Tubitextularialaevigata Loeblich and Tappan, 1957a: 180, pl. 41: fig. 6 [lower Paleocene, McBryde Limestone Mbr., Clayton Fm., Wilcox Co., Alabama]. [Olsson et al. 1999]
Taxonomic discussion: The Paleocene holotype of T. laevigata Loeblich and Tappan is very similar to the R. cretacea holotype (Plate 13: Figures 1,2) except for the presence of more globular chambers in the uniserial growth stage. Paleocene specimens of Rectoguembelina from DSDP Site 357, however, bear uniserial chambers that range in shape from the globular forms of the T. laevigata holotype to forms identical to the R. cretacea holotype (Plate 71: Figures 24-26). It is on this basis that T. laevigata is considered a junior synonym of R. cretacea. [Olsson et al. 1999]
Distinguishing features: Parent taxon (Rectoguembelina): Transition from biserial to uniserial portion of test very abrupt, occurring after first four or more pairs of biserial chambers, without an intervening interval of gradually increasing chamber overlap. Apertures on biserial portion interiomarginal with a small, narrow arch; apertures on uniserial chambers terminal, circular, and aligned in rectilinear fashion, without lip or toothplate. Wall calcareous, microperforate; surface smooth to finely pustulose. This taxon: Distinguished by its small, elongate biserial to uniserial test, usually with two to four uniserial chambers arranged in a rectilinear fashion and bearing a simple, terminal, round to oval-shaped aperture on a short neck.
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: Distinguished by its small, elongate biserial to uniserial test, usually with two to four uniserial chambers arranged in a rectilinear fashion and bearing a simple, terminal, round to oval-shaped aperture on a short neck. [Olsson et al. 1999]
Character matrix
test outline:
Elongate
chamber arrangement:
Biserial
edge view:
Equally biconvex
aperture:
Terminal
sp chamber shape:
Globular
coiling axis:
N/A
periphery:
N/A
aperture border:
Thin lip
umb chbr shape:
Globular
umbilicus:
N/A
periph margin shape:
Moderately rounded
accessory apertures:
None
spiral sutures:
Strongly depressed
umb depth:
N/A
wall texture:
Smooth
shell porosity:
Microperforate: <1µm
umbilical or test sutures:
Strongly depressed
final-whorl chambers:
1-1
N.B. These characters are used for advanced search. N/A - not applicable
Biogeography and Palaeobiology
Geographic distributionThis species has a very irregular distribution, occurring only in near-shore sediments during the Maastrichtian and in offshore sediments at several deep sea sites during the Paleocene, ranging from the low to middle latitudes. [Olsson et al. 1999] Isotope paleobiologyStable isotopic evidence that R. cretacea inhabited upper surface waters is presented in Huber and Boersma (1994, table 1; = T. laevigata). The oxygen isotopic data reveal that R. cretacea was more than 1.5%o more negative than the co-occurring benthic species Nuttalites truempyi, and it was more than 0.5 %o more negative than three other planktonic species (Globoconusadaubjergensis, Globanomalinacompressa, and Globanomalina sp.). [Olsson et al. 1999] Phylogenetic relationsThe origin ofR. cretacea is uncertain, but test dissections have revealed that apertures in the biserial growth stage are asymmetrically positioned and partially surrounded by a narrow lip of equidimensional thickness, which is identical to the apertures on biserial chambers of Zeauvigerinawaiparaensis. This suggests that Rectoguembelina and Zeauvigerina shared a common phylogenetic stock, and Laeviheterohelix is suggested as the most closely related ancestral taxon based on similarities discussed in Huber and Boersma (1994). [Olsson et al. 1999]
Biostratigraphic distribution
Geological Range: Notes: Maastrichtian through Zone P2. [Olsson et al. 1999] Last occurrence (top): within P2 zone (62.29-62.60Ma, top in Danian stage). Data source: Olsson et al. 1999 First occurrence (base): within A. mayaroensis zone (67.64-69.27Ma, base in Maastrichtian stage). Data source: Olsson et al. 1999
Plot of occurrence data:
Range-bar - range as quoted above, pink interval top occurs in, green interval base occurs in.
Triangles indicate an event for which a precise placement has been suggested
Histogram - Neptune occurrence data from DSDP and ODP proceedings. Pale shading <50 samples in time bin. Interpret with caution & read these notes
Taxon plotted: Rectoguembelina cretacea, synonyms included - Rectoguembelina cretacea;
Primary source for this page: Olsson et al. 1999 - Atlas of Paleocene Planktonic Foraminifera, p. 94
References:
Cushman, J. A. (1932). Rectoguembelina, a new genus from the Cretaceous. Contributions from the Cushman Laboratory for Foraminiferal Research. 8(1): 4-7. gs
Loeblich, A. R. & Tappan, H. (1957b). Planktonic foraminifera of Paleocene and early Eocene Age from the Gulf and Atlantic coastal plains. In, Loeblich, A. R. , Jr., Tappan, H., Beckmann, J. P., Bolli, H. M., Montanaro Gallitelli, E. & Troelsen, J. C. (eds) Studies in Foraminifera. U.S. National Museum Bulletin . 215: 173-198. gs
Olsson, R. K., Hemleben, C., Berggren, W. A. & Huber, B. T. (1999). Atlas of Paleocene Planktonic Foraminifera. Smithsonian Institution Press, Washington, DC. (85): 1-252. gs
Rectoguembelina cretacea compiled by the pforams@mikrotax project teamviewed: 22-4-2026
Olsson_etal_99_pl71_f024-26.jpg
Olsson_etal_99_pl71_f024-26.jpg
holotype: R. cretacea
holotype: R. cretacea
holotype: R. cretacea
topotype: R. cretacea
topotype: R. cretacea
