Daughter taxa (time control age-window is: 0-800Ma)![]() | |||||
Hornibrookina edwardsii Small to medium sized, normally-elliptical, central area narrow with ~8 pairs of lateral bars and a longitudinal bar. | |||||
Hornibrookina teuriensis Medium sized, narrowly elliptical, central area broad with ~10 pairs of lateral bars and a longitudinal bar. | |||||
arched species | |||||
![]() | ![]() | ![]() | Hornibrookina arca Medium sized (4-7µm), narrowly elliptical to lenticular, arched, central area with 7-11 pairs of lateral bars and a longitudinal bar. | ||
Hornibrookina australis Small to medium sized, narrowly elliptical to lenticular, arched, central area with 8-10 pairs of lateral bars. | |||||
small species | |||||
Hornibrookina weimerae Small (2-3µm) species of Hornibrookina with somewhat rounded ends and a narrow central area filled by a central longitudinal bar. Individual transverse laths are impossible to discern with the light microscope. The proximal shield is relatively bright in XPL. | |||||
![]() | Hornibrookina apellanizii Very small (2-3.5µm) Hornibrookina with a rhombohedral shape and a wide central area. | ||||
Hornibrookina sp. Specimens which cannot be assigned to any established species |
Taxonomy:
Distinguishing features: Elliptical placoliths with bicyclic distal shields with raised tube cycle and central area grill formed from robust bars.
Farinacci & Howe catalog pages: Hornibrookina *
Phylogenetic relations: Hornibrookina has long been tentatively placed in the Prinsiaceae (e.g. Perch-Neilsen 1985, Young & Bown 1997) but the coccoliths are atypical and the central structure looks to be disjunct from the rim so this assignment should be re-examined [JRY 2016]
Tags | LITHS: placolith, elliptical, CA: ca_disjunct, grill, CSPH: equant, monomorphic, |
Metrics | Lith size: 2->9µm; |
Geological Range:
Notes: Abundant in lower Paleocene high latitude settings and conspicuous around the PETM interval.
Last occurrence (top): in lower part of Ypresian Stage (22% up, 54.2Ma, in Ypresian stage). Data source: Total of range of species in this database
First occurrence (base): at base of Danian Stage (0% up, 66Ma, in Danian stage). Data source: Total of range of species in this database
Plot of occurrence data:
Edwards, A. R. (1973b). Key species of New Zealand calcareous nannofossils. New Zealand Journal of Geology and Geophysics. 16: 68-89. gs Perch-Nielsen, K. (1985a). Cenozoic calcareous nannofossils. In, Bolli, H. M., Saunders, J. B. & Perch-Nielsen, K. (eds) Plankton Stratigraphy. Cambridge University Press, Cambridge 427-555. gs Young, J. R. & Bown, P. R. (1997a). Cenozoic calcareous nannoplankton classification. Journal of Nannoplankton Research. 19(1): 36-47. gs V OReferences:
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Hornibrookina compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 22-4-2021
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