights 230, 83 and 17 kDa common to all species. Astropectin irregularis showed four additional major bands of molecular weights 150, 90, 52 and 35 kDa along with at least 12 minor bands. Luidia clathrata showed five additional major bands of molecular weights 99, 60, 40, 24 and 21 kDa and at least 13 other minor bands. Mellita tenuis showed three additional bands of molecular weights 115, 96, and 24 kDa along with at least 4 minor bands.

As the three common proteins have been found in both seastars (A. irregularis and L. clathrata) and echinoids (Mellita tenuis), further analysis of these shell matrix proteins may be used to elucidate phylogenetic relationships within the Echinodermata. In addition homoplasies may be identified and phylogenetically reassessed.
The evolution of gastropod shell form: a developmental model illustrating the roles of heterochrony and non-heterochronic changes
Authors: Rice Sean H.
Published: January 2018

The shape of an isometric gastropod shell can be described completely by specifying the pattern of shell secretion around the aperture (relative to aperture size) and the growth rate of the aperture itself. These descriptors provide a “natural” morphometric in that they correspond to the specific biological processes involved in constructing the shell.

Describing shell form in this way allows us to specify what developmental changes must occur during the transition of one shell form to another. In particular, we can distinguish between transitions that can occur through purely heterochronic processes (changes in growth rate) and those that require a change in the specific pattern in which cells of the mantle lay down shell. We can also investigate just what changes occur during the ontogeny of non-isometric shells.

Any change in either the pattern of shell secretion or the growth rate of the animal leads to changes in a number of classical morphometric measures, such as apex angle and whorl expansion rate. Those transformations resulting from changes in growth rate, however, are much more predictable than those resulting from changes in the pattern of shell production. A slight increase in the growth rate of the animal, for instance, produces a correspondingly slight increase in the apex angle and the rate of whorl expansion. By contrast, the consequences of a slight change in the pattern of shell production are highly sensitive to just how that change was achieved.

Data from 8 genera of marine snails show that the variance within each genus, relative to the variance among all genera, is smaller for measures of aperture shape (which can only be altered through a change in the pattern of secretion of shell material) than for characters that can change through heterochronic transformations (such as apex angle). Furthermore, the shell forms of a number of non isometric shells can be described by a constant pattern of shell production and a variable growth rate.

Heterochronic changes thus appear to be the preferred mechanism for changing phenotype in gastropod shells. Those characters that can only be altered by changing the pattern of shell production around the mantle, such as aperture shape, appear to be more conservative than those that can be changed through purely heterochronic transitions. This is consistent with the idea that mutations which alter many characters in a highly correlated manner have a higher probability of being favored by selection than those with relatively unpredictable consequences.
A possible archaeopriapulid trace fossil from the Middle Cambrian Stephen Formation, British Columbia
Authors: Rudkin David M.
Published: January 2018

It is generally accepted that the extraordinary preservation of fossils in the Burgess Shale is at least partly due to the exclusion of large metazoan scavengers through rapid burial in an inimical environment. Disruption of individual organisms appears to have been largely the result of mechanical processes and/or microbial decay. The absence of bioturbation through much of the classic section, including Walcott's Phyllopod Bed, supports these arguments. However, macroscopic traces are known from other horizons within the Burgess Shale section and from lateral equivalents in the Stephen Formation a short distance south of the main locality.

The sparse ichnoassemblage includes bedding-plane exposures of portions of compacted, parallel-sided burrows containing skeletal debris comprising fragmented and disarticulated hyoliths, small trilobites, and bracniopods. Walcott originally figured one such trace as Planolites sp. ? and noted, but offered no evidence for, an association with the archaeopriapulid Ottoia prolifica. This notion was subsequently rejected by Conway Morris.

