Morozovella lensiformis


Classification: pf_cenozoic -> Truncorotaloididae -> Morozovella -> Morozovella lensiformis
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 lensiformis (Subbotina 1953)
Rank: Species
Basionym: Globorotalia lensiformis
Synonyms:
Taxonomic discussion: Subbotina (1953, p. 214) described this taxon from the lower part of the Zone of conical globorotaliids (to which it was said to be essentially restricted = Zone E4-5 of this paper). She recognized its descendant affinities with the Globorotalia marginodentata and G. crassata ( =M. aequa -subbotinae group) and ancestral relationships with M. aragonensis, interpretations which have withstood the test of time, relatively unchanged. Shutskaya (1956) subsequently described the junior synonym Globorotalia nartanensis from essentially the same stratigraphic level and locality in the northern Caucasus and recognized its transitional features with aragonensis.
Blow (1979, p. 981) treated M. dolabrata (Jenkins) as the ancestor of M. lensiformis (Subbotina) (Blow, 1979, p. 1005). He distinguished the transition between the two on the following basis: an increase in tightness of coiling-mode and proportionate decrease in size of last chamber relative to earlier chambers and a relatively stronger recurvature of the spiral intercameral sutures and more tightly appressed chamber development in lensiformis. It is clear that Blow (1979) viewed dolabrata as morphogenetically transitional from aequa s.s. to lensiformis.
We view the two taxa as synonymous. Topotypes of dolabrata kindly sent to one of us (WAB) by D. Graham Jenkins exhibit a densely muricate test with 4-4½ chambers as in lensiformis. A (“buried”) muricocarina rims the test. While Jenkins (1965) indicated that a peripheral keel was developed only on the last chamber, his own figures belie this fact (Jenkins, 1965, text-fig. 106), and Blow (1979, p. 401, 982) pointed out that the presence or visibility of a peripheral muricocarina is a function of the acuteness of the peripheral margins of the chambers. In broadly rounded margins the peripheral muricae are only partially fused and coalesced and do not yield the same “morphology” as that seen when the peripheral muricocarinae fuse into a single band along the margin of a test with an acutely angled periphery. A buried keel is characteristic of lensiformis as well and is dependent upon preservation as well as degree of acuteness of the peripheral margin. Distinction between these two morphotypes by Blow (1979) appear to be based on differences of degree rather than kind and we see little purpose in their separation. The upper stratigraphic limit of Zone P10 accorded by Blow (1979, p. 1005) to lensiformis remains enigmatic. We have not found morphotypes resembling lensiformis at such stratigraphically high levels. [Berggren & Pearson 2006]

Catalog entries: Globorotalia californica Smith;
Globorotalia dolabrata;
Globorotalia lensiformis;
Globorotalia lensiformis carpatica;
Globorotalia nartanensis;

Type images:

Distinguishing features: Test subquadrate, involute, biconvex, with narrow umbilicus; covered by blunt muricae, often obscuring the peripheral muricocarina; 4-4½ chambers in last whorl.

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: This taxon is characterized by its subquadrate, involute, biconvex test with narrow umbilicus; test covered by moderately to densely distributed, blunt muricae obscuring, in some instances, the peripheral muricocarina; 4-4½ chambers in last whorl. Later forms exhibit transitional features to plano-convex, multicameral M. aragonensis. [Berggren & Pearson 2006]

Wall type: Muricate, nonspinose, normal perforate. [Berggren & Pearson 2006]

Test morphology: Test low trochospiral, subquadrate to subcircular, weakly lobulate, chambers moderately inflated on umbilical side; flat on spiral side except for initial chambers; surface densely covered by blunt/truncated muricae giving the test a granular/sugary texture; 4-4½ chambers visible in tight coil on umbilical side; primary aperture a low umbilical-extraumbilical slit extending to the periphery; sutures on umbilical side straight to slightly curved, slightly depressed; in spiral view 9-10 chambers in 2½ to 3 whorls [early chambers/ whorls elevated giving biconvex appearance and often obscured by muricate growth]; intercameral sutures moderately to strongly muricate and (re)curved yielding trapezoidal shaped chambers; weakly biconvex in edge view; moderately umbilico-convex peripheral muricocarina often obscured by fusion of muricae along margin. [Berggren & Pearson 2006]

Size: Diameter: 0.40-0.55 mm; thickness: 0.25-0.30 mm (Subbotina, 1953, p. 214). [Berggren & Pearson 2006]

Character matrix

test outline:Subquadratechamber arrangement:Trochospiraledge view:Equally biconvexaperture:-
umb chamber shape:Inflatedcoiling axis:Lowperiphery:Single keelaperture border:N/A
sp chbr shape:Petaloidumbilicus:Narrowperiph margin shape:Subangularaccessory apertures:None
umbilical or test sutures:Strongly depressedumb depth:Deepwall texture:Coarsely muricateshell porosity:Finely Perforate: 1-2.5µm
spiral sutures:Moderately depressedfinal-whorl chambers:4.0-4.5

