New calcareous dinoflagellates (Calciodinelloideae) from the Middle Coniacian to Upper Santonian chalks of Lägerdorf (N Germany). Journal of Micropalaeontology, 23(2): 181-190.
Three new calcareous dinoflagellate species from the Middle Coniacian to Upper Santonian chalks of Lägerdorf (northern Germany) are formally described: Calcicarpinum macrogranulum n. sp., Pirumella fragilis n. sp. and Ruegenia quinqueangulata n. sp. The species show differing vertical distribution patterns which might result from local sea-level changes: P. fragilis and R. quinqueangulata are restricted to the possibly transgressive upper Mid-Coniacian to Lower Santonian interval and C. macrogranulum occurs consistently only in the probably regressive lower Mid-Coniacian and Middle to Upper Santonian intervals.
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Long-term evolution of calcareous dinoflagellate associations since the Late Cretaceous: comparison of a high- and a low-latitude core from the Indian Ocean. Journal of Nannoplankton Research, 26(1): 13-45.
One high- and one low-latitude Ocean Drilling Program core, from the southern and eastern Indian Ocean, respectively, was studied to obtain a general overview of the evolution of calcareous dinoflagellate cyst associations in this region and their possible reaction to known major Cenozoic climatic changes. Despite a relatively low sample density, several shifts in calcareous dinoflagellate assemblages could be linked to periods of major climatic or environmental change, at the Cretaceous/Tertiary transition, in the Early Oligocene, and in the Neogene. Correlations between changes in the climate and in the associations appear to be more distinctive at high latitudes than at low latitudes. For the first time, shifts in the stratigraphic distribution patterns of different archeopyle types have been evaluated. The ratio between small and large archeopyles turned out to be a possible tool for the reconstruction of long-term climatic evolution at high latitudes, with small archeopyles correlating with warmer periods and large archeopyles characterizing cooler conditions. Altogether, 65 taxa have been distinguished, of which several are rare or problematic taxa, which may partly represent new species. These are informally described or described using open nomenclature. Additionally, the relationship and potential synonymy of the problematic species Thoracosphaera? prolata with Calciodinellum elongatum is discussed in detail.
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A proposed classification of archeopyle types in calcareous dinoflagellate cysts. Journal of Paleontology, 78(3): 456-483.
The phylogenetic significance of archeopyles in calcareous dinoflagellates cysts has been evaluated, and a classification model is developed that focuses on the archeopyle categories and types established for organic-walled dinoflagellates by Evitt (1967, 1985). Several of Evitt's archeopyle categories are presently recognized within the calcareous dinoflagellate cysts: apical, intercalary, and combination archeopyles, which are here subdivided into eight archeopyle types and several variations. Archeopyles that cannot be assigned to a distinct type, and those with outlines that do not allow an accurate interpretation, are together placed in a separate category: miscellaneous archeopyles. The stratigraphic distribution of the different archeopyle types reveals a phylogenetic trend characterized by an increase of the number of plates involved in archeopyle formation. The first calcareous dinoflagellate cysts to appear in the late Triassic have a monoplacoid apical archeopyle. The first taxa that show an archeopyle involving more than one plate are from the Early Cretaceous, with the first triplacoid apical archeopyle appearing at the Berriasian/Valanginian boundary. This is followed by the first combination archeopyle, which includes six plates, in the middle Aptian. Epitractal archeopyles originated no earlier than the early Oligocene. At the beginning of the Paleogene, species with a combination archeopyle increased in abundance, progressively replacing species possessing an apical archeopyle that dominated during the Mesozoic. Newly described species are: Calciodinellum clamosum, accommodating the two subspecies Calciodinellum clamosum subsp. clamosum Autonym, and Calciodinellum clamosum subsp. latum; Calciodinellum kerguelense; Fuettererella belliata; and Pernambugia? patata. New combinations are: Cervisiella operculata (Bramlette and Martini, 1964); Praecalcigonellum sulcatum (Keupp, 1979a); and Praecalcigonellum dolium (Keupp, 1979b). Because of the new interpretation of their archeopyles we emend the following genera: Cervisiella Hildebrand-Habel, Willems, and Versteegh, 1999; Echinodinella Keupp, 1980; Fuettererella Kohring, 1993a; and Pernambugia Janofske and Karwath in Karwath (2000). The species Orthopithonella? minuta and Pirumella johnstonei, which have been previously synonymized with Fuettererella deflandrei, are retained as independent taxa.
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