A recently collected specimen, from talus south of the main locality, contains a poorly preserved but recognizable body fossil of Ottoia within the outline of a “Planolites”. Although this juxtaposition may be accidental, a number of features of the association, and a consideration of the burrowing behaviour of modern priapulids, suggest that Ottoia could have been the generator of “Planolites”-like traces.
Investigation of the terrestrial occurrence and biological source of the petroleum geochemical biomarker oleanane
Authors: Taylor David W. , Moldowan J. Michael , Hickey Leo J.
Published: January 2018

Oleanane is a triterpane that is commonly found in Late Cretaceous (Campanian) through Cenozoic marine and deltaic rocks and related oils. Based on its affinity to the β-Amyrin group of natural products and its abundance in Tertiary deltaic sediments and oils, such as in the Niger Delta, oleanane is thought to be a geochemical fossil of terrestrial flowering plants. The β-Amyrin group forms the basis of many angiosperm triterpenoids and triterpenoid saponins. These compounds appear in moderately advanced flowering plant lineages and are often used as a defense against herbivores. This group of compounds has not been reported from any other seed plant group, including conifers.

We examined a suite of middle to early Cretaceous terrestrial sediments and plant fossils for the presence of oleanane. The existence of oleanane was documented by Gas Chromatography - Mass Spectrometry (GC-MS) and confirmed with Metastable Reaction Monitoring (MRM) GC-MS.

Oleanane was identified from fossil bennettitaleans, an extinct group of seed plants. Cycadeoidea paynei and C. superba are permineralized fossil stems and are from the Early Cretaceous Inyan Kara Group of the Black Hills, SD. Oleanane was also found in carbonaceous compressed leaf fossils of Dioonites from the Barremian - early Aptian (Zone I) of the Potomac Group from Richmond, VA. This increases the number of seed plant groups known to have oleanane, and is of additional interest as the bennettitaleans are thought to be closely related to angiosperms.

Oleanane was not found in contemporaneous fossil conifers. Our sample consisted of fossil conifer wood collected from the Campanian Magothy Beds of Martha's Vineyard, MA; the Cenomanian Raritan Formation of Sayreville, NJ; and the Barremian - early Aptian Patuxent Formation of Greenbelt, MD.

Confirmed reports of oleanane have been from Late Cretaceous and younger marine sediments. We now report oleanane from Early Cretaceous terrestrial strata of the Inyan Kara Group. In addition we systematically sampled the sequence of Cretaceous terrestrial sediments of the coastal plain of the eastern U.S.A, and found oleanane in the Barremian - early Aptian (Zone I) Potomac Group. Preliminary data indicate variation in the occurrence of oleanane in contemporaneous Early Cretaceous sites from the Potomac Group. The localities accumulated in different depositional environments and the occurrence may be controlled by lithofacies.
The coccolithophore Emiliania huxleyi and global climate
Authors: Westbroek Peter
Published: January 2018

Cells of Emiliania huxleyi are surrounded by ‘coccoliths', minute, elegant scales of calcium carbonate. In all the oceans, particularly at mid-latitudes, this species forms gigantic blooms, readily visualized by satellite imagery. Coccolith-bearing organisms, of which E. huxleyi is by far the most abundant representative, are the major contributors to the ocean floor limestone sediments, and this in turn is the largest long-term sink of inorganic carbon on earth. In addition, E. huxleyi blooms emit vast amounts of dimethyl-sulphide (DMS), a gas which, on oxidation, is a dominant source of cloud nuclei. The profusion of E. huxleyi and its intimate involvement with the global biogeochemical cycles of both carbon and sulphur make it a key component of the greenhouse effect (CO2), natural acid rain and albedo regulation.

E. huxleyi blooms are often almost monospecific. They can be visualized by satellite imagery and leave highly characteristic skeletal and macromolecular markers which accumulate on the deep-sea floor as a long-term record of their history. The organism is easily cultured in the laboratory and molecular genetical, biochemical and physiological studies are underway.

