Praeorbulina


Classification: pf_cenozoic -> Globigerinidae -> Praeorbulina
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)
Test nearly spherical; last chamber enveloping >75% of the earlier test; sutural apertures circular to subcircular.
Test ovoid to nearly spherical; last chamber enveloping >40% of the earlier test; sutural apertures small crescentic and slitlike
Test, subspherical to spherical, last chamber enveloping 40 to 70% of the earlier test; sutural apertures, small, few (4 to 8).
Specimens which cannot be assigned to established species

Taxonomy

Citation: Praeorbulina Olsson 1964
Rank: genus
Type species: Globigerinoides glomerosa glomerosa Blow 1956
Taxonomic discussion: Olsson (1964) proposed the genus Praeorbulina to include intermediate morphological stages connecting Globigerinoides sicanus with Orbulina universa. The species and subspecies now referred to as Praeorbulina were originally included in the genus Globigerinoides (Blow, 1956) and later placed in Porticulasphaera (Bolli, 1957b; Blow, 1959). Praeorbulina differs from Orbulina by the lack of areal apertures and from Globigerinoides in lacking a distinct umbilicus and an umbilical aperture in the adult stage. Lipps (1964) considered Praeorbulina Olsson as a junior synonym of Candorbulina. [Kennett & Srinivasan 1983]

Catalog entries: Praeorbulina;

Type images:

Distinguishing features: Terminal chamber partially enveloping previous chambers

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

Biogeography and Palaeobiology


Phylogenetic relations: The genus Praeorbulina is geographically widespread from tropical to temperate areas and is a short-ranging index form diagnostic of levels close to the Early Miocene-Middle Miocene boundary. A bioseries within Praeorbulina extends from Praeorbulina glomerosa curva -> glomerosa glomerosa -> glomerosa circularis and in turn into Orbulina suturalis and O. universa. Since the evolution is continuous, the distinction between the phylogenetic species is gradational. [Kennett & Srinivasan 1983]

Most likely ancestor: Trilobatus - at confidence level 4 (out of 5). Data source: Kennett & Srinivasan 1983.

Biostratigraphic distribution

Geological Range:
Last occurrence (top): in upper part of Langhian Stage (80% up, 14.3Ma, in Langhian stage). Data source: Total of range of species in this database
First occurrence (base): near top of Burdigalian Stage (93% up, 16.3Ma, in Burdigalian stage). Data source: Total of range of species in this database

Plot of occurrence data:

Primary source for this page: Kennett & Srinivasan 1983, p.81

References:

Blow, W.H., (1956). Origin and evolution of the foraminiferal genus Orbulina d'Orbigny. Micropaleontology, 2(1): 57-70.

Blow, W.H., (1959). Age, correlation, and biostratigraphy of the upper Tocuyo (San Lorenzo) and Pozon Formations, eastern Falcon, Venezuela. Bulletins of American Paleontology, 39(178): 67-251.

Bolli, H.M., (1957). Planktonic foraminifera from the Eocene Navet and San Fernando formations of Trinidad. In: Loeblich, A.R., Jr. et al. (Editors), Studies in Foraminifera: U.S. National Museum Bulletin 215. U.S. Government Printing Office, Washington, D.C., pp. 155-172.

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

Lipps, J.H., (1964). Miocene planktonic foraminifera from Newport Bay, California. Tulane Studies in Geology and Paleontology, 2: 109-133.

Olsson, R.K., (1964). Late Cretaceous planktonic Foraminifera from New Jersey and Delaware. Micropaleontology, 10(2): 157-188.


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Praeorbulina compiled by the pforams@mikrotax project team viewed: 18-10-2018

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