Description: Publication date: 15 January 2015 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 418 Author(s): Ashu Khosla , Karen Chin , Habib Alimohammadin , Debi Dutta A rich microbiota with distinctive plant fossils has been discovered in Type A morphotype coprolites from the Lameta Formation of Pisdura, in Maharashtra, India. Macerated fractions examined with scanning electron microscopy revealed seven ostracod taxa, ( ?Mongolianella sp., Cypridea ( Pseudocypridina ) sp., Cypridopsis sp., Eucypris sp., Gomphocythere sp., Gomphocythere paucisulcatus , and Paracypretta sp.), diatoms ( Aulacoseira sp.), a charophyte ( Microchara sp.), and sponge spicules. Abundant probable chrysophytes were also observed in thin sections of one of the coprolites. Most of the plant debris is unidentifiable, but recognizable tissues include gymnosperm tissues, a spore, cuticle, and leaf laminae replaced with silica. Chemical analyses reveal that the coprolites are phosphatic, with ~ 12.2 to 16.2 wt.% phosphorus. The microfossils support a Maastrichtian age and fluvio-lacustrine depositional conditions for the Lameta Formation at Pisdura. The unusual combination of a phosphatic composition with plant and microfossil dietary residues suggests that the ancient faecal producers were intentional or inadvertent omnivores.

Description: Publication date: 15 January 2015 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 418 Author(s): Mariana Brea , Analía E. Artabe , Juan R. Franzese , Alejandro F. Zucol , Luis A. Spalletti , Eduardo M. Morel , Gonzalo D. Veiga , Daniel G. Ganuza This research focuses on the three-dimensional reconstruction of an in situ forest based on fossil wood assemblages recovered in the Rancahué Formation (Upper Oligocene), Neuquén, Argentina. Atherospermataceae, Lauraceae, Nothofagaceae, Eucryphiaceae, Cunoniaceae and Myrtaceae specimens are described. The mapping of a forest floor section and in situ tree diameters enabled the estimation of the following palaeoecological quantitative data: tree density, dominance, basal area, biomass, diametric classes, canopy height, and age classes. Palaeoclimatical data was determined on the basis of physiognomic anatomical features using multivariate anatomical analyses. These results were compared with other proxies including Carlquist's index, Coexistence Approach (CA), Nearest Living Relatives (NLRs), and growth-rings analyses. The structural data from the Aluminé forest inferred from these analyses includes: tree density of 463–701 trees/ha, mean height of 15.22 m, dominance of the genus Nothofagoxylon (89.66 m 2 /ha), total basal area of 158.20 m 2 /ha, biomass between 43 and 712 tn/ha and mean age of 223 years (specimens between 31 and 700 years old). These results are comparable to those of mature low-to-middle altitude extant forests dominated by Nothofagus and developed under humid-temperate conditions. Based on the NLRs method, the Aluminé forest has a floristic composition similar to the present-day Valdivian forest. The persistence of Nothofagus as the dominant element in temperate rainforests correlates with regimes where large-scale disturbances, such as volcanism and earthquakes are prevalent. The fossil taxa are closely related to the extant Laurelia , Persea , Eucryphia , Nothofagus , Weinmannia , Myrceugenia and Luma . The forest shows intermixed deciduous and evergreen elements, and taxa with shade-intolerance and intermediate shade tolerance. Also, the majority of these taxa need soils with available water. The integrated analysis of multiple sets of proxy data suggests that the late Oligocene forest grew under temperate and humid climate, while the eco-anatomical features and sedimentary data provide information about the environmental stress conditions of its development and the violent causes of burial. Graphical abstract

