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Symposium 'Quaternary malacology. New developments in palaeoecology and biostratigraphy'


ABSTRACTS



ORAL
Application of marine mollusk remains from shell middens for paleoenvironmental reconstructions
Antipushina, Zhanna

A.N. Severtsov Institute of Ecology and Evolution RAS, Leninsky Prt., 33, Moscow, Russia.
zhannaipee@mail.ru


Molluscs remains from two shell middens on Adak Island, Aleutians were analysed to reconstruct the paleoenvironmental conditions in this area.
Radiocarbon analysis showed that the first shell midden was formed 6500-6100 years ago. This deposit is situated near Clam lagoon. Analysis of invertebrates’ taxonomic structure showed that seabed relief in Clam lagoon changed significantly during the existence of the ancient settlement. It is manifested in decrease of share of epifaunal molluscs’ remains (foolish mussel Mytilus trossulus and chitons) from layer 4 to layer 2 of shell midden. Also it is manifested in increase of share of Nuttall’s cockle’s remains (Clinocardium nuttallii) and other species, which live in sand ground, in the same layers. It is likely that the intertidal zone of Clam lagoon had more rocky structure at the end of 6th millennium BC. Then the portion of rock seabed decreased, and the sandy ground began to dominate.
The second shell midden, situated near Sweeper Cove, was formed 1800-750 years ago. The remains of epifaunal molluscs dominating in deposit are the evidence of rocky structure of the intertidal zone of Sweeper Cove during the 8th-19th centuries AD. Analysis of the invertebrates’ taxonomic structure allows to mark out three periods in the development of this shell midden. Conceivably warmer conditions were from the middle of the 11th till the 15th centuries and from the middle of the 16th till the 19th centuries, because thermophilous species, non typical for this region, (Nucella heyseana) were found in the layers. It is likely that higher production of intertidal community from the 15th till the middle of the 16th centuries is result of relatively cold environmental conditions in this time. The colder period correspondents to “Little Ice Age”.
Our research was supported RFBR (grant 06-04-48531) and National Science Foundation (grant OPP-0353065).
Late Glacial-Early Holocene environmental change at Favignana island (Sicily - Italy): evidence from malacological records in prehistoric deposit
Colonese, A.C., Lo Vetro, D., Martini, F.

Dipartimento di Scienze dell’Antichità “G. Pasquali”, University of Firenze. Museo e Istituto Fiorentino di Preistoria “P. Graziosi”, via S. Egidio 21, 50121, Firenze, Italy.
colonese@unisi.it


The continental shelf is a complex environment where waves, tides, currents, input from the continent and sea, and humans interplay through time and space. To understand the variability in this past evironment (i.e., Late Quaternary) multidisciplinary approaches are required, in addition to which archaeological archives in coastal zones may be of prime importance. This paper reports the ecological and geochemical analyses of marine and continental molluscan shell remains from prehistoric layers of Grotta d’Oriente, a coastal cave located on the Favignana island (37°55' N; 12°20' E - Sicily) and frequented by humans during the Late Glacial-Early Holocene. Anthropogenic Late Glacial deposits are characterized by the abundant presence and high frequency of paralic species (i.e., Pirenella conica (Blainville, 1826)) as well as by the presence of freshwater species (i.e., Lymnaea (Galba) truncatula (Müller, 1774)), probably brought into the cave by humans with aquatic plants. In contrast Early Holocenic deposits are instead characterized by the absence of paralic species and the abundance of marine intertidal species (i.e., Osilinus turbinatus (von Born, 1778)), exploited by human communities. Freshwater species are even absent in these layers. Ecological and statistical analysis shows evidence of a progressive transition from paralic to marine environment between Late Glacial and Early Holocene and the human response to this abrupt change. According to other records, this environmental transition results from both sea level rise and lower freshwater budget during the formation of Favignana island and its separation from the island of Sicily at this time. Oxygen isotopic composition of Eobania vermicolata (Müller, 1774, Gastropoda, Pulmonata) indicates, in accordance with other records from the Mediterranean region, a dry to wet climate transition between Late Glacial and Early Holocene. Results highlight the importance of multidisciplinary approaches in fossil shell analysis with regards to ascertaining past environmental changes and the human communities response.
Analysis of shell growth, structure and chemical composition of ocean quahog (Arctica islandica)
Dunca, Elena1; Mutvei, Harry1; Göransson, Peter 2; Mörth, Carl-Magnus 3; Whitehouse, Martin J 1; Elfman, Mikael 4

