Discoaster deflandrei


Ancestry: Coccolithophores -> Discoasterales -> Discoasteraceae -> Discoaster -> D. variabilis group -> Discoaster deflandrei
Sister taxa: D. surculus, D. variabilis, D. exilis, D. deflandrei, D. loeblichii, D. mendomobensis, D. bollii, D. signus, D. petaliformis, D. subsurculus, D. musicus, D. micros, D. challengeri, D. moorei, D. kugleri, D. druggii,

Short diagnosis: 6-rayed discoaster with a well developed central area; rays ending in strong short wide bifurcations.


Taxonomy:

Citation: Discoaster deflandrei Bramlette & Riedel, 1954
Rank: Species
Variants:
 
Synonyms:
Notes & discussion: The species shows considerable variation in: size, number of rays (5-7), relative size of central area, and degree of development of the ray bifurcations. Hay et al. (1967) used this variation to create 5 separate species, all from the Early Miocene of Trinidad. However, these forms intergrade and separating them has not proven useful. A possible exception are forms with small central areas (D. aulakos, D. saundersii). These become more common toward the end of the Early Miocene, and might be separated as an intermediate variety between D. deflandrei and D. exilis.

Farinacci & Howe catalog pages: Discoaster aulakos * Discoaster calculosus * Discoaster cubensis * Discoaster deflandrei * Discoaster deflandrei nodosus * Discoaster dilatus * Discoaster divaricatus * Discoaster lidzi * Discoaster nephados * Discoaster saundersi * Discoaster subdeflandrei * Discoaster tinguarensis * Discoaster trinidadensis * Discoaster woodringi * Eu-discoaster deflandrei *

Short diagnosis: 6-rayed discoaster with a well developed central area; rays ending in strong short wide bifurcations.


Morphology remarks: 6-rayed discoaster with a well developed central area; rays ending in strong short wide bifurcations. There is often a distal knob, and sometimes weak distal ridges on the rays. The proximal side is essentially featureless, although the sutures may be incised.

See also: Discoaster distinctus - very similar but bifurcations more angular;Discoaster moorei - asymmetric 5-rayed form. ;

Geological Range:
Notes: In the Middle Miocene D. exilis replaces it as the dominant form. D. deflandrei persists, however, at low abundances; the specimens of this interval show lower variation, with large centred forms dominant.
Last occurrence (top): within NN7 zone (10.89-11.90Ma, top in Tortonian stage). Data source: Young 1998
First occurrence (base): within NP13 zone (49.11-50.50Ma, base in Ypresian stage). Data source: Theodoridis 1984

Plot of occurrence data:

References:

Bramlette, M.N. & Riedel, W.R., (1954). Stratigraphic value of discoasters and some other microfossils related to Recent coccolithophores. Journal of Paleontology, 28: 385-403.

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

Furrazola, G. & Iturralde, M.A., (1967). Estudio micropaleontologico del Oligoceno superior de Cuba, en el Pozo Pijuan No. 47. Rev. Technologica (Havana), 5: 3-11.

Gartner, S., (1967). Calcareous nannofossils from Neogene of Trinidad, Jamaica, and Gulf of Mexico. Paleontological Contributions. University of Kansas, 29: 1-7.

Hay, W.W.; Mohler, H.P.; Roth, P.H.; Schmidt, R.R. & Boudreaux, J.E., (1967). Calcareous nannoplankton zonation of the Cenozoic of the Gulf Coast and Caribbean-Antillean area, and transoceanic correlation. Transactions of the Gulf Coast Association of Geological Societies, 17: 428-480.

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


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Discoaster deflandrei compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 20-8-2017

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Comments (1)

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J Kell (Lincoln Nebraska, US)
Shouldn't Discoaster moorei be asymetrical? It is in Perch-Nielsen's description on pg 476 of Plankton Statigraphy.
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Mike Styzen (Noble Energy, US)
I agree. I would just call this a 5 ray D. deflandrei. D. moorei by my concept is much less robust and very asymmetrical.
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Jeremy Young (NHM, UK)

hmm - fair call, that is not really an archetypal moorei type specimen. I have never been sure that the 5-rayed asymetric variants are really separate species but in some cases, most obviously D. asymettricus they certainly do have different ranges to the 6-rayed symettric forms. It would be interesting to know how useful people have found  the D. moorei morphotype. Also it would be good to have some photos of better specimens

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Mike Styzen (Noble Energy, US)
I don't see them very often, not even often enough to have a real handle on what kind of range they have. So stratigraphically the species is not useful. On the other hand those I've seen are virtually identical to the one illustrated in P. N. 1984 so I would say with a good degree of confidence that D. moorei should be considered a valid taxon. I don't have a photo, unfortunately.
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