Catalog entries: Globorotalia africana
Type images:Distinguishing features: Like A. sibaiyaensis but with axially-compressed test, strongly lobulate peripheral margin, and chambers change ontogenetically from globular to more lenticular shapes.
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.
Wall type: Muricate, normal perforate, nonspinose. [Berggren et al. 2006]
Morphology: Peripheral outline oval, elongate, strongly lobulate; weakly planoconvex to biconvex; test axially compressed; peripheral margin acutely pinched, occasionally with weak muricate keel; chambers triangular on both umbilical and spiral sides; low trochospiral; approximately 10-12 chambers arranged in approximately 3 whorls; chambers vary ontogenetically, with early chambers globular to subconical and later chambers more lenticular, strongly compressed; moderate rate of chamber expansion; sutures gently curved, radial, slightly raised to depressed; primary aperture a low umbilical-extraumbilical arch extending to peripheral margin, sometimes with faint lip; typically 4-6 chambers in final whorl; umbilicus narrow. [Berggren et al. 2006]
Size: Diminutive, typically <0.20 mm; holotype dimensions: maximum diameter: 0.30 mm; minimum diameter: 0.20 mm; thickness: 0.14 mm (last chamber) (El Naggar, 1966, p. 194). [Berggren et al. 2006]
Character matrix
test outline: | Lobate | chamber arrangement: | Trochospiral | edge view: | Equally biconvex | aperture: | Umbilical-extraumbilical |
sp chamber shape: | Subtriangular | coiling axis: | Very low | periphery: | N/A | aperture border: | Thin lip |
umb chbr shape: | Subtriangular | umbilicus: | Narrow | periph margin shape: | Subangular | accessory apertures: | None |
spiral sutures: | Strongly depressed | umb depth: | Deep | wall texture: | Moderately muricate | shell porosity: | Finely Perforate: 1-2.5µm |
umbilical or test sutures: | Strongly depressed | final-whorl chambers: | 4.0-6.0 | N.B. These characters are used for advanced search. N/A - not applicable |
Geographic distribution: Ranges from tropical to temperate regions; central equatorial Pacific (ODP Site 865), New Jersey Coastal Plain (Bass River),
Tethyan deposits of northern Africa (Egypt) and probable occurrences in Spain (Alamedilla). [Berggren et al. 2006]
Aze et al. 2011 summary: Low to middle latitudes; based on Berggren et al. (2006b)
Isotope paleobiology:
Aze et al. 2011 ecogroup 1 - Open ocean mixed-layer tropical/subtropical, with symbionts. Based on very heavy δ13C and relatively light δ18O. Sources cited by Aze et al. 2011 (appendix S3): this study
Phylogenetic relations: This species is closely related to A. sibaiyaensis and was probably derived from A. esnehensis via A. sibaiyaensis during the period of intense environmental stress associated with the PETM event. [Berggren et al. 2006]
Most likely ancestor: Acarinina sibaiyaensis - at confidence level 4 (out of 5). Data source: Berggren et al. (2006) fig9.2.
Geological Range:
Notes: Restricted to Zone E1, most commonly found within carbon isotope excursion interval of the PETM, although rare specimens (?reworked) have been observed at stratigraphically higher horizons (Kelly and others, 1998). [Berggren et al. 2006]
Last occurrence (top): at top of E1 zone (100% up, 55.8Ma, in Ypresian stage). Data source: Eocene Atlas
First occurrence (base): at base of E1 zone (0% up, 56Ma, in Ypresian stage). Data source: Eocene Atlas
Plot of occurrence data:
Primary source for this page: Berggren et al. 2006 - Eocene Atlas, chap. 9, p. 261
Berggren, W. A., Pearson, P. N., Huber, B. T. & Wade, B. S. (2006b). Taxonomy, biostratigraphy, and phylogeny of Eocene Acarinina. In, Pearson, P. N., Olsson, R. K., Hemleben, C., Huber, B. T. & Berggren, W. A. (eds) Atlas of Eocene Planktonic Foraminifera. Cushman Foundation for Foraminiferal Research, Special Publication. 41(Chap 9): 257-326. gs V O Blow, W. H. (1979). The Cainozoic Globigerinida: A study of the morphology, taxonomy, evolutionary relationships and stratigraphical distribution of some Globigerinida (mainly Globigerinacea). E. J. Brill, Leiden. 2: 1-1413. gs El-Naggar, Z. R. (1966). Stratigraphy and planktonic foraminifera of the Upper Cretaceous-Lower Tertiary succession in the Esna-Idfu region, Nile Valley, Egypt, U. A. R. Bulletin of the British Museum (Natural History) Geology. supplement 2: 1-291. gs Kelly, D. C., Bralower, T. J. & Zachos, J. C. (1998). Evolutionary consequences of the latest Paleocene thermal maximum for tropical planktonic foraminifera. Palaeogeography Palaeoclimatology Palaeoecology. 141: 139-161. gs Pardo, A., Adatte, T., Keller, G. & Oberhänsli, H. (1999). Paleoenvironmental changes across the Cretaceous-Tertiary boundary at Koshak, Kazakhstan, based on planktic foraminifera and clay mineralogy. Palaeogeography Palaeoclimatology Palaeoecology. 154: 247-273. gsReferences:
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Acarinina africana compiled by the pforams@mikrotax project team viewed: 22-4-2021
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