Morozovella occlusa


Classification: pf_cenozoic -> Truncorotaloididae -> Morozovella -> Morozovella occlusa
Sister taxa: M. caucasica, M. crater, M. aragonensis, M. lensiformis, M. marginodentata, M. formosa, M. gracilis, M. subbotinae, M. aequa, M. apanthesma, M. edgari, M. allisonensis, M. acuta, M. occlusa, M. acutispira, M. pasionensis, M. velascoensis, M. conicotruncata, M. angulata, M. praeangulata, M. sp.,

Taxonomy

Citation: Morozovella occlusa (Loeblich and Tappan 1957)
Rank: Species
Basionym: Globorotalia occlusa
Synonyms:
Taxonomic discussion: The enhanced, expanded concept of M. occlusa applied by Hillebrandt (1962) to include biconvex forms with 5-8 chambers is followed herein (see also Gohrbandt, 1963; Luterbacher, 1964; Samanta, 1970). Blow (1979) interpreted this form as a morphologically and phylogenetically advanced (descendant) form of M. crosswicksensis Olsson, which was said to generally lack the circumumbilical muricate coronet present in M. occlusa. The former was described from Zone P3b (Hornerstown Fm., New Jersey); the latter was described from the Velasco Fm. (Zone P4) and is characteristic of Zones P4 and P5. We include crosswicksensis in the concept of the taxon occlusa; it bears a similar relationship to that observed in the Acarinina coalingensis! triplex (earlier rounded periphery)-/?ri »izriva (later angular periphery) morphotypic series. [Olsson et al. 1999]

Catalog entries: Globorotalia crosswicksensis;
Globorotalia occlusa;

Type images:

Distinguishing features: Like M. acutispira but without raised early part of 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: Plano-convex to low biconvex, nearly circular test, 4-6 (rarely up to 8) chambers in last whorl, coalescing in a circular, subacute, weakly to moderately muricate umbilical shoulder and forming a narrow, deep umbilicus; umbilical sutures depressed, radial; elevated and beaded, tangentially curved on spiral side; sutures between final and penultimate whorl coarsely muricate; periphery distinctly muricocarinate; aperture an interiomarginal, umbilical-extraumbilical arch. [Olsson et al. 1999]

Character matrix

test outline:Lobatechamber arrangement:Trochospiraledge view:Equally biconvexaperture:-
umb chamber shape:Subtriangularcoiling axis:Moderateperiphery:Muricocarinateaperture border:Thin lip
sp chbr shape:Crescenticumbilicus:Narrowperiph margin shape:Subangularaccessory apertures:None
umbilical or test sutures:Moderately depressedumb depth:Deepwall texture:Smoothshell porosity:Finely Perforate: 1-2.5µm
spiral sutures:Raised beadedfinal-whorl chambers:4.0-5.0

Biogeography and Palaeobiology


Geographic distribution: This species is widespread in the low to middle latitudes. [Olsson et al. 1999]
Aze et al. 2011 summary: Low to middle latitudes; based on Olsson et al. (1999)

Isotope paleobiology: Morozovella occlusa has ∂13C and ∂18O similar to coexisting M. velascoensis and Acarinina mckannai and more positive ∂13C and more negative ∂18O than Subbotina spp. (Shackleton et al., 1985; Lu and Keller, 1996). [Olsson et al. 1999]
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): Shackleton et al. (1985); Lu & Keller (1996)

Phylogenetic relations: This species probably evolved from M. pasionenesis by a decrease in umbilical size, development of a biconvex test, and reduction of the muricate, sharp adumbilical ridges to lightly muricate, gently rounded surfaces around the umbilicus. Morozovella occlusa is a sister species to M. acutispira, with which it shares the biconvex test shape and relatively constricted umbilicus. [Olsson et al. 1999]

Most likely ancestor: Morozovella pasionensis - at confidence level 4 (out of 5). Data source: Olsson et al. (1999) f5a.

Biostratigraphic distribution

Geological Range:
Notes: Top of Zone P3b (typical crosswicksensis); Zone P4-P5 (typical occlusa). [Olsson et al. 1999]
Last occurrence (top): at top of E2 zone (100% up, 55.2Ma, in Ypresian stage). Data source: Olsson et al. (1999) f5a
First occurrence (base): near top of P3b subzone (90% up, 60.8Ma, in Selandian stage). Data source: Olsson et al. (1999) f5a

Plot of occurrence data:

Primary source for this page: Olsson et al. 1999 - Atlas of Paleocene Planktonic Foraminifera, p. 62

References:

Blow, W.H., (1979). The Cainozoic Globigerinida: A study of the morphology, taxonomy, evolutionary relationships and stratigraphical distribution of some Globigerinida (mainly Globigerinacea), 2. E. J. Brill, Leiden, 1413 pp.

Gohrbandt, K., (1963). Zur Gliederung des Palaeogen im Helvetikum nordlich Salzburg nach planktonischen Foraminiferen. Mitt Geol Ges, Wien, 56(1): 63.

Hillebrandt von, A., (1962). Das Paleozän und seine Foraminiferenfauna im Becken von Reichenhall und Salzburg. Bayerische Akademie der Wissenschaften Mathematisch-Naturwissenschaftliche Klasse, Abhandlungen, Neue Folge, 108: 1-182.

Loeblich, A.R. & Tappan, H., (1957). Planktonic foraminifera of Paleocene and early Eocene Age from the Gulf and Atlantic coastal plains. In: Loeblich, A.R., Jr. et al. (Editors), Studies in Foraminifera, U.S. National Museum Bulletin 215. U.S. Government Printing Office, Washington, D.C., pp. 173-198.

Luterbacher, H.P., (1964). Studies in some Globorotalia from the Paleocene and Lower Eocene of the Central Apennines. Eclogae Geologicae Helvetiae, 57: 631-730.

Olsson, R.K.; Hemleben, C.; Berggren, W.A. & Huber, B.T., (1999). Atlas of Paleocene Planktonic Foraminifera. Smithsonian Contributions to Paleobiology, 85. Smithsonian Institution Press, Washington, DC, 1-252 pp.

Samanta, B.K., (1970). Middle Eocene Planktonic Foraminifera from Lakhpat, Cutch, Western India. Micropaleontology, 16(2): 185-215.


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Morozovella occlusa compiled by the pforams@mikrotax project team viewed: 16-11-2018

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