Dinoflagellate Cyst Species Research Articles

Two areoligeracean dinoflagellate cysts from the Carstone Formation (Lower Cretaceous) at Middlegate Quarry, North Lincolnshire, UK

Five Lower Albian (Lower Cretaceous) areoligeracean dinoflagellate cyst species are present in the Carstone Formation at Middlegate Quarry, North Lincolnshire, UK: Canninginopsis monile , Circulodinium deflandrei , Cyclonephelium compactum , Cyclonephelium intonsum and Cyclonephelium longispinatum . The taxonomy of Circulodinium deflandrei is reviewed with respect to 20 measured Carstone specimens. The taxonomy of Cyclonephelium longispinatum is reviewed with respect to 70 measured Carstone specimens and a study of 40 measured specimens from its type material in Site 361, Deep Sea Drilling Project Leg 40, offshore southwestern Africa. Circulodinium deflandrei and Cyclonephelium longispinatum have recently been considered by other workers to be junior synonyms, respectively, of Circulodinium hirtellum and Tenua anaphrissa . However, following detailed study of their morphologies, the synonymies are formally rejected here. An emended diagnosis is given for C. longispinatum . A re-assessment of the stratigraphical ranges of taxa co-occurring with the type material of C. longispinatum is consistent with a Late Albian to Early Turonian age range in Site 361.

The Cretaceous to Eocene: a biostratigraphical review and a new detailed palynostratigraphy of Greenland and adjacent areas

The present paper compile and correlate for the first time Cretaceous to Eocene palynostratigraphies across the Arctic. It focus on Greenland and adjacent areas, including the Labrador–Baffin Seaway, onshore Nuussuaq Basin in central West Greenland, onshore southern East Greenland, central East Greenland, North-East Greenland, eastern North Greenland and the Danmarkshavn Basin, but also extends to Canadian Arctic Archipelago and the Barents Sea region off Norway. The paper compile data from more than three decades of detailed Arctic palynological analyses, based mainly on dinoflagellate cysts. The paper gives a historical overview of the Cretaceous to Palaeogene paleontological studies of Greenland and presents an overview of 85 palynological intervals and numerous events. The palynological assemblages from the Labrador–Baffin Seaway, Nuussuaq Basin and north-east Baffin Bay reflect the opening of the Labrador–Baffin Seaway from brackish to freshwater environment in a large embayment in the Early Cretaceous to an open marine seaway in the Late Cretaceous. Assemblages reveal in dinoflagellate cyst provincialism between the opening stages of the Labrador–Baffin Seaway and the already opened Greenland–Norwegian–Barents seaway. The Upper Cretaceous global Oceanic Anoxic Event 2 (OAE2) spanning the Cenomanian/Turonian boundary is recognised from Arctic Canada, north-east Baffin Bay, Nuussuaq Basin in central West Greenland, and North-East Greenland, and is mapped and correlated based on dinoflagellate cyst stratigraphy and carbon isotope (δ13Corg) curves. The dinoflagellate cysts assemblages of the Cretaceous/Palaeogene boundary are correlated from the Labrador Sea across to the Nuussuaq Basin in central West Greenland; in both areas the earliest Danian palynological assemblage is represented by incoming warm-water species. The presence of the global Paleocene–Eocene Thermal Maximum (PETM) in the Palaeogene successions in North-East Greenland and in exploration wells in the Labrador–Baffin Seaway is indicated by the incoming of the warm-water dinoflagellate cyst species Axiodinium augustum.

Study on the diversity and germination of dinoflagellate cysts in the sediments of foreign ships in Shanghai Port

The dinoflagellate cysts present in the ballast water sediment of foreign ships in Shanghai Port have not been previously studied. Therefore, sediment samples were collected from the ballast water of 16 foreign ships in Shanghai Port, and the types of dinoflagellate cysts were identified and their abundance was calculated, with a specific focus on the analysis of toxic and harmful dinoflagellates. Moreover, simulations of temperature and salinity conditions throughout the year in the Shanghai port waters were conducted to carry out dinoflagellate cyst germination experiments, with analyze and compare the germinated dinoflagellate cysts under different conditions. Dinoflagellate cysts were found in 100 % of the ship sediment samples, including a total of 9 species of toxic and harmful dinoflagellate cysts. In the germination experiment, 15 °C was found to be the optimal temperature for the germination of dinoflagellate cysts in ballast water sediment, and high salinity is more favorable for cyst germination.

