Taxonomy:
Distinguishing features: Proximal shield without slits between the elements; distal shield elements delicate, tips well separated
Farinacci & Howe catalog pages: I. fusa *
Morphology: Proximal and distal shield cycles are formed from the same crystal units but there are more elements in the proximal shield than in the distal shield, since some of the crstal units do not develop the distal shield spines. C-axes are approximately parallel to surface of proximal shield.
Size: 2-3µm
Tags | LITHS: placolith, circular, CA: vacant, CROSS-POLARS: rim-unicyclic, R-prominent, |
Metrics | Lith size: 3->5µm; Data source notes: lith size from OD & illustrated specimens |
Geological Range:
Last occurrence (top): within NN2 zone (19.00-22.82Ma, top in Burdigalian stage). Data source: Young 1998
First occurrence (base): within Oligocene Epoch (23.03-33.89Ma, base in Rupelian stage). Data source: Perch-Nielsen 198
Plot of occurrence data:
Bergen, J. A., de Kaenel, E., Blair, S. A., Boesiger, T. M. & Browning, E. (2017). Oligocene-Pliocene taxonomy and stratigraphy of the genus Sphenolithus in the circum North Atlantic Basin: Gulf of Mexico and ODP Leg 154. Journal of Nannoplankton Research. 37(2-3): 77-112. gs V O Bown, P. R. & Dunkley Jones, T. (2012). Calcareous nannofossils from the Paleogene equatorial Pacific (IODP Expedition 320 Sites U1331-1334). Journal of Nannoplankton Research. 32(2): 3-51. gs V O Bown, P. R. (2005d). Palaeogene calcareous nannofossils from the Kilwa and Lindi areas of coastal Tanzania (Tanzania Drilling Project 2003-4). Journal of Nannoplankton Research. 27(1): 21-95. gs V O de Kaenel, E. & Villa, G. (1996). Oligocene-Miocene calcareous nannofossil biostratigraphy and paleoeecology from the Iberian Abyssal Plain. Proceedings of the Ocean Drilling Program, Scientific Results. 149: 79-145. gs V O Perch-Nielsen, K. (1977a). Albian to Pleistocene calcareous nannofossils from the Western South Atlantic, DSDP Leg 39. Initial Reports of the Deep Sea Drilling Project. 39: 699-823. gs V O Perch-Nielsen, K. (1985a). Cenozoic calcareous nannofossils. In, Bolli, H. M., Saunders, J. B. & Perch-Nielsen, K. (eds) Plankton Stratigraphy. Cambridge University Press, Cambridge 427-555. gs Roth, P. H. (1970). Oligocene calcareous nannoplankton biostratigraphy. Eclogae Geologicae Helvetiae. 63: 799-881. gs V O Young, J. R. (1998). Neogene. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series. 225-265. gs V OReferences:
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Ilselithina fusa compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 25-2-2021
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