Eiffellithus praestigium


Classification: ntax_mesozoic -> Eiffellithales -> Eiffellithaceae -> Eiffellithus -> Eiffellithus praestigium
Sister taxa: E. eximius, E. lindiensis ⟩⟨ E. gorkae, E. keio, E. parallelus, E. pospichalii, E. turriseiffelii ⟩⟨ E. collis, E. equibiramus, E. parvus ⟩⟨ E. monechiae, E. praestigium, E. vonsalisiae, E. hancockii, E. paragogus ⟩⟨ E. primus, E. striatus, E. windii, E. sp.

Distinguishing features: Medium eiffellithid with sub-axial cross (rotated 10-20°). Struts with central suture  and clavate to blunt tips.


Taxonomy:

Citation: Eiffellithus praestigium Watkins & Bergen, 2003
Rank: Species
Taxonomic discussion: This species would be included within the species concept of E. monechiae by many authors.

Farinacci & Howe catalog pages: E. praestigium *

Distinguishing features: Medium eiffellithid with sub-axial cross (rotated 10-20°). Struts with central suture  and clavate to blunt tips.


Morphology: This species has a broadly to narrowly elliptical rim which is smooth to slightly serrate in outline. The outer rim is thin (<1µm) and composed of 40 to 60 steeply inclined elements. The inner rim is composed of blocky elements that are approximately 1–2µm wide. The rims exhibit a first order white birefringence. A small (approximately 3 by 4µm) elliptical hole characterizes the middle of the central area. The central hole is spanned by an asymmetrical, diagonal cross that might have supported a small hollow stem, although no central structure has been observed. The four arms of the cross lie obliquely to the major and minor axes of the ellipse, so that the axes of the cross and the axes of the ellipse are displaced by more than about 10° but less than about 20°. Each arm is composed of two sets of elements divided by a prominent central suture. The tips of the arms are distinctly clavate. [Watkins & Bergen 2003]

This species is an intermediate form between E. monechiae and E. vonsalisiae. The most characteristic feature of this relatively small eiffellithid is the “trick” that it exhibits under cross polarized light. The two sets of elements in each arm do not exhibit simultaneous extinction under crossed polarizers, but alternately go extinct as the orientation of the crossed polarizers changes. In one orientation, the birefringent alternate sets of elements make the cross appear to be sub-parallel to the principal axes of the ellipse. In the other orientation, the other four sets of elements are birefringent, making the cross appear to be nearly diagonal to the principal axes. The arms closest to the minor axes of the ellipse exhibit this phenomenon most strongly, which appear nearly aligned with the ellipse minor axis in one orientation and strongly divergent from it in another.

Size: Length = 5–7.5 µm [Watkins & Bergen 2003]

Most likely ancestor: Eiffellithus monechiae - at confidence level 3 (out of 5). Data source: Watkins & Bergen 2003.
Likely descendants: Eiffellithus equibiramus; Eiffellithus vonsalisiae;

Search data:
TagsLITHS: murolith, elliptical, CA: cross-axial, ca_disjunct, plate, process, diagonal cross, CROSS-POLARS: rim-bicyclic, V-prominent, R-prominent,
MetricsLith size: 5->7.5µm;
Data source notes: Watkins & Bergen 2003
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Last occurrence (top): within Late Albian Substage (100.50-107.59Ma, top in Albian stage). Data source: Watkins & Bergen 2003
First occurrence (base): within BC26 zone (103.27-104.06Ma, base in Albian stage). Data source: Watkins & Bergen 2003

Plot of occurrence data:

References:

Hill, M. E. & Bralower, T. J. (1987). Early evolution, stratigraphy and taxonomy of Eiffellithus eximius and closely-related species. In, Stradner, H. , & Perch Nielsen, K, (eds) Proceedings of the INA Meeting, Vienna 1985. Abhandlungen der Geologischen Bundesanstalt. 39: 89-97. gs V O

Watkins, D. K. & Bergen, J. A. (2003). Late Albian adaptive radiation in the calcareous nannofossil genus Eiffelithus. Micropaleontology. 49(3): 231-252. gs


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Eiffellithus praestigium compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 6-3-2021

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Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=10417 Go to Archive.is to create a permanent copy of this page - citation notes



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