Wasatchian (Early Eocene) pollen floras from the Red Hot Truck Stop, Mississippi, USA

Sediments at the Red Hot Truck Stop (RHTS), Mississippi, USA are important because they contain the lowest latitude record of both the earliest known Eocene plant and mammal fossils in North America. The RHTS contains the uppermost Tuscahoma Formation and the lowermost part of the basal Bashi and Hatchetigbee formations. The Tuscahoma Formation is composed of glauconitic sands and silts that represent estuarine to shallow marine sediments. Faunal remains indicate that the RHTS section belongs to the Wasatchian North American land mammal age and specifically to the lower Graybullian subdivision. Pollen and spore floras from the RHTS are moderately diverse (113 taxa) and contain families that today are associated with warm‐adapted vegetation types such as Annonaceae, Bombacaceae, Burseraceae and palms. Eocene first occurrences are represented by Brosipollis sp., Celtispollenites sp., Interpollis microsupplingensis, cf. Nuxpollenites psilatus, Platycarya spp., Retistephanocolporites sp. and Symplocos? contracta and by one genus of pteridophyte spore (Granulatisporites sp.). The overall composition and within‐sample diversity of the sporomorph flora is more similar to the Hatchetigbee Formation (early Eocene) than to the middle Tuscahoma Formation (late Palaeocene) but among‐sample diversity remains unchanged across the Palaeocene/Eocene boundary. The distinct composition of the RHTS demonstrates that floral change across the Palaeocene/Eocene boundary is complex and composed of several phases of floral change.     

Middle Jurassic vegetation dynamics based on quantitative analysis of spore/pollen assemblages from the Ravenscar Group,North Yorkshire,UK

Quantitative analysis of the distribution of dispersed spores and pollen (sporomorphs) has been used to assess temporal floral variation through the Middle Jurassic Ravenscar Group (Aalenian–Bathonian), North Yorkshire, UK. Aalenian, Bajocian and Bathonian strata possess relatively distinct sporomorph and palynofacies assemblages, which potentially reflect a dynamic history regarding the nature of parent vegetation. Specifically, Aalenian palynofloras are composed of a heterogeneous mixture of conifers, ferns, simple monosulcate pollen producers, sphenophytes and Caytoniales; Bajocian palynofloras are codominated by conifers and ferns; and Bathonian palynofloras are highly rich and contain assemblages of abundant ferns, conifers, lycophytes, pteridosperms/conifers and Caytoniales. Individual‐ and sample‐based rarefaction demonstrates that Bathonian samples are richer than Aalenian and Bajocian samples. Temporal variations in assemblages are a result of long‐term depositional and possible climatic fluctuations through the Middle Jurassic. Ordinations of sporomorph data using non‐metric multidimensional scaling (NMDS) demonstrate that short‐term variations between samples are largely governed by taphonomic biases as a result of slight changes in depositional processes, which give rise to highly variable catchment areas that supply deposits with sporomorphs. Long‐term compositional changes are apparent in sporomorph assemblages regardless of lithology/local depositional environments, suggesting that long‐term variations are more substantial than short‐term variations and potentially include genuine regional temporal changes in parent vegetation. Relating sporomorph assemblages with their respective depositional environments and relative catchment area sizes using lithological and palynofacies information suggests that the basin interior was occupied by mostly low‐standing species and extrabasinal vegetation was dominated by coniferous taxa. Comparisons of the dispersed sporomorph and plant megafossil records indicate that both fossil assemblages reflect different aspects of the palaeoflora due to a multitude of taphonomic and ecological biases. Such biases include variation in sporomorph production levels, depositional environment and differential sporomorph and parent plant durability.     

