Nannotax3 - ntax_main - Discoaster signus Nannotax3 - ntax_main - Discoaster signus

Discoaster signus

Variant: Discoaster signus is regarded here as a variant of Discoaster exilis.
I.e. It is a subjective junior synonym, but some workers many find it useful for some studies (e.g. experienced biostratigraphers working with abundant, well preserved material), but for most purposes differentiating it is not reccomended. Please do use the comments section at the bottom of this page if you wish to discuss this interpretation


Classification: ntax_main -> Discoasterales -> Discoasteraceae -> Discoaster -> D. exilis group -> Discoaster exilis -> Discoaster signus
Sister taxa: D. caulifloris, D. moorei, D. extensus, D. discissus, D. signus, D. apetalus

Taxonomy:

Citation: Discoaster signus Bukry 1971
Taxonomic rank: species
Taxonomic discussion: D. petaliformis is similar but has larger boss and shorter bifurcations. Theodoridis (1984) explicitly included such forms in his species concept for D. signus, however, for reliable biostratigraphy is is probably best to have a discrete label for the highly distinctive stratigraphically constrained forms.

Distinguishing features:
Parent taxon (Discoaster exilis): Small central-area; usually with weak distal and proximal bosses; bifurcations acutely angled in plan-view
This taxon: Similar to D. petaliformis but with longer bifurcations, and weaker boss.

Farinacci & Howe catalog pages: D. signus * , E. signus *


Morphology:

The boss

Search data:
LITHS: nannolith-radiate, star-shaped, CA: process, CROSS-POLARS: 1ou, V-prominent,
Lith size: 16->23µm; Segments: 6->6;
Data source notes: size from OD
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Last occurrence (top): within NN5 zone (13.53-14.91Ma, top in Serravallian stage). Data source: [JRY rough estimate]
First occurrence (base): within NN4 zone (14.91-17.95Ma, base in Burdigalian stage). Data source: [JRY rough estimate]

Plot of occurrence data:

References:

Bukry, D. (1971a). Discoaster evolutionary trends. Micropaleontology. 17: 43-52. gs

de Kaenel, E., Bergen, J. A., Browning, E., Blair, S. A. & Boesiger, T. M. (2017). Uppermost Oligocene to Middle Miocene Discoaster and Catinaster taxonomy and stratigraphy in the circum North Atlantic Basin: Gulf of Mexico and ODP Leg 154. Journal of Nannoplankton Research. 37(2-3): 215-244. gs O

Maiorano, P. & Monechi, S. (1998). Revised correlations of early and middle Miocene calcareous nannofossil events and magnetostratigraphy from DSDP Site 563 (North Atlantic Ocean). Marine Micropaleontology. 35(235-255): -. gs


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Discoaster signus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 16-11-2025

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Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=501 Go to Archive.is to create a permanent copy of this page - citation notes



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