Calcidiscus bicircus
Classification: Coccolithophores -> Coccolithales -> Calcidiscaceae -> Calcidiscus -> C. pacificanus group -> Calcidiscus bicircus
Sister taxa: C. bicircus, C. gerrardii, C. pacificanus, C. parvicrucis, C. parvus, C. scullyae, C. kamikurii,
Distinguishing features: Medium to large (5-9 µm) circular-subcircular placoliths with a non-birefringent distal shield and narrow to closed central area surrounded by a narrow, bright tube cycle.
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Taxonomy:
Citation: Calcidiscus bicircus Bown, 2005Rank: Species
Farinacci & Howe catalog pages: Calcidiscus bicircus *
Distinguishing features: Medium to large (5-9 µm) circular-subcircular placoliths with a non-birefringent distal shield and narrow to closed central area surrounded by a narrow, bright tube cycle.
Search data:
| Tags | LITHS: placolith, elliptical, sub-circular, RIM: rim-broad, CA: Placoliths: closed,
CSPH: spherical, monomorphic, V-UNITS: distal shield, tube, R-UNITS: prox shield, DETAILS: rim-bicyclic, isogyres oblique, |
| Metrics | Lith size: 5->9µm;
Sources: |
The morphological data given here can be used on the advanced search page. See also these notes
Geological Range:
Last occurrence (top): within NP17 zone (37.32-40.40Ma, top in Priabonian stage). Data source: Bown et al., 2007
First occurrence (base): within NP12 zone (50.50-53.70Ma, base in Ypresian stage). Data source: Shamrock & Watkins 2012
Plot of occurrence data:
- Range-bar - range as quoted above, pink interval top occurs in, green interval base occurs in.
- Triangles indicate an event for which a precise placement has been suggested
- (NB There is no histogram as there are no occurrence records for the taxon in the Neptune database) Parent: C. pacificanus group
References:Bown, P.R., (2005). 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.
Bown, P.R.; Dunkley-Jones, T. & Young, J.R., (2007). Umbilicosphaera jordanii Bown 2005 from the Paleogene of Tanzania: confirmation of generic assignment and a Paleocene origination for the family Calcidiscaceae. Journal of Nannoplankton Research, 29(1): 25-30.
Shamrock, J.L. & Watkins, D.K., (2012). Eocene calcareous nannofossil biostratigraphy and community structure from Exmouth Plateau, Eastern Indian Ocean (ODP Site 762). Stratigraphy, 9(1): 1-11.
