Nannotax3 - ntax_cenozoic - Cruciplacolithus cruciformis

Citation: Cruciplacolithus cruciformis (Hay & Towe, 1962) Roth, 1970

Basionym: Cyathosphaera cruciformis Hay & Towe, 1962

Synonyms:

Cruciolithus cruciformis (Hay & Towe, 1962) Stradner 1968. NB Stradner designated C. cruciformis as type species of his genus, Cruciolithus. So, if it were ever deemed useful to place this species in a separate genus, the name Cruciolithus would have priority.
Cruciplacolithus zachosii Bernaola & Monechi 2007 - NB the authors state that their species is differentiated from C. cruciformis by its larger size, and is 5-6.5µm long. Hay & Towe (1962) state that their holotype is 3µm long, however the magnification of the plate suggests it is 6 µm long, and the number of rim elements suggest it is not a minute specimen. [JRY 2015]

Distinguishing features: Large (6-10 µm) Cruiplacolithus with narrow shields, wide central area and narrow cross bars that can be axial or rotated.

Geological Range:
Last occurrence (top): within NP17 zone (37.32-40.40Ma, top in Priabonian stage). Data source: Bown, 2005
First occurrence (base): within NP15 zone (42.87-46.29Ma, base in Lutetian stage). Data source: Bown, 2005

References:

Bernaola, G. & Monechi, S. (2007). Calcareous nannofossil extinction and survivorship across the Cretaceous_Paleogene boundary at Walvis Ridge (ODP Hole 1262C, South Atlantic Ocean). Palaeogeography Palaeoclimatology Palaeoecology. 255: 132-156. gs

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

Bown, P. R. & Newsam, C. (2017). Calcareous nannofossils from the Eocene North Atlantic Ocean (IODP Expedition 342 Sites U1403–1411). Journal of Nannoplankton Research. 37(1): 25-60. gs V O

Bown, P. R. (2005d). Palaeogene calcareous nannofossils from the Kilwa and Lindi areas of coastal Tanzania (Tanzania Drilling Project 2003-4). Journal of Nannoplankton Research. 27(1): 21-95. gs V O

Dunkley Jones, T., Bown, P. R. & Pearson, P. (2009). Exceptionally well preserved upper Eocene to lower Oligocene calcareous nannofossils (Prymnesiophycidae) from the Pande Formation (Kilwa Group), Tanzania. Journal of Systematic Palaeontology. 7(4): 359-411. gs

Hay, W. W. & Towe, K. M. (1962a). Electron microscope examination of some coccoliths from Donzacq (France). Eclogae Geologicae Helvetiae. 55: 497-517. gs V O

Jones, A. P. & Dunkley Jones, T. (2020). Middle Eocene to Early Oligocene calcareous nannofossils from the Nanggulan Formation, Java, Indonesia. Journal of Nannoplankton Research. 30(1): 57-79. gs V O

Roth, P. H. (1970). Oligocene calcareous nannoplankton biostratigraphy. Eclogae Geologicae Helvetiae. 63: 799-881. gs V O

Shamrock, J. L. & Watkins, D. K. (2012). Eocene calcareous nannofossil biostratigraphy and community structure from Exmouth Plateau, Eastern Indian Ocean (ODP Site 762). Stratigraphy. 9(1): 1-11. gs

Tags	LITHS: placolith, elliptical, CA: cross-axial, ca_disjunct, diagonal cross, CSPH: equant, monomorphic, CROSS-POLARS: rim-bicyclic, V-prominent, R-prominent,
Metrics	Lith size: 5->7µm; Data source notes: lith size from Bernaoloa 7 Monechi (as C. zachosii)

Cruciplacolithus cruciformis

References:

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