Actualistic Approach Research Articles

N-Alkane and terpenoid fingerprints of modern biomass producers unveil floral changes recorded in postglacial alpine lake sediments, Tatra Mountains, Slovakia

Sediments of two alpine lakes in Tatra Mts., Slovakia, record the environmental history of their catchments from deglaciation in Late Glacial warming up to the Subboreal period. We present abiomarker-based reconstruction of changes in the surrounding biota of two contrasting lakes – a relic lake in open fen Trojrohé pleso (TROJ) and a tarn lake Batizovské pleso (BAT). Taking advantage of young unaltered sediments, well-known source area, and main biomass producers, we used an actualistic approach and interpreted sedimentary lipid distributions using fingerprints of modern plant groups. Four chemostratigraphic units were defined in TROJ lake and five units in BAT lake, with boundaries and environmental changes roughly conforming to paleoclimatic intervals of the Holocene. The dry climate was recorded in the period 13,200 BP–11,500 BP, coincident with Younger Dryas stadial. In the sediment of TROJ lake at ca. 5,200 BP asharp spike in the abundance of the aromatic terpenoid retene, decoupled from the trend of other abietane-type diterpenoids, may best be explained by episodic flooding due to the rise of the water table. Diploptene as abiomarker for bacterial activity is suggested to indicate the development of soil cover at the end of the B/A interstadial and its gradual increase in abundance in the Holocene most reflecting an extension of vegetated area and more complex development of soil cover. Based on the absence of conifer biomarkers in the sediments of BAT lake, the upper limit of the continuous Pinus mugo scrub never reached the altitude of 1880 m a.s.l. between 16,247 and 4,420 BP, whereas conifer canopy was permanently present around TROJ lake at 1611 m a.s.l. between 10,439 and 3,113 BP.

The scarcity of fossils in the African rainforest. Archaeo-paleontological surveys and actualistic taphonomy in Equatorial Guinea

ABSTRACT The African rainforest is considered a ‘palaeontological desert’, exemplified with the virtual absence of ape fossils from the last 10 Ma. To overcome this deficiency of the fossil record, archaeo-palaeontological surveys have been undertaken in the rainforest of Equatorial Guinea. We have inventoried 225 outcrops and eluvial materials and the formation of ‘stone lines’ (of diverse genesis) predominate. Close to the Atlantic estuaries, there are short fluvial sedimentary sequences (sands and gravels), where remains of lithic industry and charcoal appear, but in no case macro vertebrate fossils. Given the intensity of the survey, the scarcity of sampling is ruled out as the cause of this ‘palaeontological desert’. Besides, biogenic, biostratinomic and fossildiagenetic factors have been explored by means of an actualistic approach. The rainforest ecosystem produces very low density tanatocenosis. Simultaneously, there is a low rate of sedimentation/erosion and the action of scavengers has not been detected, although the action of ants and termites may be determinant. Two fossildiagenetic factors can be inferred: lixiviation as a destructive cause and the existence of periods of intensive erosion. The search for palaeontological record should focus on protected sedimentary environments (rockshelters) or more confined ones (maars and small endorheic basins).

EVALUATING THE ICHNOFOSSIL TEREDOLITES AS AN INDICATOR OF SALINITY AND PALEOENVIRONMENT

ABSTRACT The ichnogenus Teredolites and the Teredolites Ichnofacies is an accepted proxy for marine influence in paralic to open marine depositional environments. Actualistic approaches and the process-ichnologic framework allow independent analysis of both quantitative and semiquantitative data to interpret the physicochemical conditions when Teredolites are present. Measurements collected in modern environments and Jurassic–Eocene successions produce a spatially and temporally robust dataset of 14,137 borings from 17 tracemaking genera. Life history strategies of extant tracemakers are reflected in Mesozoic borings, which allow reconstruction of paleosalinity. Trends extrapolated indicate four ecotones in modern paralic to nearshore settings, which can be identified into the Late Cretaceous. These zones display variation in boring metrics (length [L], width [W], L:W ratio, size diversity index), densities, and relative composition of Teredolites. Zone 1 represents upper estuary to tidally modified fluvial successions with salinities from 0.5–10 ppt (oligohaline to alpha-mesohaline). Zone 2 represents upper to central estuary successions with salinities from 10–19 ppt (beta-mesohaline to lower polyhaline). Zone 3 represents central to lower estuary successions with salinities from 15–30 ppt (beta-mesohaline to euhaline). Zone 4 represents backshore to open marine successions with salinities from 20–30+ ppt (polyhaline to euhaline). Boring metrics compared against identified fossil genera suggest high species richness in the Western Interior Seaway coincided with physical adaptations to compensate for interspecific competition—differences in reproduction style and media preferences at the time of settlement—in the Late Cretaceous.

