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The composite SK-1 borehole drilled in the Songliao Basin, north-east China penetrated non-marine rocks of Late Cretaceous age, some of which yielded assemblages of Ghoshispora . Species of this megaspore genus have palaeoenvironmental and potentially also biostratigraphic significance. Their value as determinants of age is, however, currently limited because many are difficult if not impossible to differentiate as our appraisal of their morphological characters reveals. This review helped to put the specimens recovered from the SK-1 borehole into context and led to the identification of a few of the specimens as Ghoshispora kondinskayae (Srivastava et Binda) Srivastava, G. sp. cf. G. bella (Kondinskaya) subsp. deltoidea Kutluk et al., and G. sp. cf. G. rara (Kondinskaya) Srivastava. Several revealed characters under the scanning electron microscope that differ from those of previously published species: two of these are described as new, namely Ghoshispora zhaoi sp. nov. and G. bulbosa sp. nov. Owing to a lack of sufficient specimens six other morphotypes have had to be identified in open nomenclature as G. sp. A–F. It is likely that the parent plants of all of the species grew in and/or close to standing water. The comparatively large number of very small specimens in association with, and having some of the characters of, the larger representatives of G. zhaoi suggests that a few might be the microspores of this species rather than incompletely developed megaspores.

We describe a new and rather unusual megaspore recovered from Middle Jurassic terrestrial deposits of Yorkshire, England that we name Reticuspinosporites whytei gen. et sp. nov. The contact area is non-trilete and is formed where an outer sculptured layer has not developed. This outer layer covers the remainder of the megaspore and bears novel sculpture consisting of a highly irregular reticulum with areas ‘infilled’ to form plateaus that bear long spines. Analysis of wall ultrastructure reveals a four-layered wall comprising from inside to outside: (i) innermost, separated lamina; (ii) inner homogeneous layer; (iii) central spongy layer; and (iv) outermost homogeneous layer that forms the sculpture. Wall ultrastructure is not entirely diagnostic but is most suggestive of lycopsid affinities. Unusually the megaspores commonly occur in pairs. They are not attached at their contact faces but by their equatorial or distal surfaces through entanglement of their spines. We interpret this feature as possibly an adaptation for floating and transport by water.

Illustrations of, and keys to, mangrove pollen and spores from extant taxa are essential to studies of tropical Quaternary palynology and palaeoecology of estuarine and marine deposits. In this paper we present a pollen morphological “atlas” and identification keys for most of the mangrove flora of the coastal areas of south China, including an interspecific key to the major mangrove elements Rhizophora and Sonneratia. The morphology of the pollen and spores of 38 species of living mangrove and associated plants is described and illustrated by transmitted light photographs and scanning electron micrographs. These descriptions and illustrations, and the identification keys are presented at an achievable taxonomic level. The keys are open for future development so that pollen of other mangrove and associated plants can be accommodated when available. In their present state they should, nevertheless, aid palynological analyses of Quaternary mangrove and associated estuarine and marine deposits, particularly in the South China Sea and surrounding regions, but also elsewhere in tropical and subtropical regions.

Maastrichtian sediments from the eastern Spanish Pyrenees have yielded a variety of mesofossils. The megaspores and megaspore apparatuses are referred to Minerisporites succrassulus Tschudy, Ghoshispora epispinosa sp. nov., Ghoshispora sp., Molaspora lobata (Dijkstra) Hall and Parazolla vallcebrensis sp. nov. Also recovered were specimens of uncertain affinity, some of which are possibly immature P. vallcebrensis, and massulae clusters that might be attributable to either this species or Azolla Lam. Minerisporites succrassulus and megaspores referable to Parazolla have not been recorded previously from beyond North America, and hitherto only one European occurrence of Ghoshispora has been noted. Hence, these new records indicate that the parent-plant groups concerned were more widespread during the Late Cretaceous than previously recognised. It is likely that all of them lived in or close to bodies of fresh water, reflecting a wetland habitat at the time of deposition.

