Palaeoecological Changes Research Articles

Tragelaphus nakuae: evolutionary change, biochronology, and turnover in the African Plio-Pleistocene

Fossil Bovidae constitute one of the most significant proxy records for evolutionary and palaeoecological change in Africa. Tragelaphus nakuae is a regularly encountered antelope in the East African Plio-Pleistocene, and is a common component of hominin faunas. As previously understood, this species ranged for almost 2 million years, encompassed a large range of morphological variation, exhibited relative stasis in the face of environmental perturbations, and left no known living descendants. I here review and revise the fossil record of this tragelaphin bovid, finding that specimens older than ∼2.8 Mya and previously attributed to T. nakuae or a close form are in fact referable to a distinct, but ancestral, species. This new interpretation adds these fossil tragelaphins to the body of evidence supporting major faunal turnover occurring around 2.8 Mya in concert with global climatic change. I also document morphological changes that occur through the duration of T. nakuae, particularly after 2.3 Mya. These taxonomic revisions allow for refined biochronological estimates for several East African Plio-Pleistocene sites and specimen assemblages of uncertain age. A phylogenetic analysis suggests that the T. nakuae lineage is related to the extant bongo (Tragelaphus eurycerus), relating this living but enigmatic forest antelope to the fossil record. One resulting palaeoecological hypothesis is that the bongo's modern fragmented range represents the relicts of a much more widely distributed late Pliocene African forest belt. This study highlights the importance of specimen-based approaches for elucidating the pattern and timing of major evolutionary events. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 162, 699–711.

The Mid-Miocene East African Plateau: a pre-rift topographic model inferred from the emplacement of the phonolitic Yatta lava flow, Kenya

Abstract High topography in the realm of the rifted East African Plateau is commonly explained by two different mechanisms: (1) rift-flank uplift resulting from mechanical and/or isostatic relaxation and (2) lithospheric uplift due to the impingement of a mantle plume. High topography in East Africa has far-reaching effects on atmospheric circulation systems and the amount and distribution of rainfall in this region. While the climatic and palaeoenvironmental influences of high topography in East Africa are widely accepted, the timing, the magnitude and this spatiotemporal characteristic of changes in topography have remained unclear. This dilemma stems from the lack of datable, geomorphically meaningful reference horizons that could unambiguously record surface uplift. Here, we report on the formation of high topography in East Africa prior to Cenozoic rifting. We infer topographic uplift of the East African Plateau based on the emplacement characteristics of the c. 300 km long and 13.5 Ma Yatta phonolitic lava flow along a former river valley that drained high topography, centred at the present-day rift. The lava flow followed an old riverbed that once routed runoff away from the eastern flank of the plateau. Using a compositional and temperature-dependent viscosity model with subsequent cooling and adjusting for the Yatta lava-flow dimensions and the covered palaeotopography (slope angle), we use the flow as a ‘palaeo-tiltmeter’. Based on these observations and our modelling results, we determine a palaeoslope of the Kenya dome of at least 0.2° prior to rifting and deduce a minimum plateau elevation of 1400 m. We propose that this high topography was caused by thermal expansion of the lithosphere interacting with a heat source generated by a mantle plume. Interestingly, the inferred Mid-Miocene uplift coincides with fundamental palaeoecological changes including the two-step expansion of grasslands in East Africa as well as important radiation and speciation events in tropical Africa.

Late Vistulian and Holocene changes in the Ner river valley in light of geological and palaeoecological data from the Ner-Zawada peatland

Th e Ner-Zawada peatland is located in the valley of the Ner River in Central Poland. It is a small fen peatland that was formed in the Allerod Period. In the Younger Dryas, it was transformed into a lake and became a peatland again in the Holocene. Within the peatland and around it, geological and archaeological research was carried out. A sediment core collected in the central part of the peatland was subjected to the analysis of pollen, fossil Cladocera, and absolute dating. Th is study allows a reconstruction of palaeoecological changes in the peatland and drawing conclusions about the palaeogeography of the middle section of the Ner River valley during the past 13 000 years.