Transoceanic ships as a source of alien dinoflagellate invasions of inland freshwater ecosystems

Ships' ballast water and sediments have long been linked to the global transport and expansion of invasive species and thus have become a hot research topic and administrative challenge in the past decades. The relevant concerns, however, have been mainly about the ocean-to-ocean invasion and sampling practices have been almost exclusively conducted onboard. We examined and compared the dinoflagellate cysts assemblages in 49 sediment samples collected from ballast tanks of international and domestic routes ships, washing basins associated with a ship-repair yard, Jiangyin Port (PS), and the nearby area of Yangtze River (YR) during 2017–2018. A total of 43 dinoflagellates were fully identified to species level by metabarcoding, single-cyst PCR-based sequencing, cyst germination and phylogenetic analyses, including 12 species never reported from waters of China, 14 HABs-causing, 9 toxic, and 10 not strictly marine species. Our metabarcoding and single-cyst sequencing also detected many OTUs and cysts of dinoflagellates that could not be fully identified, indicating ballast tank sediments being a risky repository of currently unrecognizable invasive species. Particularly important, 10 brackish and fresh water species of dinoflagellate cysts (such as Tyrannodinium edax) were detected from the transoceanic ships, indicating these species may function as alien species potentially invading the inland rivers and adjacent lakes if these ships conduct deballast and other practices in fresh waterbodies. Significantly higher numbers of reads and OTUs of dinoflagellates in the ballast tanks and washing basins than that in PS and YR indicate a risk of releasing cysts by ships and the associated ship-repair yards to the surrounding waters. Phylogenetic analyses revealed high intra-species genetic diversity for multiple cyst species from different ballast tanks. Our work provides novel insights into the risk of bio-invasion to fresh waters conveyed in ship's ballast tank sediments and washing basins of shipyards.

Palsys.org: an open-access taxonomic and stratigraphic database of organic-walled dinoflagellate cysts

Abstract. It is with great pleasure that we introduce palsys.org (https://palsys.org/genus/, last access: 8 December 2023), a fully open-access taxonomic, stratigraphic and image database of organic-walled dinoflagellate cysts. Palsys.org started as the in-house database of the Laboratory of Palaeobotany and Palynology (LPP) Foundation over 30 years ago. It is now owned by Utrecht University and has been expanded and transformed into a public online platform for use in research and education. Palsys.org includes the taxonomic descriptions of genera and species of organic walled dinoflagellate cysts, from the (often translated) literature, and emendations and synonymy, mainly following Williams et al. (2017) and the stratigraphic calibrations from DINOSTRAT (Bijl, 2022), and has around 25 000 images of species. Here, in this launch paper, we explain the history of the database, present its current functionalities and explain our set-up of the data quality control. We call upon the community to help us keep palsys.org up to date and complete by, for example, by sending additional information, imagery and feedback in general through the platform. Palsys.org brings dinoflagellate micropaleontology in line with the open-science principles of modern academia.

Dinoflagellate cyst distribution over the past 9 kyrs BP from offshore east Tasmania, southeast Australia

Southeastern Australia’s marine waters are notably warming, surpassing global averages. This region has emerged as a strategic location for researching planktic microfossils, particularly dinoflagellate cysts, in modern and Late Quaternary sediments, offering crucial insights into the biophysical properties of mid-latitude waters. This study examined cyst distribution in marine sediment cores near Maria Island, Tasmania, southeastern Australia, up to 9000 years before present (kyrs BP). Dominant cysts included Protoceratium reticulatum, Protoperidinium spp. (P. avellana, P. conicum, P. oblongum, P. subinerme, P. shanghaiense), and Spiniferites spp. (S. bulloideus, S. hyperacanthus, S. membranaceus, S. mirabilis, S. pachydermus, and S. ramosus). Inshore, Spiniferites spp. constituted a higher proportion (up to 61%), while offshore was dominated by P. reticulatum (up to 80%). Impagidinium spp. and Nematosphaeropsis labyrinthus were exclusively found offshore and displayed increased abundance from ∼6 kyrs BP, suggesting a shift from a shallow to a deep-water habitat. Alexandrium tamarense species complex cysts were present over 140 years inshore and approaching 9 kyrs BP offshore, indicating a longstanding endemic presence. Gymnodinium catenatum cysts were detected exclusively inshore from ∼50 years ago, indicating a relatively recent bloom phenomenon. The East Australian Current’s limited southward reach is suggested by the absence of the warm-water cyst-producing taxon Lingulodinium polyedra. Similarly, the non-detection of the cold-water species Spiniferites antarctica and Impagidinium pallidum reflects Subtropical Front boundaries against subantarctic incursions from the south. In contrast to coccolithophores in the same core, no noticeable shift from cold to warm-water dinoflagellate cyst species was observed. This documentation of dinoflagellate cysts aids in predicting environmental impacts on local communities and beyond.

