Pemma triquetra


Classification: Coccolithophores -> Braarudosphaerales -> Braarudosphaeraceae -> Pemma -> Pemma triquetra
Sister taxa: P. basquense, P. bybelliae, P. papillatum, P. rotundum, P. stradneri, P. triquetra, P. uncinata, P. sp.,

Taxonomy:

Citation: Pemma? triquetra Bown & Dunkley Jones, 2006
Rank: Species
Synonyms:
Notes & discussion: Similar to disaggregated Micrantholithus segments in LM but with a more acute angle between the longer edges (~50°-60°, compared to 72° for typical pentaliths). The c-axis orientation is similar to other pentaliths, i.e., tangential. The liths consist of a series of fine calcite laminae similar to other members of the Braarudosphaeraceae. May be disaggregated liths of Micrantholithus-type pentalith with a concave base.

Distinguishing features: Relatively large (typically >5 µm), triangular-shaped nannoliths that thicken along the longer sides and exhibit low birefringence in XPL.

Farinacci & Howe catalog pages: P. triquetra *

Search data:
Tagsnannolith-radiate, pentagonal, triangular, CA: pores,
CSPH: not known, T-UNITS: all, T-prominent,
MetricsLith size: 5->8µm; Segments: 5->5;
Data source notes: lith size (diameter) from OD & illustrated specimens
Sources: lith size (diameter) 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): within NP21 zone (32.92-34.44Ma, top in Rupelian stage). Data source: Dunkley Jones et al., 2009
First occurrence (base): within NP19-20 zone (34.44-36.97Ma, base in Priabonian stage). Data source: Dunkley Jones et al., 2009

Plot of occurrence data:

References:

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 V O

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. gs


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Pemma triquetra compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 19-9-2020

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Short stable page link: http://mikrotax.org/Nannotax3/index.php?id=1041 Go to Archive.is to create a permanent copy of this page - citation notes



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