Tonromeinia deniseae
Set number: 2348
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Set number: 2349
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Set number: 2377
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Set number: 2376
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Holotype in mobile mount.
Set number: 2375
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Set number: 2374
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Set number: 2373
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Set number: 2372
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Set number: 2371
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Set number: 2370
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Set number: 2369
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Set number: 2368
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Set number: 2367
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Set number: 2366
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Set number: 2365
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Set number: 2364
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Set number: 2363
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Set number: 2362
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Set number: 2361
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Set number: 2360
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Tonromeinia deniseae Bowman & Varol, 2021
Cyclolithella esnaensis El-Dawoody, 1988 (invalid ICN Art. 35.1)
A gigantic circular species of Tonromeinia displaying two discs, a low column, all exhibiting equal height/thickness and width and a featureless, wide central opening without a tube cycle.
After Denise Varol, Petroleum Geologist at Total, Copenhagen, Denmark.
Overall diameter (max): 12.73μm; Central Opening diameter: 5.84μm; Discs/Column diameter: 3.25μm; Overall height: 5.42μm.
Gigantic (11.0–15.0μm) circular species of Tonromeinia composed of two discs and a column. The discs and a column are of equal diameter and similar height/thickness. The moderately low column generates the compressed nature of the species. The central area exhibits a large featureless opening without a tube cycle. The settling position of this species is typically restricted to the plan-view, as the limited height of the column prevents sufficient mass distribution along the height axis.
In cross-polarised light, the distal side is affiliated with dextrogyre extinction lines, but laevogyre extinction lines indicate the proximal side. When viewed using a gypsum plate, the horizontal and blue areas are linked on the distal side, whereas the vertical axis matches the blue section on the proximal side. The discs and a column are birefringent in side-view and plan-view. The plan-view shows yellowish birefringence colours, whereas the side-view displays yellowish-brownish-reddish birefringence colours.
Tonromeinia deniseae is a large circular species 11.0–15.0μm, but other circular species of Tonromeinia are <11.0μm. Tonromeinia deniseae is circular in overall shape, whereas Tonromeinia deflandrei and Tonromeinia noeliae appear elliptical. Wei (1998) also included larger specimens
(>11.0μm) into his depiction of Ericsonia robusta and determined a similar age range of NP8, upper - NP9, lower.
Bowman, A. R. & Varol, O. 2021. A Taxonomic Revision of Heliolithaceae - Applications in Resolving the Problematic Calcareous Nannofossil Biostratigraphy of the Paleocene. In: M. Montenary, M. (Ed.). Calcareous nannofossil biostratigraphy of the Stratigraphy and timescales. 6: 43-223.
El-Dawoody, A. S. 1988. New calcareous nannoplankton species from the Paleocene rocks in souhern Egypt. Bulletin of the Faculty of Science, Cairo University. 56: 549-563.
Holotype
Tonromeinia denisea
Bowman & Varol, 2021
Late Paleocene
DSDP Leg 36, Site 327A, The Maurice Ewing Bank, Falkland Plateau