Sequence stratigraphic interpretation of a Pennsylvanian (Upper Carboniferous) coal from the central Appalachian Basin, USA

AbstractPeat mires retain a sensitive record of water‐table (base‐level) fluctuations throughout their accumulation. On this basis, coals provide one of the best opportunities to interpret high‐resolution base‐level change in ancient non‐marine deposits. The petrographic composition of 275 samples collected from 11 localities along a 100 km south‐west to north‐east transect across the regionally extensive (>37 000 km2) Pennsylvanian (Upper Carboniferous) Fire Clay coal of the Central Appalachian Basin, USA was analysed to determine its internal stratigraphy. The coal is positioned within the late lowstand/early transgressive systems tract of a fourth‐order depositional sequence. The results of the petrographic analyses reveal a cyclicity in the composition of the Fire Clay coal, which defines six units that are correlated over more than 100 km. Each coal cycle is characterized by a gradual upward transition from vitrinite‐dominated to inertinite‐dominated coal, which represents a ‘drying‐up’ succession. Increased concentrations of resistant peat components at the top of the drying‐up successions indicate reduced peat accumulation rates associated with slowing rate of water‐table rise, and may represent a residue of peat remaining from a phase of exposure and erosion resulting from a falling water table. These drying‐up successions are bound by surfaces that display an abrupt coal facies shift from inertinite‐rich to vitrinite‐rich coal, representing a rapid water‐table rise. Each cycle represents markedly different mire conditions with different aerial distributions, which supports the notion of temporal disconnection between each unit of coal, and suggests that considerable time may be ‘locked‐up’ in unit bounding exposure surfaces. Recognition that the rate of peat accumulation in a mire may vary considerably through time, has important implications for studies which assume that peat and coal successions provide continuous and time‐invariant records of base‐level fluctuations or palaeoecological change.

From ice age to modern: a record of landscape change in an Andean cloud forest

AbstractAim To investigate the palaeoecological changes associated with the last ice age, subsequent deglaciation and human occupation of the central Andes.Location Lake Pacucha, Peruvian Andes (13°36′26″ S, 73°19′42″ W; 3095 m elevation).Methods Vegetation assemblages were reconstructed for the last 24 cal. kyr bp (thousand calibrated 14C years before present), based on pollen analysis of sediments from Lake Pacucha. An age model was established using 14C accelerator mass spectrometry dates on bulk sediment. Fossil pollen and sedimentological analyses followed standard methodologies.Results Puna brava replaced the Andean forest at the elevation of Lake Pacucha at the Last Glacial Maximum (LGM). Deglaciation proceeded rapidly after 16 cal. kyr bp, and near‐modern vegetation was established by c. 14 cal. kyr bp. The deglacial was marked by the range expansion of forest taxa as grassland taxa receded in importance. The mid‐Holocene was marked by a lowered lake level but relatively unchanged vegetation. Quinoa and maize pollen were found in the latter half of the Holocene.Main conclusions Temperatures were about 7–8 °C colder than present at this site during the LGM. The pattern of vegetation change was suggestive of microrefugial expansion rather than simple upslope migration. The mid‐Holocene droughts were interrupted by rainfall events sufficiently frequent to allow vegetation to survive largely unchanged, despite lowering of the lake level. Human activity at the lake included a 5500‐year history of quinoa cultivation and 3000 years of maize cultivation.

Palaeoecological methods for assessing marine ecosystem recovery following the Late Permian mass extinction event

Different authors use different methods to assess Permian–Triassic palaeoecological changes, yet no comparative study of different methodologies has been published. We compared two methods of assessing palaeoecological parameters such as diversity, richness and skeletal abundance from limestone thin sections: point-counting and an equal area approach. Results demonstrated that there are significant differences between methodologies. Point-counting is relatively quick but has drawbacks. It is biased with respect to organism size, over-estimates larger taxa/bioclasts, and underestimates smaller taxa/bioclasts. Some point-counting palaeoecological data are not considered useful for measuring biotic recovery because they are affected by taphonomic processes: for example, the presence of diagenetic veins may reduce presumed skeletal abundance; winnowing may increase it. Trends in abundance between locations and regions through time, however, tend to broadly agree between methods, although we recorded Early Triassic samples with much higher skeletal abundances (up to 75%) than in previous published studies. Data from locations in Italy, Oman, and USA were compared. The most diverse samples are Early Induan (Griesbachian) in age from Oman, whilst the Late Induan–Early Olenekian (Dienerian–Smithian) samples from western USA are less diverse. These data agree with previously published inferences of regional variability in recovery rates from field-based macrofossil analyses of tiering and trace fossils.

