Loxolithus armilla


Classification: Mesozoic -> Eiffellithales -> Chiastozygaceae -> Loxolithus -> Loxolithus armilla
Sister taxa: L. armilla, L. thiersteinii, L. sp.,

Distinguishing features: Loxolith coccoliths with broad, open central-area, probably spanned by a rarely preserved finely perforate net (e.g., see Lambert, 1993, Pl. 5, figs 1 and 2, named Millbrookia perforata therein). Typically the rim is unicyclic in XPL.


Taxonomy:

Citation: Loxolithus armilla (Black in Black & Barnes, 1959) Noël, 1965
Rank: Species
Basionym: Cyclolithus armilla Black in Black & Barnes, 1959
Synonyms: Retemediaformis teneraretis Varol (1991) [my interpretation - JRY 2017; this seems to be essentially a name for forms in which a grill is visible, Self-Trail 1999 however does regard it as a discrete species]
Notes & discussion: This is a problematic species since with dissolution and breakage many zeugrhabdotid coccoliths can lose their central area structures and so produce a similar coccolith. Conversely with good presrvation forms with a delicate grill but no other central area structure have been observed.  [my interpretation - JRY 2017]

Farinacci & Howe catalog pages: Cyclolithus armilla * , Retemediaformis teneraretis *

Distinguishing features: Loxolith coccoliths with broad, open central-area, probably spanned by a rarely preserved finely perforate net (e.g., see Lambert, 1993, Pl. 5, figs 1 and 2, named Millbrookia perforata therein). Typically the rim is unicyclic in XPL.

See also: Crepidolithus perforatus - similar Jurassic species;

Geological Range:
Last occurrence (top): at top of Maastrichtian Stage (100% up, 66Ma, in Maastrichtian stage). Data source: Lees & Bown 2005 - consistently present to end Cret
First occurrence (base): within Early Hauterivian Substage (133.09-133.88Ma, base in Hauterivian stage). Data source: Bown et al. 1998

Plot of occurrence data:

  • Histogram - Neptune occurrence data from DSDP and ODP proceedings. Pale shading <50 samples in time bin. Interpret with caution & read these notes
  • Note to users in China - the diagram may not plot unless you use a VPN since I use google services on the website. If this is a problem please contact me 谢谢.
  • Taxon plotted: Loxolithus armilla, synonyms included - Loxolithus armilla; space-time plot :: Samples map :: Parent: Loxolithus

    References:

    Black, M. & Barnes, B. (1959). The structure of Coccoliths from the English Chalk. Geological Magazine. 96: 321-328. gs

    Black, M. (1975). British Lower Cretaceous Coccoliths. I-Gault Clay (Part 3). Palaeontographical Society Monograph. 128: 113-142. gs

    Bown, P. R. (2005c). Early to Mid-Cretaceous Calcareous Nannoplankton from the Northwest Pacific Ocean, Leg 198, Shatsky Rise. Proceedings of the Ocean Drilling Program. Scientific Results. 198: 1-82. 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

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

    Gale, A. S., Kennedy, W. J., Burnett, J. A., Caron, M. & Kidd, B. E. (1996). The Late Albian to Early Cenomanian succession at Mont Risou, near Rosans (Drôme, SE France): an integrated study (ammonites, inoceramids, planktonic foraminifera, nannofossils, oxygen and carbon isotopes). Cretaceous Research. 17: 515-606. gs

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

    Lambert, B. (1993). Nannofossiles calcaires de l'Albien supérieur et du Vraconnien du Cameroun méridional (Deuxième Partie). Cahiers de Micropaleontologie. 8(2): 183-225. gs

    Lees, J. A. & Bown, P. R. (2005). Upper Cretaceous calcareous nannofossil biostratigraphy, ODP Leg 198 (Shatsky Rise, Northwest Pacific Ocean). Proceedings of the Ocean Drilling Program. Scientific Results. 198: 1-60. gs

    Noël, D. (1965). Sur les Coccolithes du Jurassique Européen et d'Afrique du Nord. Éditions du Centre National de la Recherche Scientifique, Paris. -. gs

    Self-Trail, J. (1999). Some new and rarely documented Late Cretaceous calcareous nannofossils from subsurface sediments in South Carolina. Journal of Paleontology. 73(5): 952-963. gs

    Thibault, N. (2010). Calcareous nannofossils from the boreal Upper Campanian- Maastrichtian chalk of Denmark. Journal of Nannoplankton Research. 30(1): 39-56. gs

    Varol, O. (1991). New Cretaceous and Tertiary Calcareous Nannofossils. Neues Jahrbuch für Geologie und Paläontologie Abhandlungen. 182: 211-237. gs


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    Loxolithus armilla compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 20-9-2019

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    Short stable page link: http://mikrotax.org/Nannotax3/index.php?id=10607 Go to Archive.is to create a permanent copy of this page - citation notes



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