Trilobatus


Classification: pf_cenozoic -> Globigerinidae -> Trilobatus
Sister taxa: Beella, Globigerina, Globigerinella, Protentella, Quiltyella, Ciperoella, Globigerinoides, Globigerinoidesella, Globoturborotalita, Orbulina, Praeorbulina, Sphaeroidinella, Sphaeroidinellopsis, Trilobatus, Turborotalita, Dentoglobigerina, Globoquadrina, Catapsydrax, Clavatorella, Paragloborotalia, Protentelloides, Eoglobigerina, Globigerinatheka, Globorotaloides, Guembelitrioides, Orbulinoides, Parasubbotina, Pseudoglobigerinella, Subbotina,
Daughter taxa: (blue => in age window 0-300Ma)
sacculifer group (conspecific in modern ocean)
Low trochospiral, chambers spherical except final one which is sack-like
Like T. trilobus but slightly more lobate and the primary aperture is a low umbilical arch across the antepenultimate chamber.
3½-4 globular chambers in the last whorl.
3 globular chambers in the last whorl
transitional to Orbulina
Bilobate outline, enveloping last chamber almost completely hides the umbilicus
Subspherical to spherical
other species
Like T. primordius but with a high trochospire, up to 4 chambers in the last whorl, and slit-like primary and supplementary apertures.
Like T. immaturus and T. trilobus but more subcircular and compact outline; aperture slit-like encompassing the penultimate chamber, and usually 4 chambers in the final whorl.
Last chamber forms half of the test; low trochospiral, lobulate;  3½ globular, slightly embracing chambers in the last whorl, increasing rapidly in size; sutures depressed; Primary aperture umbilical arch with a thin rim; one small arched supplementary sutural aperture.
Like T. sacculifer but last chamber only weakly sac-like chamber; test generally smaller; tande primary aperture is a lower and smaller
Specimens which cannot be assigned to established species

Taxonomy

Citation: Trilobatus Spezzaferri et al. 2015
Rank: genus
Type species: Trolobatus trilobus
Taxonomic discussion: The genus Globigerinoides was used by Kennett & Srinivasan (1983) and many other workers for all Neogene  Globigerina-type species with supplementary apertures, but it was long suspected that this was a polyphyletic group. Spezzaferri et al. (2015) conclusively proved this polyphyly using both stratophentic and molecular genetic data and so divided the species into two groups - Trilobatus and Globigerinoides, as used here. They have separate origins and different wall structures. [editor's comment - JRY 2018]

Catalog entries: Trilobatus;

Type images:

Distinguishing features: Supplementary apertures and cancellate wall.

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: <i>Trilobatus</i> has supplementary apertures on the spiral side, which are not present in <i>Globoturborotalita, Subbotina,</i> and in other globular forms. Typical of <i>Trilobatus</i> is the <i>sacculifer</i>-type wall texture and the primary aperture which is asymmetrical, generally slit-like and extending toward the peripheral margin. [Spezzaferri et al. 2018]

Wall type: Cancellate, honeycomb, sacculifer-type, with spines regularly distributed. Gametogenetic calcification may obscure spines holes.. [Spezzaferri et al. 2018]

Test morphology: Low to high trochospiral consisting of 3 whorls. The peripheral margin is rounded, the test outline is compact to lobate, slightly ovate or subtriangular to subrectangular. Chambers can be globular to ovate, symmetrical to enlarged and embracing or irregular and laterally compressed. They are generally 3 to rarely 4 in the last whorl increasing from fast to gradually in size as added. The primary aperture is an umbilical-extraumbilical elongated slit, sometimes moderately high arched and characterizes a generally narrow and concealed umbilical area. Supplementary apertures are present on the spiral side, slit-like or low to high arched, placed at the intersection of the spiral sutures, one per chamber. Thin lips may be present on the primary and supplementary apertures. The last chamber may be sac-like. [Spezzaferri et al. 2018]

Biogeography and Palaeobiology


Phylogenetic relations: Trilobatus evolved from Globoturborotalita paracancellata in upper Oligocene Zone O6. [Spezzaferri et al 2018]

Most likely ancestor: Globoturborotalita - at confidence level 3 (out of 5). Data source: Spezzaferri et al 2018.
Likely descendants: Globigerinoidesella; Praeorbulina;

Biostratigraphic distribution

Geological Range:
Last occurrence (top): Extant Data source: Total of range of species in this database
First occurrence (base): in lower part of Chattian Stage (23% up, 26.9Ma, in Chattian stage). Data source: Total of range of species in this database

Plot of occurrence data:

Primary source for this page: Spezzaferri et al. 2015; Spezzaferri et al. 2018

References:

Hemleben, C.; Spindler, M. & Anderson, O., (1989). Modern Planktonic Foraminifera. Springer-Verlag, New York.

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

Reuss, A.E., (1850). Neue Foraminiferen aus den Schichten des Osterreichischen Tertiarbeckens. Denkschr. k. Ak. Wiss. Wein, 1: 365-390.

Spezzaferri, S. & others, (2015). Fossil and genetic evidence for the polyphyletic nature of the planktonic foraminifera "Globigerinoides", and description of the new genus Trilobatus. Plos one: 1-20.

Spezzaferri, S.; Olsson, R.K. & Hemleben, C., (2018). Taxonomy, biostratigraphy, and phylogeny of Oligocene to Lower Miocene Globigerinoides and Trilobatus. In: Wade, B.S. et al. (Editors), Atlas of Oligocene Planktonic Foraminifera. Cushman Foundation for Foraminiferal Research Special Pulbication. 46, pp. 269-307.


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Trilobatus compiled by the pforams@mikrotax project team viewed: 15-12-2018

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Short stable page link: http://mikrotax.org/pforams/index.php?id=104239Go to Archive.is to create a permanent copy of this page - citation notes



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