Distinguishing features:
Parent taxon (Broinsonia): Outer rim of V-units, with slight clockwise obliquity, visible on distal surface and form dark rim in LM; central-area spanned by an axial cross, grill or perforate plate. 3 tiers visible in side view.
This taxon: small (<5µm) species with perforate plate surrounding central cross
Taxonomy:
Farinacci & Howe catalog pages: B. gammation *
Distinguishing features:
Parent taxon (Broinsonia): Outer rim of V-units, with slight clockwise obliquity, visible on distal surface and form dark rim in LM; central-area spanned by an axial cross, grill or perforate plate. 3 tiers visible in side view.
This taxon: small (<5µm) species with perforate plate surrounding central cross
Search data:
CA: placolith, grill, plate, pores, |
Lith size: 4->5µm; Data source notes: original description |
Geological Range:
Last occurrence (top): within Cenomanian Stage (93.90-100.50Ma, top in Cenomanian stage). Data source: Original description - so real range may be longer
First occurrence (base): within Middle Albian Substage (107.59-109.70Ma, base in Albian stage). Data source: Original description - so real range may be longer
Plot of occurrence data:
Hill, M. E. (1976). Lower Cretaceous calcareous nannofossils from Texas and Oklahoma. Palaeontographica Abteilung B Palaeophytologie. 156: 103-179. gsReferences:
Broinsonia gammation compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 15-9-2024
Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=10125 Go to Archive.is to create a permanent copy of this page - citation notes |
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