Morozovella velascoensis


Classification: pf_cenozoic -> muricate non-spinose -> Truncorotaloididae -> Morozovella -> Morozovella velascoensis
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 velascoensis (Cushman 1925)
Rank: Species
Basionym: Pulvinulina velascoensis
Synonyms:
Taxonomic discussion: This is the type species of the genus Morozovella McGowran (in Luterbacher, 1964) and one of the most characteristic and easily recognized Paleocene morozovellids. It has been assigned to various genera and subgenera over the past half century but would appear to have found a suitable home in the genus Morozovella as defined by McGowran in Luterbacher (1964; see also McGowran, 1968).
This species has been confused with the heterochronously isomorphic form M. caucasica (Glaessner) (see Subbotina, 1953, pl. 19: figs. la-2c, who identified strongly muricocarinate and circumumbilically muricate forms from the lower Eocene zone of conical globorotaliids of the northern Caucasus as G. velascoensis; see also El-Naggar, 1966, who was equally confused by the distinctions between these two taxa, and Blow, 1979, for clarification of the problems associated with separation and recognition of these two forms). [Olsson et al. 1999]

Catalog entries: Pulvinulina velascoensis;

Type images:

Distinguishing features: Relatively large (maximum diameter 0.5 mm), robust, plano-convex, nearly circular, moderately lobulate test composed of about 15-16 chambers arranged in 2½ to 3 whorls; last whorl with 6-7 (rarely 8) anguloconical chambers whose tips surround a moderately open umbilicus which is surmounted by an "adumbilical" or circum-umbilical rim (collar) of fused muricae; umbilical sutures radial, depressed, moderately to strongly curved, raised and beaded on spiral side; wall finely perforate, distinctly muricocarinate periphery but the spiral chamber surfaces are often nearly free of muricae; aperture a low, interiomarginal, umbilical-extraumbilical arch.

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.

Description


Diagnostic characters: Relatively large (maximum diameter 0.5 mm), robust, plano-convex, nearly circular, moderately lobulate test composed of about 15-16 chambers arranged in 2½ to 3 whorls; last whorl with 6-7 (rarely 8) anguloconical chambers whose tips surround a moderately open umbilicus which is surmounted by an "adumbilical" or circum-umbilical rim (collar) of fused muricae; umbilical sutures radial, depressed, moderately to strongly curved, raised and beaded on spiral side; wall finely perforate, distinctly muricocarinate periphery but the spiral chamber surfaces are often nearly free of muricae; aperture a low, interiomarginal, umbilical-extraumbilical arch. [Olsson et al. 1999]

Character matrix

test outline:Subcircularchamber arrangement:Trochospiraledge view:Planoconvexaperture:-
umb chamber shape:Subtriangularcoiling axis:Highperiphery:Muricocarinateaperture border:Thin flange
sp chbr shape:Crescenticumbilicus:Narrowperiph 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:width mm:-breadth mm:-
final-whorl chambers:6.5-7.5

Biogeography and Palaeobiology


Geographic distribution: Morozovella velascoensis has a wide geographic distribution but is a predominantly (sub)tropical to temperate form; it has not been recorded from high northern or southern (subantarctic) latitudes (> 45° N or S). The disappearance of this taxon is a distinct biostratigraphic event that is used to define the boundary between Zones P5 and
P6, which occurs in mid-Chron C24r, and is closely correlative with the Paleocene/Eocene boundary as denoted in the Belgian and/or London-Hampshire Basin(s) of northwestern Europe (Berggren and Aubry, 1996) (Figure 25). [Olsson et al. 1999]
Aze et al. 2011 summary: Low to middle latitudes; based on Olsson et al. (1999)

Isotope paleobiology: Morozovella velascoensis has ∂13C similar to coexisting species of Morozovella and Acarinina and more positive ∂13C and more negative ∂18O than Subbotina (Boersma and Premoli Silva, 1983; Shackleton et al., 1985; D'Hondt et al., 1994). Morozovella velascoensis displays a pronounced increase in 8UC with increased test size but little corresponding change in ∂18O (D'Hondt et al., 1994). This species typically has more negative ∂18O than all other analyzed species of 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 δ13C and relatively light δ18O. Sources cited by Aze et al. 2011 (appendix S3): Berggren & Norris (1997)

Phylogenetic relations: This species evolved from Morozovella conicotruncata (Subbotina) within Subzone P3b by the acquisition of coarsely muricate adumbilical ridges, the complete loss of muricae on the spiral chamber surfaces and between the murcrocarina and umbilical collar, as well as the formation of a thick, coarsely muricate mucrocarina. [Olsson et al. 1999]

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

Biostratigraphic distribution

Geological Range:
Notes: Zone P3b to Zone P5 (top). [Olsson et al. 1999]
The LAD of Morozovella velascoensis marks the base of zone E3 / top of E2 (Wade et al. 2011)
Last occurrence (top): at top of E2 zone (100% up, 55.2Ma, in Ypresian stage). Data source: zonal marker (Wade et al. 2011)
First occurrence (base): near base of P3b subzone (10% up, 61.3Ma, in Selandian stage). Data source: Olsson et al. 1999

Plot of occurrence data:

Primary source for this page: Olsson et al. 1999 - Atlas of Paleocene Planktonic Foraminifera, p. 66

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.

Cushman, J.A., (1925). Some new foraminifera from the Velasco shale of Mexico. Contributions from the Cushman Laboratory for Foraminiferal Research, 1(6): 18-23.

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.

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

McGowran, B., (1968). Reclassification of Early Tertiary Globorotalia. Micropaleontology, 14: 179-198.

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.

Subbotina, N., (1953). Foraminiferes fossiles d'URSS Globigerinidae, Globorotaliidae, Hantkeninidae. Bureau de Recherches Geologiques et Minieres, 2239: 1-144.

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.


logo

Morozovella velascoensis compiled by the pforams@mikrotax project team viewed: 21-7-2018

Taxon Search:
Advanced Search

Go 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