pforams@mikrotax - Morozovella pasionensis pforams@mikrotax - Morozovella pasionensis

Morozovella pasionensis

Classification: pf_cenozoic -> Truncorotaloididae -> Morozovella -> Morozovella pasionensis
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.


Citation: Morozovella pasionensis (Bermudez 1961)
taxonomic rank: Species
Basionym: Pseudogloborotalia pasionensis
Taxonomic discussion: This highly variable taxon differs from the closely related M. velascoensis in having a more loosely coiled, less vaulted angulo-conical test and a widely varying number of chambers. The chambers may be either essentially equidimensional, or there may be smaller, kummeform-like chambers inserted in the normal chamber progression of the last whorl. Morozovella pasionensis also has a relatively wider and shallower umbilicus and a more weakly ornamented periumbilcial collar.
Basic analyses of this taxon were made by Luterbacher (1964) and Blow (1979). The latter observed that the "holotype" individual of Pseudogloborotalia pasionensis Bermudez at the National Museum of Natural History is coiled in a direction (sinistral) opposite to that of the photograph (dextral) of the "holotype" (Bermudez, 1961, pl. 16: fig. 8a,b); however, it is the specimen (identified as Pseudogloborotalia velascoensis (Cushman)) illustrated on pl. 16: fig. lla,b (and not that illustrated as fig. 8a,b), which is the holotype of pasionensis and which was examined by Blow and ourselves in the Cushman Collection (USNM 639063). The holotype of P. pasionensis shows characters similar to P. velascoensis, which indicate its close relationship with that taxon, but it has a low conical test as opposed to the high conical test typical of P. velascoensis. Luterbacher (1964) provided a revised and amplified description of this species based on topotypes supplied by Bermudez. The analyses of Blow and Luterbacher are essentially compatible, with the exception that Luterbacher (1964) recorded 5-7 chambers as typical of this form, whereas Blow (1979) noted 9-10 (and occasionally up to 12) chambers
in the final whorl. [Olsson et al. 1999]

Catalog entries: Pseudogloborotalia pasionensis

Type images:

Distinguishing features:
Parent taxon (Morozovella): Test typically plano-convex, chambers strongly anguloconical.
Wall strongly pustulose (muricate) on parts of spire and umbilicus. Most species with muricocarina.

This taxon: Like M. velascoensis but with reduced spire height, a decrease in the ornament around the umbilicus, and an increase in the number of chambers (usually 5-7, up to 10).

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.


Character matrix
test outline:Lobatechamber arrangement:Trochospiraledge view:Planoconvexaperture:Umbilical-extraumbilical
sp chamber shape:Petaloidcoiling axis:Moderateperiphery:Muricocarinateaperture border:N/A
umb chbr shape:Subtriangularumbilicus:Wideperiph margin shape:Subangularaccessory apertures:None
spiral sutures:Raised muricateumb depth:Deepwall texture:Moderately muricateshell porosity:Finely Perforate: 1-2.5µm
umbilical or test sutures:Moderately depressedfinal-whorl chambers:6.5-7.5 N.B. These characters are used for advanced search. N/A - not applicable

Biogeography and Palaeobiology

Geographic distribution

Our observations agree with those of Blow (1979) that M. pasionensis had an essentially tropical (but not necessarily solely equatorial Pacific Ocean) distribution. [Olsson et al. 1999]
Aze et al. 2011 summary: Low latitudes; based on Olsson et al. (1999)

Isotope paleobiology
Morozovella pasionensis has δ13C and δ18O similar to coexisting M. velascoensis and Acarinina mckannai and more positive δ13C and more negative δ18O 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 _13C and relatively light _18O. Sources cited by Aze et al. 2011 (appendix S3): Shackleton et al. (1985); Lu & Keller (1996)

Phylogenetic relations
This species probably evolved from M. velascoensis through a reduction in spire height, a decrease in the ornament around the umbilicus, and an increase in the number of chambers. [Olsson et al. 1999]

Most likely ancestor: Morozovella velascoensis - at confidence level 4 (out of 5). Data source: Olsson et al. (1999) f5a.
Likely descendants: Morozovella acutispira; Morozovella occlusa; plot with descendants

Biostratigraphic distribution

Geological Range:
Notes: Zone P3b to Zone P5. Luterbacher (1964) considered "pasionensis" restricted to the Globorotalia aequa Zone (= Zone P6a this paper), whereas Blow (1979) considered it restricted to (his) Zone P5 (i.e., prior to the appearance of M. subbotinae) with questionable or sporadic occurrences in (his) Zones P4 and P6. In our studies, we have found that M. pasionensis appears slightly higher or later than the initial appearance ofM. velascoensis in Zone P3b, and that it ranges throughout Zones P4 and P5. We have not observed it ranging into post-M velascoensis (Zone P5) levels. It was ancestral to M. acutispira and M. occlusa, which appear in the terminal part of Zone P3b. [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): in upper part of P3b subzone (70% up, 60.9Ma, 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. 63


Bermudez, P. J. (1961). Contribucion al estudio de las Globigerinidea de la region Caribe-Antillana (Paleoceno-Reciente). Editorial Sucre, Caracas. 1119-1393. 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

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

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


Morozovella pasionensis compiled by the pforams@mikrotax project team viewed: 21-6-2024

Taxon Search:
Advanced Search

Short stable page link: Go to to create a permanent copy of this page - citation notes

Add Comment

* Required information
Captcha Image
Powered by Commentics


No comments yet. Be the first!