Distribution of calcareous dinoflagellates from the Maastrichtian to early Miocene of DSDP Site 357 (Rio Grande Rise, western South Atlantic Ocean). International Journal of Earth Sciences, 88: 694-707.
The evolution of calcareous dinoflagellate communities has been investigated for the latest Cretaceous to earliest Neogene interval of the mid-latitude South Atlantic. In doing so, the response of calcareous dinoflagellates to Cenozoic climatic change has been addressed for the first time. Trends in species composition and distribution patterns of wall types indicate significant changes which correlate with major palaeoenvironmental modifications. A first major shift concerning the relative abundance of species and wall types occurred across the Cretaceous-Tertiary boundary. The associations remained stable during the entire Paleocene and Eocene. Only in the late Eocene did a dramatic decrease in temperature cause a slight diversification. A second major shift in the abundance patterns occurred across the Eocene-Oligocene boundary. The early Miocene warming is possibly reflected in the distinct increase in relative abundance of one species. The assemblages of calcareous dinoflagellates evidently react to major climatic changes during the Cenozoic. These poorly investigated organisms may thus provide an important contribution to the understanding of earth's palaeoclimatic evolution.
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External and internal views of the same coccospheres: notes on a new cracking technique. Journal of Nannoplankton Research, 21(1): 27-29.
A novel cracking technique for coccospheres is briefly described and illustrated. This delicate method involves manual cracking of specimens with the help of a scalpel and thus enables us to obtain an internal view of some coccospheres. It is a particularly useful method for secondarily altered coccospheres, as the inner surface view frequently reveals well-preserved coccoliths. In the future, it may be a useful method for providing additional information on some enigmatic taxa.
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New calcareous dinoflagellates from the Palaeogene of the South Atlantic Ocean (DSDP Site 357, Rio Grande Rise). Journal of Micropalaeontology, 18: 89-95.
The new calcareous dinoflagellate taxa Bitorus truncus n.sp., Calcigonellum ansatum n.sp. and Fuettererella fungiforma n.sp. are formally described on the basis of on Eocene and Oligocene samples from DSDP Site 357 (western South Atlantic Ocean).
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Variations in calcareous dinoflagellate associations from the Maastrichtian to middle Eocene of the western South Atlantic Ocean (São Paulo Plateau, DSDP Leg 39, Site 356). Review of Palaeobotany and Palynology, 106: 57-87.
Calcareous dinoflagellates often dominate the dinoflagellate cyst assemblage in Cretaceous to Recent oceanic sediments. However, their distribution in Paleogene sediments has scarcely been studied. The investigation of samples from DSDP Site 356 for their calcareous dinoflagellate content revealed 35 mainly long-ranging taxa. The associations and characteristic wall types (pithonelloid, oblique, radial, tangential) fluctuate quantitatively and qualitatively in distinct stratigraphic patterns. Significant shifts, primarily at the K/T boundary and the Paleocene/Eocene boundary, reflect changes in environmental conditions. Certain dinoflagellates forming calcareous cysts, such as Operculodinella operculata, were well adapted to the relatively rapid change of environmental conditions at the K/T boundary, thus blooming to dominate the carbonate flux to the ocean floor. In contrast to the stable Paleocene associations, Eocene calcareous dinoflagellates show fluctuations in relative abundances. These fluctuations can possibly be attributed to redeposition related to increased seaward transport of specimens, due to strengthened western boundary currents. The flora includes two new genera, one new species, and two new forms: Retesphaera diadema Hildebrand-Habel, Willems et Versteegh, gen. et. sp. nov., Cervisiella saxea (Stradner, 1961) Hildebrand-Habel, Willems et Versteegh, gen. et comb. nov., Sphaerodinella? tuberosa forma elongata Hildebrand-Habel, Willems et Versteegh, comb. et forma nov., Sphaerodinella? tuberosa forma variospinosa Hildebrand-Habel, Willems et Versteegh, comb. et forma nov. Three new combinations are proposed: Cervisiella saxea (Stradner, 1961) Hildebrand-Habel, Willems et Versteegh, gen. et comb. nov., Operculodinella operculata (Bramlette et Martini, 1964) Hildebrand-Habel, Willems et Versteegh, comb. nov., and Sphaerodinella? tuberosa (Kamptner, 1963) Hildebrand-Habel, Willems et Versteegh, comb. nov. The genus Operculodinella Kienel, 1994 is emended.
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