We focus on Emiliania huxleyi as a model organism to study interactions between oceanic plankton and climate. Benefits of this approach are: (1) to highlight the idiosyncratic non-linear character of these interactions; (2) to reveal the intimate coupling of the oceanic carbon cycle and DMS productivity; and (3) to allow an integrated modelling and experimental approach, integrating multi-disciplinary studies that range from the global down to the macromolecular level and through geological time. E. huxleyi coccoliths and specific biomarkers preserved in the geological archive not only provide information on the distribution of this organism in the geological past. The connection with extensive neontological research offers a unique opportunity to reconstruct the development of the entire E. huxleyi system, including its multifarious climatic interactions, through geological time.

The ‘Global Emiliania Modeling Initiative’ (GEM), started in 1990, is a European research program intended to investigate and model the Emiliania huxleyi system.
Declining importance of trilobites in Ordovician nearshore communities: displacement or dilution?
Authors: Westrop Stephen R. , Tremblay James V. , Landing Ed
Published: January 2018

Declining importance of trilobites was a key feature of Ordovician community “evolution”. Previous work has shown that replacement of trilobite-dominated communities by mollusc- and brachiopod-dominated communities was diachronous, occurring initially in nearshore settings. The processes responsible for these changes remain unclear, although many previous discussions have invoked some form of displacement of dominants of one community by those of another.

New data from more than thirty large collections made from nearshore facies at five localities in Canada and the northern United States indicate that, in this setting, trilobite species diversity maintained a constant low level (mean and mode of 3 species) between the Early Upper Cambrian (Marjuman) and the Late Middle Ordovician (Blackriveran). Reorganization of nearshore communites proceeded by addition of new elements, especially molluscs, from the Late Cambrian (Sunwaptan) onwards. Decline in the relative importance of trilobites was a case of dilution as species of new clades accumulated, rather than actual displacement. Trilobites appear to have been passive bystanders in Ordovician nearshore community “evolution”. Towards the end of the Ordovician, trilobites vacated nearshore environments in the Appalachian region. However, this appears to be related to environmental changes associated with progradation of clastic wedges during the development of the Taconic foreland basin.

A process of dilution may at least partly explain the offshore retreat of trilobite-dominated assemblages during the Ordovician. Offshore trilobite assemblages reached much greater species diversity than those of nearshore settings, so that their dilution via the addition of species of newly radiating clades would have proceeded more slowly. That is, trilobite-dominated paleocommunities may have persisted into the Ordovician in the outer shelf simply because this was the region in which, historically, they attained maximum species richness. Moreover, given the existence of a general pattern of increasing total species diversity of communities from nearshore to offshore sites, the tendency for newly radiating clades to attain maximum species richness offshore is not surprising: they are merely conforming to a general, environmentally-related diversity gradient that has existed throughout the Phanerozoic.
Evolutionary trends in lithophagic vertebrates
Authors: Whittle Christopher
Published: January 2018

All classes of extant vertebrates have lithophagic species. The debate about why animals eat stones has quietly raged for over a century. Except for a documented physiological need in a few Recent bird and fish species, few can agree why they are ingested, but they have figured in scientific literature since the 1600s. Gastroliths have been used as stratigraphic indicators for geologists. They have been used as clues to biomechanics and feeding behavior for biologists. The presence of gastroliths in primitive archosauromorphs dates to the Jurassic mesosuchia and can be traced to Recent euschia. Gastroliths found in sauropodomorphs and ornithischians have been alleged to indicate higher levels of metabolic processes. Two large groups of sauropterygians, the younginoids and the plesiosaurs are rarely found without a clutch of stones with their skeletons. Gastroliths have been discovered in Permian and Triassic amphibians, Miocene and Recent pinnipeds, and many Recent reptiles. The presence of gastroliths in a fossil specimen is an important indicator of ontogenetic and phylogenetic characteristics that should be considered in tandem with the associated osteological material.
Paleocene-Eocene floral and climatic change in the Bighorn Basin
Authors: Wing Scott L. , Hickey Leo J.
Published: January 2018

Nearly autochthonous plant fossil assemblages are abundant in a variety of fluvial sub-environments in the Fort Union and Willwood Fms. of the Bighorn Basin (BHB), including abandoned channel fills, channel margins, levees, splays, and floodplain backswamps. Heterogeneity in the stratigraphic and geographic distribution of plant-bearing deposits limits our ability to resolve temporal change in floras and climate because depositional environment strongly affects floral composition, and must be considered in any analysis of floral change.