International audience; Six localities in western France contain deposits of mid Cretaceous age that have yielded small assemblages of megaspores. These are Archingeay-Les Nouillers, Puy-Puy, Les Renardières, La Buzinie and Le Brouillard quarries, and Fouras tidal flat. With one exception, all are within the Charente and Charente-Maritime regions; Le Brouillard is further north in Anjou Province. The productive horizons are in sub-units of previously defined stratigraphic units A, B and C, and range in age from latest Albian or earliest Cenomanian to earliest mid Cenomanian. Owing to a scarcity of records of mid Cretaceous megaspores that can be relied upon for comparison with those recovered in this study, a cautious approach to identification has been adopted. Most forms are only compared to previously described species or referred to in open nomenclature. The most productive sample was from the lower part of sub-unit A1 at Puy-Puy. The assemblage recovered is dominated by spores referable to isoetalean Minerisporites and Paxillitriletes, with a few baculate, rugulate and other lycopsid spores and marsilealean Molaspora rugosa in association. The occurrence of the last of these in particular might indicate that this lowermost unit of the mid Cretaceous succession is earliest Cenomanian rather than latest Albian in age, but the evidence is equivocal. The composition of the assemblages from sub-unit B2 (Fouras tidal flat) and higher levels (La Buzinie, Le Brouillard) is consistent with a Cenomanian age determination and, in common with those from Puy-Puy, Archingeay-Les Nouillers and Les Renardières, indicates a bias towards parent plants that lived in and adjacent to water bodies. Among the forms recorded are species of Ariadnaesporites, Dijkstraisporites and Tenellisporites. The mixed character of the assemblages and the presence of damaged specimens and fragments in all of them lend support to previous interpretations of lacustrine to paralic environments of deposition for the sedimentary units concerned.

Ultrathin sectioning and examination of gymnosperm pollen grains from various Northwest European, mid-Mesozoic successions has confirmed or added weight to previous suggestions of botanical relationships for some taxa, and indicated possible affinities for others. The sections of Araucariacites australis, Callialasporites dampieri, C. trilobatus and C. turbatus support a derivation from the coniferous family Araucariaceae. Although differing in gross morphology from pollen of both extant Ephedra and Welwitschia of the order Gnetales, Eucommiidites troedssonii has ultrastructural characters in common with these, and with Triassic Equisetosporites. Cerebropollenites macroverrucosus is widely accepted as not being closely comparable to pollen of modern Tsuga, but ultrastructural similarities suggest the possibility of an ancestral connection. The structure of the exine of Clavatipollenites hughesii sensu Schulz from Jurassic deposits is fundamentally different from that of Cretaceous grains referred to the same species, confirming observations made previously on the basis of analysis under the light microscope, and suggesting a possible derivation from cycadalean rather than angiospermous plants. Species of Chasmatosporites may also be linked to the Cycadales, or perhaps to the Ginkgoales. Pilasporites couperi is shown to be a gymnosperm pollen grain rather than a pteridophyte spore, but more precise (family) links have not been established. The protosaccate structure of Quadraeculina anellaeformis is clearly demonstrated but its botanical affinity remains enigmatic. Previously suggested relationships between Spheripollenites and members of the Araucariaceae, Cupressaceae and Taxaceae are not supported. They do not seem to lie with any modern gymnosperm family, nor with ancient angiosperms.

Megaspores with prominent acrolamellae and body-processes (appendages) from Upper Cretaceous (upper Turonian-Santonian) deposits in south Bohemia, Czech Republic, originally referred by Knobloch to Arcellites medusus (Dijkstra) Potter are redescribed as Ariadnaesporites pilifer sp. nov. and Capulisporites klikovensis sp. nov. based on SEM and TEM studies. Although differing in gross morphology and to some extent in wall-structure, they are sufficiently similar to suggest that they represent closely related plant taxa. These may have belonged to an extinct group of “water ferns” rather than to either of the modern hydropterid families Marsileaceae and Salviniaceae.

Documented changes in the composition of the vegetation of Central Europe during the Late Cretaceous and Palaeogene are compared with those for other parts of the Northern Hemisphere in order to test the validity of the supposed global bioevents at the Cretaceous-Tertiary (K/T) and Eocene-Oligocene boundaries. Many heterosporous plant species, known mainly from megaspores, became extinct by the end of the Cretaceous. Most of the plants with which the enigmatic “mesofossils” Spermatites and Costatheca were associated also disappeared towards the end of this period. On the other hand, the angiosperms seem to have evolved without significant interruption at either the K/T or the Eocene-Oligocene transitions. Although there were many extinctions during the Late Cretaceous among certain groups, the plants concerned appear to have been continually replaced by other taxa. Recent studies of fruit and seed assemblages from Central and Western Europe have revealed 270 species of angiosperms and some conifers belonging to 28 families. Of the 13 genera recovered from Maastrichtian deposits, 11 occur in the Palaeocene and are partly represented by the same species. Although the vegetation may have been damaged by the kinds of catastrophic events that are suggested to have taken place at the K/T boundary, such as a bolide impact or an episode of major volcanism, the effects are likely to have been only temporary (a few years) and not necessarily on a global scale. Overall, the palaeobotanical evidence suggests that there were continuous rather than abrupt changes in the composition and physiognomy of the vegetation throughout the Late Cretaceous and Early Tertiary. The changes that took place during the Eocene and Oligocene correspond to stepwise climatic deteriotation. The uppermost Eocene-lowermost Oligocene transition was connected with subhumid to semi-arid summer seasons which resulted in the disintegration of forest cover and increased migration of terrestrial vertebrates. A lowering of mean January temperatures during the Oligocene led to the “withdrawal” or extinction of some palaeotropical elements and immigration of deciduous trees into Central Europe in several waves, the most pronounced of which was in the middle Oligocene.