Description: Publication date: 15 January 2015 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 418 Author(s): Yanling Li , Mengna Liao , Rong Chen , Ji Shen Lake Jingpo is located in Ning'an County, Southeast Heilongjiang Province, northeast China and is strongly influenced by the East Asian monsoon system. Diatom analysis of the last 5000 cal. yr BP according to the results of AMS 14 C dating provides a detailed history of paleoenvironment changes. The relative abundance of diatom species, Asterionella formosa , Aulacoseira , Cyclostephanos , Stephanodiscus and Discostella species can be used as a proxy of spring wind speed, which is supported by the results of seasonal diatom and reviews of literature on the autoecologies of these species. In the sediment, high relative abundance of A. formosa , Aulacoseira species indicates high wind-driven turbulence of the water column. The diatom record of the past 5000 years shows that the spring wind speed shifted from weak to strong to weak. In our result, the relative abundance of Aulacoseira species decreased sharply, while that of small-cell Cyclotella sensu lato (including Stephanodiscus , Cyclostephanos and Discostella ) increased since 2000 cal. yr BP. The broad alternations between these species are probably keyed to mean temperature and wind variations that control lake circulation and stratification. Our results support the hypotheses that abiotic drivers affect the size structure of planktonic communities and that a warmer climate favors small-sized diatom cells. The change in the ratio of A. formosa and Aulacoseira species to Cyclostephanos , Stephanodiscus and Discostella species (AA/SC) basically correspond to change of the spring insolation (May) at 45°N. Abundance of diatoms in Lake Jingpo roughly corresponds to changes in the Mid- to Low-Latitude Circulation Index of the northern hemisphere as indicated by NH 4 + concentration from the GISP2 ice-core, the strength of the Asian summer monsoon as recorded from Hani Peat in Northeastern China, and from a stalagmite found in the Dongge cave in southern China. The results are important in demonstrating the sensitivity of diatoms to climate change, and providing proxy evidence for spring wind speed marked by shifts of diatom type.

Description: Publication date: 15 January 2015 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 418 Author(s): B. Ausín , J.-A. Flores , F.-J. Sierro , M.-A. Bárcena , I. Hernández-Almeida , G. Francés , E. Gutiérrez-Arnillas , B. Martrat , J.O. Grimalt , I. Cacho Coccolithophore productivity and surface water dynamics for the last 25 kyr in the Alboran Sea (Western Mediterranean) are described in a study of high-resolution sedimentary records from two cores, HER-GC-T1 and CEUTA10PC08, whose locations are currently characterized by different hydrographic conditions. Fossil coccolithophore assemblages and oxygen isotopes and alkenone- and planktonic foraminifera-derived sea surface temperature (SST) records allowed a reconstruction of the properties of the inflowing Atlantic Water (AW), which have proved to be a primary control of the variations in productivity in the neighborhood of the Strait of Gibraltar. Other local factors, such as fluvial discharge, wind-induced and eddy-induced upwelling, are proposed to have influenced marine productivity in more distant areas. The entrance of cold and less saline AW during the stadials associated with Heinrich events 2 and 1 prevented primary productivity, which increased along the Last Glacial Maximum, probably due to a greater fluvial discharge. During Terminations 1a and 1b, the upper water column was affected by stratification, although wind-induced upwelling occurred locally. The Bølling–Allerød was characterized by a gradual increase in productivity and the development of the organic-rich layer. Two phases of the Younger Dryas are recognized: a first phase, which was colder, followed by a second phase, which was warmer and wetter. Differences in productivity between both locations during these two phases can be attributed to fluvial discharge and the changing properties of the AW. Local hydrography, such as the dynamics of the western anticyclonic gyre, gained greater importance in determining productivity and its variations during the Holocene, which was the most productive period.