Antracología y paleoecología en el cuadrante suroriental de la Península Ibérica: las aportaciones del yacimiento de la Edad del Bronce de Terlinques (Villena, Alicante)

In this paper we present the results of the charcoal analyses from the Bronze Age settlement of Terlinques (Villena, Alicante). We discuss the predominance of Pinus halepensis in relation to the other woody species. Taking into account the environmental conditions (availability of materials) and the bio-geographical context, the Villena Corridor is a frontier territory where floral and climatic influences of the Spanish Meseta and of the Iberian Southeast converge. Comparison with other anthracological and palynological studies allow us to propose some thoughts on palaeoecological changes in the Iberian Southeast.

Discussion on palaeoecology of the Late Triassic extinction event in the SW UK Journal , Vol. 165, 2008, pp. 319–332

Jonathan Radley writes: The Penarth Group (of Late Triassic and possibly ranging to Early Jurassic age) of the southern UK marks a marine transgression and the establishment of a shallow epicontinental seaway (Hallam & El Shaarawy 1982; Warrington & Ivimey-Cook 1992), influenced by regressive–transgressive pulses and characterized by rapid facies changes (Hallam & Wignall 2004; Hesselbo et al . 2004). A well-documented invertebrate macrofauna includes corals, brachiopods, molluscs and echinoderms (Swift & Martill 1999). Facies developments range from storm-influenced, shallow-marine mudrocks (Westbury Formation) upwards into calcareous mudstones, siltstones and essentially fine-grained carbonates (Lilstock Formation) demonstrating extremely shallow-water conditions: wave ripples, storm beds, desiccation and omission surfaces (Swift 1999 a ; Wignall 2001; Hallam & Wignall 2004). The low-diversity macrofauna of the Lilstock Formation has frequently been attributed to salinities deviating from that of normal seawater within shallow-water, partly landlocked settings, isolated from the open sea (Hallam & El Shaarawy 1982; Swift 1995; Allison & Wright 2005). However, widespread occurrences of stenohaline marine macrofossils such as corals and echinoderms (Swift & Martill 1999) suggest that salinity fluctuations were at most slight (Wignall 2001). Mander et al . (2008) have presented high-resolution benthic macrofaunal data, principally from molluscan macrofossils, for significant palaeoecological change within the Penarth Group of two key sections in the SW UK. Their detailed results demonstrate loss of taxonomic richness within the uppermost Westbury Formation–lower Lilstock Formation (Cotham Member) interval (latest Rhaetian), followed by a poorly fossiliferous interval represented by the latest Rhaetian or early Hettangian upper Lilstock Formation (upper Cotham Member–lower Langport Member). They attributed this pattern to an extinction event followed by a post-extinction ‘Dead Zone’; the latter coinciding with the onset of a negative organic carbon-isotope excursion, and an extinction event recorded in the terrestrial palynoflora. The relatively diverse shelly …

Palaeoecology of the Late Triassic extinction event in the SW UK

A high-resolution palaeoecological study of the shelly invertebrate macrofauna across two marine Triassic–Jurassic boundary sections in the UK (St. Audrie's Bay and Lavernock Point) is presented. Loss of taxonomic richness occurs in the upper Westbury Formation to lower Lilstock Formation (late Rhaetian), but if sample size is taken into account there is little convincing evidence of a catastrophic marine extinction. There is, however, good evidence for significant palaeoecological change in the benthic marine ecosystem at this time. The immediate post-event recovery interval in the upper Lilstock Formation is characterized by assemblages of low abundance, low diversity, high dominance and low evenness. Body-sizes of taxa that survived the event and originated afterwards were low until the later Hettangian. Recovery to higher abundance, higher diversity and higher evenness is recorded in the Psiloceras planorbis Zone. Recovery of the benthic ecosystem in the aftermath of the Late Triassic event was disrupted by marine anoxia and shows additional similarities to the (much slower) recovery that followed the Late Permian event. The pattern of body-size changes recorded in the shelly fossil record closely matches that of the trace fossil record. Shell thickness trends do not support a biocalcification crisis during the Late Triassic biotic event.