Paleoecological patterns in molluscan extinctions and recoveries: comparison of the Cretaceous-Paleogene and Eocene-Oligocene extinctions in North America

Exposures across the Cretaceous-Tertiary (K-T) and Eocene-Oligocene (E-O) boundaries, in Texas and Mississippi, respectively, probably represent the most complete and best-preserved fossil molluscan sequences across these boundary intervals in the world. Outcrops from both boundaries contain pristine aragonitic and calcitic molluscan shells, which were deposited in fine-grained sediments from open marine environments. The K-T and the E-O extinctions exhibit very different recovery patterns, probably reflecting very different causes as well as magnitudes of extinction.The K-T sequence contains a molluscan fossil record that is consistent with an abrupt extinction event at the K-T boundary and a prolonged initial recovery in hostile oceanographic conditions. The uppermost 10 m of Upper Cretaceous sediments contain a diverse (approximately 40 species) molluscan fauna dominated by suspension feeders. The earliest Paleocene sediments immediately above the tsunami bed contain an impoverished fauna dominated by deposit feeders. The Paleocene fauna slowly climbs in diversity but remains relatively impoverished and dominated by deposit feeders for several hundred thousand years after the extinction in conjunction with anomalous δ¹³C values that suggest prolonged suppression of marine primary productivity. Diverse suspension-feeder dominated molluscan assemblages reappear with the resumption of normal conditions of primary production. In the long term, early to middle Paleocene gamma diversity includes evolutionary “bloom taxa,” families that exhibit unusual speciation bursts that subside in the Eocene. Total diversity for the Gulf Coast does not approach Cretaceous levels until the Late Eocene representing a total recovery interval of nearly 25 million years.While the E-O event also reflects a molluscan extinction rate of over 90% in the Gulf of Mexico, there are no signs of hostile environmental conditions in the recovery fauna. Early Oligocene molluscan assemblages are diverse and dominated by suspension feeders characteristic of normal marine conditions. The hiatus at the E-O boundary, however, could have obscured a short-term recovery fauna. There is also no sign of long-term perturbation by the E-O extinction. There are no bloom taxa and gamma diversity approaches pre-extinction levels within a few million years. The overall pattern of the E-O extinction is consistent with extinction (and/or migration) associated with long-term cooling.     

小兴安岭森林沼泽甲烷排放及其影响因子

 利用静态箱-气相色谱法, 对小兴安岭5种森林沼泽生长季甲烷(CH₄)排放通量进行研究, 并探讨了温度、地下水位和植被等主要环境因子对CH₄排放的影响。结果表明: 毛赤杨(Alnus sibirica)沼泽、落叶松(Larix gmelinii)-藓类(Moss)沼泽和落叶松-泥炭藓(Sphagnum spp.)沼泽的CH₄排放有明显的季节变化规律, 而白桦(Betula platyphylla)沼泽和落叶松-苔草(Carex schmidtii)沼泽CH₄通量的季节变化相对较小。落叶松-泥炭藓沼泽有爆发式CH₄通量现象出现, 对生长季CH₄排放通量影响较大。在生长季内落叶松-泥炭藓沼泽、毛赤杨沼泽和白桦沼泽为大气CH₄的源, 而落叶松-苔草沼泽和落叶松-藓类沼泽为大气CH₄的汇, 生长季CH₄的平均排放通量分别为(56.08 ± 200.38)、(15.34 ± 14.89)、(0.64 ± 0.88)、(–0.88 ± 1.76)和(–0.94 ± 3.00) mg·m^–2·d^–1。除落叶松-泥炭藓沼泽外, 不同森林沼泽类型间CH₄排放通量随地下水位升高而增大; 地下水位在–34.5 ~ –30.8 cm之间可能存在CH₄源与汇的临界点, 季节平均地下水位低于这一位置的森林沼泽为大气CH₄的汇。温度对森林沼泽CH₄通量的影响比较复杂, 二者间可能为正或负的显著(p＜0.05)或非显著(p＞0.05)相关关系。CH₄通量与乔木地上生物量有较强的负相关性, 这有可能成为小兴安岭森林沼泽CH₄通量的最佳预测因子。     

Stratigraphic occurrences and vegetational patterns of Pennsylvanian pteridosperms in Euramerican coal swamps