Biogeography and Palaeobiology


Geographic distribution: Relatively common in (sub)tropical areas; South Atlantic Ocean, Indo-Pacific, North Caucasus, among others. [Berggren & Pearson 2006]
Aze et al. 2011 summary: Low latitudes; based on Berggren & Pearson (2006)

Isotope paleobiology: Oxygen and carbon isotopes indicate a surface mixed layer habitat (Boersma and others, 1987). [Berggren & Pearson 2006]
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): Boersma et al. (1987)

Phylogenetic relations: This taxon (probably) evolved from M. subbotinae and is the ancestor of both M. crater in Zone E4 and M. aragonensis at the base of Zone E5. [Berggren & Pearson 2006]

Most likely ancestor: Morozovella subbotinae - at confidence level 4 (out of 5). Data source: Berggren & Pearson (2006) f11.1.

Biostratigraphic distribution

Geological Range:
Notes: Base of Zone E4 to Zone E6. [Berggren & Pearson 2006]
Last occurrence (top): in mid part of E6 zone (50% up, 50.4Ma, in Ypresian stage). Data source: Berggren & Pearson (2006) f11.1
First occurrence (base): at base of E4 zone (0% up, 54.6Ma, in Ypresian stage). Data source: Berggren & Pearson (2006) f11.1

Plot of occurrence data:

Primary source for this page: Berggren & Pearson 2006 - Eocene Atlas, chap. 11, p. 366

References:

Berggren, W.A., (1971). Paleogene planktonic foraminiferal faunas on Legs I-IV (Atlantic Ocean) JOIDES Deep Sea Drilling Program: a synthesis. In: Farinacci, A. (Editor), Proceedings of the II Planktonic Conference, Roma 1970. Edizioni Tecnoscienza, Rome, pp. 57-77.

Berggren, W.A., (1977). Atlas of Palaeogene Planktonic Foraminifera: some Species of the Genera Subbotina, Planorotalites, Morozovella, Acarinina and Truncorotaloides. In: Ramsay, A.T.S. (Editor), Oceanic Micropaleontology. Academic Press, London, pp. 205-300.

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.

Boersma, A.; Premoli Silva, I. & Shackleton, N.J., (1987). Atlantic Eocene planktonic foraminiferal paleohydrographic indicators and stable isotope paleoceanography. Paleoceanography, 2: 287-331.

Cushman, J.A. & Todd, R., (1948). A foraminiferal fauna from the New Almaden district, California. Contributions from the Cushman Laboratory for Foraminiferal Research, 24: 90-98.

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.

Jenkins, D.G., (1965). Planktonic Foraminiferal zones and new taxa from the Danian to lower Miocene of New Zealand. New Zealand Journal of Geology and Geophysics, 8(6): 1088-1126.

Jenkins, D.G., (1971). New Zealand Cenozoic Planktonic Foraminifera. New Zealand Geological Survey, Paleontological Bulletin, 42: 1-278.

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

Mallory, V.S., (1959). Lower Tertiary biostratigraphy of the California Coast Ranges. American Association of Petroleum Geologists, Tulsa, Oklahoma, 416 pp.

Samuel, O., (1972). Planktonic Foraminifera from the Eocene in the Bakony mountains (Hungary). Zbornik Geologickych Vied Zapadne Karpaty, 17: 165-206.

Smith, B.Y., (1957). Lower Tertiary foraminifera from Contra Costa county, California. University of California Publications in Geological Sciences, 32(3): 127-242.

Snyder, S.W. & Waters, V.J., (1985). Cenozoic planktonic foraminiferal biostratigraphy of the Goban Spur Region, Deep Sea Drilling Project Leg 80. Initial Reports of the Deep Sea Drilling Project, 80: 439-472.

Stainforth, R.M.; Lamb, J.L.; Luterbacher, H.; Beard, J.H. & Jeffords, R.M., (1975). Cenozoic planktonic foraminiferal zonation and characteristics of index forms. The University of Kansas Paleontological Contributions, 62: 1-425.

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

Warraich, M.Y. & Ogasawara, K., (2001). Tethyan Paleocene-Eocene planktic foraminifera from the Rakhi Nala and Zinda Pir land sections of the Sulaiman Range, Pakistan. Science Reports of the Institute of Geosciences, University of Tsukuba, Section B = Geological Sciences, 22: 1-59.

Warraich, M.Y.; Ogasawara, K. & Nishi, H., (2000). Late Paleocene to early Eocene planktic foraminiferal blostratigraphy of the Dungan Formation, Sulaiman Range, central Pakistan. Paleontological Research, 4(4): 275-301, 18 figures, 3 appendices.


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

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