Single-cell DNA from West Greenland marine sediments suggests presence of Protoperidinium tricingulatum in the Arctic.

Spiny brown dinoflagellate cysts are commonly used as sea-ice indicators in the Arctic, but their biological affinities are not well known. We present the first indication of hitherto temperate Protoperidinium tricingulatum in the Arctic based on single-cell LSU rDNA sequencing from sediments of the Disko Bay-Vaigat Sound, West Greenland. The morphological similarity of the sequenced cyst morphotype to the sea-ice indicator Islandinium? cezare morphotype 1 is striking. The morphology of the isolated cysts, as well as those observed in the total cyst assemblage following standard palynological preparation, both resemble either I.? cezare morphotype 1 or P. tricingulatum, suggesting that the specimens may in fact be close morphological variants of the same species. In addition, nine LSU rDNA sequences were obtained from morphological variants assigned to Islandinium minutum s.l.: including both subspecies minutum and subspecies barbatum. The two subspecies could not be differentiated based on partial LSU rDNA sequencing. Overall, Arctic spiny brown dinoflagellate cyst species may be morphologically more diverse and taxonomically more complex than shown earlier and further genetic and morphological studies are needed. Importantly, the value of cysts as palaeoecological indicators depends on a sound understanding of their biological affinity and taxonomy.

New dinoflagellate cyst species from the Middle Eocene of the Volgograd–Volga region, south-west Russia

The Keresta Formation, located in the Volgograd–Volga region (the Volga–Caspian subregion of south-west Russia) has been dated as Middle Eocene, Lutetian, based on dinoflagellate cysts of the Enneadocysta arcuata Zone and nannofossils from the Lutetian subzones CP13c–CP14a. Within this interval, four new species of dinoflagellate cysts are described: Spiniferella grigorovichiae sp. nov., Impagidinium tuberculatum sp. nov., Hystrichostrogylon crassitunicatum sp. nov. and Hystrichosphaeropsis tenerum sp. nov. The new species present a high correlation potential for Middle Eocene stratigraphy over the southern part of the Russian Platform. Also, the assemblage of organic-walled microphytoplankton from the Keresta Formation indicates warm-water marine environments within the marginal part of the Paratethys Basin.

Upper Cretaceous dinoflagellate cysts events from the sub-tropical northern hemisphere

Recognizing the ranking optime sequence of fossil dinoflagellate cysts can be a challenge for qualitative biostratigraphy. For this reason, we present the result of a quantitative stratigraphic study through probabilistic analysis of six wells from Baja California (Mexico) and six from the Gulf of Suez and the Mediterranean Sea (Egypt), which allows us to recognize 22 species of dinoflagellate cysts in an optimal sequence with 95% probability for the Upper Cretaceous in subtropical areas of the Northern Hemisphere. Photoautotrophic species represent the largest number in the database (159 species), indicating that they are the main producers, while heterotrophic species are in the minority (74 species). Spiniferites and Florentinia are the most abundant and diverse taxa, which, together with the absence of the genus Impagidinium, indicates a shallow marine depositional environment. The quantitative analysis estimates an optimal classified succession that allows the Upper Cretaceous to be divided into five groups (G1 to G5) of species communities with similar ages. The greatest species diversity is found in group G4, associated with the Maastrichtian, and the least in group G1, associated with the early Cenomanian to early Turonian. These results and comparison with previous studies using the same method of quantitative biostratigraphy suggest a similarity of paleoenvironmental conditions in subtropical regions of the Northern Hemisphere and tropical regions during the Upper Cretaceous.

