Anfractus harrisonii


Classification: Mesozoic -> Holococcoliths -> Rarer genera -> Anfractus -> Anfractus harrisonii
Sister taxa: A. harrisonii, A. parvus, A. youngii, A. sp.,

Distinguishing features: Small, spinous holococcolith with diagonal internal structures that are bright and diagnostic in XPL. Distal surface with perforations.


Taxonomy:

Citation: Anfractus harrisonii Medd, 1979
Rank: Species
Variants:
Notes & discussion: Lambert (1987) assigned Albian specimens to this speices, however they are larger and with much larger spines than the original Jurassic specimens and Lucianorhabdus compactus seems a better identification for them.

Farinacci & Howe catalog pages: A. harrisonii + * , A. variabilis *

Distinguishing features: Small, spinous holococcolith with diagonal internal structures that are bright and diagnostic in XPL. Distal surface with perforations.


Morphology remarks: Distal surface pierced by numerous small pores.

Search data:
TagsLITHS: holococcolith, elliptical, hollow, CA: ca_disjunct, process, diagonal cross, CROSS-POLARS: rim-unicyclic, R-prominent,
MetricsLith size: 4->5µm;
Data source notes: illustrated specimens
The morphological data given here can be used on the advanced search page. See also these notes

See also: Lucianorhabdus compactus - for specimens assigned to A. harrisonii by Lambert (1987);

Geological Range:
Last occurrence (top): at top of NJ16a subzone (100% up, 151.9Ma, in Tithonian stage). Data source: Bown & Cooper 1998 (fig 4) - zonal event
First occurrence (base): within NJ8a subzone (171.79-174.59Ma, base in Toarcian stage). Data source: Bown & Cooper 1998

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

Bown, P. R. (1993). New holococcoliths from the Toarcian-Aalenian (Jurassic) of northern Germany. Senckenbergiana Lethaea. 73: 407-419. gs

Bown, P. R., Rutledge, D. C., Crux, J. A. & Gallagher, L. T. (1998). Early Cretaceous. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series. 86-131. gs

Lambert, B. (1987). Nannofossiles calcaires de l'Albien supérieur et du Vraconnien du Cameroun méridional. Cahiers de Micropaléontologie. 2(2): 33-60. gs V O

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


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Anfractus harrisonii compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 30-9-2020

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Short stable page link: http://mikrotax.org/Nannotax3/index.php?id=10018 Go to Archive.is to create a permanent copy of this page - citation notes



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