Taxonomy:
Distinguishing features: ≥8 near-parallel-sided rays with rounded to pointed tips that radiate with little free length from a large circular central area. May show inter-ray ridges, a low central boss, and the development of nodes towards the ray tips.
Farinacci & Howe catalog pages: D. mediosus * , D. minimus *
Morphology: Typically 8-10 rays but can have more.
Tags | LITHS: nannolith-radiate, star-shaped, CROSS-POLARS: 1ou, V-prominent, |
Metrics | Lith size: 11->21µm; Segments: 7->9; Data source notes: size from OD & illustrated specs |
Geological Range:
Last occurrence (top): within NP10 zone (54.17-55.86Ma, top in Ypresian stage). Data source: PRB entry to Nannotax
First occurrence (base): within NP7 zone (58.70-58.97Ma, base in Thanetian stage). Data source: PRB entry to Nannotax
Plot of occurrence data:
Aubry, M. -P. (1984). Handbook of Cenozoic calcareous nannoplankton. Book 1: Ortholithae (Discoasters). Micropaleontology Press, American Museum of Natural History, New York. 1-266. gs 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 Bown, P. R. (2010). Calcareous nannofossils from the Paleocene/Eocene Thermal Maximum interval of southern Tanzania (TDP Site 14). Journal of Nannoplankton Research. 31(1): 11-38. gs V O Bown, P. R. (2016). Paleocene calcareous nannofossils from Tanzania (TDP sites 19, 27 and 38). Journal of Nannoplankton Research. 36(1): 1-32. gs V O Bralower, T. J. & Self-Trail, J. (2016). Nannoplankton malformation during the Paleocene-Eocene Thermal Maximum and its paleoecological and paleoceangraphic significance. Paleoceanography. 31: 1-17. gs Bramlette, M. N. & Sullivan, F. R. (1961). Coccolithophorids and related nannoplankton of the Early Tertiary in California. Micropaleontology. 7(2): 129-188. gs Bybell, L. M. & Self-Trail, J. (1995). Evolutionary, biostratigraphic and taxonomic study of calcareous nanofossils from a continuous Palaeocene-Eocene boundary section in New Jersey. U.S. Geological Survey, Professional Paper. 1554: 1-36. 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 Self-Trail, J. (2011). Paleogene Calcareous Nannofossils of the South Dover Bridge core, Southern Maryland (USA). Journal of Nannoplankton Research. 32(1): 1-28. gs V O Shepherd, C. L. & Kulhanek, D. K. (2016). Eocene nannofossil biostratigraphy of the mid-Waipara River section, Canterbury Basin, New Zealand. Journal of Nannoplankton Research. 26(1): 33-59. gs V O Theodoridis, S. (1984). Calcareous nannofossil biostratigraphy of the Miocene and revision of the helicoliths and discoasters. Utrecht Micropaleontological Bulletin. 32: 1-271. gs V O Wise, S. W. & Wind, F. H. (1977). Mesozoic and Cenozoic calcareous nannofossils recovered by DSDP Leg 36 drilling on the Falkland Plateau, south-west Atlantic sector of the Southern Ocean. Initial Reports of the Deep Sea Drilling Project. 36(269-491): -. gs V OReferences:
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Discoaster mediosus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 19-4-2021
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