The vegetation of many Euramerican coal swamps is known from coal-ball peats in the tropical rainy zone across the paleocontinent of Laurussia in the Upper Carboniferous. The stratigraphic occurrences of coal balls in Europe (lower Westphalian) and in North America (upper Westphalian and lower Stephanian) are largely complementary and a revised correlation chart is given. Quantitative analyses of the vegetation from these autochthonous peats are combined with coal palynology to determine on overview of swamp vegetation patterns during the Westphalian and early Stephanian. In comparison to the dominance and great diversity of pteridosperms in the Upper Carboniferous compression floras, seed ferns were minor to subdominant elements in the coal-ball peats. The quantitative composition of organ assemblages of the principal pteridosperms is given with stratigraphic occurrences of Medullosa and Sutcliffia (Medullosaceae), Heterangium, Lyginopteris, Microspermopteris, and Schopfiastrum (Lyginopteridaceaea) and Callistophyton (Callistophytaceae). The major peat contributors among pteridosperms are Lyginopteris (?90%) in the Westphalian A and Medullosa (?95%) in the Westphalian D and Stephanian. Lyginopteris became extinct in the early Westphalian B and Medullosa became abundant during the Westphalian C–D transition and a subdominant in the Stephanian contributing 13–21% of the permineralized peats. Paleoecological interpretations indicate that medullosan trees were most abundant but patchy in distribution in drier swamp stages with enriched nutrients and near major channels in swamps during the Westphalian D. It is suggested that the swamp pteridosperms are probably quite similar to or identical with some of the representatives in the more diverse compression floras. The evolution and diversity noted in swamp pteridosperms are considered principally the product of adjacent lowland communities which repeatedly introduced seeds into the wetlands. The swamp pteridosperms exhibit the greatest fluctuation in abundance (biomass) from site to site in the same coal, probably the highest level of diversity and the only steady pattern of increase in importance during the Late Carboniferous with the possible exception of the Westphalian B–C interval. The close relationships inferred between swamp pteridosperms and their lowland seed sources are also compatible with the frequent association of tree ferns and seed ferns during the Westphalian D and in the Stephanian when these two kinds of frond-bearing trees formed most of the vegetation in both lowland and swamp environments.     

Thanetian–Ilerdian coralline algae and benthic foraminifera from northeast India: microfacies analysis and new insights into the Tethyan perspective

Thanetian–Ilerdian carbonate deposits from the Lakadong Limestone in Assam Shelf, Meghalaya, northeast India, are studied with respect to microfacies distributions and controlling ecological factors on dominant biogenic components. Palaeoenvironmental implications are inferred following the detailed analysis of microfacies characterized by rich assemblages of coralline red algae and benthic foraminifera. The carbonate sediments have been interpreted as lagoonal to outer shelf facies. It is envisaged that the analysed benthic communities thrived in a meso‐oligotrophic regime above the fair‐weather wave base. The Lakadong Limestone constitutes a well‐preserved record of Late Palaeocene–earliest Eocene shallow marine carbonate ecosystem and has high potential to decipher its response to an interval of distinct changes in climate and tectonic settings. The abundance of oligotrophic larger benthic foraminifera in the Lakadong Limestone is comparable to the foraminiferal assemblages of west Tethys. The phylogenetic changes (‘Larger Foraminiferal Turnover’, LFT) and subsequent rapid radiation of typical Eocene larger benthic foraminifera (Alveolina, Nummulites) usually observed in the west Tethys have also been observed in the upper part of the Lakadong Limestone. The eastward migration of Eocene foraminifera from the west coincided with the India‐Asia collision and global warming events at the Palaeocene–Eocene boundary that may have produced a wide array of modifications in biogeography, seasonal run‐offs and ocean circulation pathways. The data indicate that rapid rate of migration from west before the onset of geographic barriers and/or timely restoration of pan‐Tethyan environmental conditions ensured the incidence of these forms in the earliest Eocene sediments.     

Distribution and abundance of tree species in swamp forests of Amazonian Ecuador

Research to date on Amazonian swamps has reinforced the impression that tree communities there are dominated by a small, morphologically specialized subset of the regional flora capable of surviving physiologically challenging conditions. In this paper, using data from a large‐scale tree inventory in upland, floodplain, and mixed palm swamp forests in Amazonian Ecuador, we report that tree communities growing on well‐drained and saturated soils are more similar than previously appreciated. While our data support the traditional view of Amazonian swamp forests as low‐diversity tree communities dominated by palms, they also reveal four patterns that have not been well documented in the literature to date: 1) tree communities in these swamp forests are dominated by a phylogenetically diverse oligarchy of 30 frequent and common species; 2) swamp specialists account for < 10% of species and a minority of stems; 3) most tree species recorded in swamps (> 80%) also occur in adjacent well‐drained forest types; and 4) many tree species present in swamps are common in well‐drained forests (e.g. upland oligarchs account for 34.1% of all swamp stems). These observations imply that, as in the temperate zone, the composition and structure of Amazonian swamp vegetation are determined by a combination of local‐scale environmental filters (e.g. plant survival in permanently saturated soils) and landscape‐scale patterns and processes (e.g. the composition and structure of tree communities in adjacent non‐swamp habitats, the dispersal of propagules from those habitats to swamps). We conclude with suggestions for further research to quantify the relative contributions of these factors in structuring tree communities in Amazonian swamps.     