Actualistic approaches to interpreting the role of biological decomposition in microbial preservation.

Taphonomic processes, especially post-mortem biological decomposition, act as crucial controls on the microbial fossil record. Information loss during the fossilization process obscures interpretation of ancient microbial ecology and limits our view of preserved ecosystems. Conversely, taphonomic information can itself provide insight into fossilization pathways and processes. This information-gain approach requires specific attention to taphonomic patterns in ancient assemblages and robust modern analogue data to serve as points of reference. In this study, we combine experimental taphonomy with decomposition models in order to constrain taphonomic hypotheses regarding Proterozoic microfossil assemblages. Several filamentous and coccoidal prokaryotic and eukaryotic phototrophs were evaluated for taphonomic pattern over the course of a short (~100days) decomposition experiment. In parallel, simple numerical models were constructed to explain potential taphonomic pathways. These analogue data were then compared to two Mesoproterozoic fossil assemblages, the ~1.5Ga Kotuikan Formation, Siberia, and the ~1Ga Angmaat Formation, Canada. Concordant with previous experiments and observations, our results suggest that sheath morphology is more persistent than cell/trichome morphology during early stages of decomposition. These experiments also suggest that taphonomic change in cell morphology may follow one of several trajectories, resulting in distinct taphonomic endpoints. Model output suggests two categories of underlying mechanism and resultant taphonomic trajectory: (1) uniform decomposition, resulting in a low overall taphonomic grade and poor preservation, and (2) faster decomposition of structurally compromised individuals, producing a final population with better overall preservation of very few individuals. In this experiment, cells of coccoidal organisms exhibit the first pattern and trichomes of filamentous organisms and some sheaths exhibit the second. Comparison with preserved microfossil assemblages suggests that differences in taphonomic pattern between parts of an assemblage could be useful in assessing taphonomic processes or degree of taphonomic loss in an entire assemblage.

Night Capture of Roosting Cave Birds by Neanderthals: An Actualistic Approach

Evidence is accumulating on the regular and systematic Neanderthal exploitation of birds. However, the motivations, mechanisms, and circumstances underlying this behavior remains little explored despite their potential implications on Neanderthal ecology and capabilities. Fossil remains of choughs (Pyrrhocorax, Corvidae) are among the most abundant in cave sites with Mousterian technology. We reviewed the evidence showing that Neanderthals processed choughs for food, and confirmed that it occurred frequently over a widespread spatial and temporal scale. This lead us to propose the hypothesis that the cave-like refuge is the keystone resource connecting Neanderthals and choughs captured at night in rocky shelters eventually used by both species. By adopting an actualistic approach, we documented the patterns of refuge use and population dynamics of communally roosting choughs, the strategies and technology currently used to capture them, and their behavioral response against experimental human predators at night. Actualistic experiments showed that large numbers of choughs can be captured without highly sophisticated tools at night regularly and periodically, due to their occupation year-round during long-term periods of the same nocturnal shelters, the constant turnover of individuals, and their high site tenacity at these roost-sites even after recurrent disturbance and predation. Captures even with bare hands are further facilitated because choughs tend to flee confused into the cavity in darkness when dazzled and cornered by human (experimental) predators. Given the extreme difficulty of daylight chough capturing in open country, nocturnal hunting with the help of fire in the roosting caves and consumption in situ are proposed as the most plausible explanations for the strong association of choughs and Neanderthals in fossil assemblages. Night hunting of birds has implications for the social, anatomical, technological, and cognitive capacities of Neanderthals.

GIS modeling of lithic procurement in highlands: Archaeological and actualistic approach in the Andes

The purpose of this work is to model human movements and lithic procurement costs in high-altitude environments on the basis of geographical aspects. Using GIS we analyzed movement costs that can be applied as of early occupation times in the Southern Andes. We compared curves used to analyze pedestrian movements and contrasted actualistic and ethnographic information in the Andes. We adapted the Tobler Offpath Hiking algorithm to GIS and estimated movement costs in the process of exploiting lithic resources that can be considered within local, non-local and extra-regional categories in Andean topographies as a function of isochrons or times of movement. We propose “local” to be the range of space which can be accessed in one 8-hour movement day. On this scale we establish a ranking regarding the costs of accessing the sources of raw material. The resulting movement scales can be useful for works in comparable environments and in different stages of occupation of high-altitude spaces.

