Dentoglobigerina eotripartita


Classification: pf_cenozoic -> Globigerinidae -> Dentoglobigerina -> Dentoglobigerina eotripartita
Sister taxa: D. juxtabinaiensis, D. binaiensis, D. sellii, D. tapuriensis, D. baroemoenensis, D. larmeui, D. galavisi, D. altispira, D. globosa, D. globularis, D. prasaepis, D. pseudovenezuelana, D. taci, D. tripartita, D. eotripartita, D. venezuelana, D. sp.,

Taxonomy

Citation: Dentoglobigerina eotripartita Pearson, Wade, and Olsson, in Wade et al. 2018
Rank: species
Synonyms:
Taxonomic discussion:

This species was initially identified in the Atlas of Eocene Planktonic Foraminifera (2006) as D. tripartita (Koch). At that time, an SEM of the tripartita holotype was unavailable and identification relied on a drawing of the holotype by Blow and Banner (1962), which was interpreted as a slightly deformed specimen, so we followed the well defined concept of this species set out by Blow (1969, 1979). The new holotype SEM of tripartita (Koch) (Pl. 11.14, Figs. 1-3) clearly shows, however, the large, robust, subspherical, test of this species, which is typical of the Oligocene, but is different from the specimens illustrated by Blow, and from D. cf. tripartita (Pearson and Wade, 2015). Dentoglobigerina eotripartita n. sp. is thus described to represent this smaller more compact morphotype typical of the Eocene, which was probably ancestral to the more robust tripartita sensu stricto. [Wade et al. 2018]

Catalog entries: Dentoglobigerina eotripartita;

Type images:

Distinguishing features:

Like D. tripartita but smaller, and less spherical, less compressed/reniform overall morphology.

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:

Dentoglobigerina eotripartita is distinguished from D. galavisi by its more compact morphology with 3 tightly coiled, more rapidly increasing chamber size in the final whorl and by possessing a more overarching and compressed final chamber. This species differs from D. tripartita by its smaller size, and less spherical, less compressed/reniform overall morphology, and from D. pseudovenezuelana by more tightly coiled chambers and tooth pointing down the opposing suture. [Wade et al. 2018]


Wall type: Normal perforate, cancellate, pustulose, probably spinose in life.

Test morphology: Test, compact, globular, chambers arranged in a tight, low trochospiral, subcircular to subquadrate in equatorial outline, moderately lobate; in spiral view 3-3½ ovoid compressed chambers in ultimate whorl, increasing rapidly in size, sutures straight or slightly curved, depressed; in umbilical view 3 ovoid chambers in ultimate whorl, increasing rapidly in size, sutures straight and incised, umbilicus moderate in size, aperture centered deep in the umbilicus, bordered by a thin, irregular, subtriangular-shaped lip or tooth which tends to point down the opposing suture; in edge view test oval in outline, chambers ovoid in shape, ultimate chamber projects above and bends over the umbilicus. [Wade et al. 2018]

Size: Maximum diameter of holotype 0.42 mm, minimum diameter 0.34 mm, thickness 0.41 mm. [Wade et al. 2018]

Biogeography and Palaeobiology


Geographic distribution: Global at low to mid-latitudes. [Wade et al. 2018]

Isotope paleobiology: Stable isotope data indicate a thermocline habitat, becoming deeper with increasing test size (Wade and Pearson, 2008, recorded as D. tripartita; see also Pearson and Wade, 2015). [Wade et al. 2018]

Phylogenetic relations: Dentoglobigerina eotripartita n. sp. descended from D. galavisi in the middle Eocene (Olsson and others, 2006) and probably gave rise to D. tripartita in the lower Oligocene (Pearson and Wade, 2015). [Wade et al. 2018]

Most likely ancestor: Dentoglobigerina galavisi - at confidence level 3 (out of 5). Data source: Wade et al. 2018.
Likely descendants: Dentoglobigerina tripartita;

Biostratigraphic distribution

Geological Range:
Notes: The first appearance is in upper Eocene Zone E14 according to Olsson and others (2006) although the oldest figured specimen is from Zone E15 (Olsson and others, 2006, pl. 13.3, fig. 4). This form probably developed gradually into D. tripartita by becoming larger and more spherical. All of our illustrated specimens are from the upper Eocene, but the eotripartita like morphology persists in the record until at least the upper Oligocene Zone O7 (see the dissections of Blow, 1969, pl. 29, figs. 3 and 5, and the discussion under tripartita). Our youngest confirmed occurrence is from Zone O1. [Wade et al. 2018]
Last occurrence (top): within O2 zone (30.28-32.10Ma, top in Rupelian stage). Data source: Wade et al. 2018 f11.1
First occurrence (base): within E14 zone (35.89-37.99Ma, base in Bartonian stage). Data source: Olsson et al., 2006

Plot of occurrence data:

Primary source for this page: Wade et al. 2018 - Olig Atlas chap.11 p.342

References:

Blow, W.H. & Banner, F.T., (1962). The mid-Tertiary (Upper Eocene to Aquitanian) Globigerinaceae. In: Eames, F.E. et al. (Editors), Fundamentals of mid-Tertiary Stratigraphical Correlation. Cambridge University Press, Cambridge, pp. 61-151.

Blow, W.H., (1969). Late middle Eocene to Recent planktonic foraminiferal biostratigraphy. In: Bronnimann, P. and Renz, H.H. (Editors), Proceedings of the First International Conference on Planktonic Microfossils, Geneva, 1967, Leiden, Netherlands, pp. 380-381.

Blow, W.H., (1979). The Cainozoic Globigerinida: A study of the morphology, taxonomy, evolutionary relationships and stratigraphical distribution of some Globigerinida (mainly Globigerinacea), 2. E. J. Brill, Leiden, 1413 pp.

Koch, R., (1926). Mitteltertiare Foraminiferen aus Bulongan, Ost-Borneo. Eclogae Geologicae Helvetiae, 19(3): 722-751.

Olsson, R.K.; Hemleben, C. & Pearson, P.N., (2006). Taxonomy, biostratigraphy, and phylogeny of Eocene Dentoglobigerina. In: Pearson, P.N. et al. (Editors), Atlas of Eocene Planktonic Foraminifera. Cushman Foundation Special Publication. 41 Allen Press, Lawrence, Kansas, pp. 401-412.

Pearson, P.N. & Wade, B.S., (2015). Systematic taxonomy of exceptionally well-preserved planktonic foraminifera from the Eocene/Oligocene boundary of Tanzania. Cushman Foundation Special Publication, 45: 1-85.

Stainforth, R.M.; Lamb, J.L.; Luterbacher, H.; Beard, J.H. & Jeffords, R.M., (1975). Cenozoic planktonic foraminiferal zonation and characteristics of index forms. The University of Kansas Paleontological Contributions, 62: 1-425.

Wade, B.S. & Pearson, P.N., (2008). Planktonic foraminiferal turnover, diversity fluctuations and geochemical signals across the Eocene/Oligocene boundary in Tanzania. Marine Micropaleontology, 68: 244-255.

Wade, B.S.; Pearson, P.N.; Olsson, R.K.; Fraass, A.J.; Leckie, R.M. & Hemleben, C., (2018). Taxonomy, biostratigraphy, and phylogeny of Oligocene and Lower Miocene Dentoglobigerina and Globoquadrina. In: Wade, B.S. et al. (Editors), Atlas of Oligocene Planktonic Foraminifera. Cushman Foundation for Foraminiferal Research Special Pulbication. 46, pp. 331-385.


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

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