Acarinina sibaiyaensis

Classification: pf_cenozoic -> muricate non-spinose -> Truncorotaloididae -> Acarinina -> Acarinina sibaiyaensis
Sister taxa: << < A. esnaensis, A. esnehensis, A. interposita, A. mcgowrani, A. mckannai, A. medizzai, A. nitida, A. pentacamerata, A. praetopilensis, A. primitiva, A. pseudosubsphaerica, A. pseudotopilensis, A. punctocarinata, A. quetra, A. rohri, A. sibaiyaensis, A. soldadoensis, A. strabocella, A. subsphaerica, A. topilensis, A. wilcoxensis,


Citation: Acarinina sibaiyaensis El Naggar 1966
Rank: Species
Basionym: Globorotalia sibaiyaensis
Taxonomic discussion: This form, together with A. africana and Morozovella allisonensis, 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]

Catalog entries: Globorotalia sibaiyaensis;

Type images:

Short diagnosis: 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.

NB The short diagnoses are used in the tables of daughter-taxa to act as quick summaries of the differences between e.g. species of one genus. They have initially been copied from the diagnostic characters/distinguishing features sections of the Eocene and Paleocene Atlases, they will be edited as the site is developed.


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]

Wall type: Muricate, nonspinose, normal perforate. [Berggren et al. 2006]

Test 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]

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]

Biogeography and Palaeobiology

Geographic distribution: Widely 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 paleobiology: Inferred 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 δ13C and relatively light δ18O. Sources cited by Aze et al. 2011 (appendix S3): Kelly et al. (1998)

Phylogenetic relations: Kelly and others (1996) suggested that this taxon evolved from Acarinina soldadoensis, 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]

Biostratigraphic distribution

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): within E1 zone (55.81-55.96Ma, top in Ypresian stage). Data source: Eocene Atlas
First occurrence (base): at base of E1 zone (0% up, 56Ma, in Ypresian stage). Data source: zonal marker (Wade et al. 2011)

Plot of occurrence data:

Primary source for this page: Berggren et al. 2006 - Atlas of Eocene Planktonic Foraminifera, chapter 9, p. 318


Berggren, W.A.; Pearson, P.N.; Huber, B.T. & Wade, B.S., (2006). Taxonomy, biostratigraphy, and phylogeny of Eocene Acarinina. In: Pearson, P.N. et al. (Editors), Atlas of Eocene Planktonic Foraminifera, Cushman Foundation Special Publication 41. Allen Press, Lawrence, Kansas, pp. 257-326.

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.

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.

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.

Pardo et al 1999 [sorry, not in our bibliography yet]

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.

Acarinina sibaiyaensis compiled by the pforams@mikrotax project team viewed: 29-5-2017

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