Hedbergellidae


Classification: pf_cenozoic -> smooth non-spinose -> Hedbergellidae
Sister taxa: Hantkeninidae, Hedbergellidae,
Daughter taxa (blue => in age window 0-300Ma) Granddaughter taxa
Test very low trochospiral with 12-15 chambers, with 5-6 chambers in ultimate whorl; chambers vary from globular to ovoid to low conical in shape. Aperture interiomarginal, umbilical-extraumbilical, a moderately high arch bordered by narrow lip that may broaden slightly towards umbilicus; aperture may extend slightly onto spiral side. Umbilicus small, generally deep. Wall normal perforate, smooth, but may be covered with pustule growth in some species, particularly in umbilical area. Peripheral margin either perforate, an imperforate band, or keeled. [Olsson et al. 1999]

Test low to very low trochospiral with 18 or more globular chambers. Number of chambers in ultimate whorl varing from 5 to 8. Aperture interiomarginal, umbilical-extraumbilical, a low to high arch, bordered by a narrow lip. Umbilicus small, deep, and open to apertures of previous chambers. Normal perforate wall, smooth to heavily pustulose, nonspinose.

Planoglobanomalina n. gen. is distinguished from the homeomorphic genus Pseudohastigerina by its more compressed test, pinched periphery and ogyval-shaped chambers in edge view. Planoglobanomalina is more loosely coiled, more evolute, and the last few chambers show a tendency towards uncoiling. Pseudohastigerina is more tightly coiled, more involute, and develops bipartite, biumbilicate apertures in some specimens, in contrast to Planoglobanomalina, which has a single primary aperture and in some specimens relict apertures between fused apertural lips.


The genus is characterized by a planispirally coiled, smooth-walled, normal perforate test, with an equatorial aperture which may vary from asymmetrical to symmetrical in position. The primary aperture may be singular or bipartite, arched openings bordered by a thin lip.
DISCUSSION.— Blow (1979) followed the concept of Pseudohastigerina set forth by Berggren and others (1967) who emended the genus to include tests with asymmetric to symmetric equatorial apertures. He drew (arbitrarily) the boundary between (Globorotalia = Globanomalina) and Pseudohastigerina “at the point where the primary aperture opens dorsally in direct continuation of the trace of the spiral suture” where “ a true planispiral coiling-mode can be said to have been attained” (p. 1060). This definition is followed here. In the transition from the ancestral Globanomalina luxorensis (Nakkady) to the descendent Pseudohastigerina wilcoxensis the aperture is, at first, equatorially asymmetrical but becomes symmetrical as symmetrical planispiral tests evolve. All later species in the Pseudohastigerina lineage have symmetrical planispiral tests. Another feature which Berggren and others (1967) first pointed out is the development of bipartite apertures in some individuals. Blow also described this feature and emended it to the definition of Pseudohastigerina.

A wide range of test morphologies is included in the genus. Turborotalia is distinguished from other Eocene genera by the umbilical-extraumbilical aperture and smooth, pustulose wall, which is sometimes weakly cancellate, and has a tendency to defoliate in dissolved or recrystallized material.

Taxonomy

Citation: Hedbergellidae Loeblich and Tappan, 1961
Rank: Family
Taxonomic discussion: The vast majority of hedbergellids are represented by Cretaceous genera. Only one genus, Hedbergella, a very common form throughout the Cretaceous, survived into the Cenozoic where it gave rise to Globanomalina in the early Danian. [Olsson et al. 1999]

Catalog entries: Hedbergellidae;

Type images:

Short diagnosis: Test trochospiral with umbilical-extraumbilical aperture with a prominent lip. Apertures of earlier formed chambers remain visible around the umbilicus.

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: Test trochospiral with umbilical-extraumbilical aperture with a prominent lip. Apertures of earlier formed chambers remain visible around the umbilicus. [Olsson et al. 1999]

Biogeography and Palaeobiology

Biostratigraphic distribution

Geological Range:
Last occurrence (top): within Rupelian Stage (28.09-33.89Ma, top in Rupelian stage). Data source: Total of range of species in this database
First occurrence (base): within Maastrichtian Stage (66.04-72.05Ma, base in Maastrichtian stage). Data source: Total of range of species in this database

Plot of occurrence data:

Primary source for this page: Olsson & Hemleben 2006 - Atlas of Eocene Planktonic Foraminifera, chapter 14, p. 415

References:

Loeblich, A.R., Jr. & Tappan, H., (1961). Cretaceous planktonic foraminifera: Part I-Cenomanian. Micropaleontology, 7: 257-304.

Olsson, R.K. & Hemleben, C., (2006). Taxonomy, biostratigraphy, and phylogeny of Eocene Globanomalina, Planoglobanomalina n. gen and Pseudohastigerina. In: Pearson, P.N. et al. (Editors), Atlas of Eocene Planktonic Foraminifera, Cushman Foundation Special Publication 41. Cushman Foundation Special Publication. Allen Press, Lawrence, Kansas, pp. 413-432.


Hedbergellidae compiled by the pforams@mikrotax project team viewed: 28-6-2017

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