Distinguishing features:
Parent taxon (Calciosolenia): Coccosphere with rhombic muroliths with central area floored by transverse laths (scapholiths); varimorphic or dimorphic. Rim bicyclic in LM (the outer part of the rim is dark in xpl, the inner part bright). Typically small, fragile and dissolution susceptible, and so only consistently seen as fossils when preservation is good.
This taxon: Small Calciosolenia with a relatively broad central-area filled by a plate-like structure that displays a four-fold, alternating light-dark birefringence image.
Farinacci & Howe catalog pages: C. alternans *
Search data:
| LITHS: murolith, quadrate, CA: ca_disjunct, grill, CROSS-POLARS: rim-bicyclic, V-prominent, R-prominent, |
| Lith size: 4->5µm; Data source notes: lith size from OD & illustrated specimens |
Geological Range:
Last occurrence (top): within NP17 zone (37.32-40.40Ma, top in Priabonian stage). Data source: [PRB rough estimate]
First occurrence (base): within NP14 zone (46.29-49.11Ma, base in Ypresian stage). Data source: [PRB rough estimate]
Plot of occurrence data:
Bown, P. R. & Dunkley Jones, T. (2006). New Paleogene calcareous nannofossil taxa from coastal Tanzania: Tanzania Drilling Project Sites 11 to 14. Journal of Nannoplankton Research. 28(1): 17-34. gs Bown, P. R. & Newsam, C. (2017). Calcareous nannofossils from the Eocene North Atlantic Ocean (IODP Expedition 342 Sites U1403–1411). Journal of Nannoplankton Research. 37(1): 25-60. gs O Jones, A. P. & Dunkley Jones, T. (2020). Middle Eocene to Early Oligocene calcareous nannofossils from the Nanggulan Formation, Java, Indonesia. Journal of Nannoplankton Research. 38(1): 57-79. gs 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. gsReferences:

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Calciosolenia alternans compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 8-12-2025
Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=201 Go to Archive.is to create a permanent copy of this page - citation notes |
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