Cenozoic deep-sea ostracods from Maud Rise, Weddell Sea, Antarctica (ODP Site 689): a palaeoceanographical perspective

Cenozoic palaeoceanography of the Maude Rise, Weddell Sea, Antarctica, has been investigated using Palaeocene to Quaternary deep-sea ostracod faunas from 23 samples of ODP Site 689. The abundance of ostracods is high enough only during the Palaeogene (Palaeocene-Oligocene) to allow palaeoceanographical inferences based on changes in diversity, dominance, endemism and faunal turnover (first and last occurrences). The abundance is particularly high throughout the Palaeocene and Eocene, but declines irreversibly near the Eocene/Oligocene boundary. The diversity increases more or less continuously from the Early Palaeocene to the Middle Eocene, and then it generally decreases throughout the remaining part of the Palaeogene (Middle Eocene-Oligocene); an exception is a positive peak in the Shannon-Weaver index in a single sample in the Late Oligocene. No positive peaks in diversity and taxa originations (first occurrences) at c. 40-38 Ma, occurs at Site 689; so the site provides no evidence for the establishment of the psychrosphere at this time. This corroborates similar regional results from an earlier study of benthonic foraminifera. Explanations for this may be related to Late Eocene-Early Oligocene changes in sedimentology and clay-mineralogy (associated with the progressive cooling of the Antarctica) which could have negatively affected abundance and diversity locally at Site 689. Alternatively, by this time, the ostracod fauna could also have been subjected to selective removal (with possible local extinction) of taxa (due to increased ventilation) or to thanatocoenosis dissolution (due to a decrease in temperature and availability of CaCO₃). A further possibility may be related to the fact that Site 689 was at intermediate water depths and may have remained within older water masses near the Eocene/Oligocene boundary. Failing these explanations, the results could indicate that the Late Eocene-Early Oligocene palaeoenvironmental changes in the world oceans were more gradual and occurred over a longer time interval than the global ostracod data show, at least at southern high latitudes.     

Paleocene and Eocene floras of Russia and adjacent regions: Climatic conditions of their development

Climatic changes in the western and central regions of Russian Eurasia in the Paleocene and in the first half of the Eocene were caused by the dynamics and rearrangement of the systems of marine seaways: the longitudinal one, which connected the Arctic Basin with marginal seas of the Northern Peri-Tethys, and the latitudinal one, which connected the latter seas with the Atlantic. As these systems were progressively reduced, the climate in the middle latitudes changed from paratropical to a subtropical monsoon climate with a moist summer, and later to a climate with a moist winter, and, in the Late Eocene, to a humid climate without any marked seasonal variation in precipitation. The type of flora changed in agreement with these changes. In the Paleogene, cold currents constantly influenced the climate of the Northwestern Pacific rim and facilitated the development of a warm-temperate mesophilic flora.     

