Praemurica


Classification: pf_cenozoic -> Truncorotaloididae -> Praemurica
Sister taxa: Acarinina, Praemurica, Igorina, Planorotalites, Astrorotalia, Morozovella, Morozovelloides,
Daughter taxa: (blue => in age window 0-300Ma)
Moderately high, evolute, trochospiral test, 5-6 globular chambers in final whorl; predominantly, intraumbilical aperture.
Plano-convex to moderately high spired, moderately lobulate test, 5-8 chambers in final whorl; sutures on spiral side incised and strongly recurved; axial periphery subangular, with rugose muricae; umbilicus typically narrow and deep
5-7 chambered test; rapidly expanding final whorl; sutures radial; aperture an interiomarginal, umbilical-extraumbilical slit with distinct lipped rim.
Like P. taurica but with increased rate of expansion of the final few chambers; also apertural lip less pronounced. 
Very low trochospiral test, 5-6 chambers in the ultimate whorl. Umbilicus fairly wide and broad. Aperture bordered by a narrow lip which broadens towards the umbilicus and becomes somewhat triangular in shape. 
Very small trochospiral test, 4½–5 subglobular chambers in the last whorl; equatorial periphery lobate; ; very small umbilicus; last chamber inflated, with well-developed apertural lip projecting over the umbilicus and covering most of it.
Specimens which cannot be assigned to established species

Taxonomy

Citation: Praemurica Olsson, Hemleben, Berggren, and Liu, 1992
Rank: Genus
Type species: Globigerina (Eoglobigerina) taurica Morozova, 1961.
Taxonomic discussion: Praemurica should probably be included in the Globigerinidae since Koutsoukos (2014) demonstrated that it was ancestral to both Eoglobigerina (and so Subbotina) and Parasubbotina. [editor's comment - JRY 2018]

The wall texture of Praemurica (Plate 6: Figures 2-4) is similar to that observed in the modern Neogloboquadrina dutertrei (d'Orbigny) (Plate 5: Figures 9, 10). Elongate subparallel ridges, often with an orientation towards the aperture, are connected by shorter less well-developed ridges that are thicker and broader on one side. This gives the test a cancellate wall texture, which is herein termed praemuricate. It is the first distinctive nonspinose, pustulose wall texture to evolve in the phylogeny of the early Paleocene planktonic foraminifera. [Olsson et al. 1999]

Catalog entries: Praemurica;

Type images:

Distinguishing features: Test very low trochospiral, usually 5-6, globular to oval chambers in last whorl, periphery lobulate;
Wall non-spinose, weakly cancellate;

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: Test very low trochospiral, 5-6, up to 8 in some species, globular to oval chambers in last whorl that increase slowly to moderately in size; periphery moderately to distinctly lobulate; nonspinose, cancellate wall texture weakly developed; aperture an interiomarginal, umbilical-extraumbilical low to high rounded arch, bordered by a thin lip.

Biogeography and Palaeobiology

Most likely ancestor: Benthic foraminifera - at confidence level 3 (out of 5). Data source: Koutsoukos 2014.
Likely descendants: Eoglobigerina; Igorina; Morozovella;

Biostratigraphic distribution

Geological Range:
Last occurrence (top): near top of Lutetian Stage (89% up, 41.9Ma, in Lutetian stage). Data source: Total of range of species in this database
First occurrence (base): within Danian Stage (61.61-66.04Ma, base in Danian stage). Data source: Total of range of species in this database

Plot of occurrence data:

Primary source for this page: Berggren et al. 2006 - Eocene Atlas, chap. 12, p. 397

References:

Berggren, W.A.; Olsson, R.K. & Premoli Silva, I., (2006). Taxonomy, biostratigraphy and phylogenetic affinities of Eocene Astrorotalia, Igorina, Planorotalites, and Problematica (Praemurica? lozanoi). In: Pearson, P.N. et al. (Editors), Atlas of Eocene Planktonic Foraminifera. Cushman Foundation Special Publication. 41 Allen Press, Lawrence, Kansas, pp. 377-400.

Koutsoukos, E., (2014). Phenotypic plasticity, speciation, and phylogeny in Early Danian planktic foraminifera. Journal of Foraminiferal Research, 44: 109-142.

Morozova, V.G., (1961). Datsko-Montskie planktonnye foraminifery yuga SSSR [Danian-Montian Planktonic Foraminifera of the Southern USSR]. Paleontologicheskiy Zhurnal, 2(8-19).

Olsson, R.K.; Hemleben, C.; Berggren, W.A. & Liu, C., (1992). Wall Texture Classification of planktonic foraminifera genera in the Lower Danian. Journal of Foraminiferal Research, 22(3): 195-213.


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

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