Nannotax3 - Mesozoic

Hexalithus

Classification: Mesozoic -> Braarudosphaerales -> Transitional genera -> Hexalithus
Sister taxa: Hexalithus, Polycostella,

Distinguishing features: Six-rayed, stellate to hexagonal nannoliths.

Daughter taxa: (blue => in age window 0-800Ma)
				Hexalithus gardetiae Minute (2-4 µm), subcircular nannolith with six elements.
				Hexalithus noeliae Small (4-6 µm), elements with lobate edges.
				Hexalithus strictus Elements with straight edges.
				Hexalithus sp. Specimens not identified to species level

Taxonomy:

Citation: Hexalithus Gardet, 1955

Rank: Genus

Type species: Hexalithus lecali Gardet, 1955.

Notes & discussion: The type species H. lecaliae Garet was decribed from the Miocene, is poorly ifgured and has never been rediscovered. So, the genus is inadequately typified.

Farinacci & Howe catalog pages: Hexalithus *

Distinguishing features: Six-rayed, stellate to hexagonal nannoliths.

Evolution & Phylogeny: Hexalithus appears in the Tithonian at about the same time as Nannoconus and Micrantholithus and it shows both tangential orientation and laminar substructure so it should be included within the Braarudosphaeraceae [my interpretation - JRY 2017] The species H. geometricus Casellato 2010 has been argued to be a junior synonym of Polycostella infans by Varol & Bowman (2019)

Search data:

Tags	LITHS: nannolith-radiate, polygonal, CA: closed, CSPH: equant, monomorphic, T-UNITS: T-prominent,
Metrics	Lith size: 2->0µm; Segments: 6->6; Sources: 6

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 range of species in this database
First occurrence (base): in lower part of Tithonian Stage (44% up, 149Ma, in Tithonian stage). Data source: Total of range of species in this database

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. See also: customisable plot Parent: Transitional genera

References:

Bown, P. R. & Cooper, M. K. E. (1998). Jurassic. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series. 34-85. gs :: ::

Burnett, J. A. (1998). Upper Cretaceous. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series. 132-199. gs :: ::

Gardet, M. (1955). Contribution à l'étude des coccolithes des terrains néogènes de l'Algérie. Publications du Service de la Carte Géologique de l'Algérie (Nouvelle Série). 5: 477-550. gs :: ::

Hexalithus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 7-7-2020

Taxon Search:

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Short stable page link: http://mikrotax.org/Nannotax3/index.php?id=10524 Go to Archive.is to create a permanent copy of this page - citation notes

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