1. Swedish Museum of Natural History, Box 50007, 10405 Stockholm, Sweden.
elena.dunca@nrm.se harry.mutvei@nrm.se martin.whitehouse@nrm.se
2. Miljökontoret, S-251 89 Helsingborg, Sweden
peter.goransson@helsingborg.se
3. Stockholm University, Dept of Geology and Geochemistry, Stockholm, Sweden,
magnus.morth@geo.su.se
4. University of Lund, Dept of Nuclear Physics, Box 118, S-22100 Lund, Sweden,
Mikael.Elfman@nuclear.lu.se


Recent studies of ocean quahog (Arctica islandica) demonstrate that the shell growth and structure, as well as its chemical composition reflect changes in the environment. Sclerochronologies (growth increment chronologies) together with isotope analyses allow reconstruction of palaeotemperatures. Consequently, the bivalve shells are considered as reliable proxies for climate reconstructions and there is an increasing trend to use bivalves as environmental bio-monitors. However, shells from shallow water environments along the costal regions are more exposed to salinity fluctuations and to pollutants from human activities than shells from deeper regions. This affects the reliability of temperature reconstructions yet the chemistry of these shells reveals the history of water pollution.
In our work we compare the shell structure of ocean quahog collected recently from Kiel Bay, along the Swedish West Coast to Iceland, Spitsbergen and the White Sea with sub-fossil shells from museum collections dated from the Tertiary to Holocene.
Shells from Kiel Bay, Öresund and Kattegat, as well as shells from the White Sea, are considerable thinner and smaller, with many growth disturbance lines, compared to shells from Skagerrak and the North Sea. Shells from Iceland, Spitsbergen and from the Tertiary are particularly large sized, and considerably thicker. They have also a highly organized crossed lamellar microstructure with a very thin outermost granular homogenous sub-layer. In contrast, shells from the Swedish West Coast and the White Sea have a very poorly organized microstructure, mostly homogenous, and only the outer aragonitic layer shows sporadically crossed acicular microstructure. These observations indicate that the microstructure, size and thickness of Arctica shells are induced by stress factors, such as salinity changes and water pollution.
Analyses carried out with SIMS, ICP-OES, nuclear microprobe and neutron activation analysis show that higher contents of S, N, Cu, Zn, As, Cd and P in shell portions formed during the last century are related to human activities such as mining and industrial development.
In order to use shells as archives for climate change models it is necessary to evaluate the full range of environmental data recorded in the shells by employing different analytical techniques including chemical analyses that combine high multi-elemental capacity with high sensitivity and high spatial resolution, as well as growth rate and structural analyses.
Reconstruction of the Pleniglacial Environment Based of Molluscan Assemblages of the Titel Old Brickyard Section (Vojvodina, Serbia)
Gaudenyi, Tivadar; Jovanovic, Mladjen; Markovic, Slobodan B.

Department of Geography, University of Novi Sad, Trg D. Obradovica 3. 21000 Novi Sad, Serbia.
tiv@neobee.net; mladjenov@neobee.net; zbir@im.ns.ac.yu


If the carbonate content is sufficient Molluscs are one of the most abundant fossils in loess-paleosol sequences. The quantitative malacological investigations could help in reconstructing the environment dynamics of past. The Titel Old Brickyard exposure is located in the southeastern part of the Carpathian Basin, on the Titel Loess Plateau northwest from the confluence of Danube and Tisza rivers, south from the former periglacial regions of Central Europe. The main task was the reconstruct the local environmental conditions of the 16 m thick Pleniglacial loess series. Here we show the the environmental conditions of Titel Old Brickyard section during the Pleniglacial the conditions were arid, steppe-like where the cold demanding species were absent. The Early Pleniglacial (MIS 4) characterized with the forming of sandy loess layer with poor xerotherm steppe demanding Striata-Pupillafauna which has been preserved only at a parts near the contact of the other strata and a 20 thick layer. The Upper Pleniglacial (MIS 3) during which the humic horizon was formed and the molluscan record of Pupilla-Striata faunal assemblage represents stable sedimentation record and the arid, steppe-like environment. During the Upper Pleniglacial (MIS 2) the conditions for preservation were excellent, the stable loess sedimentation and its fauna shows the continuous arid, steppe-like environment with the dominant Pupilla fauna. The Last glacial maximum was manifested with decreasing number of the land snails and the temperate conditions preferring Granaria frumentum minimum, no cold demanding species were found. In the youngest part of the MIS 2 the open woodland species (Clausilia dubia) has been detected in low numbers but the environment keeps its steppe-like character. As a lowland plain relief the snail assemblages is quite monotonous with low number of species and connected to the arid, temperate steppe like environment.
Environmental insights into the Crag Sea: investigation of growth rates of Pliocene Arctica islandica from the Coralline Crag (UK)
Harper, E.M.1, Finlayson, A.1 and Richardson, C.A.2

1. Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EQ, UK,
emh21@cam.ac.uk
2. School of Ocean Sciences, College of Natural Sciences, University of Wales, Bangor, Menai Bridge, Anglesey, LL59 5AB, UK.
c.a.richardson@bangor.ac.uk


Annually resolved growth lines in Recent shells of the long-lived bivalve Arctica islandica have been shown to have great potential for the study of the effects of environmental change on annual growth rates and the study of stable oxygen isotopes have shells have allowed for the reconstruction of water temperatures. The occurrence of fossil A. islandica in the Pliocene shallow marine Coralline Crag of eastern England, offers an opportunity for the study of seasonal growth rates and the reconstruction of seawater temperatures during the ‘mid Pliocene warm period’ of the late Holocene. Examination of the microstructure and mineralogy of the Crag A. islandica, using scanning electron microscopy and cathodoluminesence, showed them to be well preserved with no evidence of diagenesis. Measurement of the growth increments showed rapid growth rates in all individuals, higher than those recorded for modern individuals. The largest clams attained an age >160 years and this longevity is similar to those of live- caught clams from the North Sea and Atlantic Ocean. Analysis of 18O/16O ratios in shell material showed clear seasonality of growth line deposition during the lowest seawater temperatures. Reconstruction of the seawater temperatures from the oxygen isotopes at the time of shell deposition suggest an annual temperature range of between 3.6 and 12.8°C.
Occurrence of Retinella (Lyrodiscus) in Quaternary west-european sequences : taxonomical status and palaeoclimatic implication
Limondin-Lozouet, Nicole

Laboratoire de Géographie Physique, 1 Pl. A. Briand, 92195 Meudon cedex France.
limondin@cnrs-bellevue.fr


Recent studies undertaken at several sites in the Somme and the Seine valleys (Northern France) together with revision of ancient collections have provided new data on occurrences of the genus Retinella (Lyrodiscus) within Pleistocene interglacial deposits. This new material has led to a revision of first the taxonomic status and second the palaeoenvironmental and climatic significance of the genus in a Quaternary perspective.
Taxonomic reassessment of the species shows that Retinella (Lyrodiscus) skertchlyi Kerney 1976 is a junior synonym of Retinella (Lyrodiscus) elephantium (Bourguignat, 1869) and that at least two extinct species of R. (Lyrodiscus) are known in western Europe during the Quaternary.
Occurrences of Retinella (Lyrodiscus) within interglacial deposits are discussed using records of different temperate periods at different European locations, mainly British, German and Deutsch sites. Until now the genus does not appear after the Holsteinian. Within MIS 11 north-west European tufa deposits the species belongs to a peculiar assemblage representative of humid forest biotopes developed under fully temperate conditions. However R. (Lyrodiscus) might also appear in silt sequences, associated with species representative of more open environments which induce a different palaeoenvironmental significance. Variations of shell morphology, morphostratigraphical context and malacological assemblages are discussed at a west-european scale.
The Holsteinian: MIS 7, 9 or 11 ?
Meijer, Tom

Naturalis, Dept of Paleontology, P.O. Box 9517, 2300 RA Leiden, The Netherlands.
meijert@naturalis.nl