Plant-bearing levee, splay, and backswamp strata are common through much of the Fort Union Fm. in both the central and northern BHB. In the central basin, such deposits are abundant in the lower 200 m and upper 150 m of the Willwood Fm. with a gap from 350 to 620 m. In the northern BHB, the Willwood Fm. is almost entirely devoid of such plant-bearing deposits. Abandoned channel fills are scattered throughout the Fort Union and Willwood Fms. with the exception of the upper Willwood in the northern BHB and the 460-620 m interval of the Willwood in the central BHB. Deposition of plant-bearing floodplain backswamps was probably controlled by rates of aggradation, and the proximity and stability of major channels, as well as by regional climatic change. The formation of plant-preserving ponds was probably controlled less by climate than by the rate of channel cut-off and the degree to which channels reworked previous floodplain deposits. At a larger scale than these local depositional settings are sub-regional scale environments, including coal swamps, lakes, and conglomerate fans, that have a stratigraphic distribution controlled largely by tectonic activity.

Samples of fossil floras matched for depositional environment and sampling effort reveal several long-term patterns. One, the greatest number of species and fastest rate of turnover are seen in the alluvial ridge environments; backswamp samples have fewer species and slower rates of turnover. Two, floristic change during the Paleocene was relatively slow, and the Paleocene/Eocene (Clarkforkian/Wasatchian) boundary is marked by just a few extinctions and originations. The most pronounced turnover in the BHB sequence occurred between the early and late Wasatchian, probably as a result of climatic drying. Three, species number decreased from the early to mid-Paleocene, then increased steadily from 8 spp./sample in the late Clarkforkian to >12 spp./sample in the late Wasatchian.

Physiognomic analysis of floras indicates a rise in mean annual temperature from about 10° C in the Tiffanian to about 13° in the Clarkforkian and more than 18° in the early late Wasatchian; this may have been a major factor in the increasing diversity of the flora. Recent correlations of Bighorn Basin sections to standard marine zonations show that this warming trend was synchronous with global warming indicated by the oxygen isotope record.
Biology and functional morphology of Cloudina, the earliest known metazoan with a mineralized skeleton
Authors: Yue Zhao , Bengtson Stefan , Grant Stephen W.F.
Published: January 2018

The earliest known skeletal metazoan, Cloudina, was widespread in the late Neoproterozoic. We report here on phosphatized specimens of Cloudina sp. from dolomites of the Dengying Formation, 30 m below the first Cambrian skeletal fauna, in the Lijiagou section, Shaanxi Province, China. The specimens exhibit new details of shell morphology and fine structure that offer insights concerning the mechanism of shell accretion and the selective pressures influencing skeletogenesis in metazaons.

Cloudina formed curved to sinous tubular shells 0.2-8 mm in diameter and up to 4 cm in length. They consist of numerous thin (5-10 μm) calcareous layers, each in the form of a slightly flaring tube. New layers were deposited above and to one side of the previous layer, giving rise to a series of eccentrically nested shell laminae. Some of the phosphatized layers exhibit tight folding or wrinkling that may have been primary (imparting additional strength) or secondary (related to plastic deformation of organic-rich shell material). Pore space existed between terminal thin flanges, but concentric ridges may have served to strengthen the free standing portions of shell layers. SEM and cathodoluminescence of polished thin sections also reveal that each shell layer may itself have been constructed of an organized layering of organic matrix and carbonate, suggesting a fairly sophisticated biologic control over shell formation. The presence of circular holes, the size of which correlates positively with tube diameter, moreover, strongly suggests that one function of the shell was to protect the Cloudina organism from predatorial and/or parasitic attack.