Bushmeat skeletal waste from an Atlantic African rainforest (Equatorial Guinea) as a test for the Mammal Community Structure Analysis in paleoecology

AbstractMammalian Community Structure Analysis (MCSA) is a widely used paleoecological method for reconstructing environments in fossil sites where apes and hominins are present. However, any fossil assemblage is the result of complex ecological and taphonomic processes that may obscure biological interpretation. In this work, we test the validity of the MCSA for the reconstruction of African rain forest environments through an actualistic approach. For this purpose, we compare the living Mammalian Community Structure of the National Park of Monte Alen (MA) and surrounding areas (Equatorial Guinea, Río Muni) with the one inferred from associations of skeletal remains (ASRs) collected in villages of the area. It was found that in equatorial rain forest contexts, humans are a significant accumulating agent of skeletal remains, in contrast to other accumulating organisms, which are absent. In villages where hunting of wild animals (bushmeat) is regular, a good number of osteological remains from food residues are deposited near the houses. We collected six samples from five villages and treated each of them as “skeletal associations.” We also considered a cumulative deposit composed by the total sample of 3153 skeletal remains. Mammalian Community Structure was estimated using three ecovariables: weight, locomotor adaptation, and diet. Cluster and Correspondence Analysis of the three ecological variables validated the fauna of MA as that of an African tropical forest. Next, the ASRs were compared with the fauna of MA. Some of the localities allowed accurate environmental reconstruction; however, three “skeletal associations” do not provide the minimum amount of data needed for their characterization, ecological biases being evident. The skeletal assemblage that best matches the living reference community is the composite sample. From a paleoecological reconstruction viewpoint, the tropical forest signal is conserved when evaluating percentage relationships between the most diagnostic ecovariables, particularly fruit‐eating mammals versus carnivores and arboreal mammals. Taken together, the MCSA is effective in detecting African tropical ecosystems.

Regurgitalites – a window into the trophic ecology of fossil cephalopods

Fossil oral ejecta that exclusively contain bivalved calcitic lower jaws of ammonites (=aptychi) from Late Jurassic Solnhofen-type deposits of southern Germany are described. Based on the symphysis length of aptychi the ammonite shell diameters were reconstructed, ranging from 5 to 170 mm. To identify the potential ammonite predator published reports on stomach contents, coprolites and ammonite-palaeopathology were critically assessed. Implementation of the actualistic approach, together with some functional considerations, includes the identification of modern cephalopod predators with a focus on the modern Nautilus , and the distribution of vomiting behaviour among them. Stomach fluid pH is also important because species with an alkaline stomach pH are unable to dissolve calcareous hardparts and have to orally eject such material. Herein, we regard coleoids with an opportunistic diet as the most likely producers of the aptychi-bearing regurgitalites. This is based on finds of aptychi in the stomachs of the two coleoids Plesioteuthis and Trachyteuthis. They were likely fast, highly manoeuvrable swimmers. Both share a strong, triangular-shaped jaw apparatus that could possibly crush ammonite shells as well as arms equipped with suckers to hold their prey. Circumstantial evidence for coleoids as the producers comes from the alkaline pH of the stomach fluids of modern coleoids. Supplementary material: Data for lamellaptychi are available at https://doi.org/10.6084/m9.figshare.c.4695002

Alteration of rocks by endolithic organisms is one of the pathways for the beginning of soils on Earth

Subaerial endolithic systems of the current extreme environments on Earth provide exclusive insight into emergence and development of soils in the Precambrian when due to various stresses on the surfaces of hard rocks the cryptic niches inside them were much more plausible habitats for organisms than epilithic ones. Using an actualistic approach we demonstrate that transformation of silicate rocks by endolithic organisms is one of the possible pathways for the beginning of soils on Earth. This process led to the formation of soil-like bodies on rocks in situ and contributed to the raise of complexity in subaerial geosystems. Endolithic systems of East Antarctica lack the noise from vascular plants and are among the best available natural models to explore organo-mineral interactions of a very old “phylogenetic age” (cyanobacteria-to-mineral, fungi-to-mineral, lichen-to-mineral). On the basis of our case study from East Antarctica we demonstrate that relatively simple endolithic systems of microbial and/or cryptogamic origin that exist and replicate on Earth over geological time scales employ the principles of organic matter stabilization strikingly similar to those known for modern full-scale soils of various climates.

