Citation: Acarinina sibaiyaensis El Naggar 1966Taxonomic rank: speciesBasionym: Globorotalia sibaiyaensisSynonyms:
Globorotaliasibaiyaensis El Naggar, 1966:235, pl. 23: fig. 6a-c [G. aequa/G. esnaensis Subzone, G. velascoensis Zone, Gebel Owaina section, Egypt].
Acarininasibaiyaensis (El Naggar).—Kelly and others, 1996:424, fig. 2-1a-b [upper Zone P5, from within carbon isotope excursion of the Paleocene-Eocene Thermal Maximum, ODP Hole 865C, Allison Guyot, equatorial Pacific Ocean].—Kelly and others, 1998:159, figs. 5c, 9d-e [upper Zone P5, from within carbon isotope excursion of Paleocene-Eocene Thermal Maximum, ODP Hole 865C, Allison Guyot, equatorial Pacific Ocean].— Pardo and others, 1999:44, pl. 2: figs. 19-20.[Zone P5b, Kaurtakapy, Kazakhstan].
Acarinina aff. sibaiyaensis (El Naggar).—Pardo and others, 1999:44, pl. 2: figs. 17-18 [Zone P5b, Kaurtakapy, Kazakhstan].
Taxonomic discussion: This form, together with A. africana and Morozovellaallisonensis, constitute an assemblage of small, morphologically distinct taxa that are characteristic of the temporally short (~200 kyrs) Paleocene Eocene Thermal Maximum. [Berggren et al. 2006]
Distinguishing features: Parent taxon (Acarinina): Moderate to low trochospire; chambers ovoid, usually 4-6 in final whorl. Wall muricate with pustules on umbilical shoulders; This taxon: Numerous (5-9) chambers in final whorl, and almost planispiral test
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: Diagnostic characteristics are the relatively large (5-9) number of chambers in final whorl, and the test coiled in a very low trochospiral (approaching planispiral) mode. [Berggren et al. 2006] Morphology: Planoconvex; generally umbilico-convex, although some specimens approach being planispiral; peripheral margin round to subround; chambers inflated, subtriangular to round on both umbilical and spiral sides; approximately 12-14 chambers arranged in 3 whorls; gradual increase in chamber size throughout; sutures depressed and radial; primary aperture circular, arch-like opening with lip to well-developed flange, umbilical-extraumbilical position extending to peripheral margin.[Berggren et al. 2006] Wall type: Muricate, nonspinose, normal perforate. [Berggren et al. 2006] Size: Maximum diameter of holotype 0.29 mm, minimum diameter 0.19 mm, thickness 0.17 mm; our observations suggest that this form is typically <0.35 mm in maximum diameter. [Berggren et al. 2006]
Character matrix
test outline:
Lobate
chamber arrangement:
Pseudoplanispiral
edge view:
Equally biconvex
aperture:
Umbilical-extraumbilical
sp chamber shape:
Inflated
coiling axis:
Very low
periphery:
N/A
aperture border:
Thin lip
umb chbr shape:
Inflated
umbilicus:
Wide
periph margin shape:
Broadly rounded
accessory apertures:
None
spiral sutures:
Strongly depressed
umb depth:
Shallow
wall texture:
Moderately muricate
shell porosity:
Finely Perforate: 1-2.5µm
umbilical or test sutures:
Strongly depressed
final-whorl chambers:
5-9
N.B. These characters are used for advanced search. N/A - not applicable
Biogeography and Palaeobiology
Geographic distributionWidely distributed throughout the (sub)tropics and temperate regions; common in the central equatorial Pacific (ODP Site 865), found in New Jersey Coastal Plain (Bass River), North Atlantic Ocean (ODP Site 1051), and also present in Tethyan sections of Europe (Alamedilla, Spain) and North Africa (Egypt). [Berggren et al. 2006]
Aze et al. 2011 summary: Low latitudes; based on Berggren et al. (2006b) Isotope paleobiologyInferred depth-habitat primarily shallow mixed-layer; carbon isotope signature exhibits strong covariance with shell size; overall stable isotopic signature is analogous to that of modern, symbiotic species (Kelly and others, 1998). [Berggren et al. 2006] Aze et al. 2011 ecogroup 1 - Open ocean mixed-layer tropical/subtropical, with symbionts. Based on very heavy _13C and relatively light _18O. Sources cited by Aze et al. 2011 (appendix S3): Kelly et al. (1998) Phylogenetic relationsKelly and others (1996) suggested that this taxon evolved from Acarininasoldadoensis, but it shows much greater similarity with A. esnehensis which we suggest was the ancestor. Further flattening of the test produced the africana morphology (Kelly and others, 1998). [Berggren et al. 2006]
Geological Range: Notes: Zone E1, restricted to carbon isotope excursion of the PETM. [Berggren et al. 2006]
The FAD of Acarinina sibaiyaensis marks the base of zone E1 / top of P5 (Wade et al. 2011) 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 Thanetian stage). Data source: zonal marker (Wade et al. 2011)
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: Acarinina sibaiyaensis, synonyms included - Acarinina sibaiyaensis;
Primary source for this page: Berggren et al. 2006 - Eocene Atlas, chap. 9, p. 318
References:
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. gsO
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). supplement 2: 1-291. gs
Kelly, D. C., Bralower, T. J., Zachos, J. C. & Premoli Silva, I. T. , E. (1996). Rapid diversification of planktonic foramiifer in the tropical Pacific (ODP Site 865) during the late Paleocene thermal maximum. Geology. 24: 423-426. 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. gs
Wade, B. S., Pearson, P. N., Berggren, W. A. & Pälike, H. (2011). Review and revision of Cenozoic tropical planktonic foraminiferal biostratigraphy and calibration to the geomagnetic polarity and astronomical time scale. Earth-Science Reviews. 104: 111-142. gs
Acarinina sibaiyaensis compiled by the pforams@mikrotax project teamviewed: 14-6-2026
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Eocene_Atlas_pl09-21_fig6-7-9-11A.jpg
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Eocene_Atlas_pl09-21_fig8.jpg
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holotype: G. sibaiyaensis
holotype: G. sibaiyaensis
paratype: G. sibaiyaensis
