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

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]

Morphology:

Size:

Search data:

Lith size: 0->0µm;

The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Last occurrence (top): within Berriasian Stage (139.39-145.01Ma, top in Berriasian stage). Data source:
First occurrence (base): within Tithonian Stage (145.01-152.06Ma, base in Tithonian stage). Data source:

Plot of occurrence data:

Range-bar - range as quoted above, pink interval top occurs in, green interval base occurs in.
Triangles indicate an event for which a precise placement has been suggested
Neptune data: this is a higher taxon page so Neptune data is not plotted. For the customisable plot option go to a genus page Parent: Braarudosphaerales

References:

Transitional genera compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 3-10-2022

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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