Paleoecological and isotopic analysis of fossil continental mollusks of Sandelzhausen (Miocene, Germany)

The fossil molluscan fauna of Sandelzhausen (Early/Middle Miocene, SE Germany) comprises a total of 44 species, mostly terrestrial pulmonate snails. Herein we present a paleoecological analysis of this fauna based on an actualistic approach and on data on stable isotopes of carbon and oxygen (assessed from specimens of the freshwater lymnaeid snail Galba dupuyiana and the terrestrial clausiliid snail Pseudidyla moersingensis). The paleoecological reconstruction achieved here is in line with previous works, with some novelties and minor modifications. The basal sediment layers point to a swampy area with ponds and/or oxbow lakes (closed system, as indicated by the covariation between oxygen and carbon isotopic signals of G. dupuyiana), prone to seasonal flooding events. This environment would then gradually transition into a perennial lake, as indicated by: the proportion of planorbids, the appearance of aquatic species intolerant to desiccation, and the decoupling of the covariation between oxygen and carbon isotopic signals of G. dupuyiana. The terrestrial habitat would have developed from a more open environment (semi-arid/sub-humid scrubland) to a sub-humid/humid denser forest afterwards. Still, species from drier and more open environments are present throughout all the layers, suggesting that these habitats persisted in the lake’s hinterland. The mean annual temperature, calculated from the oxygen isotopic composition of P. moersingensis, ranges from 18.5 to 20.5 °C, but with no significant trend of change throughout the layers.

Остракоди крайових частин Борисфенської затоки Східного Паратетису в середньому сарматі

This work continues the analysis of assemblages of ostracoda from the Middle Sarmatian deposits of the Borisphen Gulf of the Eastern Paratethys. Ivanova at al. (2007), Bondar (2015) present data on the history of the study of Sarmatian ostracods, on the factual data, methods of study, and lithological and palaeontological description of the composite Sarmatian sections of the marginal parts of the Borisphen Gulf. This publication presents a palaeoecological analysis of the ostracod assemblages, which contributes to the description of the shallow-marine environment which existed in the Middle Sarmatian basin. The material studied consists mainly of benthic ostracods, closely associated with the near-bottom environment of the basin. This makes them a reliable indicator of the palaeoecological environment. Any changes of the living environment is leaded to restructuring of the entire ostracod assemblage. The main environmental factors, influencing the systematic and quantitative composition, and the domination of one taxa over others, include water depth, salinity, hydrodynamic conditions in the basin, temperature conditions, substrate type, and organic carbonate and oxygen content of the water. The reconstruction of the palaeoenvironment is based primarily on the actualistic approach, where the environmental parameters of modem communities are extrapolated to the ancient fauna with certain assumptions. A total of 16 species of ostracod, belonging to 6 genera of 6 families, were identified in the Middle Sarmatian deposits. Investigation of these ostracod assemblages included taxonomic, quantitative, taphonomic and palaeoecological analyses. The palaeoecological analysis of ostracods from the deposits of the marginal parts Middle Sarmatian sea demonstrates that the assemblages developed in the more or less favorable environments of a warm shallow basin (deep up to 20 m, temperature about 20 oC). Limited diversity of the species, abundance of certain specimens, large and heavy shells of ostracods are typical of the shallowest parts of a basin with active hydrodynamic environments (Aurila). The highest taxonomic diversity of the ostracod associations was encountered in the fairly shallow and calm environments with low sorting of substrate and weak near-bottom hydrodynamics (Loxoconcha, Leptocythere). The salinity of the basin was unstable. So there are Cyprideis torosa, Cyprinotus luminosus in the assemblages.

Longitudinal Taphonomic Studies of Mammal Carcasses from the Rio Salado Valley, Mendoza, Argentina

Taphonomic studies aid in understanding the transition of organic matter from living contexts (the biosphere) to geological contexts (the lithosphere), and how agents and processes affect skeletal remains in the archaeological record. Archaeological research in the Atuel River valley, Mendoza, Argentina, has been carried out for several years. However, actualistic approaches to examine local and regional taphonomic processes have only been recently developed in this area. Longitudinal studies of disarticulation and dispersion of bones from carcasses are presented here in order to understand how skeletal materials are naturally added to, subtracted from, and mixed within the archaeological record. In this paper we explore variability in the influence of taphonomic processes in different microhabitats of the valley and how these mechanisms impact the potential of mixing during bone deposition in the archaeological record. There are some qualitative differences between carcasses deposited in different landforms, showing that each place has its own taphonomic history, principally influenced by the geomorphic and ecologic processes that operate in different landforms.

