Nannotax3 - ntax_mesozoic - Stradnerlithus

Distinguishing features:
Parent taxon (Stephanolithiaceae): Murolith (protolith type) coccoliths with rims of non-imbricate V-units and weakly-developed, or vestigial, proximal/inner-cycles (R-units), with central-areas spanned by one to numerous bars.
This taxon: Elliptical to diamond-shaped; rims low, narrow, unicyclic; central-area spanned by bars, radiating from central node or a longitudinal bar, usually spine bearing; typically small fragile and inconspicuous in LM.

Citation: Stradnerlithus Black, 1971

Type species: Stradnerlithus comptus Black, 1971.

Synonyms:

Diadozygus Rood, Hay and Barnard, 1971;
Nodosella Rood, Hay and Barnard, 1973;

Protolith coccoliths with low, narrow rims and a central-area spanned by bars, which typically radiate from a central point or from a longitudinally positioned bar. The coccoliths are typically small and fragile, dark, unicyclic and inconspicuous in XPL, and may have polygonal outlines. The upper surface of the rim is often crenulate. Central structure is usually spine bearing.

Geological Range:
Notes: Typically only present when preservation is good and so reported stratigraphic ranges are often discontinuous.
Last occurrence (top): at top of Maastrichtian Stage (100% up, 66Ma, in Danian stage). Data source: Total of range of species in this database
First occurrence (base): in lower part of Pliensbachian Stage (21% up, 189.1Ma, in Pliensbachian stage). Data source: Total of range of species in this database

References:

Black, M. (1971a). Coccoliths of the Speeton Clay and Sutterby Marl. Proceedings of the Yorkshire Geological Society. 38: 381-424. gs V O

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

Bown, P. R. & Cooper, M. K. E. (1998). Jurassic. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series . 34-85. gs O

Bown, P. R. & Young, J. R. (1997). Mesozoic calcareous nannoplankton classification. Journal of Nannoplankton Research. 19(1): 21-36. gs V O

Burnett, J. A. (1998). Upper Cretaceous. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series . 132-199. gs O

Goy, G., Noël, D. & Busson, G. (1979). Les conditions de sédimentation des schistes-carton (Toarcien inf.) du bassin de Paris déduites de l'étude des nannofossiles calcaires et des diagraphies. Documents des laboratories de géologie Lyon. 75: 33-57. gs O

Rood, A. P., Hay, W. W. & Barnard, T. (1971). Electron Microscope Studies of Oxford Clay Coccoliths. Eclogae Geologicae Helvetiae. 64: 245-272. gs O

Rood, A. P., Hay, W. W. & Barnard, T. (1973). Electron microscope studies of Lower and Middle Jurassic coccoliths. Eclogae Geologicae Helvetiae. 66: 365-382. gs O

Worsley, T. R. (1971). Calcareous nannofossil zonation of Upper Jurassic and Lower Cretaceous sediments from the Western Atlantic. In, Farinacci, A. (ed.) Proceedings of the Second Planktonic Conference Roma 1970. Edizioni Tecnoscienza, Rome 2: 1301-1321. gs O

Daughter taxa (time control age-window is: 0-800Ma)
				4 bars
				Stradnerlithus helotatus Elliptical murolith with narrow rim and wide central area spanned by diagonal cross bars.
				Stradnerlithus primitus Narrowly elliptical/lenticular murolith with narrow rim and central area spanned by diagonal cross bars.
				6 bars
				Stradnerlithus geometricus Stradnerlithus with central area spanned by 6 radial bars; 2 along short axis, 4 diagonal.
				Stradnerlithus fractus Described by Black (1971) as having 6 unequally spaced central area bars some of which curve. Arguably a junior synonym of S. geometricus.
				Stradnerlithus bifurcatus Stradnerlithus with 6 central area bars that meet at a longitudinal structure.
				Stradnerlithus langii Stradnerlithus with central area spanned by 6 bars that join at a longitudinal structure.
				Stradnerlithus tortuosus Gracile, elliptical Stradnerlithus with central area spanned by 6 bars (4 diagonal and 2 longitudinal).
				8 bars
				Stradnerlithus asymmetricus Elliptical Stradnerlithus with eight, non-axial, central area bars.
				Stradnerlithus escovillensis Stradnerlithus with central area spanned by a longitudinal bar and 6 lateral bars (8 bars total, delimiting 8 holes).
				Stradnerlithus fragilis Gracile Stradnerlithus with central area spanned by 8 radial bars.
				>8 bars
				Stradnerlithus callomonii Stradnerlithus with central area spanned by 10 cross bars that run from the mid-point of each side.
				Stradnerlithus comptus Narrowly elliptical Stradnerlithus with central area spanned by a longitudinal bar and ~12 lateral bars (delimiting ~14 holes).
				Stradnerlithus clatriatus Stradnerlithus with high, narrow rim and central area spanned by a longitudinal bar and numerous (~16-22) lateral bars.
				Stradnerlithus wendleri Very small, with ca. 12 lateral bars per side and longitudunal bar
				Stradnerlithus haynesiae About 12 short lateral bars and perforate central plate.
				Stradnerlithus silvaradius Elliptical Stradnerlithus with multiple (~22) radial bars and a central spine. Inconspicuous but distinctive appearance in LM XPL with narrow rim and weakly birefringent central area bars/plate.
				Stradnerlithus sp. Specimens not identified to species level

Stradnerlithus

References:

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