The taxonomic status of Cloudina remains problematic. Rare specimens of the Lijiagou Cloudina which show two younger tubes growing within an older single tube suggest that the organism was capable of asexual reproduction by longitudinal fission. Such a latent tendency is not compatible with previously proposed affinities with polychaete worms.
Remarkably High Hole Mobility Metal-Oxide Thin-Film Transistors
Authors: Shih Cheng Wei , Chin Albert , Lu Chun Fu , Su Wei Fang
Published: January 2018

High performance p-type thin-film transistor (p-TFT) was realized by a simple process of reactive sputtering from a tin (Sn) target under oxygen ambient, where remarkably high field-effect mobility (μ
FE
) of 7.6 cm2/Vs, 140 mV/dec subthreshold slope, and 3 × 104 on-current/off-current were measured. In sharp contrast, the SnO formed by direct sputtering from a SnO target showed much degraded μ
FE
, because of the limited low process temperature of SnO and sputtering damage. From the first principle quantum-mechanical calculation, the high hole μ
FE
of SnO p-TFT is due to its considerably unique merit of the small effective mass and single hole band without the heavy hole band. The high performance p-TFTs are the enabling technology for future ultra-low-power complementary-logic circuits on display and three-dimensional brain-mimicking integrated circuits.
The MICALs are a Family of F-actin Dismantling Oxidoreductases Conserved from Drosophila to Humans
Authors: Wu Heng , Yesilyurt Hunkar Gizem , Yoon Jimok , Terman Jonathan R.
Published: January 2018

Cellular form and function – and thus normal development and physiology – are specified via proteins that control the organization and dynamic properties of the actin cytoskeleton. Using the Drosophila model, we have recently identified an unusual actin regulatory enzyme, Mical, which is directly activated by F-actin to selectively post-translationally oxidize and destabilize filaments – regulating numerous cellular behaviors. Mical proteins are also present in mammals, but their actin regulatory properties, including comparisons among different family members, remain poorly defined. We now find that each human MICAL family member, MICAL-1, MICAL-2, and MICAL-3, directly induces F-actin dismantling and controls F-actin-mediated cellular remodeling. Specifically, each human MICAL selectively associates with F-actin, which directly induces MICALs catalytic activity. We also find that each human MICAL uses an NADPH-dependent Redox activity to post-translationally oxidize actin’s methionine (M) M44/M47 residues, directly dismantling filaments and limiting new polymerization. Genetic experiments also demonstrate that each human MICAL drives F-actin disassemblyin vivo, reshaping cells and their membranous extensions. Our results go on to reveal that MsrB/SelR reductase enzymes counteract each MICAL’s effect on F-actinin vitroandin vivo. Collectively, our results therefore define the MICALs as an important phylogenetically-conserved family of catalytically-acting F-actin disassembly factors.
The hidden cost of using low-resolution concentration data in the estimation of NH3 dry deposition fluxes
Authors: Schrader Frederik , Schaap Martijn , Zöll Undine , Kranenburg Richard , Brümmer Christian
Published: January 2018

Long-term monitoring stations for atmospheric pollutants are often equipped with low-resolution concentration samplers. In this study, we analyse the errors associated with using monthly average ammonia concentrations as input variables for bidirectional biosphere-atmosphere exchange models, which are commonly used to estimate dry deposition fluxes. Previous studies often failed to account for a potential correlation between ammonia exchange velocities and ambient concentrations. We formally derive the exact magnitude of these errors from statistical considerations and propose a correction scheme based on parallel measurements using high-frequency analysers. In case studies using both modelled and measured ammonia concentrations and micrometeorological drivers from sites with varying pollution levels, we were able to substantially reduce bias in the predicted ammonia fluxes. Neglecting to account for these errors can, in some cases, lead to significantly biased deposition estimates compared to using high-frequency instrumentation or corrected averaging strategies. Our study presents a first step towards a unified correction scheme for data from nation-wide air pollutant monitoring networks to be used in chemical transport and air quality models.
Targeting murine leukemic stem cells by antibody functionalized mesoporous silica nanoparticles
Authors: Mandal Tamoghna , Beck Michaela , Kirsten Nicole , Lindén Mika , Buske Christian
Published: January 2018

