pforams@mikrotax - Trilobatus sicanus

pforams@mikrotax - Trilobatus sicanus pforams@mikrotax - Trilobatus sicanus

Trilobatus sicanus

Classification: pf_cenozoic -> Globigerinidae -> Trilobatus -> Trilobatus sicanus
Sister taxa: T. sacculifer, T. quadrilobatus, T. immaturus, T. trilobus ⟩⟨ T. bisphericus, T. sicanus ⟩⟨ T. altospiralis, T. praeimmaturus, T. primordius, T. subsacculifer, T. sp.

K_S 1983 13-4.JPG
Miller & Katz 1987 pl. 12 fig. 2.jpg
Norris98 pl2-13.JPG
Postuma 1971 p305-4.JPG
Postuma 1971 p305-7.JPG

Taxonomy

Citation: Trilobatus sicanus (de Stefani 1952)

Taxonomic rank: species

Basionym: Globigerinoides sicanus de Stefani 1952

Synonyms:

Praeorbulina sicana (de Stefani 1952)

Catalog entries: Globigerinoides sicanus

Type images:

holotype: G. sicanus
holotype: G. sicanus

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

NB These concise distinguishing features statements are used in the tables of daughter-taxa to act as quick summaries of the differences between e.g. species of one genus.
They are being edited as the site is developed and comments on them are especially welcome.

Description

Diagnostic characters:

Subspherical to spherical

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

Morphology:

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.

Wall type:

Spinose; Cancellate [Aze 2011]

Character matrix
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

Biogeography and Palaeobiology

Geographic distribution

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

[SCOR WG138]

Isotope paleobiology

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)

Phylogenetic relations

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]

Most likely ancestor:
Trilobatus bisphericus - at confidence level 4 (out of 5). Data source: Spezzaferri et al. 2015 f5.
Likely descendants: Praeorbulina curva; plot with descendants

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

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.
Grey shading between taxa indicates intergrading species within an anagenetic lineage (data from Lamyman et al. 2026).
Histogram - Neptune occurrence data from DSDP and ODP proceedings. Pale shading <50 samples in time bin. Interpret with caution & read these notes
Taxon plotted: Trilobatus sicanus, synonyms included - Globigerinoides sicanus; Globigerinoides sicanus praesicanus; Globigerinoides sicanus sicanus; Praeorbulina sicana; Praeorbulina sicana s.s.; Praeorbulina sicanus; Praeorbulina sicanus;
See also space-time plot :: Samples map :: Parent: Trilobatus

Primary source for this page: Kennett & Srinivasan 1983, p.62

References:

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

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. gs

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

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. gs

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

Miller, K. G. & Katz, M. E. (1987). Micropaleontology. 33(2): 97-149. gs

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

Pearson, P. N., Shackleton, N. J. & Hall, M. A. (1997a). 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. gs

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

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

Trilobatus sicanus compiled by the pforams@mikrotax project team viewed: 15-8-2026

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Short stable page link: https://mikrotax.org/pforams/index.php?id=104242 Go to Archive.is to create a permanent copy of this page - citation notes

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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