Discoaster berggrenii


Ancestry: Coccolithophores -> Discoasterales -> Discoasteraceae -> Discoaster -> D. quinqueramus group -> Discoaster berggrenii
Sister taxa: D. quinqueramus, D. berggrenii, D. bergenii,

Short diagnosis: Intermediate between D. bergennii and D. quinqueramus; central-area 1-2x free ray length [or, adjacent rays separated at central area].


Taxonomy:

Citation: Discoaster berggrenii Bukry, 1971
Rank: Species
Variants: Discoaster berggrenii ssp. extensus Wei 2003 variant in which the sutural ridges protrude beyond the edges of the central disk.
Notes & discussion: As observed by Muller (1974) and Theodoridis (1984) D. berggrenii grades into D. quinqueramus, and is probably not a separate species. It is, however, only common in the lower part of the range of D. quinqueramus; and discrimination of it is easy.

Farinacci & Howe catalog pages: Discoaster berggrenii *

Short diagnosis: Intermediate between D. bergennii and D. quinqueramus; central-area 1-2x free ray length [or, adjacent rays separated at central area].

Geological Range:
Notes: D. bergenii, D. bergrennii and D. quinqueramus apparently form an anagenetic lineage, with central area size deceasing and free ray length increasing. Distinguishing them is useful for determining position within the early part of zone NN11.
Last occurrence (top): within NN11b subzone (6.91-7.42Ma, top in Messinian stage). Data source: Young 1998 (fig. 8.4)
First occurrence (base): at base of NN11 zone (0% up, 8.3Ma, in Tortonian stage). Data source: zonal marker, with D. quinqueramus (see e.g. Young 1998)

Plot of occurrence data:

References:

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

Wei, W., (2003). Upper Miocene nannofossil bistratigraphy and taxonomy of Exxon core CH30-43-2 from the Gulf of Mexico Journal of Nannoplankton Research, 25(1): 17-23.

Young, J.R., (1998). Neogene. In: Bown, P.R. (Editor), Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publications Series. Chapman & Hall, London, pp. 225-265.


Nannotax3 - Coccolithophores - Discoaster berggrenii by: Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 28-4-2017

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Mike Styzen (Noble Energy, US)
Discoaster quinqueramus/berggrenii plexus: I posted a document with some sketches from the original Gulf Coast Taxonomic Equivalency Project of this group in the forum.
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Magdy (ALS - Ellington Associates, Jamaica)
Mike...
Thanks for producing sketches for the Discoaster quinqueramus/berggrenii plexus. I found it very useful.
Some how I lost the original copy. Could you tell where you have posted this document, hopefully I will be able to download it.
Regards
Magdy
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Jeremy Young (UCL, UK)
Hi Magdy
A copy of the diagram is here. GECP chart - and it is linked to from the D. quinqueramus group page. I have slightly cleaned up Mike's original diagram and added the coloured columns on the right but otherwise it is his figure."""
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Mike Styzen (Noble Energy, US)
Discoaster berggrenii extensus: A few years ago Wuchang Wei erected a new subspecies, Discoaster berggrenii extensus for forms in which the star in the central area extends beyond the central area. This taxon is used pretty universally in the GOM as a Late Miocene under the name of \Discoaster C". I think, however that the name D. berggrenii extensus should be supressed. I have started to see reports from various sources that list this taxon simply as \""Discoaster extensus\"" which, of course, is something else alltogether. In my opinion, since this form is used as an index fossil by such a lirge number of workers, that we should consider making it a seperate species."""
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Jeremy Young (NHM, UK)
do you have the reference for the original description? It would be good to add it to the system.
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