Upper Valanginian – Hauterivian calcareous dinoflagellate cyst and calpionellid zones from the Agrio Formation (Neuquén Basin), Argentina

In this paper we describe for the first time the calcareous dinoflagellate cysts and calpionellid associations from upper Valanginian-Hauterivian orbital-driven rhythmic distal ramp deposits (Agrio Formation) in the Neuquén Basin, Argentina. Three stratigraphic sections from the northern Neuquén province (Loma La Torre and El Portón) and southern Mendoza province (Arroyo Loncoche) were studied. The Agrio Formation contains a low diverse association of these microfossils, among which ten calcareous dinoflagellate cyst species and five calpionellid species were recognized, all of them known from the Lower Cretaceous pelagic sediments of the Tethyan region. Two calcareous dinoflagellate cyst zones (Carpistomiosphaera valanginiana, and Stomiosphaera echinata), as well one calpionellid zone (Tintinnopsella), previously proposed for the Tethyan realm, are confirmed for the Agrio Formation. These zones are consistent to late Valanginian - Hauterivian age assignments previously established based on ammonites, nannofossils, and organic-walled dinoflagellate cysts.

Late maastrichtian- early eocene dinoflagellate cyst biostratigraphy and aleoenvironmental study of sediments in Akukwa-1 well in the Anambra Basin

Dinoflagellate cyst biostratigraphy and palaeoenvironment of deposition of sediments penetrated by Akukwa-1 Well was carried out with a total of 253ditch cuttings using the conventional maceration technique for recovering of acid insoluble organic-walled microfossils from sediments. Sedimentological description delineated five (5) lithological units within the well, which included those of Nkporo Shale, Mamu Formation, Ajali Sandstone, Nsukka Formation and Imo Shale. A total of 14 genera and 35 species of dinoflagellate cyst were identified. The recovered dinocysts were used to establish palaeoenvironment which ranged from marginal to shallow marine, the forms were also used to propose four (4) informal dinoflagellate cyst zonations labelled (A-D) based on the first and last occurrences of two or more species. They included Zone A (Apectodinium paniculatum zone), occurring at 7990ft(Maastrichtian), zone B(Paleocystodinium australinium zone) occurring between 7990ft -4000ft (Upper Maastrichtian), zone C(Apectodinium homomorphum zone) occurring between 4000ft -2550ft (Upper Maastrichtian), and zone D(Homotryblum palladium zone) occurring between 5550ft-1520ft(Paleocene- Early Eocene). The erected dinocyst zones were correlated with the existing biozones in tropical areas of Africa and northern South America.

The abundance and species assemblages of dinoflagellate cysts at sediments in the three estuaries of the Southern part of South Sulawesi

Harmful algal blooms (HAB) are a phenomenon of drastically increasing phytoplankton populations, which can cause problems in aquatic ecosystems. Dinoflagellate cysts are a type of phytoplankton that are the main source of causing the HAB phenomenon; this occurs due to unfavorable environmental conditions. The Southern Estuary of South Sulawesi has high fishery resources and high primary productivity. The coastal areas around these waters are widely used for anthropogenic activities that trigger nutrient increases. There are no studies on HAB, especially the abundance and community structure of dinoflagellate cysts at this location. This study aims to identify the types, abundance, and species assemblages of dinoflagellate cysts in the three estuaries of southern South Sulawesi. Sampling was carried out at three locations, namely the Pappa River Estuary, the Kelara River Estuary, and the Calendu River Estuary, in January 2022. Each location consists of 4 stations, 3 sub-stations with 3 repetitions sampling for each substation. Results showed that there were 34 species of dinoflagellate cysts belonging to 6 families, namely Gonyaulacaceae, Gymnodiniaceae, Osteropsidaceae, Peridiniaceae, Polykrikaceae, and Protoperidiaceae. The highest abundance of dinoflagellate cysts was at the Calendu River estuary station III, accounting for 82 cysts g−1, while the lowest abundance of dinoflagellate cysts was found at Pappa River estuaries stations I and II, accounting for 8 cysts g−1. The level of diversity, uniformity, and richness of dinoflagellate cysts was not significantly different in the three study sites. The family Osteropsidaceae was the most common type of dinoflagellate cyst found in the three study sites. The Osteropsidaceae family is a type of dinoflagellate cyst that contains toxins, so it can be assumed that the three research sites have the potential for HAB.

