Daughter taxa (time control age-window is: 0-800Ma)
Granddaughter taxa
Blackites atanii Spine relatively low, hollow sacculiformt; broadens rapidly from narrow base, then tapers to form low, pointed dome. Typically the spine height and width are similar and the spine is similar in width or slightly wider than the base.
Blackites deflandrei Spine relatively low, wide, hollow sacculiform; constructed from at least two distinct structural units when viewed in XPL; there may be a small, terminal papilla. Typically the height and width are similar but the height can be greater. The spine is always slightly narrower than the base.
Blackites mericii Small rhabdoliths with relatively low, hollow, sacculiform spines. Spine broadens from base and is capped by curving upper surface that appears to be constructed from two parts (XPL); spine usually slightly wider than coccolith. Coccolith rim appears to be narrow, and only one cycle has been observed
Blackites morionum Spine relatively short, wide, hollow sacculiform; may have a small terminal papilla. The base is relatively broad, and typically the spine height and basal width are similar. The spine broadens slightly before tapering to a point and is always slightly narrower than the base.
Blackites shafikii Small, varimorphic, sub-circular to elliptical rhabdoliths with a low domed process, formed of a continuous whorl of one lamellar cycle, and a distinct collar formed from an outwardly directed lamellar cycle.
Citation: Blackites morionum grouptaxonomic rank: species groupTaxonomic discussion: informal grouping used here to sort species within this large genus. The genera Amitha, Cruxia, Cepekiella, Discoturbella, Notiocyrtolithus and Ommatolithus have been proposed for species falling in this group (see Blackites page).
Distinguishing features: Parent taxon (Blackites): Coccoliths process-bearing with complex base including outer rim, radial lath and lamellar cycles This taxon: Spine low, globular, height<2x width
Farinacci & Howe catalog pages:
Morphology: These species typically show rather complex tiering of the spine with :
An upper tier of small spirally-arranged plates (like typical Blackites)
A central tier of vertical laths with openings between them
A lower tier of anti-clockwise imbricate elments
B. deflandrei, B. shafikii, C. mericii, A. perfecta, A. prolata, and N. rothii all clearly show this structure B. morionum (lower tier non-imbricate) and O. australiensis (no central tier) are arguable variants. B. atanii, D. moori & C. elongata are not well-enough characterised to tell.
It is not clear whether this structure is genuinely different from that of other Blackites species but the multiplicity of genera that have been described for them is clearly excessive. [JRY 2017] Size: Mostly small, 2-5 µm, spines can get up to about 8 µm high.
Search data:
Lith size: 2->8µm;
The morphological data given here can be used on the advanced search page. See also these notes
Geological Range: Last occurrence (top): at top of Oligocene Epoch (100% up, 23Ma, in Aquitanian stage). Data source: Total of ranges of the species in this database First occurrence (base): within NP9 zone (55.86-57.21Ma, base in Thanetian stage). Data source: Total of ranges of species in this database
Plot of occurrence data:
Range-bar - range as quoted above, pink interval top occurs in, green interval base occurs in.
Triangles indicate an event for which a precise placement has been suggested
Neptune data: this is a higher taxon page so Neptune data is not plotted. For the customisable plot option go to a genus page Parent: Blackites
References:
Shafik, S. (1989). Some new calcareous nannofossils from Upper Eocene and Lower Oligocene sediments in the Otway Basin, southeastern Australia. Alcheringa. 13: 69-83. gs
B. morionum group compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 20-9-2024
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