An analysis of Mesozoic and Tertiary megaspore assemblages from NW Europe has shown that several zonate and coronate genera are not adequately differentiated on the basis of their original diagnoses. A number of the species that have been described previously, and a few new forms recently encountered, display characters and are attributable to more than one genus. The genera considered are Auriculizonospora, Capillisporites, Dijkstraisporites, Flabellisporites, Henrisporites, Herbosisporites, Membranisporites, Minerisporites, Pavlovisporites (a monotypic Permian form), Paxillitriletes, Sepisporites, Tenellisporites and Triangulatisporites. A comparison of the morphology of all of the species within this group that are known to us has enabled a reassessment of the criteria on which they can be distinguished. As a result (1) Auriculizonospora is reinstated as a genus that is distinct from Minerisporites, (2) the diagnoses of these two genera, Dijkstraisporites, Paxillitriletes and Tenellisporites are emended, (3) Membranisporites is placed in synonymy with Paxillitriletes, (4) six species are newly combined with other genera, and (5) one is renamed. The nomenclatural changes are as follows: Dijkstraisporites (al. Minerisporites) pterotus (Singh, 1983) comb. nov., ?Flabellisporites (Al Tenellisporites) spinatus (Peake, 1986) comb. nov., Minerisporites archangvillarae nom. nov. (new name for Minerisporites elegans Archangelsky and Villar de Seoane, 1989, a junior homonym of M. elegans Li Wenben and Batten, 1987), Minerisporites (al. Henrisporites) levis (Lachkar, 1979) comb. nov., Minerisporites (al. Dijkstraisporites) psilites (Gunther and Hills, 1972) comb. nov., Paxilitriletes (al. Triletes) ales (Harris, 1935) comb. nov., and Paxillitriletes (al. Triletes) samarus (Dijkstra, 1951) comb. nov. Although a few forms remain difficult to place because of their “intermediate” character, it is now possible to refer the majority to genera with greater confidence than hitherto. The chances of both taxonomic and nomenclatural confusion, and of biostratigraphic misinterpretation should, therefore, be reduced in the future. Most of the genera are thought to have isoetalean origins but the three Triassic species that have been referred to Triangulatisporites, and some of the other species from this geological period may well be selaginellalean spores.

Species of the megaspore genus Minerisporites Potonie, megaspore apparatuses of species of the water fern Azolla Lamarck, and some associated organic-walled microfossils recovered from deposits of the Upper Palaeocene and Palaeocene/Eocene transition in the southern part of the Netherlands and neighbouring Belgium are redescribed on the basis of an examination of specimens under scanning and transmission electron microscopes. Originally studied about 40 years ago by S.J. Dijkstra, the re-examination has enabled emended diagnoses to be produced for six taxa: Minerisporites glossoferus (Dijkstra) Tschudy, M. mirabilis (Miner) Potonie, M. mirabilissimus (Dijkstra) Potonie, Azolla schopfii Dijkstra, A. teschiana Florschutz, and A. velus (Dijkstra) Jain and Hall. In addition, a revised description is provided for massulae of Salvinia Seguier that were originally thought to be megaspores and, hence, named by Dijkstra as Triletes? exiguus. The gross morphology and construction of the exospore of the species of Minerisporites are similar, but nevertheless sufficiently distinct for them to be maintained as separate taxa. Monolete microspores are preserved in hollows in the reticulate surface of some of the specimens of M. mirabilissimus. This is consistent with the presumed isoetalean affinity of Minerisporites. An apparent stratigraphic morphocline from M. glossoferus to M. mirabilis, suggested previously, is confirmed following our reassessment of their characteristics. The species of Azolla are all multi-floated, but they differ from each other in several ways, in particular with respect to the ultrastructure of the megaspore wall. They are also distinct from all other species that have been considered in sufficient detail for satisfactory comparisons to be made. The massulae of A. teschiana are described for the first time. The floats in A. velus are attached to the proximal part of the megaspore only by suprafilosal hairs. There are no maniculae. It is argued that these structures do not exist in either this or any other species of Azolla. Whole fertile fossil remains that demonstrate the nature and habitat of the living plants are known for all three genera. Hence, their reproductive structures can be used with confidence in palaeoenvironmental interpretation. The overall assemblage, which also includes a few specimens of the marsilealean megaspore Molaspora lobata (Dijkstra) Hall, undoubtedly reflects the presence of lowland aquatic and semi-aquatic vegetation.

