Zeugrhabdotus trivectis


Classification: Mesozoic -> Eiffellithales -> Chiastozygaceae -> Zeugrhabdotus -> Zeugrhabdotus trivectis
Sister taxa: Z. blowii, Z. burolletii, Z. burwellensis, Z. erectus, Z. fissus, Z. moulladei, Z. noeliae ⟩⟨ Z. bicrescenticus, Z. diplogrammus, Z. fluxus, Z. howei, Z. petrizzoae, Z. reticulatus, Z. scutula ⟩⟨ Z. biperforatus, Z. kerguelenensis, Z. large spine, Z. clubhousensis ⟩⟨ Z. clarus, Z. acanthus, Z. trivectis, Z. xenotus ⟩⟨ Z. angelozziae, Z. cooperi, Z. embergeri, Z. praesigmoides, Z. sigmoides, Z. simplex, Z. streetiae, Z. sp.

Distinguishing features: Bicyclic, medium sized (5-6µm); bar complex


Taxonomy:

Citation: Zeugrhabdotus trivectis Bergen, 1994
Rank: Species

Farinacci & Howe catalog pages: Z. trivectis *

Distinguishing features: Bicyclic, medium sized (5-6µm); bar complex


Morphology: Medium-sized (5-6µm) Zeugrhabdotus with a well-developed inner/proximal rim cycle and, in XPL, the rim appears clearly bicyclic throughout its height, with equally well-developed inner and outer cycles; the inner cycle is brighter (white) than the outer (grey) and the extinction gyres are spirally-arranged. The bridge, which arises from the inner wall cycle, consists of two fused bars and bears a relatively small, solid, distal process.

This form is differentiated from other species of Zeugrhabdotus by its bicyclic rim extinction pattern and relatively simple bridge. The construction of its rim is most similar to Zeugrhabdotus xenotus, but the latter species has an X-shaped bridge and a prominent hollow spine.

Search data:
TagsLITHS: murolith, ca_disjunct, process, bar, CROSS-POLARS: rim-bicyclic, V-prominent,
MetricsLith size: 5->6µm;
Data source notes: original description & illustrated specimens
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Last occurrence (top): within Maastrichtian Stage (66.04-72.05Ma, top in Maastrichtian stage). Data source: Bown et al. 1998
First occurrence (base): within Early Valanginian Substage (136.41-139.39Ma, base in Valanginian stage). Data source: Bown et al. 1998

Plot of occurrence data:

References:

Bergen, J. A. (1994). Berriasian to early Aptian calcareous nannofossils from the Vocontian Trough (SE France) and Deep Sea Drilling Site 534: new nannofossil taxa and a summary of low-latitude biostratigraphic events. Journal of Nannoplankton Research. 16(2): 59-69. gs V O

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 V O

Thibault, N. (2010). Calcareous nannofossils from the boreal Upper Campanian- Maastrichtian chalk of Denmark. Journal of Nannoplankton Research. 31(1): 39-56. gs V O


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Zeugrhabdotus trivectis compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 3-12-2020

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Short stable page link: http://mikrotax.org/Nannotax3/index.php?id=11347 Go to Archive.is to create a permanent copy of this page - citation notes



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