The Holsteinian is a Middle Pleistocene interglacial that has been introduced on the basis of marine mollusc bearing deposits in Northern Germany. In Europe, the interglacial shows (except for marine taxa) a remarkable molluscan record. Although individual species also occur in other interglacials, the fluvial assemblages include Theodoxus danubialis, Viviparus diluvianus, Valvata naticina, Parafossarulus crassitesta, Pisidium clessini, etc. Notably, many of these taxa are also present in the preceding Fourth Cromerian Interglacial. The terrestrial 'Lyrodiscus assemblage' is considered to be of Holsteinian age (is, however, absent in the Holsteinian type area) and includes Lyrodiscus elephantium, Zonitoides sepultus, Aegopinella bourdieri, Aegopis acieformis, Ruthenica filograna, Laminifera pauli, etc. All mentioned taxa (fluvial and terrestrial) occur far beyond their modern area or are extinct.
The age of the Holsteinian was controversial and attributed to MIS (Marine Isotope Stage) 7, 9 or 11 respectively. Now, most authors consider the Holsteinian to represent MIS 11. However, the problems in dating the Holsteinian stratotype show that this conclusion is premature and probably incorrect.
Recently, Amino Acid Racemization dating of marine molluscs showed that the Holsteinian stratotype dates from MIS 9. The Fourth Cromerian Interglacial at its type site appears to date from MIS 11, and this was similarly shown for the Dutch 'Holsteinian' site of Neede. Therefore, at least the characteristic fluvial assemblages with Viviparus diluvianus are NOT Holsteinian but date from the preceding interglacial (but still MIS 11). These conclusions are corroborated by new insights in the lithostratigraphy of the areas in question as well as absolute dating of the Holsteinian parastratotype.
These results have no bearing for the 'Lyrodiscus Assemblage' although many other data point to MIS 11, implying an age of Fourth Cromerian Interglacial as well. Similarly, any site attributed on sound data to MIS 11, is not Holsteinian but Fourth Cromerian Interglacial.
Millennial-Timescale Environmental Changes Recorded by Molluscan Fauna at Nussloch (Germany) during the Last Glaciation and Perspectives in Quantitative Palaeoclimatic Reconstructions in Quaternary Malacology
Moine, Olivier1, Rousseau Denis-Didier1,2, Antoine, Pierre3

1. Institut des Sciences de l’Evolution, Université Montpellier II, Place Eugène Bataillon, cc 61, 34095 Montpellier Cedex 05, France.
omoine@isem.univ-montp2.fr; denis@dstu.univ-montp2.fr
2. Lamont-Doherty Earth Observatory of Columbia Observatory, Palisades, NY 10964, USA.
3. Laboratoire de Géographie Physique, 1 Place Aristide Briand, 92195 Meudon Cedex, France.
pierre.antoine@cnrs-bellevue.fr


The millennial-timescale climatic variability of the last glaciation has already been shown through the study of ice- and marine-cores in the North Atlantic area. Its influence on European environments was mainly studied in Mediterranean domain through long pollen records and speleothems, which lack in continental domain. The terrestrial molluscs, sampled every 10 cm in the loess section of Nussloch (Germany), thus provides a high-resolution record of millennial-scale environmental changes between -70000 and -20000 years that has been correlated with the GRIP ice-core (Greenland). Increases in mollusc abundance and juvenile proportions are linked with warmer phases, i.e. Dansgaard-Oeschger interstadials.
These cyclical climatic oscillations also triggered humidity and vegetation changes recorded by malacological populations and sedimentological features. The pattern proposed for the Upper Pleniglacial (-35 to -20 kyr) is also valid for the Lower Pleniglacial (-75 to -50 kyr) with some differences, but partly differs for the Middle Pleniglacial due to a lower sedimentation rate and warmer climatic conditions. Moreover, according to the composition of the malacofauna, each interstadial has a particular environmental signature in terms of temperature, humidity and vegetation.
In Western Europe, Upper Weichselian malacofauna from England, northern France and Benelux are similar, poor and homogeneous through the whole Upper Pleniglacial indicating a persistence of homogeneous and poorly vegetated environments. In the Rhine Valley, the malacofauna are richer and partly different from site to site. However, this relative richness varies synchronously with sedimentological features through the Upper Weichselian. In four sites from this area, the development of tundra soils is associated with cold and moister conditions reflected by poorer malacofauna, which tend to resemble those observed in North-Western Europe. This suggests the occurrence of cyclical shifts to the East of the environmental conditions prevailing in North-Western Europe in response to millennial timescale changes of the climate dynamics.
Changes in Quaternary mollusc Assemblages in Eastern Hungary in Late Quaternary
Nyilas, István

Department of Evolutionary Zoology, University of Debrecen, Egyetem tér 1, H-4010 Debrecen, Hungary,
steve@tigris.klte.hu