Comment on the paper of Gierlowski-Kordesch and Cassle “The ‘Spirorbis’ problem revisited: Sedimentology and biology of microconchids in marine–nonmarine transitions” [Earth-Science Reviews, 148 (2015): 209–227

Gierlowski-Kordesch and Cassle (2015, Earth-Science Reviews 148, 209–227) interpreted microconchids (extinct tentaculitoid encrusters) as strictly marine, rejecting the previous conclusions that these organisms occupied a variety of habitats ranging from marine to non-marine. We argue that due to misunderstanding of previous statements concerning the affinity of microconchids, the authors used an actualistic approach and incorrectly compared microconchids with modern phoronids, which led to oversimplifications and misinterpretations. Also their idea that microconchids, as supposedly strictly marine organisms, were preserved in non-marine settings only because of transport by storm surges and tsunamis is unsupported on paleontological grounds. These errors led to mistaken conclusions about microconchid paleoecology that must be discussed in order to avoid an erroneous interpretation of microconchid paleoenvironments.

Making numbers count: Beyond minimum numbers of individuals (MNI) for the quantification of mollusc assemblages from shell matrix sites

Abstract Inferences on the relative importance of marine mollusc taxa from archaeological assemblages are usually based on counts of minimum numbers of individuals (MNI) for each taxon present. The exact procedure adopted for estimating MNI will vary according to a range of factors, including the structural properties of the shells of various taxa, the specific characteristics of the shell matrix site and the degree of preservation of the taxa present. This is illustrated by reference to the assemblages of marine molluscs from the shell matrix site of Culverwell, southern Britain. Various indices of quantification are considered (crude MNI, standardized MNI, weight of shell, meat-yield adjusted MNI, and rates of incorporation of shell into the site) and the applicability of each is examined in relation to a range of research objectives. Our study shows that issues relating to counting MNIs are not only taxon-, but also site-, specific. Even when MNI counts are accurate estimates of shells surviving at and recovered from a site, they are not necessarily reliable estimates of the relative dietary importance of the quantified taxa. We suggest an additional means of addressing such methodological challenges, based on meat yields derived from studies of living molluscs of taxa encountered archaeologically. The Culverwell case study is an example of how sampling, recovery and quantification procedures need to be adapted to the characteristics of the site and the preservation characteristics of the mollusc assemblages, and shows the difficulty of gaining fully standardized MNI counts across all the principal taxa. Moreover, counting MNIs will not always give accurate estimates of the relative importance of mollusc taxa in past human subsistence. Archaeomalacological investigations of past human diets should, we suggest, include studies of the living animals as well as of the shells of the species encountered in the archaeological record. Actualistic approaches, by permitting more nuanced interpretations of marine molluscs from archaeological sites, are likely to be of value to many archaeomalacological research objectives.

Paleodietary reconstruction using stable isotopes and abundance analysis of bovids from the Shungura Formation of South Omo, Ethiopia

Preservation of the stable carbon isotopic composition of fossil tooth enamel enables us to estimate the relative proportion of C3 versus C4 vegetation in an animal's diet, which, combined with analysis of faunal abundance, may provide complementary methods of paleoenvironmental reconstruction. To this end, we analyzed stable carbon isotopic composition (δ13C values) of tooth enamel from four bovid tribes (Tragelaphini, Aepycerotini, Reduncini, and Alcelaphini) derived from six members of the Shungura Formation (Members B, C, D, F, G, and L; ages from ca. 2.90–1.05 Ma (millions of years ago) in the Lower Omo Valley of southwestern Ethiopia. The bovids show a wide range of δ13C values within taxa and stratigraphic members, as well as temporal changes in the feeding strategies of taxa analyzed throughout the middle to late Pliocene and early Pleistocene. Such variation suggests that the use of actualistic approaches for paleoenvironmental reconstruction may not always be warranted. Alcelaphini was the only taxon analyzed that retained a consistent dietary preference throughout the sequence, with entirely C4-dominated diets. Reduncini had a mixed C3/C4 to C4-dominated diet prior to 2.4 Ma, after which this taxon shifted to a largely C4-dominated diet. Aepycerotini generally showed a mixed C3/C4 diet, with a period of increased C4 diet from 2.5 to 2.3 Ma. Tragelaphini showed a range of mixed C3/C4 diets, with a median value that was briefly nearer the C4 end member from 2.9 to 2.4 Ma but was otherwise towards the C3 end member. These isotopic results, combined with relative abundance data for these bovids, imply that the environment of the Lower Omo Valley consisted of a mosaic of closed woodlands, with riverine forests and open grasslands. However, our data also signify that the overall environment gradually became more open, and that C4 grasses became more dominant. Finally, these results help document the range and extent of environments and potential diets that were available to the four hominin species encountered in the Shungura sequence.

