Nannotax3 - ntax_mesozoic - Helicolithus leckiei Nannotax3 - ntax_mesozoic - Helicolithus leckiei

Helicolithus leckiei


Classification: ntax_mesozoic -> Eiffellithales -> Eiffellithaceae -> Helicolithus -> Helicolithus leckiei
Sister taxa: H. anceps, H. trabeculatus, H. leckiei, H. tectufissus ⟩⟨ H. turonicus, H. varolii, H. compactus, H. blairiae, H. sp.

Distinguishing features:
Parent taxon (Helicolithus): Loxolith coccoliths with bicyclic rim with broad inner cycle and narrow central-area, filled by broad cross bars. The rim image is distinctly bicyclic and the inner cycle and cross bars are birefringent. 
This taxon: Small (3-4µm), strongly bicyclic, margin between cycles scalloped; birefringent diagonal cross; cross-bars straight and simply constructed.


Taxonomy:

Citation: Helicolithus leckiei Bown, 2005
taxonomic rank: Species

Farinacci & Howe catalog pages: H. leckiei *

Distinguishing features:
Parent taxon (Helicolithus): Loxolith coccoliths with bicyclic rim with broad inner cycle and narrow central-area, filled by broad cross bars. The rim image is distinctly bicyclic and the inner cycle and cross bars are birefringent. 
This taxon: Small (3-4µm), strongly bicyclic, margin between cycles scalloped; birefringent diagonal cross; cross-bars straight and simply constructed.


Morphology:

Strongly bicyclic, with a prominent bright, inner cycle and central area spanned by a birefringent, diagonal cross. The two rim cycles are comparable in width but the inner cycle may be broader. The junction between the two cycles is usually distinctly scalloped. The cross bars are straight and simply constructed.
Similar to Corollithion? madagaskarensis Perch-Nielsen 1973, but the latter has a delicate cross, does not show the distinctive scalloped cycle junction, and has a rim that shows Corollithion-like characteristics (i.e., a protolith-like rim) (see Bown, 1987; Young et al., 1997). In addition, it has only been recorded from much younger strata (i.e., Maastrichtian). It also resembles Ellipsochiastus quadriserratus Worsley, 1971, but the latter is larger, with narrower bars and more open central area. [Bown 2005]

Size:
Length = 3.4-3.7µm

Search data:
LITHS: murolith, elliptical, CA: ca_disjunct, diagonal cross, CROSS-POLARS: rim-bicyclic, V-prominent, R-prominent,
Lith size: 3->4µm;
Data source notes: original description & illustrated specimens
The morphological data given here can be used on the advanced search page. See also these notes

See also: Corollithion madagaskarensis - similar species; ;

Geological Range:
Last occurrence (top): within Cenomanian Stage (93.90-100.50Ma, top in Cenomanian stage). Data source: Bown 2005
First occurrence (base): within NC7a subzone (118.27-119.40Ma, base in Aptian stage). Data source: Bown 2005

Plot of occurrence data:

References:

Bown, P. R. (1987a). Taxonomy, evolution, and biostratigraphy of Late Triassic-Early Jurassic calcareous nannofossils. Special Papers in Palaeontology. 38: 1-118. gs

Bown, P. R. (2005b). Cenozoic calcareous nannofossil biostratigraphy, ODP Leg 198 Site 1208 (Shatsky Rise, northwest Pacific Ocean). Proceedings of the Ocean Drilling Program, Scientific Results. 198: 1-44. 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 O

Gale, A. S. et al. (2011). The uppermost Middle and Upper Albian succession at the Col de Palluel, Hautes-Alpes, France: An integrated study (ammonites, inoceramid bivalves, planktonic foraminifera, nannofossils, geochemistry, stable oxygen and carbon isotopes, cyclostratigraphy). Cretaceous Research. 32: 59-130. gs

Kanungo, S., Bown, P. R. & Gale, A. S. (2020). Cretaceous (Albian-Turonian) calcareous nannofossil biostratigraphy of the onshore Cauvery Basin, southeastern India. Cretaceous Research. 118 [2021]: 1-22. gs

Kennedy, W. J. et al. (2000). Integrated stratigraphy across the Aptian-Albian boundary in the Marnes Bleues, at the Col de Pre _-Guittard, Arnayon (Drome), and at Tartonne (Alpes-de-Haute-Provence), France: a candidate Global Boundary Stratotype Section and Boundary Point for the base of the Albian Stage. Cretaceous Research. 21: 591-720. gs

Perch-Nielsen, K. (1973). Neue Coccolithen aus dem Maastrichtien von Danemark, Madagaskar und Agypten. Bulletin of the Geological Society of Denmark. 22: 306-333. gs

Worsley, T. R. (1971). Calcareous nannofossil zonation of Upper Jurassic and Lower Cretaceous sediments from the Western Atlantic. In, Farinacci, A. (ed.) Proceedings of the Second Planktonic Conference Roma 1970. Edizioni Tecnoscienza, Rome 2: 1301-1321. gs O

Young, J. R. et al. (1997). Guidelines for coccolith and calcareous nannofossil terminology. Palaeontology. 40: 875-912. gs


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Helicolithus leckiei compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 21-4-2024

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