Dinoflagellate cyst biostratigraphy of the Bathonian, Callovian, and the Upper Jurassic in North Bulgaria

Forty-four selected organic-walled dinoflagellate cyst species have been used for biozonation of the Bathonian, Callovian, and the Upper Jurassic in North Bulgaria. The dinocysts were collected from 49 borehole sections and two exposures. The following dinocyst zones are herein introduced and described: Lithodinium valensii–Gongylodinium erymnoteichos Concurrent-range Zone (lower–middle Bathonian); Ellipsoidictyon reticulatum Assemblage Zone (upper Bathonian–lower Callovian); Dingodinium harsveldtii Taxon-range Zone (middle–upper Callovian); Lambodinium absidatum Assemblage Zone (lower Oxfordian); Scriniodinium dictyotum papillatum–Caddasphaera halosa Concurrent-range Zone (middle–upper Oxfordian); Rhyncodiniopsis gongylos Assemblage Zone (lower Kimmeridgian); Systematophora varispinosa–Gonyaulacysta? crassicornuta Concurrent-range Zone (middle–upper Kimmeridgian); Edmontodinium polyplacophorum Assemblage Zone (lower Tithonian); and Leptodinium? plagatum–Prolixosphaeridium perforospineum Concurrent-range Zone (middle–upper Tithonian). Some of the zones were partly or completely subdivided in subzones. The dinocyst zones and subzones were correlated with the Bulgarian ammonite and calpionellid zones and subzones.

The taxonomy of selected marine microplankton from the Middle and Upper Jurassic (Callovian–Kimmeridgian) of the North West Shelf, Australia

The palynological assemblages of 134 legacy and 212 new palynological preparations from the Callovian–Kimmeridgian of the North West Shelf of Western Australia, were used to identify new species of dinoflagellate cysts with biostratigraphic utility. Samples were derived from cores and sidewall cores from nine wells; four from the Bonaparte Basin, and five from the Northern Carnarvon Basin. This work describes 11 new species of dinoflagellate cyst, one species of acritarch, and emends the descriptions of two genera and five species of dinoflagellate cyst. The new forms include: Batiacasphaera elongata, Cleistosphaeridium? oxfordianum, Egmontodinium twiggii, Evansia? rotundata, Jansonia thormalleus, Lanterna foveolata, Lanterna reticulata, Lanterna spongiosa, Orobodinium tantillum, Oligosphaeridium? varifenestratum, and Sepispinula florida, and the acritarch Triovalium attenuatum. Emendations are proposed for the genera Lanterna and Tringadinium, and the species Broomea fusticula, Egmontodinium toryna, Pyxidiella pandora, Microdinium jurassicum, Jansonia jurassica, and Tringadinium bjaerkei.

New data on the palynostratigraphy and paleoenvironments of the late Miocene (Tortonian) Quifangondo Formation in the Cabo Ledo section, Kwanza Basin, Angola

A detailed palynostratigraphic and palynofacies analysis, associated with a lithological control, was carried out on eleven outcrop samples from the Quifangondo Formation in the Cabo Ledo (Petrofina) section, Kwanza Basin, Angola. The samples yield relatively diverse and well-preserved terrestrial and marine palynomorphs. A systematic analysis of the samples enables the identification of nine spore genera and 3 species, 20 pollen genera and 13 species, and 32 dinoflagellate cyst genera and 34 species. In addition, 10 genera of other aquatic palynomorphs, such as Chlorophyceae green algae, are identified. Dinoflagellate cysts and other aquatic palynomorphs typically dominate throughout the assemblages. In this section, a combined pollen - dinoflagellate cyst zonation is used to define two palynoassociations. The first palynoassociation is middle Tortonian in age and is characterized by the presence of the pollen grain Fenestrites spinosus and the first occurrence of the dinoflagellate cyst species Selenopemphix armageddonensis. Additionally, diverse Chlorophyceae green algae dominate most of this interval samples. The second palynoassociation is assigned to the late Tortonian and is characterized by a drastic decrease in Chlorophyceae green algae, as opposed to the gonyaulacales dinoflagellate cysts. The first occurrence of the pollen grain Fenestrites longispinosus marks the transition between the palynoassociations. Lithologically, the Cabo Ledo (Petrofina) section is dominated by a claystone with an increase in the silt and carbonate components towards the upper section. The lithological data, integrated with palynostratigraphy and palynofacies, suggests that the upper part of the Quifangondo Formation was mainly deposited in an inner to middle neritic environment characterized by dysoxic conditions punctuated by periods of terrestrial inflows. Such conditions typically result from seasonal fluctuations. The age and depositional environment of the upper Quifangondo Formation inferred from this new data allows a correlation with the other Quifangondo sequences previously studied by the authors. This multi-proxy approach is important for further stratigraphic analysis with other age-controlled lithostratigraphic units in the basin. Furthermore, the improvement of paleoenvironmental and depositional models for this unit is of great importance for cross-basin correlation and future petroleum exploration plays.