Standard survey designs drive bias in the mapping of upland swamp communities

Vegetation maps are critical biodiversity planning instruments, but the classification of vegetation for mapping can be strongly biased by survey design. Standardization of survey design across different vegetation types is therefore increasingly recommended for vegetation mapping programs. However, some vegetation types have complex small‐scale vegetation patterns that are important in characterizing these vegetation types, and standard designs will often not capture these patterns. The objective of this paper was to investigate the magnitude of potential map bias that results from survey design standardization and recommend approaches to deal with this bias. We surveyed upland swamps of the Greater Blue Mountains World Heritage Area Australia using two contrasting survey designs, including the standard 400 m² single quadrat design recommended and used by authorities. We then derived a classification for these swamps and tested the effect of survey design on this classification, species richness and the type of species detected (obligate or facultative swamp species). Species richness and species type were not significantly different among survey techniques. However, more than 40% of swamps clustered differently among survey designs. Thus, one of the 10 derived communities (which is floristically consistent with a previously mapped endangered community) was indistinct, and some individual swamps misclassified using the standard survey design. An effect of landscape position on swamp floristic patterns and a significant trend for high similarity scores among swamps surveyed with multiple small quadrats compared to the standard survey design was also determined. Australian upland swamps are classified at the global scale as shrub‐dominated wetlands, and complex floristic patterns have been recorded in shrub‐dominated wetlands in both northern and southern hemispheres. We therefore advocate either multiple survey designs or different survey standards for upland swamp communities and other vegetation types that have complex floristic patterns at small scales.     

排水疏干胁迫下若尔盖高原沼泽退化评价指标体系

沼泽退化评价指标体系研究是国际湿地科学研究前沿领域的关键科学问题之一.在长期野外考察的基础上,根据2009年3个排水疏干沼泽退化研究样带20个沼泽的植物群落生态观测和土壤分析数据,基于沼泽植物群落物种重要值的双向指示种分析(TWINSPAN),将沼泽样地划分为未受干扰(A型)、受长期低强度排水干扰(B～D型)和受短期高强度排水干扰(E～G型)3类,其中又可分为7个植物群落类型.采用主成分分析法(PCA)对沼泽退化进行分级,建立了若尔盖高原沼泽评价的植被指标体系(SVEI)和土壤指标体系(SSEI).基于SVEI,将沼泽划分为原始沼泽、轻度退化沼泽、中度退化沼泽和重度退化沼泽.基于SSEI,将红原县沼泽划分为原始沼泽、轻度退化沼泽和重度退化沼泽3个等级,将若尔盖县沼泽划分为轻度退化沼泽、中度退化沼泽和重度退化沼泽3个等级.SVEI或SSEI评价结果与TWINSPAN分类结果相似度均在70%以上,说明SVEI或SSEI对沼泽退化分级均具有较好的效果,可采用不同方法相结合的方式对高原沼泽进行综合评价.     

基于植被数量分类的排水疏干影响下若尔盖高原沼泽退化特征

2009年,在对若尔盖高原沼泽的生态特征、环境质量考察和排水疏干沼泽样带生态调查的基础上,采用TWINSPAN分类方法,将研究区20个典型沼泽样地划分为原始沼泽、长期排水退化沼泽和短期排水退化沼泽3种类型,每类退化沼泽包含轻度退化、中度退化和重度退化3个退化等级,研究不同程度退化沼泽的植被和土壤退化特征.结果表明: 若尔盖高原沼泽退化主要受排水方式、排水强度和土壤水分梯度的驱动.植物群落退化过程较土壤退化过程变化明显.其中,植物群落水分生态型的结构变化最显著,在长期排水和短期排水的影响下,沼生植物重要值由0.920分别下降至0.183和0.053,中生植物重要值由0.029分别上升至0.613和0.686.土壤对沼泽退化的响应具有滞后性,其理化性质呈一定的变化规律,但差异尚未达到显著水平.土壤水分和氮、钾等养分含量是影响若尔盖高原排水疏干退化沼泽植物物种分布的关键因素.     

No post-Cretaceous ecosystem depression in European forests? Rich insect-feeding damage on diverse middle Palaeocene plants,Menat, France

Insect herbivores are considered vulnerable to extinctions of their plant hosts. Previous studies of insect-damaged fossil leaves in the US Western Interior showed major plant and insect herbivore extinction at the Cretaceous–Palaeogene (K–T) boundary. Further, the regional plant–insect system remained depressed or ecologically unbalanced throughout the Palaeocene. Whereas Cretaceous floras had high plant and insect-feeding diversity, all Palaeocene assemblages to date had low richness of plants, insect feeding or both. Here, we use leaf fossils from the middle Palaeocene Menat site, France, which has the oldest well-preserved leaf assemblage from the Palaeocene of Europe, to test the generality of the observed Palaeocene US pattern. Surprisingly, Menat combines high floral diversity with high insect activity, making it the first observation of a ‘healthy’ Palaeocene plant–insect system. Furthermore, rich and abundant leaf mines across plant species indicate well-developed host specialization. The diversity and complexity of plant–insect interactions at Menat suggest that the net effects of the K–T extinction were less at this greater distance from the Chicxulub, Mexico, impact site. Along with the available data from other regions, our results show that the end-Cretaceous event did not cause a uniform, long-lasting depression of global terrestrial ecosystems. Rather, it gave rise to varying regional patterns of ecological collapse and recovery that appear to have been strongly influenced by distance from the Chicxulub structure.     

