Termite coprolites (Insecta: Isoptera) from the Cretaceous of western France: A palaeoecological insight

This paper presents fossil faecal pellets - also named coprolites or frass - attributed to termites, which were found in amber and lignitic clay from the Wealden (Hauterivian-Barremian?), Late Albian and Early Cenomanian of south-western France. These coprolites have a characteristic subcylindrical shape and hexagonal transverse section and are assignable to Microcarpolithes hexagonalis Vangerow. The termite families that possibly produced these coprolites are discussed. The noticeable lack of termite attacks on the fossil wood associated with amber and lignitic clay is taphonomically analyzed in relation with the palaeoflora and palaeoclimate of these amber forests. The different medium where coprolites were found (amber, wood, sediments) suggests that primitive Cretaceous termites had already developed various biologies, such as wood or cryptic foraging, but probably not yet soil-feeding.     

The past and present occurrence of <Emphasis Type="Italic">Elatine</Emphasis> and implications for palaeoenvironmental reconstructions

The past and present occurrence of Elatine hydropiper L. (eight-stamened waterwort), E. hexandra (Lapierre) DC. (six-stamened waterwort) and E. triandra Schkuhr (three-stamened waterwort) in the Netherlands is discussed. It has proved possible to distinguish the slightly curved seeds of E. hexandra and E. triandra in subfossil material on morphological grounds. E. hexandra is the most common species at present, but subfossil finds are confined to Late-glacial and Pre-boreal sediments of one lake in the Pleistocene area of the Netherlands. Living plants of E. triandra have only been found in the Netherlands in 1838–1839, but there are 17 records from five archaeological sites, all located in the western Dutch estuarine area. Several of these sites also yielded E. hydropiper, archaeobotanically the most common species. The occurrence of E. triandra and E. hydropiper in the Netherlands seems to have been favoured by high summer temperatures. The ecological amplitude of this combination of species gives firm clues for the reconstruction of the environment, which must have been a freshwater tidal area. Since this type of environment is strongly threatened on a worldwide scale, the presence of these species in the past may also provide interesting information for present nature development projects in the Dutch estuarine area.     

Palynological investigations on vegetation and climate change in the Late Quaternary of Lake Rukche area,Gorkha Himal,Central Nepal

Palynological data and pedological investigations including stable isotopes and lignin biomarkers (Glaser et al. in press) from a 4 m core of Lake Rukche (3500 m a.s.l.) enhance our palaeoecological knowledge of the time since the LGM in the Gorkha Himal, Central Nepal. Even before 15000 B.P. forest types became established which prove the existence in Central Nepal of a temperate-humid climate with a considerable amount of winter and spring precipitation from westerly disturbances. Lignin input and pollen data point to a patchy vegetation cover around Lake Rukche with meadow-steppes dominated by Poaceae. Around 15000 B.P. Quercus and Pinus roxburghii dominated the lower altitudes while the vegetation around Lake Rukche was more steppe-like (Chenopodiaceae, Artemisia). Subsequently the climate became warmer and drier as winter and spring precipitation decreased while summer rain remained low. Later on more resource-demanding forests became established under improved temperature and precipitation conditions (Engelhardia). Around Lake Rukche coniferous forests (Abies, Picea) occurred beside meadow-steppes. The transition from the Pleistocene to the Holocene is not recorded. In the Holocene alpine Kobresia-meadows stabilised the soil surface causing sand accumulation to end. During the mid-Holocene (7800–2750 B.P.) humid oak forests with demanding elements (Ilex, Coriaria, Myrsine and Engelhardia) dominated the vegetation cover. A charcoal layer and a marked emergence of fire-induced communities with Pinus roxburghii, Poaceae, Ericaceae and Pteridium are proofs of a first strong anthropogenic change in vegetation which coincided with the climatic deterioration at the onset of the Subatlantic. Since 900 B.P. grazing pressure and the frequency of fires increased, resulting in a replacement of Betula utilis-forests by meadows and woods of Juniperus and Rhododendron. While previous anthropogenic influence increased the biodiversity by promoting replacement communities, recent developments have led to a decrease in biodiversity through loss of natural vegetation communities.     

Benthic palaeoecology of Danian deep-shelf bryozoan mounds in the Danish Basin

Early Danian cool-water bryozoan mounds exposed in the coastal cliff Stevns Klint in Denmark were formed shortly after the Cretaceous–Tertiary mass extinction. They represent a relatively deep-water, highly diverse benthic ecosystem within the epeiric seaway that covered the Danish Basin. The mounds are 50–110 m long and reached a height of about 5–10 m above the seafloor; they are asymmetrical with a steep southern and a gentle northern flank, and were dominated by small suspension feeders. The benthic elements generally occur as fragments set in a carbonate mud matrix. The main skeletal contributors are delicate branching bryozoans with minor contributions of bryozoan sheets, and nodular/arborescent bryozoans. Locally abundant octocorals occur on the mound crests and upper parts of the steep flanks. Echinoids are present in minor amounts, but are locally abundant. Serpulids, crinoids, asteroids, brachiopods, bivalves, massive calcareous sponges, and benthic foraminifers are generally minor contributors to the benthic mound fauna. Influx of planktonic foraminifers, coccoliths and other planktonic organisms was high and was probably a major source of nutrient supply to the mainly suspension-feeding benthic fauna.