Santonian‐Campanian dinoflagellate cyst biostratigraphy and paleoenvironment of the Krishna‐Godavari Basin, India

AbstractThe present study deals with the biostratigraphic framework of Late Cretaceous sediments of the subsurface Well (DNG) “A” (2085–1840 m depth) from the Raghavapuram/Chintalapalli Shale of the Krishna‐Godavari Basin and analyzed the palynological assemblage. The recorded palynological assemblage is dominated by marker dinoflagellate cyst viz. Areoligera coronata, Areoligera senonensis, Heterosphaeridium spinaconjunctum, Nelsoniella aceras, Nelsoniella semireticulata, Odontochitina porifera, Xenascus ceratioides, and Xenascus gochtii species. The last occurrence (LO) of significant species of dinoflagellate cysts is considered for the biostratigraphic establishment. On the basis of dinoflagellate cyst biostratigraphy, the examined sequences correspond to the Santonian‐Campanian age. The dominance of gonyaulacoid dinoflagellate cysts is interpreted in terms of sea‐level fluctuation and other paleoenvironmental signals through this biostratigraphic establishment. The recorded dinoflagellate cysts indicate the outer neritic, cool depositional environment. The sea‐level rise, recorded in our study is linked with the transgressive phase during the Late Cretaceous (Santonian‐Campanian) period.

Revision of the endemic dinoflagellate cyst genus Pontiadinium Stover & Evitt, 1978 from Lake Pannon and the Paratethys realm (Late Miocene–Early Pliocene, Central Europe)

The biota of the brackish-water Lake Pannon in the Pannonian Basin is characterised by remarkable endemism due to the isolated evolution of the lake for 8 myr after the last Miocene marine connection ceased (∼11.6 Ma). A conspicuous feature of this endemism is the large, probably ecophenotypic variation in the morphology of brackish-water dinoflagellate cysts that challenges taxonomy and complicates biostratigraphical and ecological interpretations. We conclude that a widely debated Lake Pannon genus, Pontiadinium, includes several proximate dinoflagellate cyst species with prominent apical and antapical protuberances, and we show how the genus differs from the morphologically similar gonyaulacacean cyst genera Impagidinium, Leptodinium, Cribroperidinium and Komewuia. The generic description of Pontiadinium is emended together with the species descriptions of Pontiadinium inequicornutum, Pontiadinium obesum and Pontiadinium pecsvaradanesis. A new species is described as Pontiadinium szentaiae sp. nov. from Našice (northern Croatia) that is characterised by unique trabeculate sutural septa formed from a beaded tegillum supported by columellae or rod-like luxuriae. The dinoflagellate cyst assemblages of the long-lived brackish-water Lake Pannon clearly demonstrate that dinoflagellate cysts in low-salinity, isolated epicontinental seas display greater morphological plasticity than their normal-marine relatives. The development of an antapical horn appears to be a previously undocumented example of phenotypic morphological features that developed in response to subnormal salinities within at least two dinoflagellate cyst genera endemic to Lake Pannon and the Post-Paratethyan seas of the Ponto-Caspian realm. This ecophenotypic variation resulted in a higher level of morphological adaptation, leading to the evolutionary development of new dinoflagellate cyst species and genera.