A multiproxy peat record of Holocene mangrove palaeoecology from Twin Cays, Belize

The extent and function of coastal mangrove ecosystems are likely to be influenced by future changes in sea level. Multiple proxies of past mangrove ecosystems preserved in a 780 cm long peat core (TCC2) taken from Twin Cays, Belize, record palaeoecological changes since ~8000 cal. yr BP. The proxies included pollen and the stable-isotope (C, N and O) compositions of mangrove leaf fragments. Rhizophora mangle (red mangrove) has been dominant at this site on Twin Cays for over ~8000 years. Variations in δ13 C and δ15N suggest past changes in stand structure between dwarf, transition and tall R. mangle through the Holocene. Marked changes in the δ18O (up to ~4‰) of mangrove leaf fragments throughout TCC2 most likely record variations in the proportion of seawater versus precipitation taken up by past mangroves, reflecting the degree of inundation of the site with seawater resulting from changes in the rate of Holocene sea-level rise. Notably, a decline in peat accumulation rate at ~7200 cal. yr BP correlates with a decrease in the rate of rise in sea level. This was not accompanied by a marked change in the pollen assemblages. However, changes in assemblage composition began to occur ~6300 cal. yr BP, with an increase in Myrsine-type and Avicennia germinans (black mangrove) pollen. An increase in the δ18O between 6100 and 5300 cal. yr BP, which correlates with other records from Central America, indicates a significant increase in the rate of rise in sea level.

A sequence stratigraphical model for the Late Ludfordian (Silurian) of Gotland, Sweden: implications for timing between changes in sea level, palaeoecology, and the global carbon cycle

This paper investigates a time interval within the Late Ludfordian (Late Silurian), involving changes in faunal composition (the Lau Event), a major positive carbon isotope excursion (CIE), and contemporaneous sea-level changes in remote palaeo-basins. Based on the Silurian strata of Gotland (Sweden), we integrate sequence stratigraphy, carbon isotope stratigraphy, and platform-scale palaeoecological changes associated with this turbulent time period in Earth history. Three depositional sequences (sequences Nos. 1–3), including two separate periods of forced regression (falling stage systems tracts, FSSTs) are identified from outcrop and drillcore studies. The sequence stratigraphical framework is interpreted to reflect glacio-eustatic sea-level changes. The CIE starts at the onset of the initial FSST (sequence No. 1), just below the last appearance datum of the conodont Polygnathoides siluricus. The values increase through the ensuing lowstand and transgressive systems tracts (LST and TST) of sequence No. 2 and peak in the following highstand systems tract (HST). A second forced regression (FSST of sequence No. 2) took place in the lower Ozarkodina snajdri Zone. δ13C data are scarce from these siliciclastic strata, but inferably remain high. The δ13C values increase within the LST and earliest TST of sequence No. 3, before a decreasing trend starts within the early TST. δ13C values return to pre-excursion levels within the ensuing HST. The CIE is closely associated with an increase in stromatolites (mats and oncoids) across a wide range of depths and sedimentary environments, and correlations to other basins indicate a global increase in cyanobacterial activity. A drastic decline in level-bottom benthic faunas during the FSST of sequence No. 2 is, however, interpreted as a local response to the progradation of a delta complex (the Burgsvik Sandstone). Biological carbonate production replenishes rapidly within the TST of sequence No. 3, succeeding a thin LST dominated by reworked siliciclastics and chemically precipitated carbonates (ooids). The detailed relationship between the CIE and sea-level change presented herein is not fully consistent with previous reports on the CIEs associated with the lower Silurian Ireviken and Mulde events, respectively. Based on our facies analysis and sequence stratigraphical interpretation, two main mechanisms are suggested as responsible for the Late Ludfordian CIE: (1) a change in the riverine C-weathering flux towards the 13C end member following glacio-eustatically induced subaerial exposure of carbonate platforms throughout the tropics, and, (2) increased photosynthetic activity by benthic cyanobacteria exaggerating the δ13C values of precipitated carbonates.

