Globorotalia (Morozovella) tadjikistanensisBykova.—Belford, 1984:10, pl. 18: figs. 18-23 [upper Paleocene, Wabag Sheet, Papua, New Guinea].
Morozovellaconvexa (Subbotina).—Stott and Kennett, 1990:560, pl. 3:figs.5, 6 [Zone AP3, near AP3/4 boundary, ODP Hole 690B/19H/4: 36-40 cm; Maud Rise, Weddell Sea, Southern Ocean]. [Olsson et al. 1999]
Taxonomic discussion: This taxon is a distinct component of late Paleocene and earliest Eocene assemblages. Recent examination and SEM reillustration of the holotype specimen of the taxon tadjikistanensis (Plate 11: Figures 4 - 6 ) and convexa (Plate 11: Figures 1-3), described originally from the upper Paleocene of Kazakhstan (Bykova, 1953) and from the zone of conical globorotaliids (= Zones P6-P8) in the Kuban River section near Nal'chik, in the northern Caucasus (Subbotina, 1953), respectively, has shown the two forms to be conspecific, with the former having priority. We essentially follow the interpretation of Blow (1979), although unlike Blow we include certain forms illustrated by Loeblich and Tappan (1957a) from the synonymy of this species. We also include the multichambered variety identified as cf. convexa in this taxon, which presages its descendant /. broedermanni Cushman and Bermudez. [Olsson et al. 1999]
Distinguishing features: Parent taxon (Igorina): Test small, biconvex, evolute, margin narrowly rounded or angular, sometimes with a keel; 5-6 chambers in final whorl Wall, coarsely cancellate, praemuricate, often pustulose. This taxon: Test small, biconvex, moderately lobulate, densely and finely praemuricate test; axial periphery subrounded to subacute, noncarinate; spiral sutures depressed, strongly recurved, tangential to inner whorl, often obscured by dense murical network; umbilicus small, shallow as a result of tight coiling mode.
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: Relatively small (<0.25 mm in diameter), nonspinose, biconvex, ovate to subcircular, moderately lobulate, densely and finely praemuricate test with 5-7 (rarely up to 9-10) chambers in last whorl; axial periphery subrounded to subacute, noncarinate; umbilical intercameral sutures curved, depressed, spiral sutures depressed, strongly recurved, tangential to inner whorl, often obscured by dense murical network; umbilicus small, shallow as a result of tight coiling mode, surrounded by an irregularly wavy umbilical shoulder formed by undulating periumbilical chamber apices; aperture a low, narrow interiomarginal, umbilical-extraumbilical slit bordered by a distinct lip and extending towards, but, not reaching, the peripheral margin. [Olsson et al. 1999] Wall type:
Soldan et al 2011 f18-03.JPG
Soldan et al 2014 f01-5d.JPG
Soldan et al 2014 f08-g.JPG
Soldan et al 2014 f08-h.JPG
Soldan et al 2014 f08-i.JPG
Character matrix
test outline:
Subcircular
chamber arrangement:
Trochospiral
edge view:
Inequally biconvex
aperture:
Umbilical-extraumbilical
sp chamber shape:
Inflated
coiling axis:
Low-moderate
periphery:
N/A
aperture border:
N/A
umb chbr shape:
Inflated
umbilicus:
Narrow
periph margin shape:
Broadly rounded
accessory apertures:
None
spiral sutures:
Weakly depressed
umb depth:
Shallow
wall texture:
Coarsely pustulose
shell porosity:
Finely Perforate: 1-2.5µm
umbilical or test sutures:
Weakly depressed
final-whorl chambers:
5-9
N.B. These characters are used for advanced search. N/A - not applicable
Biogeography and Palaeobiology
Geographic distributionIgorinatadjikistanensis was broadly distributed in tropical and subtropical latitudes. [Olsson et al. 1999]
Aze et al. 2011 summary: Low to middle latitudes; based on Olsson et al. (1999) Isotope paleobiologyIgorinatajikistanensis has δ18O slightly lighter than coexisting M. velascoensis at equivalent sizes and has distinctly more negative δ18O than Subbotina 13 (Shackleton et al., 1985; Berggren and Norris, 1997). The δ13C of I. tajikistanensis displays a strong increase in δ13C with increased size, which is similar to Acarinina and Morozovella (Berggren and Norris, 1997). [Olsson et al. 1999] 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): Berggren & Norris (1997) Phylogenetic relationsThis species probably evolved from /. pusilla in middle to upper Zone P3 by developing a more involute coiling mode, increasing the number of chambers in the final whorl, and developing a dense, finely praemuricate ornament. Igorinatadjikistanensis differs from /. albeariin being generally smaller, lower spired, and without a peripheral keel. [Olsson et al. 1999]
Most likely ancestor:Igorina pusilla - at confidence level 4 (out of 5). Data source: Olsson et al. (1999), f5a.