Maastrichtian–Danian palynomorphs from the Pedro Luro Formation, Ombucta 1 Borehole, Colorado Basin, Argentina

In this contribution, the palynomorphs of the Pedro Luro Formation, Ombucta 1 Borehole, Colorado Basin, Argentina, were recorded to perform palinostratigraphic analysis, evaluate dinoflagellate cyst provincialism, recognise trends in sea surface temperature (SST) and estimate palaeobiogeographic affinities. Sixty eight species of palynomorphs were identified and three informal biostratigraphic intervals were recognised. The first, determined by Hafniasphaera australis associated with Alterbidinium acutulum, implies that deposits below 984 mbrf would not be younger than late Maastrichtian (calcareous nannofossil biozone CC26). The second interval between 982 and 954 mbrf is assigned to the upper Maastrichtian–Danian. It is difficult to give more accuracy to the age of this interval due to the absence of species with LADs (last appearance datum) in the latest Maastrichtian and the lack of early Danian taxa. This together with the recognition of CC26 (Maastrichtian) followed by NP2-NP3 (Danian) could suggest that the K/Pg boundary is not represented. The third interval includes Senoniasphaera inornata (LAD: 62.6 Ma), suggesting an age no younger than Danian for deposits between 952 and 946 mbrf (NP2-NP3). The typical taxa of the Tropical-subtropical Province predominate (Phelodinium magnificum, Lejeunecysta spp. and Senegalinium leavigatum) followed by genera from the Warm-temperate Province (Alterbidinium acutulum, Spinidinium macmurdoense, Spinidinium styloniferum and Diconodinium lurense), suggesting changes in SST trends, from tropical-subtropical to warm-temperate conditions. The coincidences of dinoflagellate cyst species recorded between the Colorado Basin and basins of equatorial South America, the African counterpart, Brazil and Uruguay, would suggest the exchange of dinoflagellates, reflecting palaeobiogeographic affinities.

Out of the Blue and into the Black: Preparation, Mounting, and Image Rendering of Complex, Chorate Dinoflagellate Cysts for Scanning Electron Microscopy

Abstract:We describe an experimental approach for achieving an optimal black background for scanning electron photomicrographs of small samples with elaborate and intricate structures. Specimens of the highly ornate, 66-million-year-old chorate dinoflagellate cyst species Cannosphaeropsis franciscana were selected as the subject of this study. Photomicrographs collected following standard aluminum stub surface placement were compared to those taken of specimens mounted using a novel pin-and-pedestal method. This simplistic mounting technique minimizes the need for post-production image editing and extraneous background removal.

Using microplankton proxies to evaluate marine palaeonvironmental changes during late Maastrichtian: Evidence from the Møre Basin (Norwegian continental shelf)

This work presents high-resolution palynological and micropalaeontological analyses of a cored succession across the upper Maastrichtian from a well in the Møre Basin (Norwegian continental shelf). Diverse assemblages of dinoflagellate cysts and foraminifera provide insights into the palaeobiogeography and palaeoenvironmental conditions during the late Maastrichtian in this region. An outer neritic setting is interpreted based on the general high abundance of planktonic foraminifera. A subdivision of the biostratigraphic record into three Ecozones has allowed for a detailed documentation of the phytoplankton communities during the late Maastrichtian until the K-Pg boundary. Ecozone A is characterised by a predominance of peridinoid cysts which together with abrupt fluctuations in planktonic foraminifera suggests high nutrient availability and, possibly, high terrestrial input potentially associated with regional turbiditic currents. Also, the occurrence of taxa characteristic of boreal affinity suggests colder waters for this Ecozone. Ecozone B is characterised by consecutive influxes of areoligeracean species such as Palynodinium grallator, Areoligera senonensis and Circulodinium distinctum in the dinoflagellate cyst assemblages. The increase abundances of planktonic foraminifera across this interval suggests an increase in palaeowater depth into a more outer shelf to upper slope. Immediately before the K-Pg boundary (Ecozone C), an increase in abundance of low latitude dinoflagellate species and the planktonic foraminifera Pseudotextularia elegans may represent the local signal of the global latest Maastrichtian Warming Event. Two new dinoflagellate cyst species restricted to the late Maastrichtian, Glaphyrocysta turgida sp. nov. and Heterosphaeridium silybum sp. nov. are also formally described.