Description: Publication date: 15 January 2015 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 418 Author(s): A. Pictet , G. Delanoy , T. Adatte , J.E. Spangenberg , C. Baudouin , P. Boselli , M. Boselli , P. Kindler , K.B. Föllmi A stratigraphic and depositional model, constrained by biostratigraphy, geochemistry, total phosphorus contents, and bulk-rock mineralogy, is proposed for lower Aptian sediments from the Languedoc platform in Ardèche, SE France. The upper lower Aptian is documented by the Chabert Formation (upper Deshayesites forbesi Zone to upper Dufrenoyia dufrenoyi Subzone), deposited on a discontinuity surface on top of the Urgonian platform, recording a first emersion phase and consecutive drowning event. The Chabert Formation starts with the marly Violette Member, which passes into crinoidal limestone of the Rocherenard Member. The top of this member is associated with a second discontinuity, recording a further drowning phase, which is followed by the deposition of the glauconitic and partly phosphatic Picourel Member (upper Deshayesites grandis to upper Dufrenoyia dufrenoyi Subzone). A third erosive phase is documented by a phosphatic conglomerate (upper Dufrenoyia furcata Zone), which represents a lag deposit derived from underlying sediments. The formation of this conglomerate was associated with a substantial emersion phase. This emersion was followed by a drowning event reworking the phosphatic conglomerate into the base of the upper Aptian black marls (Frayol Formation). The carbon-isotope record shows a negative excursion which coincides with the onset of the early Aptian oceanic anoxic Selli episode (OAE 1a) in the middle/upper part of the Deshayesites forbesi Zone. Emersion phases were an important factor implied in the formation of the sequence boundaries, which were transformed into drowning unconformities during subsequent phases of significant transgressions. These phases were associated with the installation of higher trophic levels, transforming or impeding carbonate production. The first drowning phase preceded the onset of the Selli episode, suggesting that rapid sea-level change and associated environmental change were already an important element of the early Aptian before the major phase of environmental change during the Selli episode.

Description: Publication date: 15 January 2015 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 418 Author(s): Robert J. Daly , David W. Jolley The Normapolles were an extinct group of early angiosperms which dominated much of the northern hemisphere during the Cretaceous. Although a product of early angiosperm radiation, they persisted beyond the K–Pg boundary, representing a significant proportion of the earliest Palaeocene palynological assemblage recovered from the Boltysh meteorite crater in Ukraine. While it is likely that many forms represent an ancestral lineage to modern day Fagales, particularly the walnut family (Juglandaceae), clear trends in certain species indicate that separate ecological preferences relating to temperature existed amongst them. In the Boltysh record the most abundant taxa occur preferentially within the early Danian hyperthermal, indicating a warm environment. Allied to their co-association with pollen of modern affinity, this suggests that they were scrubby, sclerophyllous plants akin to those which thrive in winter-wet ecosystems today. During and subsequent to the recovery from the early Danian hyperthermal these species decline and are replaced by different types. The Boltysh record demonstrates that in the very earliest Cenozoic, the Normapolles were a considerably more resilient and complex group than they are often portrayed and potentially important palaeoecological indicators.

Description: Publication date: 15 January 2015 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 418 Author(s): Cassiane N. Cardoso , Javier Sanz-López , Silvia Blanco-Ferrera , Valesca B. Lemos , Ana K. Scomazzon A conodont fauna is studied from the subsurface of Upper Devonian black shales belonging to the Abacaxis Member of the Barreirinha Formation, Amazonas Basin. Two samples of other members of this formation are barren. The fauna consists of Cryptotaxis sp. A, Mehlina gradata , ‘ Ozarkodina ’ aff. sannemanni , Polygnathus sp. and, probably, Prioniodina sp. This association suggests a late Frasnian age, agreeing with the age previously assigned to the latest Frasnian to middle Famennian palynomorphs. The conodont fauna is added to another two late Frasnian–middle Famennian conodont occurrences in Bolivia and Brazil. The coincidence in age and facies (black shales) seems to indicate a unique time/environment favourable to the immigration and development of conodonts in the Devonian of northern South America. The low diversity association suggests cold water-dwelling taxa spreading to a high palaeolatitude during an episode of gentler latitudinal temperature gradient. Graphical abstract

Description: Publication date: 15 January 2015 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 418 Author(s): C.R.C. Paul Large samples of pyritized ammonites of Bifericeras and Leptonotoceras from the Lower Jurassic of Bishop's Cleeve, Gloucestershire, England, reveal that the majority have asymmetrical suture lines due to siphuncular offset from the usual mid-ventral position. Siphuncular offset is most common (95% of specimens) and most extreme (modes 12–23° left, 23–34° right, maximum 93°) in Leptonotoceras , but less frequent and less extreme in Bifericeras (92%, mean 5°, maximum 26° in B. bifer ; 70%, mean 5°, maximum 21° in B . sp. 2). In both genera there is a marked preference for offset to the right side of the ammonite, and in Leptonotoceras the modal value is higher to the right. Trochospiral shells are more frequently found in Bifericeras bifer than in either Leptonotoceras or B . sp. 2. All trochospiral shells have siphuncular offset, with the siphuncle always displaced towards the ‘umbilical’ side of the shell. It is suggested that the position of the siphuncle can be used to interpret the life orientation of the ammonites in the water column, but the relationship is not simple. The frequent occurrence of mature individuals suggests that this unusual inferred orientation was not harmful to the ammonites. Differences in sutures and in body chamber length, together with the presence of at least two species of Bifericeras , but only one of Leptonotoceras , call into question Bayer's (1972) interpretation that B. bifer and Leptonotoceras are sexual dimorphs of the same biological species.

