Nannotax3 - ntax_cenozoic - Blackites inversus

Blackites inversus


Classification: ntax_cenozoic -> Syracosphaerales -> Rhabdosphaeraceae -> Blackites -> B. spinosus group -> Blackites inversus
Sister taxa: B. inversus, B. minusculus, B. perlongus, B. rectus, B. singulus, B. spinosus, B. stilus, B. subtilis, B. tenuis, B. tortilis, B. trochos, B. truncatus

Taxonomy:

Citation: Blackites inversus (Bukry & Bramlette, 1969) Bown & Newsam 2017
Rank: Species
Basionym: Triquetrorhabdulus inversus Bukry & Bramlette, 1969
Synonyms:

Taxonomic discussion:
The correct generic name for this species was unclear for a while due to confusion with a substitute name for Pseudotriquetrorhabdulus and the valid combination Wiseorhabdus inversus. This is explained by Aubry (1988): 

"Although the genus Pseudotriquetrorhabdulus Wise, 1976, is valid, the combination Pseudotriquetrorhobdulus inversus (Bukry and Bramlette) Wise, 1976, is invalid as erected (ICBN, Art.33, para.4) (see Van Heck, 1981, p. 4:1982, p.50). Bukry(1981, p. 463) proposed Wiseorhabdus as a substitute name for Pseudotriquetrorhabdulus and the valid combination Wiseorhabdus inversus (Bukry and Bramlette, emend. Wise and Constans) Bukry, 1981. Wiseorhabdus, however, is superfluous because the original name is valid (ICBN, Art. 63) (see Van Heck, 1982, p.50). The combination Pseudotriquetrorhabdulus inversus (Bukry and Bramlette) emend. Wise, 1976, was validated through re-emendation by Wise (1983, p. 505)."

Explanation of recombination in Blackites:
Previously placed in Triquetrorhabdulus by Bukry & Bramlette (1969) and Pseudotriquetrorhabdulus by Wise (in Wise & Constans, 1976), these spinose forms occur alongside other Blackites spines with similar LM image and cystallographic orientation, and they most likely represents a Blackites species that readily detaches from its coccolith base. It can occur abundantly and has a relatively restricted stratigraphic range in the middle Eocene (Zones NP14–15), with a particular acme interval in Zone NP14 (Backman, 1986). [Bown & Newsam 2017]



Distinguishing features:
Parent taxon (B. spinosus group): Spine tall with narrow central opening
This taxon: Large, narrow, spine-like nannofossil that tapers towards both ends and has a narrow central canal.

Farinacci & Howe catalog pages: T. inversus *


Morphology: Originally compared with Neogene Triquetrorhabdulus due to presence of ‘keels' but may represent disarticulated rhabdolith spines, hence tentative inclusion here in the Rhabdosphaeraceae.
Nannolith goes into extinction when parallel to polarisers but c-axis is perpendicular to length of the nannolith. This is the origin of the name inversus, since the more normal orientation is for the c-axis to be parallel to length of the nannolith, as in Triquetrorhabdulus carinatus.

Search data:
TagsLITHS: planolith, rod-shaped, CA: ca_disjunct, grill, process, CROSS-POLARS: T-prominent,
MetricsLith size: 10->20µm;
Data source notes: lith size (spine height) from OD & illustrated specimens
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Last occurrence (top): within NP15 zone (42.87-46.29Ma, top in Lutetian stage). Data source: Bown & Newsam 2017
First occurrence (base): within NP14 zone (46.29-49.11Ma, base in Ypresian stage). Data source: Bown & Newsam 2017

Plot of occurrence data:

References:

Aubry, M. -P. (1988a). Handbook of Cenozoic calcareous nannoplankton. Book 2: Ortholithae (Catinasters, Ceratholiths, Rhabdoliths). Micropaleontology Press, American Museum of Natural History, New York. 1-279. gs

Backman, J. (1986). Late Paleocene to middle Eocene calcareous- nannofossil biochronology from the Shatsky Rise, Walvis Ridge and Italy. Palaeogeography Palaeoclimatology Palaeoecology. 43-59. 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

Bukry, D. & Bramlette, M. N. (1969b). Some new and stratigraphically useful calcareous nannofossils of the Cenozoic. Tulane Studies in Geology. 7: 131-142. gs V O

Bukry, D. (1981b). Pacific coast coccolith stratigraphy between Point Conception and Cabo Orientes, Deep Sea Drilling Project Leg 63. Initial Reports of the Deep Sea Drilling Project. 63: 445-471. 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

Perch-Nielsen, K. (1977a). Albian to Pleistocene calcareous nannofossils from the Western South Atlantic, DSDP Leg 39. Initial Reports of the Deep Sea Drilling Project. 39: 699-823. gs V O

Wise, S. W. & Constans, R. E. (1976). Mid Eocene plankton correlations Northern Italy - Jamaica W.I. Transactions of the Gulf-Coast Association of Geological Societies. 26: 144-155. gs

Wise, S. W. (1983). Mesozoic and Cenozoic calcareous nannofossils recovered by DSDP Leg 71 in the Falkland Plateau region, Southwest Atlantic Ocean. Initial Reports of the Deep Sea Drilling Project. 71: 481-550. gs V O


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Blackites inversus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 20-9-2021

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