Palaeoecological changes after the end-permian mass extinction: early Triassic ostracods from northwestern Guangxi Province, South China

Early Triassic (Griesbachian to Spathian) ostracod faunas are here first discovered and described form the Guangxi Province, South China. Thirty-seven species belonging to fourteen genera are recognized. Seven species are new: Bairdia fengshanensis n.sp., Bairdia wailiensis n.sp., Liuzhinia guangxiensis n.sp., Ptychobairdia luciaae n.sp., Ptychobairdia aldaae n.sp., Paracypris jinyaensis n.sp. and Paracypris gaetanii n.sp. The Griesbachian assemblage from the basal microbial limestone is well diversified and does not suggest any abnormal palaeoenvironmental conditions in terms of salinity, temperature or oxygen content. Particularly, the ostracods are typical of well oxygenated water and do not reflect any anoxia. Dienerian and Smithian ostracods are evidenced for the first time and the assemblages suggest less favourable palaeoenviromental conditions. Diversity and abundance of ostracod assemblages recovered from the Spathian on. The main taxonomic turnover among ostracod assemblages occurred seemingly between the Griesbachian and the Spathian.

Replacements of benthic associations in a sequence stratigraphic framework, examples from Upper Ordovician of Sardinia and Lower Devonian of the Massif Armoricain

Sedimentological, palaeoecological and taphonomic analyses were carried out to establish the impact of relative sea-level variations on benthic faunas in a platform depositional context and to propose a reliable palaeoecological model for different palaeogeographic areas during different periods of the Palaeozoic. One Caradocian–Ashgillian section in Sardinia and one Lower Emsian section in the Massif Armoricain have been selected. The approach combines sequence stratigraphy, taphonomy and delineation of recurrent fossil associations. Several sedimentary facies have been recognized in relation to the distance from the shoreline. The succession consists of the stacking of genetic sequences related to sea-level changes linked to cyclic variations of orbital parameters. Several fossil associations, identified by means of multivariate analyses, are recurrent in similar facies. Eleven associations are recognized. These are the Longvillia, Nicolella, Paucicrura and Iberomena associations in the Upper Ordovician of Sardinia; the Adolfia, Stenorhynchia, Chonetid, Crinoid–Brachiopod, Ostracod–Tentaculitid, Bryozoan and Dacryoconarid associations in the Lower Devonian of the Massif Armoricain. The results of multivariate analyses based on the faunal contents are in good accordance with the clustering based on the sequence stratigraphic analysis. Benthic associations are closely related to relative sea-level variations. When the sea-level fluctuations were gradual and moderate, the association replacement is characterized by reorganization of the taxonomic composition, changes in diversity and trophic webs (association replacement by reorganization). When the sea-level changes rapidly, the association replacement is characterized by renewal of the ecological structure (association replacement by renewal). Palaeoecological changes are recognized to be strongly related to sea-level variations.

δ13C and δ15N in the ornithogenic sediments from the Antarctic maritime as palaeoecological proxies during the past 2000 yr

In this paper, we have examined carbon and nitrogen isotopic compositions in two ornithogenic sediment profiles from the Ardley Island and Barton Peninsula of Antarctica for palaeoecological changes during the past 2000 yr. The δ 13C values of the two sediment profiles range from − 22.26‰ to − 19.15‰ (PDB) in Core G and from − 24.01‰ to − 19.87‰ in profile A, showing that the predominant carbon source in the sediments plausibly comes from terrestrial and aquatic plants in Antarctic such as mosses, lichens, and algae in lakes. As these δ 13C values are also close to those in the fresh lake sediments that are not influenced by penguin guano, one may not use the δ 13C values as evidence for the influence of guano on the sediments. The δ 15N values of the two profiles range from 4.75‰ to 18.34‰ (air) and from 5.17‰ to 10.38‰ for Core G and Core A, respectively. The δ 15N variations have positive correlations with the trends of the bio-element contents in the sediments. As the levels of these bio-elements in ornithogenic sediments had been used to reconstruct the changes of historical penguin population and tundra vegetation abundance and diversity, we then suggest that the δ 15N records can be utilized to study palaeoecological processes of penguin. Our results show that penguin population and activity has generally decreased over the past 2000 yr. From 1300 to 900 yr BP and from 1790 to 1860 AD, penguin population and activity experienced two strong decreases. It will be interesting to understand the cause of these decreases.

