Stephanolithiales


Classification: Mesozoic -> Stephanolithiales
Sister taxa: Arkhangelskiales, Eiffellithales, Stephanolithiales, Podorhabdales, Watznaueriales, Syracosphaerales, Heterococcoliths inc sedis, Holococcoliths, Braarudosphaerales, Nannoliths inc sedis, Mesozoic non–coccoliths, hidden,

Distinguishing features: Murolith coccoliths with a distal/outer cycle of non-imbricating elements, i.e., in side view, the sutures are vertical or near-vertical.


Daughter taxa: (blue => in age window 0-800Ma) Granddaughter taxa
Murolith (protolith type) coccoliths with bicylic rims and central-areas spanned by an axial-cross or transverse bar bearing a broad, often long, spine.

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. 

Taxonomy:

Citation: Stephanolithiales Bown & Young, 1997
Rank: Order
Notes & discussion: The order Stephanolithiales probably gave rise to the Order Syracosphaerales, since Calciosolenia is very similar to various Stephanolthaceae genera and early Syracosphaera species are similar to Stradnerlithus. This is also compatible with molecular gentic data since the Syracosphaerales appear to have diverged from he other coccolithophres in the basal radiatition of the group (i.e. in the Early Jurassic). So, it may well prove useful to subsume the Stephanolithiales into the Syracosphaerales, see also discussion in Bown et al. (2017)

Farinacci & Howe catalog pages: Stephanolithiales [no catalog entry yet]

Distinguishing features: Murolith coccoliths with a distal/outer cycle of non-imbricating elements, i.e., in side view, the sutures are vertical or near-vertical.


Morphology remarks: Muroliths with a distal/outer-cycle composed of non-imbricating elements, i.e. in side view, the sutures are vertical or near vertical. This feature is not distinguishable from imbrication in the LM. The term protolith is applied to this rim structure (Bown, 1987). The order comprises (1) the Parhabdolithaceae a group of murolith coccoliths typified by thick, robust, high walls, which are characteristic component of Early Jurassic nannofloras, and (2) the Stephanolithaceae which have similar wall-structure but a more diverse range of morphologies and which occur throughout the Jurassic and Cretaceous.
Crystallographically the rims consist of an outer cycle of V-units and inner cycle of R-units, giving a bicyclic apearnce in cross-polars. The central structures are disjunct, and most often show low birefringence.   

Search data:
TagsLITHS: murolith, elliptical, V-UNITS: V-prominent, R-UNITS: R-prominent, DETAILS: ca_disjunct, rim-bicyclic,
MetricsLith size: 0->0µm;
Sources:
The morphological data given here can be used on the advanced search page. See also these notes

See also: Syracosphaerales ;

Geological Range:
Last occurrence (top): at top of Maastrichtian Stage (100% up, 66Ma, in Maastrichtian stage). Data source: Total of range of species in this database
First occurrence (base): in mid part of Norian Stage (50% up, 218.9Ma, in Norian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

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

Bown, P. R. (1987). Taxonomy, evolution, and biostratigraphy of Late Triassic-Early Jurassic calcareous nannofossils. Special Papers in Palaeontology. 38: 1-118. gs :: ::

Bown, P. R. (1998). Triassic. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series. 29-33. gs :: ::

Bown, P. R., Rutledge, D. C., Crux, J. A. & Gallagher, L. T. (1998). Early Cretaceous. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series. 86-131. gs :: ::

Bown, P. R., Lees, J. A. & Young, J. R. (2017). On the Cretaceous origin of the Order Syracosphaerales and the genus Syracosphaera. Journal of Micropalaeontology. 36(2): 153-165. gs :: view :: open


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Stephanolithiales compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 4-7-2020

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Short stable page link: http://mikrotax.org/Nannotax3/index.php?id=11145 Go to Archive.is to create a permanent copy of this page - citation notes



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