Calcareous dinoflagellate associations and Maastrichtian–Tertiary climatic change in a high latitude core (ODP Hole 689B, Maud Rise, Weddell Sea). Palaeogeography, Palaeoclimatology, Palaeoecology, 197: 293-321.
The distribution of calcareous dinoflagellates has been analysed for the Maastrichtian to Miocene interval of ODP Hole 689B (Maud Rise, Weddell Sea). The investigation thus represents a primary evaluation of the long-term evolution in high latitude calcareous dinoflagellate assemblages during the transition from a relatively warm Late Cretaceous to a cold Neogene climate. Major assemblage changes during this interval occurred in characteristic steps: (1) an increase in relative abundance of tangentially structured species - particularly Operculodinella operculata - at the K/T boundary; (2) a diversity decrease and several first and last appearances across the middle-late Eocene boundary, possibly attributed to increased climate cooling; (3) a diversity decrease associated with the dominance of Calciodinellum levantinum in the late early Oligocene; (4) the reappearance and dominance of Pirumella edgarii in the early Miocene, probably reflecting a warming trend; (5) monogeneric assemblages dominated by Caracomia spp. denoting strong middle Miocene cooling. The results not only extend the biogeographic ranges of many taxa into the Antarctic region, but also indicate that the evolution of high latitude calcareous dinoflagellate assemblages parallels the changing environmental conditions in the course of the Cenozoic climate transition. Therefore, calcareous dinoflagellates contribute to our understanding of the biotic effects associated with palaeoenvironmental changes and might possess the potential for reconstructing past conditions. The flora in the core includes one new taxon: Caracomia arctica forma spinosa Hildebrand-Habel and Streng, forma nov. Additionally, two new combinations are proposed: Fuettererella deflandrei (Kamptner, 1956) Hildebrand-Habel and Streng, comb. nov. and Fuettererella flora (Fütterer, 1990) Hildebrand-Habel and Streng, comb. nov.
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Die Entwicklung kalkiger Dinoflagellaten im Südatlantik seit der höheren Oberkreide. Berichte aus dem Fachbereich Geowissenschaften der Universität Bremen, 192: 152pp.
Fossil calcareous dinoflagellate associations differ significantly from those in modern oceans in a number of aspects, including the abundance of taxa, diversity and wall type. The exact nature as well as the causes and effects of this association change are still obscure. In order to shed light on the evolutionary history of calcareous dinoflagellate associations, this study focuses on the long-term temporal and spatial distribution patterns in the South Atlantic Ocean for the Maastrichtian to Miocene time-interval. The study thereby not only addresses the effect of the biotic crisis at the Cretaceous– Tertiary boundary, but also concentrates on the influence of Cenozoic climate evolution. Using scanning electron microscopy and polarisation microscopy, about 6,500 calcareous dinoflagellate specimens have been examined in sediments originating from three DSDP and ODP cores (Holes 356, 357 and 689B). The broad time-interval led to a redefinition of biogeographic and stratigraphic ranges of numerous taxa.
The evolution of the oceanic calcareous dinoflagellate associations in the South Atlantic is characterised by stepwise transitions since the latest Cretaceous that were effectively controlled by changes in the environmental conditions. The extent of the modifications is highly variable and shows regional differences. The initial development of latitudinal differences in association has now been verified for the late Paleocene.
Main stages of alterations occurred in certain stratigraphic intervals, particularly at the Cretaceous–Tertiary boundary, the boundary between the middle and late Eocene, the Eocene– Oligocene boundary, in the early Oligocene, at the Oligocene–Miocene boundary, and in the middle Miocene. These steps indicate that the evolution of calcareous dinoflagellates has been considerably influenced by the effects of the extraterrestrial impact at the Cretaceous–Tertiary boundary as well as by Cenozoic climate change. In particular, strong cooling events correlate with changing calcareous dinoflagellate assemblages.
The development of characteristic temporal and spatial distribution patterns as a reaction to changing environmental conditions substantiate the potential of calcareous dinoflagellates for reconstructing (palaeo-)environmental conditions in the marine realm. Despite the fact that much 'pioneering' research remains to be done, the results illustrate that the organisms can provide important and unique information, especially in the fields of palaeoclimatology and ecostratigraphy.
The calcareous dinoflagellate analyses led to the description of the following new taxa: Bitorus truncus n. sp., Calcigonellum ansatum n. sp., Caracomia arctica n. gen. n. comb., Caracomia arctica forma spinosa n. forma, Caracomia stella n. gen. n. sp., Cervisiella saxea n. gen. n. comb., Fuettererella deflandrei n. comb., Fuettererella flora n. comb., Fuettererella fungiforma n.sp., Sphaerodinella tuberosa forma elongata n. comb. n. forma, Sphaerodinella tuberosa forma variospinosa n. comb. n. forma, Retesphaera diadema n. gen. n. sp. The genera Operculodinella Kienel, 1994 and Orthopithonella Keupp in Keupp & Mutterlose, 1984 have been emended.
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Revision of the genera Sphaerodinella Keupp and Versteegh, 1989 and Orthopithonella Keupp in Keupp and Mutterlose, 1984 (Calciodinelloideae, calcareous dinoflagellate cysts). Journal of Paleontology, 76(3): 397-407.
The genus Sphaerodinella Keupp and Versteegh, 1989, became obsolete by the assignment of its type S. albatrosiana (Kamptner, 1963) to the genus Calciodinellum Deflandre, 1947. For the single remaining species of Sphaerodinella, which does not fit into the genus Calciodinellum, the new genus Caracomia is proposed, whose type is C. arctica (Gilbert and Clark, 1983) new genus, new combination. Additionally, a new species of Caracomia is described: Caracomia stella new genus and species. The regional distribution of the two species of Caracomia shows distinct regional preferences: Caracomia arctica is restricted to cold waters of both hemispheres, whereas Caracomia stella as yet has only been described from warmer environments. Thus, C. arctica can be used as a cold water indicator. Comparison of Caracomia with other genera has shown a close relationship to the type of Orthopithonella and exposed a common misinterpretation of this genus. Therefore, the genus Orthopithonella Keupp in Keupp and Mutterlose, 1984, is emended to unquestionably accommodate only the type O. gustafsonii.
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