pforams@mikrotax - Trilobatus sicanus

Citation: Trilobatus sicanus (de Stefani 1952)

Basionym: Globigerinoides sicanus de Stefani 1952

Synonyms:

Praeorbulina sicana (de Stefani 1952)

Distinguishing features:
Parent taxon (Trilobatus): Supplementary apertures and cancellate wall.
This taxon: Subspherical to spherical

Description

Subspherical to spherical

Aperture: : Two-three irregular narrow slits at the base of the final chamber [Aze 2011, based on Kennett & Srinivasan 1983]

Test spherical to subspherical, two and one-half to three chambers in the final whorl. In general, test consists of two equal or nearly equal spheres, one consisting of final chamber, the other consisting of the penultimate chamber strongly embracing the earlier ones, sutures distinct and depressed. Surface distinctly cancellate; aperture two to three irregular, narrow, elongate slits at the base of the final chamber.

Biogeography and Palaeobiology

Tropical to temperate. Low to middle latitudes [Aze et al. 2011, based on Kennett & Srinivasan (1983)]

[SCOR WG138]

Aze et al. 2011 ecogroup 1 - Open ocean mixed-layer tropical/subtropical, with symbionts. Based on very heavy δ¹³C and relatively light δ¹⁸O. Sources cited by Aze et al. 2011 (appendix S3): Pearson et al. (1997, 2001b)

Part of the evolutionary series from Trilobatus to Orbulina [editor's comment - JRY 2018]

A re-study of the holotype of this species has shown that it has 4 apertures around the base of the last chamber (Jenkins et al. 1981 and holotype refigured here as Fig. 24.7). For this reason is placed in the genus Praeorbulina. Also for this reason and because of the greater envelopment of the test by the last chamber with subsequent complete loss of the umbilicus. the species is not considered to be conspecific with G. bisphericus as has been suggested (Blow. 1969). It is believed to be an intermediate form in the lineage between G. bisphericus and P. glomerosa curva. [Bolli & Saunders 1985]

Biostratigraphic distribution

Geological Range:
Last occurrence (top): in upper part of M6 zone (62% up, 14.6Ma, in Langhian stage). Data source: Wade et al. (2011), additional event; position within zone determined by linear interpolation from data in table 1 of Wade et al. (2011).
First occurrence (base): at base of M5a subzone (0% up, 16.4Ma, in Burdigalian stage). Data source: Wade et al. (2011), zonal marker

References:

Aze, T., et al. (2011). Aze, T. et al. (2011). A phylogeny of Cenozoic macroperforate planktonic foraminifera from fossil data. Biological Reviews. 86: 900-927. Biological Reviews. 86: 900-927. gs

Bolli, H. M. & Saunders, J. B. (1985). Bolli, H. M. & Saunders, J. B. (1985). Oligocene to Holocene low latitude planktic foraminifera. In, Bolli, H. M. , Saunders, J. B. & Perch-Neilsen, K. (eds) Plankton Stratigraphy. Cambridge University Press, Cambridge, UK 155-262. In, Bolli, H. M., Saunders, J. B. & Perch-Neilsen, K. (eds) Plankton Stratigraphy. Cambridge University Press, Cambridge, UK 155-262. gs

de Stefani, T. (1952). de Stefani, T. (1952). Su alcune manifestazioni di idrocarburi in provincia di Palermo e descrizione di Foraminiferi nuovi. Plinia. 3(4): 1-12. Plinia. 3(4): 1-12. gs

Jenkins, D. G., Saunders, J. B. & Cifelli, R. (1981). Jenkins, D. G., Saunders, J. B. & Cifelli, R. (1981). The relationship of Globigerinoides bisphericus Todd 1954 to Praeorbulina sicana (de Stefani) 1952,. Journal of Foraminiferal Research. 11(4): 262-267. Journal of Foraminiferal Research. 11(4): 262-267. gs

Kennett, J. P. & Srinivasan, M. S. (1983). Kennett, J. P. & Srinivasan, M. S. (1983). Neogene Planktonic Foraminifera. Hutchinson Ross Publishing Co., Stroudsburg, Pennsylvania. 1-265. Hutchinson Ross Publishing Co., Stroudsburg, Pennsylvania. 1-265. gs

Norris, R. D. (1998). Norris, R. D. (1998). Planktonic foraminifer biostratigraphy: Eastern Equatorial Atlantic. Proceedings of the Ocean Drilling Program, Scientific Results. 159: 445-479. Proceedings of the Ocean Drilling Program, Scientific Results. 159: 445-479. gs O

Pearson, P. N., Shackleton, N. J. & Hall, M. A. (1997a). Pearson, P. N., Shackleton, N. J. & Hall, M. A. (1997). Stable isotopic evidence for the sympatric divergence of Globigerinoides trilobus and Orbulina universa (planktonic foraminifera). Journal of the Geological Society of London. 154: 295-302. Journal of the Geological Society of London. 154: 295-302. gs

Pearson, P. N., et al. (2001a). Pearson, P. N. et al. (2001). Warm tropical sea surface temperatures in the Late Cretaceous and Eocene epochs. Nature. 413: 481-487. Nature. 413: 481-487. gs

Postuma, J. A. (1971). Postuma, J. A. (1971). Manual of planktonic foraminifera. Elsevier for Shell Group, The Hague. 1-406. Elsevier for Shell Group, The Hague. 1-406. gs

test outline:	Subcircular	chamber arrangement:	Enveloping	edge view:	Equally biconvex	aperture:	Umbilical
sp chamber shape:	Globular	coiling axis:	Low-moderate	periphery:	N/A	aperture border:
umb chbr shape:	Globular	umbilicus:	Wide	periph margin shape:	Broadly rounded	accessory apertures:	Sutural
spiral sutures:	Moderately depressed	umb depth:	Deep	wall texture:	Cancellate	shell porosity:	Macroperforate: >2.5µm
umbilical or test sutures:	Strongly depressed	final-whorl chambers:	2-3	N.B. These characters are used for advanced search. N/A - not applicable

Trilobatus sicanus

Taxonomy

Description

Biogeography and Palaeobiology

Biostratigraphic distribution

References:

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