Guembelitriaalabamensis Liu and Olsson, 1992:341, pl. 2: figs. 1-7 [Zone Pla, Pine Barren Mbr., Clayton Fm., Millers Ferry, Alabama]. [Olsson et al. 1999]
Taxonomic discussion: Parvularugoglobigerinaalabamensis differs from Guembelitriacretacea by possessing 3½-4 (rather than 3) chambers in the outer whorl. It resembles G. cretacea in its apertural characteristics and presence of pore-mounds. Parvularugoglobigerinaalabamensis sensu stricto differs from Parvularugoglobigerinaextensa in having a less elongate aperture that does not extend extraumbilically. [Olsson et al. 1999]
Distinguishing features: Parent taxon (Parvularugoglobigerina): Small, moderate to low trochospire of 2½ whorls of (sub)globular chambers. Chambers gradually increase in size; 3½-7 chambers per whorl, separated by radial and depressed sutures on both spiral and umbilical sides. Umbilicus closed. Aperture umbilical to extraumbilical, comma-shaped arch to long narrow opening in nearly equatorial position; bordered by a slight lip. Microperforate. This taxon: Test of 2½ whorls, each composed of 3 to 4 inflated subglobular chambers, increasing slowly in size. The aperture is low, centrally located, umbilical, and marked by a distinct lip.
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: Typically characterized by 2½ whorls, each composed of 3 to 4 inflated subglobular chambers, increasing slowly in size. The aperture is low, centrally located, umbilical, and marked by a distinct lip. Like Guembelitria cretacea, Parvularugoglobigerina eugubina, and Woodringina claytonensis, this form is sometimes characterized by the presence of pore-mounds. [Olsson et al. 1999]
Character matrix
test outline:
Lobate
chamber arrangement:
Trochospiral
edge view:
Inequally biconvex
aperture:
Umbilical
sp chamber shape:
Inflated
coiling axis:
High
periphery:
N/A
aperture border:
Thick lip
umb chbr shape:
Inflated
umbilicus:
Narrow
periph margin shape:
Broadly rounded
accessory apertures:
None
spiral sutures:
Strongly depressed
umb depth:
Shallow
wall texture:
Pore mounds
shell porosity:
Microperforate: <1µm
umbilical or test sutures:
Strongly depressed
final-whorl chambers:
3-4
N.B. These characters are used for advanced search. N/A - not applicable
Biogeography and Palaeobiology
Geographic distributionSimilar to Parvularugoglobigerinaeugubina. [Olsson et al. 1999] Isotope paleobiologyNo data available. [Olsson et al. 1999] Phylogenetic relationsThis species evolved from Guembelitriacretacea. Parvularugoglobigerinaalabamensis appears as a morphologically intermediate form between G. cretacea and Parvularugoglobigerinaextensa Blow. For example, the apertural characteristics of P. alabamensis more closely resemblethoseofG.cretaceathandothoseoftypicalP. extensa (compare Plates 63 and 65); however, the exact phylogenetic relationship of Parvularugoglobigerinaalabamensis to Parvularugoglobigerinaextensa is unclear, in part because the first known occurrence of P. extensa is stratigraphically lower than the first known occurrence of P. alabamensis. It appears likely that either P. alabamensis evolved from G. cretacea independently of P. extensa (Liu and Olsson, 1992) or P. alabamensis was ancestral to P. extensa, but the known stratigraphic record of P. alabamensis is incomplete. The first hypothesis is stratigraphically simpler, but evolutionarily more complex, than the second because the former necessarily entails iterative evolution of four-chambered parvularugoglobigerine morphotypes from G. cretacea. [Olsson et al. 1999]
Biostratigraphic distribution
Geological Range: Notes: Zone Pa to Zone P3b. [Olsson et al. 1999] Last occurrence (top): within P3b subzone (60.73-61.33Ma, top in Selandian stage). Data source: Olsson et al. 1999 First occurrence (base): within P0 zone (66.00-66.04Ma, base in Danian 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: Parvularugoglobigerina alabamensis, synonyms included - Parvularugoglobigerina alabamensis;
Primary source for this page: Olsson et al. 1999 - Atlas of Paleocene Planktonic Foraminifera, p. 83
References:
Liu, C. & Olsson, R. K. (1992). Liu, C. & Olsson, R. K. (1992). Evolutionary radiation of microperforate planktonic foraminifera following the K/T mass extinction event. Journal of Foraminiferal Research. 22: 328-346. Journal of Foraminiferal Research. 22: 328-346. gs
Olsson, R. K., Hemleben, C., Berggren, W. A. & Huber, B. T. (1999). Olsson, R. K., Hemleben, C., Berggren, W. A. & Huber, B. T. (1999). Atlas of Paleocene Planktonic Foraminifera. Smithsonian Institution Press, Washington, DC. 1-252. Smithsonian Institution Press, Washington, DC. (85): 1-252. gs
Parvularugoglobigerina alabamensis compiled by the pforams@mikrotax project teamviewed: 17-6-2025
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holotype: G. alabamensis
