arrayname: original
Distinguishing features:
Parent taxon (Polycostella): Globular and stellate nannoliths formed of 5-8 segments of stacked elements. Nannoconus-like in side view.
This taxon: Small (<6 µm) form formed of 5 segments
Taxonomy:
The combination P. parvistellatus was proposed by Bergen et al. 2014, but, as noted by Varol & Bowman (2019), the combination was not validly proposed (ICN Art 45.1), since the Varol 1991 reference was missing from their bibliography.
Farinacci & Howe catalog pages: M. parvistellatus *
Distinguishing features:
Parent taxon (Polycostella): Globular and stellate nannoliths formed of 5-8 segments of stacked elements. Nannoconus-like in side view.
This taxon: Small (<6 µm) form formed of 5 segments
Small (< 6.0 μm) nannoconid having five longitudinal ridges. The wall cycles are thin and low- angled, and the axial canal is very narrow. It is stellate in plan view and has sutures between the segments, which meet at the periphery of the vertices of the nannolith. It is strongly birefringent in plan view, but weakly birefringent or non-birefringent in side view.
Morphology:
LITHS: nannolith-radiate, pentagonal, star-shaped, cylindrical, CA: closed, CROSS-POLARS: T-prominent, |
Lith size: 4->6µm; Segments: 5->5; Data source notes: original description & illustrated specimens |
Geological Range:
Last occurrence (top): within Early Berriasian Substage (141.40-143.10Ma, top in Berriasian stage). Data source: Varol & Bowman 2019
First occurrence (base): within Late Tithonian Substage (143.10-145.00Ma, base in Tithonian stage). Data source: Varol & Bowman 2019
Plot of occurrence data:
Bergen, J. A., Boesiger, T. M. & Pospichal, J. J. (2014). Low-latitude Oxfordian to Early Berriasian nannofossil biostratigraphy and its application to the subsurface of Eastern Texas. In, Hammes, U. & Gale, J. (eds) Geology of the Haynesville Gas Shale in East Texas and West Louisiana, U.S.A. American Association of Petroleum Geologists, Memoirs . 105: 69-102. gs Varol, O. & Bowman, A. R. (2019). Taxonomic revision of selected Late Jurassic (Tithonian) calcareous nannofossils and the application of mobile mounting. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen. 291: 65-87. gs Varol, O. (1991). New Cretaceous and Tertiary Calcareous Nannofossils. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen. 182: 211-237. gsReferences:
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Polycostella parvistellatus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 21-4-2025
Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=10660 Go to Archive.is to create a permanent copy of this page - citation notes |
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