The Exceptional Preservation of Plant Fossils: A Review of Taphonomic Pathways and Biases in the Fossil Record

The exceptional preservation of plant fossils falls into two categories: whole plant preservation and anatomical detail. Whole plant preservation is controlled primarily by transport and event preservation (e.g., ash falls), whereas anatomical preservation can occur through one of several taphonomic pathways: compression-impression, silicification, coal-ball formation, pyritization, and charcoalification. This review focuses on these taphonomic pathways, highlighting important factors and controls on the exceptional preservation of plants. Special emphasis is given to data garnered from experimental and actualistic approaches.

Decomposing biases in paleoenvironmental proxy data from pollen and micromammalian remains in caves: An actualistic approach

Multiple forms of bias must be taken into account when interpreting paleoenvironmental proxy records in terrestrial Quaternary sequences. This fact complicates attempts to correlate records from different types of proxy data accumulated at the same site. We applied an actualistic approach to assess the correspondence between two major types of proxy data – pollen and micromammalian remains – in their representation of background vegetation within a cave site in Mount Carmel, Israel. Data on both pollen and micromammalian remains were extracted from a relatively large sample of 27 owl pellets accumulated inside the cave. These pellets were compared to other pollen sources from inside as well as outside the cave including owl nest sediment and samples from moss and lichen. These data were analyzed through multivariate correspondence analysis to examine associations among different pollen sources as well as between the pollen and micromammalian remains within the pellets. The pooled composition of the pellets revealed close association between pellets and moss samples from inside the cave. Moss and lichen samples from outside the cave, on the other hand, showed clear over-representation of Pinus pollen. In spite of some associations that we detected among specific pollen types and micromammalian taxa in the pellets when considering frequency data, there was good correspondence among the cave sources in representation of the Mediterranean Quercus maquis vegetation formation extending below the cave. We attribute these results in part to the relatively large sample of pellets and high taxonomic diversity. These findings are also explained by the interaction between two key factors including the orientation of the cave towards the nearby Quercus maquis and accumulation of both windblown pollen and pellets within the cave from this nearby source. We conclude that long-term pellet accumulations inside caves can contribute to inter-proxy correlation when dealing with pollen and micromammalian remains from pellet sources and provide important and reliable sources of paleoenvironmental data.

Characterisation of Ottnangian (middle Burdigalian) palaeoenvironments in the North Alpine Foreland Basin using benthic foraminifera—A review of the Upper Marine Molasse of southern Germany

