Discoaster petaliformis


Classification: Coccolithophores -> Discoasterales -> Discoasteraceae -> Discoaster -> D. exilis group -> Discoaster petaliformis
Sister taxa: D. exilis, D. cauliflorus, D. moorei, D. extensus, D. discissus ⟩⟨ D. bollii ⟩⟨ D. petaliformis, D. signus, D. apetalus

Taxonomy:

Citation: Discoaster petaliformis Moshkovitz and Ehrlich, 1980
Rank: Species
Synonyms:
Variants:
Taxonomic discussion: This form was independently illustrated by Filewicz (1985) as D. tuberi; Theodoridis (1984) as D. signus emend, and Moshkovitz & Ehrlich (1980) as D. petaliformis. The forms illustrated are of the same age (NN4-5) and extremely similar. They are clearly the same taxon, and given their distinctive form and restricted range it is useful to distinguish them. D. signus is an inappropriate name for them, since D. signus as described and illustrated by Bukry (1971) has only a moderate-sized central boss. Apart from the boss they are normal D. exilis specimens and all authors noted that forms with large bosses graded into others with small bosses.

D. petaliformis is unique amongst Neogene discoasters in having both bosses oriented radially usually the points of the proximal boss are directed radially and those of the distal boss interadially (typically the distal boss develops from thickened sutural ridges.
The orientation of the distal knob in D. petailformis thus appears aberrant, with its rays pointing in radial rather than inter-radial directions. However, it has normal sutural ridges and the peculiar orientation of knob may be associated with its flaring form.

Distinguishing features: Similar to D. exilis but with very large mushroom-shaped distal boss and distinct proximal boss. Central-area narrow.

Farinacci & Howe catalog pages: D. petaliformis * , D. tuberi * , D. petaliformis coincidentalis *


Morphology: The distal boss is not only large but mushroom-shaped, it is quite narrow intially then flares into a hexagonal disk. This is often very clear when one focuses thruogh the specieme in the light microscope.

Search data:
TagsLITHS: nannolith-radiate, star-shaped, CA: process, CROSS-POLARS: 1ou, V-prominent,
MetricsLith size: 8->17µm; Segments: 6->6;
Data source notes: size from OD & illustrated specs
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: Young 1998
First occurrence (base): within NN4 zone (14.91-17.95Ma, base in Burdigalian stage). Data source: Young 1998

Plot of occurrence data:

References:

Akers, W. H. (1995). Discoaster petaliformis Moshkovitz and Ehrlich 1984 coincidentalis, a new subspecies from the subsurface of Louisiana. Tulane Studies in Geology and Paleontology. 28: 131-132. gs V O

Bown, P. R. & Dunkley Jones, T. (2012). Calcareous nannofossils from the Paleogene equatorial Pacific (IODP Expedition 320 Sites U1331-1334). Journal of Nannoplankton Research. 32(2): 3-51. gs V O

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 V O

Filewicz, M. V. (1985). Calcareous nannofossil biostratigraphy of the Middle America Trench and slope, Deep Sea Drilling Project Leg 84. Initial Reports of the Deep Sea Drilling Project. 84: 339-361. gs V O

Moshkovitz, S. & Ehrlich, A. (1980). Distribution of the calcareous nannofossils in the Neogene sequence of the Jaffa-1 Borehole, Central Coastal Plain, Israel. Geological Survey of Israel Report. PD/1/80: 1-25. gs

Theodoridis, S. (1984). Calcareous nannofossil biostratigraphy of the Miocene and revision of the helicoliths and discoasters. Utrecht Micropaleontological Bulletin. 32: 1-271. gs V O

Young, J. R. (1998). Neogene. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series. 225-265. gs V O


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Discoaster petaliformis compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 2-12-2020

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Short stable page link: http://mikrotax.org/Nannotax3/index.php?id=494 Go to Archive.is to create a permanent copy of this page - citation notes



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