Morozovella pasionensis


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

Taxonomy

Citation: Morozovella pasionensis (Bermudez 1961)
Rank: Species
Basionym: Pseudogloborotalia pasionensis
Synonyms:
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: Relatively large, low umbilico-convex test with flat spiral side, distinctly lobulate, heavily keeled periphery; generally 5-7 (but up to 10, particularly in younger, Zone P4c-P5 horizons), relatively equidimensional chambers in final whorl but with insertion of smaller chambers between larger chambers in some individuals; intercameral sutures depressed, radial on umbilical side; curved, moderately retorse, raised and beaded on spiral side; umbilicus wide but shallow, periumbilical collar only weakly developed; aperture a low slit extending along peri-intraumbilical margin to peripheral margin of last chamber.

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 large, low umbilico-convex test with flat spiral side, distinctly lobulate, heavily keeled periphery; generally 5-7 (but up to 10, particularly in younger, Zone P4c-P5 horizons), relatively equidimensional chambers in final whorl but with insertion of smaller chambers between larger chambers in some individuals; intercameral sutures depressed, radial on umbilical side; curved, moderately retorse, raised and beaded on spiral side; umbilicus wide but shallow, periumbilical collar only weakly developed; aperture a low slit extending along peri-intraumbilical margin to peripheral margin of last chamber. [Olsson et al. 1999]

Character matrix

test outline:Lobatechamber arrangement:Trochospiraledge view:Planoconvexaperture:Umb.-extraumbilical
umb chamber shape:Subtriangularcoiling axis:Moderateperiphery:Muricocarinateaperture border:N/A
sp chbr shape:Petaloidumbilicus:Wideperiph margin shape:Subangularaccessory apertures:None
umbilical or test sutures:Moderately depressedumb depth:Deepwall texture:Spinoseshell porosity:Finely Perforate: 1-2.5µm
spiral sutures:Raised muricatediameter mm:0.5width mm:0.25breadth mm:-
final-whorl chambers:6.5-7.5

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 ∂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. 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.

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

References:

Bermudez, P.J., (1961). Contribucion al estudio de las Globigerinidea de la region Caribe-Antillana (Paleoceno-Reciente). Mem. III Congreso Geol. Venez., 3. Editorial Sucre, Caracas, 1119-1393 pp.

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.

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.


logo

Morozovella pasionensis compiled by the pforams@mikrotax project team viewed: 18-9-2018

Taxon Search:
Advanced Search
Short stable page link: http://mikrotax.org/pforams/index.php?id=100202Go to Archive.is to create a permanent copy of this page - citation notes



Comments (0)

No comments yet. Be the first!

Add Comment

* Required information
1000
Captcha Image
Powered by Commentics