Description: Publication date: 15 January 2015 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 418 Author(s): Henrik H. Svensen , Øyvind Hammer , Fernando Corfu The Late Ordovician world experienced a series of huge volcanic eruptions, recorded as the big Deicke, Millbrig and Kinnekulle bentonites, together with numerous thinner beds. The Kinnekulle event can be traced across northwestern Europe. U–Pb zircon ages are here presented of both the Kinnekulle K-bentonite and the uppermost recorded tephra layer in the Upper Ordovician of the Oslo Region, Norway. The tephras are located in the upper part of the Arnestad Formation (Sandbian) south of Oslo and gave ages of 454.52 ± 0.50 Ma (the Kinnekulle K-bentonite) and 453.91 ± 0.37 Ma (the upper Grimstorp K-bentonite). The dated tephras are separated by a 7 m thick shale succession with subordinate nodular limestone beds. Although the two U–Pb ages overlap within errors, statistical considerations indicate a most likely time interval of about 600 kyr between the tephras. High-resolution magnetic susceptibility logging in the same section shows cycles that likely represent changes in sediment supply in response to astronomical forcing. Spectral analysis shows the presence of long (400 kyr) and short (100 kyr) eccentricity bands, and obliquity components in the 30 kyr band. Precessional cycles are not detected. Based on this method, it is possible to estimate a time interval of 766 kyr between the two tephra events, and the radiometric dating therefore does not exclude a Milankovitch interpretation of the cycles. This opens new possibilities for understanding the evolution of one of the world's best preserved Ordovician marine systems.

Description: Publication date: 15 January 2015 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 418 Author(s): Tracy D. Frank , Aaron I. Shultis , Christopher R. Fielding Palaeoenvironmental reconstructions from across the globe indicate that the climatic and oceanographic changes that accompanied the Permian transition from deep icehouse to greenhouse conditions were uneven and asynchronous. Because of a paucity of well-constrained data, environmental changes in Gondwana remain poorly understood relative to tropical Pangaea. In this regard, the Permian System of eastern Australia provides a unique record of this transition along a high-latitude, open marine shelf. Not only was glaciation protracted here relative to other regions of Gondwana, but the record also spans temperate to polar palaeolatitudes, providing an opportunity to examine environmental changes along a latitudinal transect. We integrate proxies for δ 18 O seawater , palaeotemperature, pCO 2 , and depositional environment to assess the evolution of nearshore conditions through the Permian. Glaciation was not continuous, but rather focused into four discrete, glacial epochs (P1–P4), each several million years in length, which alternated with nonglacial intervals of similar duration. During the Asselian–mid-Artinskian (P1–P2 time), uniform conditions along the full extent of the margin were maintained by a cold boundary current coupled with oceanic upwelling. Increased spatiotemporal variability is evident at the end of glacial P2 (mid-Artinskian), perhaps due to tectonic changes that impacted the palaeogeography of the margin. Although glaciers had disappeared by this time elsewhere in Gondwana, eastern Australia saw two additional periods of glaciation, P3 (Roadian–earliest Captianian) and P4 (early Wuchiagingian). Continued, albeit intermittent, glaciation was facilitated by drift toward higher palaeolatitudes, orogenic activity that led to the development of areas of high elevation that could serve as nucleation points for glaciers, and transient drops in atmospheric pCO 2 . Variations in meltwater input exerted a strong effect on local δ 18 O seawater values, complicating attempts to reconstruct latitudinal gradients in palaeotemperature. Results point to atmospheric CO 2 as the primary driver responsible for the dynamic climate variations evident in the record.