Abstract Considerable facies changes and varying foraminiferal assemblages have been described from the lower Miocene sediments of the Upper Marine Molasse in the North Alpine Foreland Basin of southern Germany, and have resulted in the distinction of a “Western Molasse” and “Eastern Molasse”. However, the causes and processes leading to these local differences have largely remained unexplored to date. The aim of this study is to explore possible explanations in order to better understand the palaeogeographic, stratigraphic and environmental setting. The study focuses on the Ottnangian (middle Burdigalian) segment of the Upper Marine Molasse in southern Germany, and includes a review of previously published data, together with new data from the borehole Stockhausen which is located between the areas of the Eastern and Western Molasse. Methods include quantitative analysis of benthic foraminiferal assemblages, qualitative studies of planktonic foraminifera and calcareous nannoplankton, as well as palaeoenvironmental considerations based on the actualistic approach. The results of these studies demonstrate that the lower and middle Ottnangian Upper Marine Molasse include a single transgressive–regressive sedimentary cycle with gradual changes of foraminiferal assemblages in the Eastern Molasse. On the other hand, two sedimentation cycles are recognizable in the Western Molasse and in the borehole Stockhausen where the lower and middle Ottnangian sediments are separated from one another by an unconformity and display an abrupt change in lithofacies and foraminiferal content. The benthic foraminiferal assemblages from the area of the Western Molasse are indicative of a rather shallow sea, but indicative of a much deeper facies in the basin area of the Eastern Molasse. It can therefore be concluded that the shallow sea to the west was more sensitive to minor changes in sea level than the area of the Eastern Molasse, either because of global sea level variation or as a result of regional tectonics. This means that the occurrence of two sedimentary cycles in the Western Molasse, and absence of the second cycle in the Eastern Molasse, may be the result of shallower water depths and a lower subsidence rate in the area of the Western Molasse. Another interesting result from our studies relates to the sea-level highstand and maximum extension of the Upper Marine Molasse Sea that, based on our studies, has occurred during the early Ottnangian, rather than during the middle Ottnangian as suggested previously. During this highstand, the area of the Eastern Molasse displays a differentiation into a deep neritic basin facies characterised by high organic flux and moderate oxygen depletion at times, and a marginal marine facies with well oxygenated environments. The latter facies remained poorly understood until recently. The entire region of the South German Molasse Basin was affected by a regression during the middle Ottnangian. This phase is characterised by unstable environmental conditions in the Eastern Molasse, i.e. salinity fluctuations and temporarily strong oxygen depletion of bottom waters. In the Western Molasse, life conditions became even worse and, as a result, a drastic decline in marine life is observable.

Actualistic approaches to the systematics and facies relations of clastic karst deposits

Clastic karst deposits occur at different positions within karst areas, whereas surface karst deposits, sediments of the crack filling facies, the cave entrance facies and the inner cave facies have to be distinguished. The karstification itself is of minor importance for the formation of clastic deposits. Except for incasional debris and impure limestones or marls the contribution of carbonate rocks to clastic karst deposits is low. The majority of clastic material is allogenic and siliciclastic. Regarding the depositional processes cave sediments can be divided into fluvial cave deposits, gravitative or percolative deposits, decomposition deposits and rock breakdown. An actualistic approach could be a useful tool for the identification of fluvial cave deposits. By means of the depositional features of recent cave sediments and classical sedimentological features cave deposits of unknown origin can be classified.

Taphonomy and taphofacies analysis of lingulid brachiopods from Devonian sequences of the Paraná Basin, Brazil

The extreme abundance of lingulid valves in some outcrops of the Devonian sequences of the Paraná Basin, and their absence in others, where other benthic taxa dominate, was the starting point to the present research. Twenty-one outcrops were sampled and characterized taphonomically. These outcrops record an epeiric muddy sea, influenced by episodic storms. In twelve out of the 21 outcrops (the Devonian sequences B, C, D and E), massive occurrences of complete and fragmented valves of lingulids, oriented parallel to the bedding plane, were documented. The occurrence of fragments together with complete, but disarticulated valves, suggests that the post-mortem sorting and transport is unlikely to have been notable. This claim is also supported by the fact that in situ preserved lingulid valves were always recorded, even if in low numbers. However, some time averaging may have occurred. This is because entire valves (presumably removed from their burrows just prior to burial) and fragmented ones (probably reworked or exposed on sediment–water interface for some days or a few weeks) were found together. Rosette and stringer arrangements of the lingulid pavements represent the first record of distal reworking of this kind of bioclastic material. The Devonian “lingulid outcrops” studied here represent fossil accumulations that likely formed with contributions from multiple factors. However, the extrinsic physico-chemical factors are difficult to infer by analogy with modern environments because of the unique setting that typified Palaeozoic epeiric seas. On the other hand, an actualistic approach can be used to assess some of the taphonomic controls exerted by intrinsic characteristics of lingulid brachiopods, including shell thickness and life habit. The lingulid-rich units, with their distinct taphonomical signatures, represent a clearly definable taphofacies (“lingulid taphofacies”) characterized by abundant (often complete) occurrence of lingulid valves parallel to the bedding plane in light grey and dark grey siltstones and rare occurrences of lingulid valves in black shales. The lingulid taphofacies is associated with a range of proximal marine settings, ranging from the lower shoreface (lowermost intertidal) to the distal transitional offshore (shallow subtidal) zones. The pattern of patchy distribution of lingulids, observed in some present-day environments, was rarely seen in the studied sequences.