Taxonomy:
Distinguishing features:
Parent taxon (Pemma): Pentaliths with a central depression/perforation in each segment; often producing elevated, robust structures that are commonly observed in side view.
This taxon: Large (typically >7 µm), triangular-, rectangular- or rhomb-shaped nannoliths, which are thickened along two sides (‘base’ and ‘side’) to give a hook-shaped appearance. Dark in XPL but birefringent where thickened; c-axis orientation is parallel with the long axis.
Farinacci & Howe catalog pages: P. uncinata *
Search data:
LITHS: nannolith-radiate, pentagonal, quadrate, CA: pores, CROSS-POLARS: T-prominent, |
Lith size: 7->18µm; Segments: 5->5; Data source notes: lith size (diameter) from OD |
Geological Range:
Last occurrence (top): within NP21 zone (32.92-34.44Ma, top in Rupelian stage). Data source: Dunkley Jones et al., 2009
First occurrence (base): within NP17 zone (37.32-40.40Ma, base in Bartonian stage). Data source: Shamrock & Watkins 2012
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 Dunkley Jones, T., Bown, P. R. & Pearson, P. (2009). Exceptionally well preserved upper Eocene to lower Oligocene calcareous nannofossils (Prymnesiophycidae) from the Pande Formation (Kilwa Group), Tanzania. Journal of Systematic Palaeontology. 7(4): 359-411. 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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Pemma uncinata compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 22-5-2025
Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=1042 Go to Archive.is to create a permanent copy of this page - citation notes |
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