Biostratigraphic distribution
Geological Range: Notes: Zone P3b to Zone P7. [Olsson et al. 1999] Last occurrence (top): at top of P5 zone (100% up, 56Ma, in Thanetian stage). Data source: Berggren et al. (2006), f12.1 First occurrence (base): at base of P3b subzone (0% up, 61.3Ma, in Selandian stage). Data source: Olsson et al. (1999), f5a
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
Primary source for this page: Olsson et al. 1999 - Atlas of Paleocene Planktonic Foraminifera, p. 71
References:
Belford, D. J. (1984). Tertiary foraminifera and age of sediments, Ok Tedi-Wabag, Papua New Guinea. Australia Bureau of Mineral Resources Geology and Geophysics, Bulletin. 216: 1-52. gs
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
Bykova, N. K. (1953). Фораминиферы сузакского яруса Таджикской депрессии [Foraminifera of the Suzakian Stage of the Tajik depression]. In, unknown (ed.) Microfauna of the USSR, 6. Trudy Vsesoyuznego Neftyanogo Nauchno-Issledovatel'skogo Geologo-Razvedochnogo Instituta (VNIGRI) . 69: 3-114. gs
Jenkins, D. G. (1971). New Zealand Cenozoic Planktonic Foraminifera. New Zealand Geological Survey, Paleontological Bulletin. 42: 1-278. gs
Leonov, G. P. & Alimarina, V. (1960). Stratigrafiya i planktonnye foraminifery "perekhodnykh" ot mela k paleogeny sloev tsentral'nogo Predkavkazya [Stratigraphy and Plantonic Foraminifera of the Cretaceous-Paleogene "Transition" Beds of the Central Part of the North Caucasus]. In Problema V: Granitsa melovoi i paleogenovoi sistem. Mezhdunarodnyi Geologicheskii Kongress, XXI Sessiya, Doklady Sovetskikh Geologov, Izdatelstvo Akademiya Nauk. 29-60. 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
Luterbacher, H. P. (1964). Studies in some Globorotalia from the Paleocene and Lower Eocene of the Central Apennines. Eclogae Geologicae Helvetiae. 57: 631-730. gsO
McGowran, B. J. (1968). Reclassification of Early Tertiary Globorotalia. Micropaleontology. 14: 179-198. 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
Soldan, D. M., Petrizzo, M. R., Silva, I. P. & Cau, A. (2011). Phylogenetic relationships and evolutionary history of the Paleogene genus through parsimony analysis. Journal of Foraminiferal Research. 41: 260-284. gs
Soldan, D. M., Petrizzo, M. R. & Silva, I. P. (2014). Pearsonites, a new Paleogene planktonic foraminiferal genus for the broedermanni lineage. Journal of Foraminiferal Research. 44: 17-27. gs
Stott, L. D. & Kennett, J. P. (1990). The Paleoceanographic and Paleoclimatic signature of the Cretaceous/Paleogene boundary in the Antarctic: Stable isotopic results from ODP Leg 113. Proceedings of the Ocean Drilling Program, Scientific Results. 113: 829-848. gs
Subbotina, N. N. (1953). Foraminiferes fossiles d'URSS Globigerinidae, Globorotaliidae, Hantkeninidae. Bureau de Recherches Geologiques et Minieres. 2239: 1-144. gs
Igorina tadjikistanensis compiled by the pforams@mikrotax project teamviewed: 30-4-2025