The faunal association reflects a relatively low energy environment with a high, possibly seasonal influx of particulate nutrients. The best growth conditions with respect to nutrient influx were on the mound crest and upper steep flank reflected by the diverse and relatively largest benthic faunal elements. Periodic reworking and winnowing occurred across the entire mound structure but most prominent on the gentle northern flanks limiting the benthic growth and notably the colony density and size of delicate branching bryozoans. Vagile benthic faunas were also adapted to different areas on the mound. Irregular echinoids preferred the intermound areas within fine-grained wackestone–packstone facies where they ploughed through the sediment, whereas regular echinoids were epifaunal and preferred the upper parts of the mounds, possibly feeding mainly on bryozoans. Skeletons of both groups became concentrated at the toe of the steep flanks and in the intermound areas by physical reworking during major storms.

Changes in faunal composition on the mound crests occurred rhythmically on both small and large scale during mound growth. Rhythmically recurring faunal assemblages reflect alternating hydrodynamic conditions on the seafloor with respect to nutrient influx and energy, which probably were linked to short-term seasonal and long-term climatic variations; the long-term alternation may be within the Milankovitch frequency band. Blooming events of bryozoan sheets resulted from relatively short periods with large amounts of available food and suitable substrate. Successful colonisation by octocorals on the other hand reflected longer-term favourable conditions on the mounds possibly associated with overall higher energy levels.

A possible Pleistocene analogue to the bryozoan-dominated Danian mounds occurs at the shelf-slope break of the Great Australian Bight. Both of these cool-water mound systems deviate from most other biogenic mounds known from the fossil record in their non-cemented nature, regular geometry and a lack of core and flank facies.     

西藏南部聂拉木地区晚泥盆世—早石炭世的介形类

本文系统描述西藏南部聂拉木地区晚泥盆世–早石炭世介形类共计15属24种。根据介形类的组合面貌及孢子、牙形刺的研究结果推断,亚里剖面上的亚里组时代为晚泥盆世–早石炭世,泥盆系-石炭系界线(D-CB)大致位于亚里东沟段顶部至沟陇日段。亚里组产出的介形类生态组合属于光滑速足目集群或艾菲尔生态型,指示亚里组在沉积时为远岸浅水沉积环境,且在上部腊扎蒲段水深变浅。亚里组介形类面貌与华南泥盆纪介形类相似程度高,与俄罗斯和欧美地区也有相似的属种,说明泥盆纪-石炭纪之交介形类的地理隔离并不显著,在各个板块之间有属种交流的可能。     

The palaeoecology of the micromammals from the late middle Pleistocene site of Hoedjiespunt 1 (Cape Province, South Africa)

The palaeontological site of Hoedjiespunt 1 (HDP1) represents a fossilized hyaena lair. A rich mammalian fauna, including four hominid teeth, has been recovered from the site. Micromammals were recovered from the same sediments as the larger fauna. Taphonomic analysis suggests that the micromammal assemblages from HDP1 were accumulated by a barn owl. The barn owl produces micromammal assemblages that provide a broad sample of micromammals, within a certain size range, living in the hunting area of the owl. There are size-related and other biases inherent in the prey selection of this predator, and owls may roost in one area and hunt in another however, the barn owl has frequently been found to provide a better indication of micromammals living within an area than trapping. The micromammals from HDP1 were used to reconstruct the microhabitats in the vicinity of the site. Two taxonomic habitat indexes were used to assess the environment and dominant habitat types at Hoedjiespunt 1. The variability and adaptability of many of the southern African micromammals complicates interpretation of the results, however, it appears that the micromammals from the HDP1 fossil assemblages utilized habitats of open, scrub vegetation, and rocky and sandy areas. It is suggested that the environment was not markedly different from today, but it may have been relatively more arid. A comparison between HDP1 and other fossil sites in the area dating from the terminal Pleistocene to the Holocene indicates that HDP1 is lacking certain species that are common to all the other west coast fossil sites. There is some discrepancy in the environment indicated by the large mammals as compared that indicated by to the micromammals at the site. It is suggested that this discrepancy may reflect the fact that an owl is likely to have hunted in the vicinity of the hyaena den, probably in the more open areas around the roost site, whereas the macrofauna, accumulated by the further-ranging brown hyaena (Hyaena brunnea), represents environments from further afield.     

