Broinsonia


Ancestry: Mesozoic -> Arkhangelskiales -> Arkhangelskiellaceae -> Broinsonia
Sister taxa: Arkhangelskiella, Broinsonia, Thiersteinia,

Short diagnosis: 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.


Daughter taxa (blue => in age window 0-300Ma) Granddaughter taxa
Species with plate
central structure perforate plate; rim broad

central structure imperforate plate; rim broad

axial cross with rows of perforations parallel to cross bars

small (<5µm) species with perforate plate surrounding central cross

Species with lateral bars
small (<6µm) elongate species with lozenge-like central body and lateral bars

axial cross with lateral bars

axial cross with lateral bars, supporting low spine

Species with sieve plate
axial cross and sieve plate

Species open quadrants
axial cross with open quadrants

Small Broinsonia (<5.5µm) with broad axial cross bars.

Medium Broinsonia (5.5-8 µm) with broad axial cross bars.

Large Broinsonia (>8 µm) with broad axial cross bars.

Specimens not identified to species level

Taxonomy:

Citation: Broinsonia Bukry, 1969
Rank: Genus
Type species: Broinsonia dentata Bukry, 1969
Synonyms: Acaenolithus Black, 1973; Aspidolithus Noel, 1969
Notes & discussion: Black (1973) described the genus Acaenolithus for “coccoliths in most respects resembling Broinsonia Bukry, 1969, but differing in the presence of a knob or spine at the centre of the distal surface”. We consider this genus a junior synonym of Broinsonia - see also discussion by Bown in Kennedy et al. 2000.
Aspidolithus Nöel (1969) was published slightly after Broinsonia Bukry (1969) and Nöel (1970) placed the genera in synonymy. Nonetheless, Broinsonia has been used by some authors (e.g. Perch-Nielsen 1985) for forms with an axial cross, and Aspidolithus for those with a central plate.

Farinacci & Howe catalog pages: Acaenolithus * Aspidolithus * Broinsonia *

Short diagnosis: 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.


Morphology remarks: The LM image is typically bicyclic, with a broad, bright inner-cycle and narrow, dark outer-cycle. The central structure typically includes a boss or spine.
In the SEM in side view three tiers of elements are visible (vs. four in Arkhangelskiella).
In the SEM in distal view two cycles of elements are visible, an outer one usualy with well developed sutures showing weak dextral obliquity, and an inner one with obscured surures and often a fluted surface.

Geological Range:
Last occurrence (top): within Maastrichtian Stage (66.04-72.05Ma, top in Maastrichtian stage). Data source: Total of range of species in this database
First occurrence (base): within Valanginian Stage (133.88-139.39Ma, base in Valanginian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

Black, M., (1973). British Lower Cretaceous Coccoliths. I-Gault Clay (Part 2). Palaeontographical Society Monograph, 127: 49-112.

Bown, P.R.; Rutledge, D.C.; Crux, J.A. & Gallagher, L.T., (1998). Early Cretaceous. In: Bown, P.R. (Editor), Calcareous nannofossil biostratigraphy. British Micropalaeontological Society Publication Series. Chapman & Hall, pp. 86-131.

Bukry, D., (1969). Upper Cretaceous coccoliths from Texas and Europe. The University of Kansas Paleontological Contributions, Article 51 (Protista 2): 1-79.

Kennedy, W.J.; Gale, A.S.; Bown, P.R.; Caron, M.; Davey, R.J.; Grocke, D. & Wray, D.S., (2000). Integrated stratigraphy across the Aptian-Albian boundary in the Marnes Bleues, at the Col de Pre ́-Guittard, Arnayon (Drome), and at Tartonne (Alpes-de-Haute-Provence), France: a candidate Global Boundary Stratotype Section and Boundary Point for the base of the Albian Stage. Cretaceous Research, 21(591-720).

Noël, D., (1970). Coccolithes Crétacés: La Craie Campanienne du Bassin de Paris. Éditions du Centre National de la Recherche Scientifique, Paris.

Noël, D., (1969). Arkhangelskiella (coccolithes Crétacés) et formes affines du Bassin de Paris. Revue de Micropaleontologie, 11: 191-204.

Perch-Nielsen, K., (1985). Mesozoic calcareous nannofossils. In: Bolli, H.M., Saunders, J.B. and Perch-Nielsen, K. (Editors), Plankton Stratigraphy. Cambridge University Press, Cambridge, pp. 329-426.


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Broinsonia compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 19-10-2017

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