Hungary played an important role in the Late Quaternary development of the European Mollusc fauna, as it is located in the central part of Europe and it was not covered with ice even in the coldest periods of Pleistocene. As a periglacial territory, it has preserved the majority of its earlier fauna and was also a refuge area for arctic-alpine (Columella columella) and boreo-alpine species (Vertigo geyeri, Vertigo substriata).
One of the most outstanding faunas of Late Quaternary with a species number over 50, was studied in one study site in Hortobágy National Park. Hortobágy is a perfectly flat area where some tens of centimeters difference can greatly influence the moisture content, vegetation and microclimate of the base, as well as the mollusc fauna forming on it. The quatermollusc assemblages in Hortobágy seem to have a double character, i.e. besides land species represented in bigger numbers (e.g. Succinea oblonga, Oxyloma elegans, Cochlicopa lubrica, Columella edentula, Columella columella, Vertigo substriata, Vertigo geyeri, Pupilla muscorum, Vallonia pulchella, Vitrea crystallina, Trichia hispida) aquatic species can also be found in one third of the total individual number (e.g. Valvata pulchella, Bythinia leachi, Anisus leucostomus, Anisus spirorbis, Gyraulus laevis, Pisidium obtusale, Pisidium casertanum).
The other study site was a typical loess area in the Hajdúság (eastern Hungary), where over 20.000 individuals of the two profiles were analysed. The diversity of this region is low, its fauna was made up of only land species, the most typical of which are: Succinea oblonga, Columella edentula, Columella columella, Vertigo parcedentata, Pupilla muscorum, Vallonia tenuilabris.
The mollusc assemblages of the two study sites have been compared. Radiocarbon method was used to identify their age. For better comparison fine stratigraphic method was used, samples were taken by 10 centimeters. In addition to the abundance and dominance data we analysed the population structure of the same species at the two sampling sites (e.g. Succinea oblonga, Columella edentula, Vertigo parcedentata). The analysis of some aquatic species in the profile at Hortobágy has also been done. The correlation between mollusc species and environmental factors was revealed using Canonic Correspondence Analysis.
Amino acids in calcite: a tiny time-capsule for the Quaternary
Penkman, K.E.H.1, Maddy, D. 2, Keen, D.H.3, Preece, R.C.4 & Collins M.J.1

1. BioArch, Biology S Block, University of York, PO Box 373, York, YO10 5YW, UK.
kp9@york.ac.uk
2. Department of Geography, University of Newcastle, Newcastle-upon-Tyne, NE1 7RU, UK.
darrel.maddy@ncl.ac.uk
3. Birmingham Archaeology, University of Birmingham, Birmingham, B15 2TT, UK.
4. Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK.
rcp1001@cam.ac.uk


Whilst amino acid racemization (AAR) in mollusc shells was once applied widely as a dating technique for the Quaternary, recently other geochronological tools have become more routinely used, at the expense of AAR. However, successful results have been achieved using AAR of proteins in ratite eggshell, proposed to act as a closed-system with respect to the entrapped protein. At those sites not lucky enough to have an abundance of large flightless birds, a commonly occurring biomineral with similar closed-system properties would extend the potential of AAR to provide a simple dating tool. In an attempt to isolate a closed system in gastropod shells, we: (i) use multiple amino acid DL ratios, (ii) cross-check the Free amino acids (released from degraded proteins) against the Total amino acid compositions in the biomineral, (iii) bleach to remove contaminants and the degradable organic matrix. This approach both ensures the analysis of only the original amino acids, and allows the identification of bacterial contamination and post-depositional recrystallization.
Despite these innovations, beyond MIS 9 the level of resolution in gastropod shells becomes limited. However, this work has been recently eclipsed by results obtained from the analysis of the tiny Bithynia opercula, common fossils in Quaternary freshwater deposits. The shells are aragonite, but the humble operculum which closes the gastropod aperture is calcite. Preliminary results with opercula are spectacular and as a consequence, the extent of protein degradation in opercula can be used to resolve not only stages but sub-stages within the Quaternary. The analyses of over 600 single opercula from 100 northern European sites are reported, with this coherent calcite intra-crystalline system allowing the development of an AAR chronology to at least 2.5 Ma.
Holocene molluscan successions from the Lake Baikal region, Siberia
Preece, Richard C.1; White, Dustin1,2; Shchetnikov, Alexander A.3

1. Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK.
rcp1001@cam.ac.uk
2.Department of Anthropology, 13-15 HM Tory Building, University of Alberta, Edmonton, Alberta T6G 2H4, Canada.
dw330@cam.ac.uk
3. Institute of the Earth's Crust, Siberian Branch of the Russian Academy of Sciences, Irkutsk 664033, Russia.
shchet@crust.irk.ru


This paper reviews the Holocene molluscan successions from two well-dated sites in the Baikal region of south-central Siberia, the most detailed yet reported from the entire eastern Palaearctic. Floodplain sediments of the upper Lena River near Basovo, west of the northern tip of Lake Baikal, yielded over 72 500 shells from at least 28 species of terrestrial and 23 species of freshwater mollusc, an abundance and diversity far higher than previously reported from the region. The molluscan assemblages are dominated by land snails, especially Vallonia, represented by five species including V. tenuilabris and two poorly known taxa V. kamtschatica and V. cf. chinensis. Other noteworthy species recovered include Gastrocopta theeli, Carychium pessimum, Vertigo extima (southernmost record), V. microsphaera (fourth record) and the first Asian records of three other taxa (V. geyeri, V. genesii and V. parcedentata). The molluscan assemblages show clear successional trends during the early to mid Holocene, reflecting episodes of dryness/wetness on the floodplain. Drier conditions at c. 6350 14C yr BP coincide with major changes in the archaeological record seen at other sites in the region but it remains unclear whether the two are linked. A prominent charcoal-rich horizon dated to c. 2800 14C yr BP marks a burning event in the catchment, which resulted in a twofold increase in sediment accumulation rate. The faunal analyses have been integrated with a detailed pedological study of the sedimentary profile and a chronology provided by means of twelve AMS radiocarbon dates. The second site near Burdukovo lies east of Lake Baikal and it too has provided a clear Holocene succession but somewhat less dynamic than that at Basovo. This study provides the first detailed palaeoecological information relating to Holocene molluscan assemblages from the Baikal region and lays the foundation for future work in the eastern Palaearctic.
Molluscan evidence of woodland disturbance in the Irish Holocene
Speller, George R1; Preece, Richard C.2

Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK.
gspeller@gmail.com rcp1001@cam.ac.uk


Radiocarbon dated molluscan sequences from three extensive Irish Holocene tufa deposits have provided information relating to human impact on the environment. Work at Newlands Cross, situated in the outskirts of Dublin in the east of Ireland, builds on an earlier study, which demonstrated that this thin deposit of tufa (only about 1 m thick) covered much of the early to mid Holocene, providing the most detailed succession of land snails known from Ireland. The new work includes the analyses of five further profiles, with a much-improved sampling resolution (down to 1 cm). These have amplified aspects of faunal history and enabled further light to be shed on a Mesolithic disturbance horizon previously identified at the site. The new records suggest that the area affected by the disturbance was extremely limited (perhaps less than 50 m2) and of relatively brief duration (a few hundred years). Two sites (Graffy and Cartronmacmanus) located only 3 km apart in Co Mayo in western Ireland provided less complete records for the very early Holocene but furnished excellent sequences from about 8200 yrs BP to 2000 yrs BP. The faunal successions were less dynamic than those at Newlands Cross but they too yielded evidence of woodland disturbance, this time dating from the late Bronze Age and early-middle Iron Age. The registration of at least five such events differed significantly from the characteristic faunal signatures associated with comparable impacts in southern Britain. This results from the relative scarcity in Ireland of species such as Vallonia costata, although the impacts are clearly indicated by declines in shade-demanding species, such as Discus rotundatus.
POSTERS
Using an electron microscopy shell morphometry in identifying the Weichselian Pupilla muscorum and Pupilla triplicata species from the loess series of Vojvodina (Serbia)
Gaudenyi, Tivadar; Jovanovic, Mladjen.