Late Quaternary vegetation and climatic history of eastern Nepal

The late Quaternary vegetation and climatic history at high altitude in eastern Nepal was studied through stratigraphy, radiocarbon dating and pollen analysis. The Thulo Pokhari lake (27°41′ N, 87°43′ E, ca. 3980 m a.s.l.) is just above the subalpine Abies spectabilis–Betula utilis forest zone and surrounded by Rhododendron scrub. The climate in the studied area is very humid under the influence of the monsoon. Silty sediments suggesting lake conditions prevailed at the lower part of the sediment samples, whereas the upper part consisted mainly of herbaceous peat indicating a mire condition. The pollen record extends back to ca. 11000 yr bp . Although the absence of major changes between the pollen assemblages of the Pleistocene and those in the Holocene was attributed to the situation of the sampling plot above the forest limit, the results suggest the following history. (1) The abundance of Pinus pollen around 11000 yr bp represents expansion of the area unoccupied by late successional trees and/or a drier condition. Significant occurrence of Picea pollen is noteworthy, since this genus is absent in eastern Nepal at present in spite of its wide distribution throughout the neighbouring areas of the Himalayas. (2) The increase in abundance of Quercus pollen and the decline in Pinus pollen in the latest Pleistocene represent climatic amelioration favourable to late successional mesophytes. (3) The climate was most moist and mild in the SP-III, although the absolute age of the pollen zone is not distinct. The percentages of broadleaved trees such as Alnus, Betula, Carpinus and Corylus were increased at the expense of Quercus and coniferous pollen types. Sedimentation was interrupted by lake level decline and/or glacial advance during the period from ca. 11000–1600 yr bp . (4) The increase in abundance of coniferous pollen types such as Pinus, Abies and Tsuga indicates that the climate became drier and cooler, and the present subalpine forest zone composed of A. spectabilis, T. dumosa and Betula utilis was established around 1600 yr bp . The formation of bog or alpine meadow vegetation during the period was shown by the ¹⁴C dates of the peat and the increase in Rosaceae and herbaceous pollen. (5) The increase in abundance of Ericaceae and Alnus pollen in the SP-V indicates that the present alpine Rhododendron scrub zone has been established since ca. 940 yr bp as a result of human influence on the original vegetation. This interpretation is supported by the decline in the proportion of arboreal pollen. Since the age of the initiation of human influence varies with the altitude and region, further study will be necessary to determine the accurate age.     

Réflexion sur la coexistence de flores hygrophile,mésophile et mésoxérophile durant le Paléozoïque Supérieur en Euramérie

At the end of Namurian A, in Eurameria, we see agreat change in the composition of the flora, probably instigated by a great modification in the climatic conditions. This flora adapted to very humid places persist during whole the Westphalian and up to the end of Stephanian where it is relayed by a mesoxerophytic flora of which the most typical elements are the Coniferales of the family Lebachiaceae. This «autunian flora is usualy considered as subsequent to the stephanian hygrophytic flora and as the transition to the permian flora which is determined by a new modification of the general climatic conditions.Some observations about the macroflora and about the microflora lead to prove the coexistence of hygrophytic, mesophytic and mesoxerophytic floras, not only during the upper Stephanian but also during Westphalian and Namurian B and C. So, from Devonian to Permian, in Eurameria, there was probably continuity of a mesoxerophytic and mesophytic type floras on which was superimposed during the upper Carboniferous an hygrophytic flora adapted to the swamps surrounding the coal-lakes and coal-lagoon. The time of the appearance of Coniferales is older as we think usually.     

Diversity, composition and structure of Late Eocene shelf-edge coral associations (Nago Limestone, Northern Italy)

Summary During the Late Eocene, shelf-edge patch reefs developed on the western margin of the Lessini Shelf. The coral fauna, studied in the Nago Limestone type locality, is described and interpreted for the first time, and provides further data for better understanding of the generally poorly known Eocene reef communities. Facies analysis was carried out across the shallowing upward succession that characterizes the well exposed type-section of the Nago Limestone. Four distinct facies are identified and a detailed qualitative-quantitative investigation has been applied to the coral-bearing facies in particular, in order to describe and quantify the distribution and palaeoecological zonation of corals. By a comparison of sedimentological and palaeoecological data, it is possible to reconstruct a depositional model of the Nago Limestone at its type locality. In particular, the palaeoecological study clearly reveals that corals change with depth in taxonomic composition, in percentage and proportion within the framework and in growth form, allowing the definition of a relative depth coral zonation. Three coral associations are recognized from the base to the top of the shallowing upward sequence. These differ from each other in the relative abundance of main reefbuilders, in the growth form exhibited by corals in growth position and in the density of the reef framework. These variations are interpreted as responses to major environmental controls which prevailed during the deposition of the different facies (mainly light intensity and hydrodynamic energy). The coral speciesActinacis rollei Reuss is the most abundant and ubiquitous coral of the Nago Limestone. Its adaptation to low-light levels is described here for the first time, confirming the high plasticity of this important Paleogene reef-builder. The results of the present study are finally compared with data from other Middle-Late Eocene European reef sites and some common features are inferred.     