Application of palynology to describe vegetation succession in estuarine wetlands on Great Barrier Island,northern New Zealand

Question: This paper compares published palynological studies from coastal swamps containing the same suite of species. We ask the following questions: (1) does succession follow the same pathways in different swamp systems, or (2) at different times? If not, (3) how variable are the patterns and (4) what are the likely driving factors? Location: Great Barrier Island, Northern New Zealand. Methods: Eighteen pollen profile diagrams were studied from four estuarine wetlands, ranging from mangroves to swamp forest. Recognition of a transition between vegetation stages was by subjective consideration of the relative abundances of pollen of key indicator species at different depths in the sedimentary sequence. Results: A linear sequence of vegetation communities beginning with mangroves and followed by estuarine marsh communities composed of Juncus kraussii, Leptocarpus similis and Baumea juncea was recognised in almost all pollen diagrams. Further transitions, from Baumea to a terrestrial system of Leptospermum shrubland or Cordyline/Dacry‐carpus swamp forest, followed two main pathways associated with autogenic accumulation of peat and terrigenous sediment input respectively. At Kaitoke and Awana the marine/freshwater transition occurred before the arrival of humans on Great Barrier Island. At Whangapoua, increased sedimentation followed anthropogenic burning of adjacent forest, and this transition was faster and is still in progress. Conclusion: Palynology and current vegetation zonation patterns concur to demonstrate that the marine sedimentation phase of estuarine succession is predictable and linear. Baumea marks the transition to the freshwater phase, in which varied successional patterns are determined by interactions between hydrology, sediment input, and peat accumulation. Natural and human disturbances drive sedimentation rates, and interact with autogenic factors, to dictate vegetation transitions in these later stages. The intensive impact (mainly burning) during Polynesian times had a much greater effect on estuaries and swamps than the pre‐Polynesian natural processes, greatly accelerating plant succession.     

Evergreen swamp forest in Cambodia: floristic composition,ecological characteristics,and conservation status

As part of recent field studies, a hitherto undescribed type of evergreen freshwater swamp forest was discovered in Stung Treng Province, Cambodia. The swamp forest occurs in at least six disjunct localities and is dominated by hydrophytic trees (Eugenia spp., Ficus spp., Litsea spp., Macaranga triloba, Myristica iners and Pternandra caerulescens). Although these same genera also occur in upland forests, most are represented by different species in the swamps. Livistona saribus emerges from the canopy as an indicator species of this vegetation type while dense stands of other palms (Calamus, Areca, Licuala) and sporadic, dense populations of tree ferns (Cibotium barometz) dominate the understory. Pneumatophores, stilt roots, and aerial roots characterize the hydrophytes. The floristic composition indicates that the forest type is distinct compared to other swamp forests described from the region and worthy of protection based on its rarity and ecological uniqueness.     

Re-assignment of the Affinities of the Fossil Pollen Type Tricolpites trioblatus Mildenhall and Pocknall to Wilsonia (Convolvulaceae) and a reassessment of the ecological interpretations

Tricolpites trioblatus Mildenhall and Pocknall was described from Upper Miocene-Pliocene sediments of New Zealand and attributed to the Hebe complex (Scrophulariaceae), which is common in the New Zealand vegetation, especially in montane and subalpine habitats. Pollen in Miocene-Pliocene sediments in central Australia is identified with T. trioblatus, and the depositional situations included shallow lakes, with fresh or brackish waters, sometimes becoming saline. The affinities of T. trioblatus are re-examined in the light of these disparate environments in Australia and New Zealand. It has been found that all the fossil grains examined are more comparable to pollen of Wilsonia, and perhaps Cressa (Convolvulaceae), than to those of the Hebe complex. Wilsonia and Cressa are found in salt marshes, hence affinities with them are ecologically more credible for central Australia. T. trioblatus is found in late Eocene sediments deposited under episodic marine transgressions; an environment likely to stimulate the evolution of new species tolerant to saline conditions.     

