Tribrachiatus contortus

Classification: Coccolithophores -> Nannolith families inc sed -> Rhomboasteraceae -> Tribrachiatus -> Tribrachiatus contortus
Sister taxa: T. contortus, T. digitalis, T. orthostylus, T. absidatus, T. lunatus, T. sp.,


Citation: Tribrachiatus contortus (Stradner, 1958) Bukry, 1972
Rank: Species
Basionym: Discoaster contortus Stradner, 1958

Distinguishing features: Tri-radiate forms with long ray tip bifurcations that deviate strongly from the plane of the nannolith, giving the appearance of two asymmetrically offset and superimposed tri-radiate cycles.

Farinacci & Howe catalog pages: Discoaster contortus [no catalog entry yet]

Search data:
TagsLITHS: nannolith-radiate, star-shaped, RIM: tips-bifurcate,
CSPH: not known, V-UNITS: all, R-UNITS: none, DETAILS: 1ou,
MetricsLith size: 10->20µm; Segments: 3->3;
Sources: lith size from OD & illustrated specimens
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Last occurrence (top): at top of NP10 zone (100% up, 54.2Ma, in Ypresian stage). Data source: Agnini et al. 2007 fig 8, 9; zonal marker (Perch-Nielsen 1985)
First occurrence (base): in upper part of NP10 zone (65% up, 54.8Ma, in Ypresian stage). Data source: Agnini et al. 2007 fig 8, 9

Plot of occurrence data:

  • Histogram - Neptune occurrence data from DSDP and ODP proceedings. Pale shading <50 samples in time bin. Interpret with caution & read these notes
  • Note to users in China - the diagram may not plot unless you use a VPN since I use google services on the website. If this is a problem please contact me 谢谢.
  • Taxon plotted: Tribrachiatus contortus, synonyms included - Marthasterites contortus; Rhomboaster contortus; Tribrachiatus contortus;
  • space-time plot :: Samples map :: Parent: Tribrachiatus


    Agnini, C., Fornaciari, E., Raffi, I., Rio, D., Rohl, U. & Westerhold, T. (2007). High-resolution nannofossil biochronology of middle Paleocene to early Eocene at ODP Site 1262: Implications for calcareous nannoplankton evolution. Marine Micropaleontology. 64: 215-248. gs

    Bukry, D. (1972). Further comments on coccolith stratigraphy, Leg 12 Deep Sea Drilling Project. Initial Reports of the Deep Sea Drilling Project. 12: 1071-1083. 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. US Geological Survey professional paper. 1554: 1-36. gs

    Bybell, L. & Self-Trail, J. (1998). Late Paleocene and Early Eocene calcareous nannofossils from three boreholes in an onshore-offshore transect from New Jersey to the Atlantic continental rise. Proceedings of the Ocean Drilling Program. Scientific Results. 150: 91-110. gs

    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

    Pospichal, J. J. & Wise, S. W. (1990c). Paleocene to Middle Eocene calcareous nannofossils of ODP sites 689 and 690, Maud Rise, Weddell Sea. Proceedings of the Ocean Drilling Program. Scientific Results. 113: 613-638. gs

    Stradner, H. (1958). Die fossilen Discoasteriden Osterreichs. I. Erdoel-Zeitschrift. 74(6): 178-188. gs


    Tribrachiatus contortus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 6-12-2019

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    Short stable page link: Go to to create a permanent copy of this page - citation notes

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