Late Oligocene climatic changes: Evidence from calcareous nannofossils at Kerguelen Plateau Site 748 (Southern Ocean)

Palaeoecological changes in nannofossil assemblages in the Southern Ocean during Oligocene times are examined through high-resolution, quantitative analyses of samples from Ocean Drilling Program (ODP) Site 748 (Kerguelen Plateau). We quantitatively characterized the palaeoecological preference of groups of species and compared their general trends with those determined at Maud Rise (ODP Sites 690 and 689) (Persico, D., Villa, G., 2004. Eocene–Oligocene calcareous nannofossils from Maud Rise and Kerguelen Plateau (Antarctica): palaeoecological and palaeoceanographic implications. Marine Micropaleontology 52, 153–179). We then attempt a correlation between the main assemblage variation and sea-surface temperature (SST) changes in the Southern Ocean at this time. Relatively stable, cool conditions are interpreted to have persisted from earliest to late Oligocene times, when an increase in abundance of temperate-water taxa is recorded, both at Maud Rise and Kerguelen Plateau, before the Mi-1 event. This reveals a climatic event that probably involved both sites, and which is comparable to that indicated by the global oxygen isotope curve ([Miller, K.G., Wright, J.D., Fairbanks, R.G., 1991. Unlocking the Ice House: Oligocene–Miocene oxygen isotopes, eustasy, and margin erosion. Journal of Geophysical Research, 96, 6829–6848; Zachos, J., Pagani, M., Sloan, L., Thomas, E., Billups, K., 2001. Trends, rhythms, and aberrations in global climate 65 Ma to present. Science, 292, 686–693.]). In the uppermost Oligocene at Site 689, the temperate-water taxa index ([temperate / temperate + cool] * 100) increases from 25.2 Ma. Similarly, at Site 748, the temperate-water taxa index indicates an increase in SST in the late Oligocene, from about 26.5 Ma, at the base of Chron C8n.2n, which is offset by about 1 m.y. between the two areas. The reason for this time difference can probably be found in the location of Site 748 with respect to Site 689, and in the palaeoceanographic setting, taking into account that Site 748 lies north of a deep water passage that separates Kerguelen Plateau from Antarctica, and north of the present day front of the Antarctic Circumpolar Current. The presence of warm-water taxa, exclusively at Site 748, corroborates this hypothesis.

A 3000-Year Culture Sequence from Palau, Western Micronesia

In western Micronesia archaeological sites containing material-culture remains spanning millennia are rare. This paper reports one from Ulong Island in Palau, which is radiocarbon dated to 3000 cal. B.P. The pottery sequence was divided into three assemblages, each distinguished by distinct vessel forms and by the type and proportion of nonplastic temper inclusions. An abrupt transformation of the ceramic assemblage is tentatively dated to around 2400 cal. B.P., coincident with substantial landscape alteration on the main island where pottery was manufactured, indicating that anthropogenic activity may have constrained the raw materials available to prehistoric potters. There is a discontinuity in the sequence from 2000-1000 B.P. that might represent an hiatus in site use. Critical consideration of paleoenvironmental data pointing to human arrival at 4500-4300 cal. B.P. suggests, instead, that climatic events may be responsible for the observed palaeoecological changes. If so, then sites dating to 3300-3000 cal. B.P., such as Ulong, could well be among the oldest in western Micronesia.

