Nannotax3 - ntax_mesozoic - Eiffellithus parvus Nannotax3 - ntax_mesozoic - Eiffellithus parvus

Eiffellithus parvus


Classification: ntax_mesozoic -> Eiffellithales -> Eiffellithaceae -> Eiffellithus -> Eiffellithus parvus
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:
Parent taxon (Eiffellithus): Loxolith coccoliths with a prominent inner rim cycle that is birefringent and conspicuous in cross-polarised light; this cycle is broader than the outer rim cycle. The central area is spanned by variably-orientated cross-bars.
This taxon: Medium eiffellithid with stem base of four trapezohedral arms forming a symmetrical diagonal cross whose outline is roughly rectangular.


Taxonomy:

Citation: Eiffellithus parvus Watkins & Bergen, 2003
taxonomic rank: Species
Taxonomic discussion: This species differs from the closely related E. equibiramus by the distinctly rectangular outline of the stem base occupying the central area in E. parvus as opposed to the symmetrical, diagonal cross in E. equibiramus. Eiffellithus gorkae Reinhardt 1965 resembles E. parvus in that both taxa have a stem base that is restricted to the central area without touching the inner margin of the rim. The size range for E. Górkae, given as 5–9µm in length by Reinhardt (1965), overlaps with E. parvus, but includes specimens larger than any yet observed for E. parvus. More importantly, the stratigraphic ranges of these two species are incompatible, as E. parvus existed during the late Albian and earliest Cenomanian, while E. gorkae was restricted to the Campanian-Maastrichtian (Perch-Nielsen 1985). Given this discrepancy in biostratigraphic ranges, it appears likely that E. gorkae is a morphologically iterative form.

Farinacci & Howe catalog pages: E. parvus *

Distinguishing features:
Parent taxon (Eiffellithus): Loxolith coccoliths with a prominent inner rim cycle that is birefringent and conspicuous in cross-polarised light; this cycle is broader than the outer rim cycle. The central area is spanned by variably-orientated cross-bars.
This taxon: Medium eiffellithid with stem base of four trapezohedral arms forming a symmetrical diagonal cross whose outline is roughly rectangular.


Morphology:

This species has a normally to narrowly elliptical rim which is smooth to slightly serrate in outline. The outer rim is thin (<0.8µm) and composed of steeply inclined elements, although it is generally impossible to count the elements in the light microscope. The inner rim is composed of blocky elements that fill much of the central area. The rims exhibit a first order white birefringence. A small (approximately 0.2µm) round hole characterizes the middle of the central area. A symmetrical, diagonal cross spans the central hole. This compact species is characterized by a cross composed of four trapezohedral arms approximately 1µm in length and < 1µm in width. Each trapezohedral arm is constructed of two sets of crystallites, although these are often difficult to differentiate in the light microscope due to their small size. The individual shapes of the arms combine to give the overall outline of the cross a distinctly rectangular outline.The evidence from the Blake Nose sections, considered in the context of the proposed age model, suggests that this species lived from approximately 100.7 to 98.9 Ma (a total species duration of 1.8 m.y.) During this interval, it comprised as much as 45% of the total eiffellithids and 2.7% of the total assemblage. Occurrence: upper Albian from Blake Nose (ODP Leg 171B).

Size:
Length = 5.2–7.3µm (µ=6.0, s.d.=0.5, n=30) Width = 3.2–5.2µm (µ=4.3, s.d.=0.5, n=30) Eccentricity = 1.2–1.8 (µ=1.4, s.d.=0.39, n=30)

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

Search data:
LITHS: murolith, elliptical, CA: ca_disjunct, plate, process, diagonal cross, CROSS-POLARS: rim-bicyclic, V-prominent, R-prominent,
Lith size: 5->7µm;
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 Early Cenomanian Substage (96.24-100.50Ma, top in Cenomanian 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:

Perch-Nielsen, K. (1985). Mesozoic calcareous nannofossils. In, Bolli, H. M., Saunders, J. B. & Perch-Nielsen, K. (eds) Plankton Stratigraphy. Cambridge University Press, Cambridge (1): 329-426. gs

Reinhardt, P. (1965). Neue Familien für fossile Kalkflagellaten (Coccolithophoriden, Coccolithineen). Monatsberichte der Deutschen Akademie der Wissenschaften zu Berlin. 7: 30-40. gs

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 parvus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 9-10-2024

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Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=10415 Go to Archive.is to create a permanent copy of this page - citation notes
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