Globanomalina ehrenbergi


Classification: pf_cenozoic -> smooth non-spinose -> Hedbergellidae -> Globanomalina -> Globanomalina ehrenbergi
Sister taxa: G. archeocompressa, G. australiformis, G. chapmani, G. compressa, G. ehrenbergi, G. imitata, G. luxorensis, G. ovalis, G. planocompressa, G. planoconica, G. pseudomenardii, G. sp.,

Taxonomy

Citation: Globanomalina ehrenbergi (Bolli 1957)
Rank: Species
Basionym: Globorotalia ehrenbergi
Synonyms:
Taxonomic discussion: Bolli (1957a) erected this species for Paleocene morphotypes that had been referred to Ehrenberg's species. The basis for distinguishing this species from G. compressa is the pinched periphery and the thickened imperforate margin, which is more strongly developed than in G. compressa. Although Blow (1979) separated G. ehrenbergi from G. haunsbergensis, we include morphotypes with a more sharply acute periphery within the range of variation of G. ehrenbergi. Blow (1979) drew attention to the more lax coiling of G. haunsbergensis morphotypes, which results in a wide, shallow umbilicus. The trend towards a more strongly developed imperforate margin was recognized by Bolli and Blow as a trend towards a true keel, which resulted in the evolution of G. pseudomenardii. Globanomalina chapmani is also allied to G. ehrenbergi in having a pinched periphery and a thickened imperforate margin. As in G. pseudomenardii, the rate of chamber-size increase is greater than in G. ehrenbergi. [Olsson et al. 1999]

Catalog entries: Globorotalia ehrenbergi;

Type images:

Short diagnosis: Compressed, smooth-walled test, with chambers moderately increasing in size, often with the ultimate chamber smaller than the penultimate one, pinched periphery that has a thickened imperforate margin (faint keel of Bolli), 5-5½ chambers in the ultimate whorl.

NB The short diagnoses are used in the tables of daughter-taxa to act as quick summaries of the differences between e.g. species of one genus. They have initially been copied from the diagnostic characters/distinguishing features sections of the Eocene and Paleocene Atlases, they will be edited as the site is developed.

Description


Diagnostic characters: Compressed, smooth-walled test, with chambers moderately increasing in size, often with the ultimate chamber smaller than the penultimate one, pinched periphery that has a thickened imperforate margin (faint keel of Bolli), 5-5½ chambers in the ultimate whorl. [Olsson et al. 1999]

Character matrix

test outline:Lobatecoiling axis:Lowchamber arrangement:Trochospiralumbilicus:Narrow
edge view:Compressedumbilical or test sutures:Moderately depressedspiral sutures:Strongly depressedshell porosity:Finely Perforate: 1-2.5
wall texture:Smoothaperture:Umb.-extraumbilicalaperture border:Thin lipaccessory apertures:None
periphery:Single keelumb chamber shape:Inflatedsp chbr shape:Inflatedperiph margin shape:Subangular
umb depth:Shallowdiameter mm:0.28width mm:-breadth mm:-
final-whorl chambers:5.0-5.5

Biogeography and Palaeobiology


Geographic distribution: Apparently a worldwide distribution in the low to middle latitudes. [Olsson et al. 1999]
Aze et al. 2011 summary: Cosmopolitan in low to middle latitudes; based on Olsson et al. (1999)

Isotope paleobiology: Globanomalina ehrenbergi has ∂18O and ∂13C similar to Parasubbotina varianta, S. triloculinoides, and G. compressa. The species has distinctly more positive ∂18O and more negative ∂13C than Morozovella and Igorina. [Olsson et al. 1999]
Aze et al. 2011 ecogroup 3 - Open ocean thermocline. Based on light δ13C and relatively heavy δ18O. Sources cited by Aze et al. 2011 (appendix S3): this study

Phylogenetic relations: As pointed out by Bolli (1957a) and
Blow (1979), this species is transitional to G. pseudomenardii. It evolved from G. compressa by developing a more highly developed imperforate margin and a more sharply angular axial margin. [Olsson et al. 1999]

Biostratigraphic distribution

Geological Range:
Notes: Zone P2 to Zone P4. [Olsson et al. 1999]
Last occurrence (top): within P4 zone (57.10-60.73Ma, top in Thanetian stage). Data source: Olsson et al. 1999
First occurrence (base): within P2 zone (62.29-62.60Ma, base in Danian stage). Data source: Olsson et al. 1999

Plot of occurrence data:

Primary source for this page: Olsson et al. 1999 - Atlas of Paleocene Planktonic Foraminifera, p. 42

References:

Olsson, R.K.; Hemleben, C.; Berggren, W.A. & Huber, B.T., (1999). Atlas of Paleocene Planktonic Foraminifera. Smithsonian Contributions to Paleobiology. Smithsonian Institution Press, Washington, DC, 1-252 pp.


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Globanomalina ehrenbergi compiled by the pforams@mikrotax project team viewed: 22-7-2017

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