Syracosphaerales
Classification: ntax_mesozoic -> Syracosphaerales
Sister taxa: Arkhangelskiales, Eiffellithales, Stephanolithiales, Podorhabdales, Watznaueriales, Syracosphaerales, Heterococcoliths inc sedis ⟩⟨ Holococcoliths, Braarudosphaerales, Nannoliths inc sedis, Mesozoic non–coccoliths, hidden
Distinguishing features: Heterocococcoliths with central area including a cycle of radial laths alternating with rim elements but with tangential c-axis orientations
Taxonomy:
Citation: Syracosphaerales Hay 1977, emend Young et al. 2003Rank: OrderTaxonomic discussion: The Order Syracosphaerales has not generally been used in the Mesozoic; however, the Calciosoleniaceae occur in the Cretaceous, where it shows affinities with the families Stephanolithiaceae and Parhabdolithaceae, which have been classified in the Order Stephanolithiales Bown & Young, 1997. The Calciosolenia specimens seen in the Mesozoic are identical to those in the Cenozoic, and they have a continuous record across the K/Pg boundary, so are clearly the same taxon and need to be classified in the same higher taxonomic group. Therefore, the Syracosphaerales already does occur in the Mesozoic and it appears increasingly likely that it evolved from the Stephanolithiaceae. This leaves the question of whether there is strong enough evidence to transfer the families Stephanolithiaceae and Parhabdolithaceae into the Syracosphaerales, which would make the Order Stephanolithiales redundant. Whilst we think the balance of probabilities is that the Syracosphaerales evolved from the Stephanolithiaceae, we do not have a problem with using paraphyletic taxa, and we are strongly aware both of the value of stability in nomenclature and of the likelihood of new evidence from molecular genetics and/or study of exceptionally-preserved coccoliths from other time intervals. As a general rule, we believe that taxonomic reorganization should be based on conclusive evidence and we feel it is sensible to follow this principle here. So we retain the traditional classification. [Bown et al. 2017]
Farinacci & Howe catalog pages: Syracosphaerales [no catalog entry yet]
Distinguishing features: Heterocococcoliths with central area including a cycle of radial laths alternating with rim elements but with tangential c-axis orientations
Search data:
| Tags | LITHS: murolith, ca_disjunct, |
| Metrics | Lith size: 0->0µm; |
The morphological data given here can be used on the advanced search page. See also these notes
See also: Stephanolithiales ;
Geological Range:
Last occurrence (top): Extant Data source: Total of range of species in this database
First occurrence (base): at base of Hauterivian Stage (0% up, 133.9Ma, in Hauterivian stage). Data source: Total of range of species in this database
Plot of occurrence data:
- Range-bar - range as quoted above, pink interval top occurs in, green interval base occurs in.
- Triangles indicate an event for which a precise placement has been suggested
- Neptune data: this is a higher taxon page so Neptune data is not plotted. For the customisable plot option go to a genus page Parent: ntax_mesozoic
References:
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 V O
Hay, W. W. (1977). Calcareous nannofossils. In, Ramsay, A. T. S. (ed.) Oceanic Micropalaentology. Academic Press, London 1055-1200. gs
Young, J. R., Geisen, M., Cros, L., Kleijne, A., Probert, I. & Ostergaard, J. B. (2003). A guide to extant coccolithophore taxonomy. Journal of Nannoplankton Research, Special Issue. 1: 1-132. gs V O