The origin of Jurassic reefs: Current research developments and results

Summary In order to elucidate the control of local, regional and global factors on occurrence, distribution and character of Jurassic reefs, reefal settings of Mid and Late Jurassic age from southwestern Germany, Iberia and Romania were compared in terms of their sedimentological (including diagenetic), palaeoecological, architectural, stratigraphic and sequential aspects. Upper Jurassic reefs of southern Germany are dominated by siliceous sponge—microbial crust automicritic to allomicritic mounds. During the Oxfordian these form small to large buildups, whereas during the Kimmeridgian they more frequently are but marginal parts of large grain-dominated massive buildups. Diagenesis of sponge facies is largely governed by the original composition and fabric of sediments. The latest Kimmeridgian and Tithonian spongiolite development is locally accompanied by coral facies, forming large reefs on spongiolitic topographic elevations or, more frequently, small meadows and patch reefs within bioclastic to oolitic shoal and apron sediments. New biostratigraphic results indicate a narrower time gap between Swabian and Franconian coral development than previously thought. Palynostratigraphy and mineralostratigraphy partly allow good stratigraphic resolution also in spongiolitic buildups, and even in dolomitised massive limestones. Spongiolite development of the Bajocian and Oxfordian of eastern Spain shares many similarities. They are both dominated by extensive biostromal development which is related to hardground formation during flooding events. The Upper Jurassic siliceous sponge facies from Portugal is more localised, though more differentiated, comprising biostromal, mudmound and sponge-thrombolite as well as frequent mixed coral-sponge facies. The Iberian Upper Jurassic coral facies includes a great variety of coral reef and platform types, a pattern which together with the analysis of coral associations reflects the great variability of reefal environments. Microbial reefs ranging from coralrich to siliceous sponge-bearing to pure thrombolites frequently developed at different water depths. Reef corals even thrived within terrigeneous settings. In eastern Romania, small coral reefs of various types as well as larger siliceous sponge-microbial crust mounds grew contemporaneously during the Oxfordian, occupying different bathymetric positions on a homoclinal ramp. Application of sequence stratigraphic concepts demonstrates that onset or, in other cases, maximum development of reef growth is related to sea level rise (transgressions and early highstand) which caused a reduction in allochthonous sedimentation. The connection of reef development with low background sedimentation is corroborated by the richness of reefs in encrusting organisms, borers and microbial crusts. Microbial crusts and other automicrites can largely contribute to the formation of reef rock during allosedimentary hiatuses. However, many reefs could cope with variable, though reduced, rates of background sedimentation. This is reflected by differences in faunal diversities and the partial dominance of morphologically adapted forms. Besides corals, some sponges and associated brachiopods show distinct morphologies reflecting sedimentation rate and substrate consistency. Bathymetry is another important factor in the determination of reefal composition. Not only a generally deeper position of siliceous sponge facies relative to coral facies, but also further bathymetric differentiation within both facies groups is reflected by changes in the composition, diversity and, partly, morphology of sponges, corals, cementing bivalves and microencrusters. Criteria such as authigenic glauconite, dysaerobic epibentic bivalves,Chondrites burrows or framboidal pyrite in the surrounding sediments of many Upper Jurassic thrombolitic buildups suggest that oxygen depletion excluded higher reefal metazoans in many of these reefs. Their position within shallowing-upwards successions and associated fauna from aerated settings show that thrombolitic reefs occurred over a broad bathymetric area, from moderately shallow to deep water. Increases in the alkalinity of sea water possibly enhanced calcification. Reefs were much more common during the Late Jurassic than during the older parts of this period. Particularly the differences between the Mid and Late Jurassic frequencies of reefs can be largely explained by a wider availability of suitable reef habitats provided by the general sea level rise, rather than by an evolutionary radiation of reef biota. The scarcity of siliceous sponge reefs on the tectonically more active southern Tethyan margin as well as in the Lusitanian Basin of west-central Portugal reflects the scarcity of suitable mid to outer ramp niches. Coral reefs occurred in a larger variety of structural settings. Upper Jurassic coral reefs partly grew in high latitudinal areas suggesting an equilibrated climate. This appears to be an effect of the buffering capacity of high sea level. These feedback effects of high sea level also may have reduced oceanic circulation particularly during flooding events of third and higher order, which gave rise to the development of black shales and dysaerobic thrombolite reefs. Hence, the interplay of local, regional and global factors caused Jurassic reefs to be more differentiated than modern ones, including near-actualistic coral reefs as well as non-actualistic sponge and microbial reefs.