nmn

Heterohelicidae


Classification: pf_mesozoic -> Heterohelicidae
Sister taxa: Guembelitriidae, Heterohelicidae, Planomalinidae, Globigerinelloididae, Schackoinidae, Conoglobigerinidae, Chilostomellidae, Favusellidae, Praehedbergellidae, Hedbergellidae, Rugoglobigerinidae, Rotaliporidae, Globotruncanidae, hidden,
Daughter taxa (blue => in age window 0-300Ma) Granddaughter taxa
Test biserial, with subspherical chambers throughout. Chambers increase more or less regularly in size as added. Sutures distinct and depressed. Main aperture in the shape of a low- to medium-high arch, situated at the base of the last-formed chamber. Test ornamentation irregularly reticulate, at least in the earlier portion; chambers sometimes costate.

Test compressed, flabelliform, early stage planispiral, later biserial and increasing rapidly in breadth, the two series of chambers diverging to leave a broad nonseptate central area that later is partially occupied by chamber proliferation, sutures depressed; wall calcareous, finely perforate, ornamented with longitudinal costae and nodes, most prominently in the early stage; aperture an arch at the base of the final chamber.



Test with early chambers in a tiny planispiral coil, at least in the microspheric generation, later with biserially arranged inflated to globular chambers, final one to two pairs of chambers subtriangular in outline with a short blunt spine at the outer angle of the chamber, sutures depressed; wall calcareous, perforate, ornamented with numerous fine longitudinal striae; aperture a high narrow arch at the base of the last chamber.

Test biserial throughout; last-formed chambers with test wall flexure resulting in projections attached to the previous chamber in the row; no accessory apertures are present along the zigzag suture; chamber surface finely costate; test wall calcareous, microperforate.



Test elongate, early chambers subglobular, inflated, and biserially arranged, later chambers more elongate and cuneate to nearly uniserial and rectilinear, the final one or more chambers commonly with an elongate tubulospinelike lateral projection, sutures depressed; wall calcareous, of optically radial calcite, finely perforate; aperture a high interiomarginal arch with narrow bordering lip in the early biserial chambers, in later uniserial chambers the aperture is terminal and the bordering lips merge to form a trough with lateral buttresses that connects directly to the preceding chamber.

Test flabelliform, early biserial stage with rapidly enlarging chambers followed by a proliferation of chambers in the same plane, chambers inflated, subglobular, sutures distinct, depressed; wall calcareous, hyaline, perforate, surface with medium to coarse but discontinuous longitudinal costae that parallel the margins of the chambers, lateral cameral flanges with bordering rims may merge and become continuous ridges on the later chambers; arched basal apertures in the adult commonly at both sides of the multiseriate chambers.



Tests are biserial throughout or with a multiserial chamber stage in the adult portion; a chamber proliferation stage follows the biaperturate progressive chamber; maximum of three multiserial chamber sets that gradually increase their number by one; test ornamentation costate or reticulate throughout, or a combination of the two kinds.



Test subtriangular in outline, microspheric early stage may have tiny planispiral coil, remainder of test biserial, chambers somewhat inflated, sutures depressed; wall calcareous, low, and somewhat oblique imperforate longitudinal costae parallel the test periphery, intercostal surface perforate; aperture an interiomarginal arch, with secondary sutural apertures along the median zigzag suture between pairs of chambers, partially covered by very finely perforate tubular to flaring flaplike projections and may be bordered by a distinct imperforate lip.

Test subtriangular in outline, with biserially arranged, inflated chambers compressed parallel to the line of junction between the two series of chambers so that the test appears broader in apertural or edge view than from the sides with the zigzag suture between chambers, sutures depressed; wall calcareous, finely perforate, surface with longitudinal, slightly irregular to discontinuous fine to medium coarse costae; aperture a broad low to medium arched basal opening bordered by a narrow lip.

Test subconical, microspheric early stage may be planispiral and later stage biserial, regularly enlarging globular chambers proliferate in the later stage in a plane perpendicular to the earlier plane of growth, forming an open cone only partially joined by a bridgelike coverplate, sutures depressed; wall calcareous, hyaline, surface with longitudinal irregular to discontinuous imperforate costae, alternating with distinctly perforate areas of the wall, coverplate over the apertures with much finer perforations; aperture consists of broad arched interiomarginal openings directed toward the umbilicus on all chambers in the final whorl, apertures may be partially covered by the bridge like cover plate that extends from one apertural face to another in the same series of chambers, each coverplate bordered by large infralaminal accessory apertures.



Test subtriangular in outline, compressed, biserial throughout, sutures moderately inflated but not globular, terminal face appearing truncate because of the elevated and beaded sutures; wall calcareous, surface with low and discontinuous ribs and distinctly perforate between the raised and strongly beaded sutures; aperture an arch at the base of the final chamber.

Test with early chambers in a planispiral coil, at least in the microspheric stage, later biserial, chambers globular and inflated, sutures depressed; wall calcareous, perforate, commonly ornamented with fine longitudinal striae; aperture a symmetrical arch at the base of the final chamber.

Test subtriangular to flabelliform in outline, laterally compressed, chambers globular to pyriform, those of early stage biserially arranged, later with chamber proliferation in the plane of biseriality, sutures distinct, depressed; wall calcareous, hyaline, perforate, surface with longitudinal discontinuous and somewhat irregular low costae; arched basal apertures on both margins of many chambers in the multiseriate stage, cameral flanges present, and these and the cameral ridges may be merged on the final series of chambers.



Taxonomy

Citation: Heterohelicidae Cushman 1927
Rank: Family

Type images:

Original description: :

Entries in the Catalog of original descriptions: Heterohelicidae [not in catalog yet]

Short diagnosis: Aperture symmetrical, ranging from a low slit to a high arch at the base of the final chamber, becoming terminal in uniserial taxa.

Geological Range:
Last occurrence (top): within Maastrichtian Stage (66.04-72.05Ma, top in Maastrichtian stage). Data source: Total of range of species in this database
First occurrence (base): within Albian Stage (100.50-112.95Ma, base in Albian stage). Data source: Total of range of species in this database

Plot of occurrence data:

NB Plotting of Neptune data has been disabled on the Mesozoic pages because the dataset is both small and badly affected by a few sites with erroneous age models (our obs Huber, Petrizzo, Young, Nov 2016). The data can still be viewed via the range plottertool - tools menu.

References:

Cushman, J.A., (1927). An outline of a re-classification of the Foraminifera. . Contributions from the Cushman Laboratory for Foraminiferal Research, 3: 1-105.

Loeblich, A.R., Jr. & Tappan, H. (Editors), (1988). Foraminiferal Genera and Their Classification (Volume I-II). Van Nostrand Reinhold Co., New York, 1059 pp.


Heterohelicidae compiled by the pforams@mikrotax project team viewed: 23-5-2017

Taxon Search:
Advanced Search




Comments (0)

No comments yet. Be the first!

Add Comment

* Required information
1000
Captcha Image
Powered by Commentics