Acute leukemia is initiated and maintained by leukemia stem cells (LSCs) and therefore there is great interest to develop innovative therapeutic approaches which target LSCs. Here we show that mesoporous silica nanoparticles (MSNs) functionalized with succinic anhydride, tagged with an anti-B220 antibody and loaded with the anthracycline daunorubicin are efficiently incorporated into murine B220-positive AML LSCs and preferentially kill these cells in comparison to B220-negative AML LSCs in vitro. Furthermore, short – term treatment of the AML LSCs with these MSNs before transplant significantly delayed leukemia development in recipient mice. These data demonstrate that targeting of AML LSCs can be improved by using functionalized and antigen directed MSNs as carriers for anti-leukemic drugs.
Cooper Pairing in A Doped 2D Antiferromagnet with Spin-Orbit Coupling
Authors: Zhao Jingxiang , Gu Qiang
Published: January 2018

We study the two-dimensional Hubbard model with the Rashba type spin-orbit coupling within and beyond the mean-field theory. The antiferromagnetic ground state for the model at half-filling and the Cooper pairing induced by antiferromagnetic spin fluctuations near half-filling are examined based on the random-phase approximation. We show that the antiferromagnetic order is suppressed and the magnetic susceptibility turns out to be anisotropic in the presence of the spin-orbit coupling. Energy spectrums of transverse spin fluctuations are obtained and the effective interactions between holes mediated by antiferromagnetic spin fluctuations are deduced in the case of low hole doping. It seems that the spin-orbit coupling tends to form s+p-wave Cooper pairs, while the s+d-wave pairing is dominant when the spin-orbit coupling is absent.
Association of S100B polymorphisms and serum S100B with risk of ischemic stroke in a Chinese population
Authors: Lu Yu-Lan , Wang Rong , Huang Hua-Tuo , Qin Hai-Mei , Liu Chun-Hong , Xiang Yang , Wang Chun-Fang , Luo Hong-Cheng , Wang Jun-Li , Lan Yan , Wei Ye-Sheng
Published: January 2018

The levels of serum S100B were elevated in patients with ischemic stroke (IS), which may be a novel biomarker for diagnosing IS. The aim of this study was to investigate the association of S100B polymorphisms and serum S100B with IS risk. We genotyped the S100B polymorphisms rs9722, rs9984765, rs2839356, rs1051169 and rs2186358 in 396 IS patients and 398 controls using polymerase chain reaction-single base extension (SBE-PCR). Serum S100B levels were measured by enzyme-linked immunosorbent assay (ELISA). Rs9722 was associated with an increased risk of IS (AA vs. GG: adjusted OR = 2.172, 95% CI, 1.175–4.014, P = 0.013; dominant: adjusted OR = 1.507, 95% CI, 1.071–2.123, P = 0.019; recessive: adjusted OR = 1.846, 95% CI, 1.025–3.323, P = 0.041; additive: adjusted OR=1.371, 95% CI, 1.109-1.694, P = 0.003). The A-C-C-C-A haplotype was associated with an increased risk of IS (OR = 1.325, 95% CI, 1.035–1.696, P = 0.025). In addition, individuals carrying the rs9722 GA/AA genotypes had a higher serum S100B compared with the rs9722 GG genotype in IS patients (P = 0.018). Our results suggest that the S100B gene rs9722 polymorphism may contribute to the susceptibility of IS, probably by promoting the expression of serum S100B.