Submillennial palynology and palaeoecology of the last glaciation at Taiquemó (∼50,000 cal yr, MIS 2–4) in southern Chile

Stratigraphic palynology of core HE94-2B from a mire at Taiquemó (42.17°S, 73.60°W) on Isla Grande de Chiloé is one of the most closely sampled, continuous Pleistocene records in southern South America. Chronology of the 655-cm core that extends from Marine Isotope Stage (MIS) 4 through the Lateglacial is controlled by 27 finite radiocarbon dates. Sampled at 1-cm intervals, the high temporal resolution (mean ∼85 yr cm −1) captures short-term palaeoecological changes and successional restabilization of plant communities. Preponderance of Gramineae (grass) with Nothofagus dombeyi type (southern beech) characterizing Subantarctic Parkland under a cold climate in MIS 4 was followed by a conspicuously milder interval that lasted for some ten millennia in MIS 3. Of greater frequency and diversity at this time were more thermophilic taxa associated with North Patagonian Evergreen Forest ( Podocarpus, Pilgerodendron type , Pseudopanax, Myrtaceae). Subsequently with increasing cold and hyperhumidity, N. dombeyi type–Gramineae assemblages that included Subantarctic Parkland indicator taxa ( Lepidothamnus, Astelia, Gaimardia) increased stepwise in MIS 2–3. Parkland maxima in MIS 2 during the Last Glacial Maximum (LGM) date to glacial advances between ∼17,800 and 33,400 cal yr BP. On deglaciation, Lateglacial North Patagonian Evergreen Forest was subject to short-term stadial and interstadial climatic fluctuations. The high-resolution Taiquemó pollen record details and supports previous conclusions of interhemispheric synchrony of climatic and glacial events.

The influence of biotic drivers on North American palaeorecords: alternatives to climate

Biotic causes of changes in palaeorecords are discussed as a counterbalance to the (over) emphasis on climatic drivers in the interpretation of palaeoecological change. Biotic and climatic drivers are considered as competing hypotheses with particular reference to the importance of early-Holocene drought in the northern central grassland region of North America. It is concluded that the observed patterns are explained better by grazers than by the direct effects of climatic variation. The elevation of biotic factors as competing hypotheses with climate will require new conceptual and methodological approaches to palaeoecology in North America.

IGCP 469 - Late Westphalian terrestrial biotas and environments of the Variscan Foreland and adjacent intramontane basins

This five-year project is to investigate the palaeoecological changes in Europe and North America that resulted from the Variscan Orogeny (late Westphalian-early Stephanian). In particular, we will be looking at the pattern of disruption to the lowland palaeotropical swamp habitats and the development of intramontane basins within the adjoining Variscan Mountains. The project will integrate data from the sedimentological and fossil record. Evidence of sedimentological changes that took place in the different basins will be collated and compared, especially those changes that affected drainage patterns and water-table levels. An integrated palaeofloristic database is to be developed for each of the main late Westphalian and earliest Stephanian coal basins in the study area, and investigated by multivariate statistical analysis. Palynology will be used to investigate overall changes in the palaeotropical vegetation. Terrestrial faunas of this age are on the whole limited, but where available we will integrate palaeozoological data, especially from insects, arachnids and vertebrates (including tracks). The resulting synthesis will provide the most complete environmental picture to date of these Variscan-affected habitats, and will have important consequences for our understanding of the evolution of the Variscan Orogeny.

Mammoth bone deposits and subsistence practices during Mid-Upper Palaeolithic in Central Europe: three cases from Moravia and Poland

The lowlands of Lower Austria–Moravia–South Poland form an important natural corridor in Central Europe, allowing migrations of both animals and humans between the Danube valley and the North European Plain. The paper examines the relationship between mammoth bone deposits and Gravettian settlements along this corridor, basing on contextual archaeological evidence in general, and on zooarchaeological analyses of the individual sites: Dolnı́ Věstonice I–II, Milovice G, and Kraków Spadzista Street (B). Mammoth bone accumulations from these areas can be interpreted as butchery places on the death locations (as in Milovice G) and as butchery places on death/hunting site (as in Kraków Spadzista Street (B)). At these sites, Gravettian people may have seasonally gathered, taking advantage of landscape geomorphology and marshy conditions to organize collective mammoth hunts. The long-term occupations, as recorded at the Moravian sites with their exceptional archaeological evidence, support this idea. The mammoth-dominated sites probably result from specialized mammoth hunts as well as from other means of exploitation of these animals during peculiar environmental stresses, both seasonal (e.g., the palaeoecological changes during the end spring thawing period), and long-term in nature (the declining features of the mammoth population, as shown in Kraków Spadzista Street (B)).