Tracking Taphonomic Regimes Using Chemical and Mechanical Damage of Pollen and Spores: An Example from the Triassic–Jurassic Mass Extinction

The interpretation of biotic changes in the geological past relies on the assumption that samples from different time intervals represent an equivalent suite of natural sampling conditions. As a result, detailed investigations of taphonomic regimes during intervals of major biotic upheaval, such as mass extinctions, are crucial. In this paper, we have used variations in the frequency of chemical and mechanical sporomorph (pollen and spore) damage as a guide to taphonomic regimes across the Triassic–Jurassic mass extinction (Tr-J; ∼201.3 Ma) at a boundary section at Astartekløft, East Greenland. We find that the frequency of sporomorph damage is extremely variable in samples from this locality. This likely reflects a combination of taxon-specific susceptibility to damage and the mixing of sporomorphs from a mosaic of environments and taphonomic regimes. The stratigraphic interval containing evidence of plant extinction and compositional change in the source vegetation at Astartekløft is not marked by a consistent rise or fall in the frequency of sporomorph damage. This indicates that natural taphonomic regimes did not shift radically during this critical interval. We find no evidence of a consistent relationship between the taxonomic richness of sporomorph assemblages and the frequency of damage among sporomorphs at Astartekløft. This indicates that previously reported patterns of sporomorph richness across the Tr-J at this locality are likely to be robust. Taken together, our results suggest that the patterns of vegetation change at Astartekløft represent a real biological response to environmental change at the Tr-J.     

Fossil evidence of interactions between plants and plant-eating mammals.

We document changes in mammalian dietary and foraging locomotor adaptation, and appearances and developments of angiosperm fruiting strategies and vegetation types since the late Cretaceous in the Euramerican region, and to some extent in low latitude Africa. These changes suggest: (i): an expansion in the exploitation of dry fruits and seeds by mammals on the ground as well as in the trees after the terminal Cretaceous dinosaur extinction; (ii) a relation between large nuts and rodents, which appear in the late Palaeocene and radiate in the late Eocene; (iii) a relation between primates and fleshy fruits established in the early-Middle Eocene when tropical forests reached their maximum latitudinal extent; (iv) a hiatus of several million years in the vertebrate exploitation of leaves after dinosaur extinction and before the first few mammalian herbivores in the Middle Palaeocene, followed by an expansion in the late Eocene when climates cooled and more open vegetation became established.     

苏北盆地高邮凹陷D1井白垩纪-古近纪微体古生物地层及沉积环境

高邮凹陷D1井富含介形虫、轮藻和孢粉等化石。通过系统的微体古生物分析,首次对该地区白垩纪一古近纪微体古生物地层进行了精确划分,从下到上共建立11个化石组合：其中介形虫4个,轮藻4个,孢粉3个。文中还简要探讨了沉积环境演变,为该地区油气勘探提供有力的生物地层依据。     

Global patterns of terrestrial assemblage turnover within and among land uses

Land use has large effects on the diversity of ecological assemblages. Differences among land uses in the diversity of local assemblages (alpha diversity) have been quantified at a global scale. Effects on the turnover of species composition between locations (beta diversity) are less clear, with previous studies focusing on particular regions or groups of species. Using a global database on the composition of ecological assemblages in different land uses, we test for differences in the between‐site turnover of species composition, within and among land‐use types. Overall, we show a strong impact of land use on assemblage composition. While we find that compositional turnover within land uses does not differ strongly among land uses, human land uses and secondary vegetation in an early stage of recovery are poor at retaining the species that characterise primary vegetation. The dissimilarity of assemblages in human‐impacted habitats compared with primary vegetation was more pronounced in the tropical than temperate realm. An exploratory analysis suggests that this geographic difference might be caused primarily by differences in climate seasonality and in the numbers of species sampled. Taken together the results suggest that, while small‐scale beta diversity within land uses is not strongly impacted by land‐use type, compositional turnover between land uses is substantial. Therefore, land‐use change will lead to profound changes in the structure of ecological assemblages.