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Praeglobotruncana delrioensis


Classification: pf_mesozoic -> Hedbergellidae -> Praeglobotruncana -> Praeglobotruncana delrioensis
Sister taxa: P. algeriana, P. clotensis, P. compressa, P. delrioensis, P. gibba, P. hilalensis, P. inermis, P. kalaati, P. oraviensis, P. pseudoalgeriana, P. shirakinensis, P. stephani, P. sp.,

Taxonomy

Citation: Praeglobotruncana delrioensis (Plummer, 1931)
Rank: Species
Basionym: Globorotalia delrioensis
Synonyms:
Taxonomic discussion: This species displays wide morphological variability mainly regarding the number of chambers of the last whorl (5 to 7) and the shape of the chambers (globular to compressed). It is distinguished by having an imperforate band on the equatorial periphery.
[From Loeblich and Tappan (1961): "This species has been confused in the past with the younger species Praeglobotruncana stephani (Gandolfi), and has even been regarded as synonymous by Bronnimann and Brown (1956, p. 531), Ziegler (1957, p. 199) and Banner and Blow ( 1959, p. 8). The two species are quite distinct morphologically, as can be seen by an examination of type material, such as the topotypes herein illustrated. Praeglobotruncana stephani is planoconvex and has angular to rhomboidal chambers, and is somewhat larger in size. It also occurs higher in the Cenomanian than does the nearly wholly biconvex P. delrioensis. There is considerable variation in the amount of compression of the present species, with all gradations from the somewhat compressed and subangular tests, like the holotype (and the topotype here shown in figure 10), to the almost globular chambered forms described as Globorotalia marginaculeata, but now considered conspecific. Praeglobotruncana delrioensis is probably ancestral to P. stephani. In the type area in Texas, it occurs in Albian and lower Cenomanian strata (upper Washita group) and the younger P. stephani occurs in the Eagle Ford group. This lineage excellently demonstrates several of the evolutionary trends suggested by Bronnimann and Brown ( 1956, p. 515) in that there is an increase in size (P. stephani being larger than P. delrioensis), an increased angularity of chambers from the rounded ones of adult P. delrioensis to the subrhomboidal ones of the planoconvex P. stephani, and an increase in the height of coiling." [copied from Chronos database]

Type images:

Original description: Test broadly elliptical to round in peripheral outline, strongly lobate, singly carinate, about equally biconvex, periphery marked by short, conspicuous, spinose processes; chambers 5 or six in each convolution, roughened somewhat by small blunt beadlike elevations of shell matter especially toward the peripheral margin on each side; dorsal sutures marked by beaded shell material, moderately curved; ventral sutures depressed and radiate; umbilicus distinct, small, shallow, closed; aperture a narrow slit on the inner edge of the base of the septal face under a narrow extended rim. Average diameter about .3 mm.

Entries in the Catalog of original descriptions: Globorotalia delrioensis, Praeglobotruncana barbui, Globorotalia marginaculeata, Praeglobotruncana prahovae

Geological Range:
Last occurrence (top): within H. helvetica zone (92.56-93.52Ma, top in Turonian stage). Data source: [copied from Chronos database]
First occurrence (base): within P. appenninica zone (100.50-101.92Ma, base in Albian stage). Data source: [copied from Chronos database]

Plot of occurrence data:

Dec 2017 - Plotting of Neptune data has been re-enabled on the Mesozoic pages following revision of the age-models in Neptune. The data is, however, still very sparse for the Early Cretaceous

  • Histogram - Neptune occurrence data from DSDP and ODP proceedings. Pale shading <50 samples in time bin. Interpret with caution & read these notes
  • Note to users in China - the diagram may not plot unless you use a VPN since I use google services on the website. If this is a problem please contact me 谢谢.
  • Taxon plotted: Praeglobotruncana delrioensis, synonyms included - Praeglobotruncana barbui; Praeglobotruncana delrioensis; Praeglobotruncana marginaculeata; Praeglobotruncana prahovae;
  • space-time plot :: Samples map :: Parent: Praeglobotruncana

    Character matrix

    test outline:Subcircularchamber arrangement:Trochospiraledge view:Spiroconvexaperture:Umbilical-extraumbilical
    sp chamber shape:Inflatedcoiling axis:Very lowperiphery:Single keelaperture border:Thick lip
    umb chbr shape:Subtriangularumbilicus:Narrowperiph margin shape:Subangularaccessory apertures:None
    spiral sutures:Strongly depressedumb depth:Deepwall texture:Smoothshell porosity:Finely Perforate: 1-2.5µm
    umbilical or test sutures:Moderately depressedfinal-whorl chambers:5.0-6.0 N.B. These characters are used for advanced search. N/A - not applicable

    References:

    Leckie, M. (1984). Mid-Cretaceous planktonic foraminiferal biostratigraphy off Central Morocco, Deep Sea Drilling Project Leg 79, Sites 545 and 547. Initial Reports of the Deep Sea Drilling Project. 79: 579-620. gs

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

    Neagu, T. (1969). Cenomanian planktonic foraminifera in the southern part of the eastern Carpathians. Annales de la Societe Geologique de Pologne. 39: 132-181. gs

    Petrizzo, M. R. & Huber, B. T. (2006). Biostratigraphy and taxonomy of late Albian planktonic foraminifera from ODP Leg 171B (western North Atlantic Ocean). Journal of Foraminiferal Research. 36: 166-190. gs

    Plummer, H. J. (1931b). Some Cretaceous foraminifera in Texas. University of Texas Bulletin. 3101: 109-203. gs


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    Praeglobotruncana delrioensis compiled by the pforams@mikrotax project team viewed: 15-12-2019

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    Short stable page link: http://mikrotax.org/pforams/index.php?id=110429 Go to Archive.is to create a permanent copy of this page - citation notes



    Comments (1)

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    Jeremy Young (UCL, UK)
    This is an example of a foram with rather full data coverage
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