Assemblages of dinoflagellate cysts of Cenomanian-Turonian age recovered from sequences containing bituminous marls (“black shales” of most authors) in the Lower Saxony Basin, Helgoland and eastern England vary in composition according to lithofacies and palynofacies. Two main associations have been recognised. The first is dominated by Spiniferites and generally occurs in chalks and marls that accumulated in an open marine environment. It is, however, also present locally in comparatively organic-rich marls where it suggests the presence of well-oxygenated conditions above an oxygen-depleted zone in a stratified water column. Species of Cyclophelium and/or Eurydinium ( E. saxoniensis sp. nov.) dominate the second association which usually occurs in samples that contain an abundance of granular amorphous organic matter. This palynofacies points to deposition in a stressed environment with a low level of oxygen extending high up the water column, a phenomenon that is believed to have been caused by the formation of temporarily silled basins within which circulation was restricted. The position of the Cenomanian-Turonian boundary in the Lower Saxony sequences has yet to be determined precisely but the stratigraphic distribution of the dinoflagellate cysts Adnatosphaeridium tutulosum, Carpodinium obliquicostalum and Lithosphaeridium siphoniphorum supports a recent assessment based on macrofossils.

A dichotomous key to the recognition of 86 Normapolles and morphologically similar pollen genera is presented. The key is accompanied by line drawings of each genus and an illustrated glossary of descriptive terms.

The megasporesArcellites plicatus sp. nov. and A. yiminensis sp. nov. and adherent microspores Crybelosporites minor (Qian and Wang 1981) comb. nov. and C. astrictus sp. nov. are described and illustrated from the Damoguihe and Yimin Formations of the Jalainor Group of northeast Inner Mongolia. Transmission electron micrographs of thin-sectioned specimens reveal a close similarity between the wall structure of the megaspores and microspores, thus lending further support to previously recognised indications of a natural relationship between Arcellites and Crybelosporites. Comparison with the morphology, and consideration of the stratigraphic distribution of all known species of Arcellites suggest that the strata from which the new taxa were recorded range from Barremian to Aptian in age. Single specimens of Arcellites sp. cf. A. rugosus Singh 1964 and an unnamed species of the genus are also described, and Triletes fecheri Huckriede 1982 is reported to be a junior synonym of Arcellites pyriformis (Dijkstra) Potter 1963.

Pollen grains referable to the Normapolles group first appeared during the Cenomanian. They diversified rapidly through the remainder of the Cretaceous and during the early Palaeogene, but by the end of the Eocene they were virtually extinct. They were most numerous in a province which extended from what is now West Siberia across Europe to eastern North America. The Western Interior of North America and West Siberia are considered to delimit the longitudinal boundaries of this province. These areas were submerged during the Late Cretaceous and formed physical barriers to wider dispersal of many Normapolles-producing plants. The Normapolles that have been reported from further afield comprise only minor elements of palynofloras except locally in a few areas where they are apparently relatively abundant. Such records do not invalidate the Siberian and American longitudinal limits but they do require that the concept of the province be altered somewhat to indicate region within which Normapolles are more consistently abundant than elsewhere. Climate must have been as significant an influence on the evolution of the parent plants as it appears to have been in determining the northern and southern boundaries of the province, however vaguely defined these are at present. Palynological analyses of core and cuttings samples from the U.K. continental shelf have helped to refine the northern limit to some extent. Until recently, published maps have included both Svalbard and Greenland in the Normapolles Province. Whilst possibly correct for some of the early Tertiary, Late Cretaceous (Campanian-Maastrichtian) strata in the Northern North Sea and west of the Shetland Islands have yielded Aquilapollenites, Wodehouseia and other taxa typical of the Aquilapollenites Province. The transition between the flora of this boreal region and the European part of the Normapolles Province, which is known to extend as far north as southern Sweden, would thus appear to lie approximately on the latitude of the central North Sea.

The morphological resemblance between the sheaths of modern Gloeotrichia and Early Cretaceous Celyphus rallus Batten strongly suggests that the latter is a Mesozoic relative of extant blue-green algal species belonging to the family Rivulariaceae. The fossils are typically encountered in argillaceous sediments that were deposited in non-marine environments. When living, they could have been planktonic, but because all the colonies recovered to date are compressed, the possibility that they formed hemispherical rather than spherical masses and grew attached to a substrate cannot be entirely excluded. In common with many blue-greens, C. rallus may have been a pioneering species, perhaps at the transition from brackish to fresh water deposition. Local abundances might well reflect “blooms” in neutral or slightly alkaline conditions at this juncture, but could also be connected with seasonal changes and fixing nitrogen from the atmosphere in nitrogen-poor environments.

The European to West Siberian/Central Asian part of the Late Cretaceous—early Tertiary Normapolles Province in known as the European-Turanian palaeofloristic region and has nothing to do with the Turonian Stage.