Nannotax3 - ntax_mesozoic - Anfractus Nannotax3 - ntax_mesozoic - Anfractus

Anfractus


Classification: ntax_mesozoic -> Holococcoliths -> Rarer genera -> Anfractus
Sister taxa: Bifidalithus, Bilapillus, Multipartis, Munarinus, Octolithus, Okkolithus, Ottavianus, Pharus, Ramsaya, Russellia, Saepiovirgata ⟩⟨ Acuturris, Anfractus, Duocameratus, Lacunolithus-Bown, Metadoga, Nicholasia, Paulpearsonia, Petrobrasiella, Pseudoconus, Semihololithus, Stereorhabdus, Tanzanella, Thecatus, unidentified holococcoliths

Distinguishing features:
Parent taxon (Rarer genera): Less common genera
This taxon: Elliptical, cavate (and usually septate) holococcoliths, often bearing hollow spines. Distal surfaces may be perforate and there may be internal buttresses.


Daughter taxa (time control age-window is: 0-800Ma)
Anfractus harrisonii
Small, spinous holococcolith with diagonal internal structures that are bright and diagnostic in XPL. Distal surface with perforations.
Anfractus parvus
Small Anfractus species with a sharply tapering spine and low rim
Anfractus variabilis
Very small holococcolith with distal surface pierced by 8-10 pores.
Anfractus youngii
Holococcolith with broad, tall, tapering spine and diagonal internal septa.
Anfractus sp.
Specimens not identified to species level

Taxonomy:

Citation: Anfractus Medd, 1979
taxonomic rank: Genus
Type species: Anfractus harrisonii Medd, 1979

Farinacci & Howe catalog pages: Anfractus + *

Distinguishing features:
Parent taxon (Rarer genera): Less common genera
This taxon: Elliptical, cavate (and usually septate) holococcoliths, often bearing hollow spines. Distal surfaces may be perforate and there may be internal buttresses.

Search data:
LITHS: holococcolith, elliptical, hollow, CA: diagonal cross, process, ca_disjunct, CROSS-POLARS: R-prominent, rim-unicyclic,
Lith size: 1->5µm;
Data source notes: size range of included species
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 NJ16a subzone (100% up, 149.1Ma, in Tithonian stage). Data source: Total of ranges of the species in this database
First occurrence (base): within Toarcian Stage (174.70-184.20Ma, base in Toarcian stage). Data source: Total of ranges of species in this database

Plot of occurrence data:

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 O

Medd, A. W. (1979). The Upper Jurassic coccoliths from the Haddenham and Gamlingay boreholes (Cambridgeshire, England). Eclogae Geologicae Helvetiae. 72: 19-109. gs O


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Anfractus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 10-12-2024

Taxon Search:
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Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=10017 Go to Archive.is to create a permanent copy of this page - citation notes
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