Department of Geography, University of Novi Sad, Trg D. Obradovica 3. 21000 Novi Sad, Serbia.
tiv@neobee.net, mladjenov@neobee.net


Molluscs’ remains represent one of the most abundant Quaternary fossils. Their correct interpretations clearly depend on the accuracy with which the species of the fossil molluscan assemblage can be identified. Quantitative palaeontological investigations of Quaternary loess molluscs face to the problem of identifying of species of Pupilla muscorum and P. triplicata from the Weichseilan loess series at the Vojvodina Province (Serbia). If the shell is preserved only fragmentary the identification could be quite difficult because of the shell size and microsculpture similarities. The P. muscorum and P. triplicata have different ecological requirements (P. muscorum is a typical loess steppes [periglacial and non-periglacial] species with a big environmental tolerance, while a P. triplicata is a species related to more milder climate of xerophilous, steppe like environment ), thus why the species level identifying is welcome. The main task in this study was to try to separate/identify the shell fragments on species level according the shell apex morphometry. The complete shells in total number of 80, previously clearly identified individuals have been studied. The selection of 40 specimens of each species (P. triplicata and P. muscorum) has been analysed. The shells were scanned on electron microscopy and the maximum cross arbitrary distance of the apex has been measured. The morphometrical results shows the apex value for P. triplicata population is between 317 µ and 565 µ, while the apex size for P. muscorum starts from 472 µ. According the morphometrical measurements the apex values of shells form 317 µ to 472 µ referred as P. triplicata, apex values from 472 µ to 565 µ are classified as Pupilla spp. and the values bigger than 565 µ belongs to P. muscorum. The results could be applied for the Weichselian Pupilla shells from the loess series of the analysed region.
On the invasion of Biomphalaria (Gastropoda: Planorbidae) in Africa and the evolution of the human bloodfluke Schistosoma mansoni: the palaeontological evidence
Van Damme, Dirk; Van Bocxlaer, Bert.

Research Unit Palaeontology, Department of Geology and Soil Science, Geological Institute, Ghent University, Krijgslaan 281 (S8), B-9000 Ghent, Belgium.
Dirk.VanDamme@ugent.be, Bert.VanBocxlaer@ugent.be


Modern genetic research indicated Biomphalaria (Preston, 1910) to have invaded Africa from South America during the Late Cenozoic and molecular clock calculations suggest this invasion to have taken place between 4.5 and 2.3 Ma, or even later, 1.1-1.8 Ma. Molecular biologists claim this to be in correspondence with fossil evidence of Biomphalaria in Africa, which is incorrect. The paleontological record of Africa corroborates the genetically based invasion hypothesis, but suggests the timescale provided by molecular clock data to be unfounded. Fossil-bearing beds all over the African continent document Biomphalaria to be absent, until it makes an explosive, sudden appearance around 250-200 ka. This geologically very recent appearance of Biomphalaria in Africa, coinciding with the onset of an Interglacial, and the latest evidence on the origin of Shistosoma mansoni, has far reaching ramifications for research concerning zoogeography as well as parasite-intermediate host evolution and human parasitology, for the presence of Schistosoma mansoni, a digenetic trematode and parasite of humans, is determined by the occurrence of its intermediate host, freshwater snails of the genus Biomphalaria. This study indicates the resolution of molecular inferred age determinations to be often too poor to make accurate claims on the divergence of taxa. The sudden appearance of Biomphalaria in African molluscan assemblages during Late Pleistocene times provides a useful biostratigraphic marker.
Extinction and immigration in the wake of climatic deterioration: Marine molluscan diversity in the Pliocene-Quaternary in the southern North Sea Basin
Wesselingh, Frank P.; Janse, Anton; Meijer, Tom

Naturalis, P.O. Box 9517, 2300 RA, Leiden, The Netherlands.
wesselingh@naturalis.nnm.nl


During the Pliocene and early Quaternary, a strong marine molluscan faunal turnover occurred in the North Sea Basin. In this poster we document the extinction of warm-temperate/subtropical taxa as well as species endemic to the North Sea Basin during the Zanclean-Gelasian and their replacement by Pacific and Arctic immigrant species. During the Zanclean (ca. 4 million years ago) the mollusc fauna was rich in species, several of which persist nowadays in more southerly areas such as the Mediterranean. Also, a considerable number of supposed North Sea endemics occurred. Diversity deteriorated drastically during the Piacenzian and Gelasian (c. 1.8-3.5 million years ago). This is in part explained due to cooler climate regimes and a general shallowing of the North Sea, but mostly caused by the disappearance of oligotrophic habitats as a result of increased glacial cyclicity and associated hinterland erosion. Immigrants expanded to become major faunal elements in the North Sea Basin at the same time. At the end of the Gelasian, an impoverished boreal fauna inhabited the North Sea.








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