Nannotax3 - ntax_cenozoic - Hornibrookina australis Nannotax3 - ntax_cenozoic - Hornibrookina australis

Hornibrookina australis

Classification: ntax_cenozoic -> Isochrysidales -> Prinsiaceae -> Hornibrookina -> Hornibrookina australis
Sister taxa: H. australis, H. elegans, H. indistincta, H. teuriensis ⟩⟨ H. weimerae, H. gracilis, H. sp.

Sub-taxa & variants (time control age-window is: 0-800Ma)
Hornibrookina australis australis
Small to medium sized, narrowly elliptical to lenticular, arched, central area with 8-10 pairs of lateral bars.
Hornibrookina australis arca
with longitudinal bar; wide geographic distribution outside Southern Ocean 


Citation: Hornibrookina australis Edwards and Perch-Nielsen 1975
taxonomic rank: species
Basionym: Hornibrookina australis Edwards and Perch-Nielsen 1975
Taxonomic discussion: Self-Trail et al. 2022 noted that H. australis and H. arca were essentialy identical, apart from the presence of a longtiudinal bar in H. australis, but that they had discrete biogeogpraphic ranges. They inferred that they were likely to be ecophenotypes and changed them to sub-species. 

Distinguishing features:
Parent taxon (Hornibrookina): Elliptical placoliths with bicyclic distal shields with raised tube cycle and central area grill formed from robust bars.
This taxon: Medium-sized (4-7µm), narrowly elliptical to lenticular, arched, central area with 7-11 pairs of lateral bars

Farinacci & Howe catalog pages: H. australis *

Search data:
LITHS: placolith, elliptical, CA: grill,
CSPH: equant, monomorphic, CROSS-POLARS: rim-bicyclic, V-prominent, R-prominent, T-prominent,
Lith size: 4->7µm;
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Last occurrence (top): within NP11 zone (53.70-54.17Ma, top in Ypresian stage). Data source: Self-Trail et al. 2022;
First occurrence (base): within NP5 zone (59.54-61.51Ma, base in Selandian stage). Data source: Self-Trail et al. 2022;

Plot of occurrence data:


Edwards, A. R. & Perch-Nielsen, K. (1975). Calcareous nannofossils from the southern Southwest Pacific, Deep Sea Drilling Project, Leg 29. Initial Reports of the Deep Sea Drilling Project. 29: 469-539. gs O

Self-Trail, J. M., Watkins, D. K., Pospichal, J. J. & Seefelt, E. L. (2022). Evolution and taxonomy of the Paleogene calcareous nannofossil genus Hornibrookina. Micropaleontology. 68(1): 85-113. gs


Hornibrookina australis compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 3-3-2024

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Short stable page link: Go to to create a permanent copy of this page - citation notes

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