Nannotax3 - ntax_mesozoic - Transitional genera Nannotax3 - ntax_mesozoic - Transitional genera

Transitional genera


Classification: ntax_mesozoic -> Braarudosphaerales -> Transitional genera
Sister taxa: Braarudosphaeraceae, Transitional genera, Nannoconaceae ⟩⟨ Polycyclolithaceae, Other nannoliths with tangential c-axes

Distinguishing features:
Parent taxon (Braarudosphaerales): Nannoliths formed of multiple layers of thin elements, arranged with rotational symmetry, and showing tangential c-axis orientations.
This taxon: Nannoliths intermediate between Nannoconacaea and Braarudosphaeraceae


Daughter taxa (time control age-window is: 0-800Ma)Granddaughter taxa
Hexalithus
Six-rayed, stellate to hexagonal nannoliths.
Hexalithus gardetiae
Hexalithus noeliae
Hexalithus strictus
Hexalithus geometricus
Hexalithus sp.

Polycostella
Globular and stellate nannoliths formed of 5-8 segments of stacked elements. Nannoconus-like in side view.  
Polycostella senaria
Polycostella beckmannii
Polycostella parvistellatus
Polycostella sp.

Taxonomy:

Citation: Transitional genera
taxonomic rank: Family
Taxonomic discussion: The genera Polycostella and Hexalithus are both predomiantly Tithonian andappear to be transitional forms between small nannoconids and Braarudosphaeraceae. it is not clear which family they should be placed in, or whether the two genera are discrete. To highlight their postion and similarities they are grouped together here as "transitional genera".

Farinacci & Howe catalog pages: Transitional genera [no catalog entry yet]

Distinguishing features:
Parent taxon (Braarudosphaerales): Nannoliths formed of multiple layers of thin elements, arranged with rotational symmetry, and showing tangential c-axis orientations.
This taxon: Nannoliths intermediate between Nannoconacaea and Braarudosphaeraceae

Search data:
Lith size: 0->0┬Ám;
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Last occurrence (top): at top of Campanian Stage (100% up, 72.1Ma, in Campanian stage). Data source: Total of ranges of the species in this database
First occurrence (base): within NJT15b subzone (148.44-149.8Ma, base in Tithonian stage). Data source: Total of ranges of species in this database

Plot of occurrence data:

References:


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Transitional genera compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 6-12-2023

Taxon Search:
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Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=11375 Go to Archive.is to create a permanent copy of this page - citation notes
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