Morozovelloides crassatus

Classification: pf_cenozoic -> Truncorotaloididae -> Morozovelloides -> Morozovelloides crassatus
Sister taxa: M. lehneri, M. coronatus, M. crassatus, M. bandyi, M. sp.,


Citation: Morozovelloides crassatus (Cushman 1925)
Rank: Species
Basionym: Pulvinulina crassata crassatus
Taxonomic discussion: Originally described as crassata, the ending has been changed to agree in gender with the genus Morozovelloides (ICZN, Art. 32.1). Morozovelloides crassatus and its synonym spinulosa have been recognized many times in the literature. They have been lumped by some authors and split by others, and have frequently been confused with lower Eocene morozovellids. The holotypes of both crassatus and spinulosa are illustrated here in SEM for the first time. Both are poorly preserved specimens with (apparently) about 4½ chambers in the final whorl. Both come from the middle Eocene of Mexico. The illustration of the lectotype of crassata selected by Bandy (1964) is highly misleading and should not be used to form a taxonomic judgment of this species. The taxonomic vicissitudes of M. crassatus may be summarized as follows:
1. Cushman (1925) named Pulvinulina crassata and Pulvinulina crassata var. densa from the middle Eocene of Mexico. Two years later he also named Globorotalia spinulosa from the Eocene of Mexico (Cushman, 1927). The type series of all these species are poorly preserved and the original illustrations are unsatisfactory by modern standards. Nevertheless, many authors have reported finding these species in subsequent investigations in various parts of the world.
2. Bandy (1964) erected and described a lectotype (USNM 3026) for Pulvinulina crassata Cushman from a syntypic series in the Cushman collections. Unfortunately, he was apparently misled by earlier, incorrect references to crassatus in giving the taxon a stratigraphic range of upper Paleocene through middle Eocene and suggesting phylogenetic affinities intermediate between G. angulata and G. rex.
3. Blow (1969, p. 370) subsequently stated that he had studied the types of crassatus (as lectotypified) and spinulosa at the USNM and found them to be synonymous, but different from the hypotypes described by Bolli (1957b) from Trinidad as G. spinulosa. He drew attention to the fact that a new taxon would subsequently be described for G. spinulosa of Bolli (1957b) by himself and one of us (WAB). This paper was never written; Blow died in 1972, but the taxon coronatus appeared in his posthumous work (Blow, 1979) (see Morozovelloides coronatus, this paper).
4. In his posthumously published work, Blow (1979, p. 1012) reported that Bandy’s lectotype of crassatus was missing from the USNM (during a visit in 1970) and stated his opinion that the remaining syntypes were not conspecific with Bandy’s lectotype illustration of crassatus (although Bandy [1964] had stated that “most of the syntypes of Globorotalia crassata agree very closely with the specimen selected and designated the lectotype herein”). In view of the tedious procedure of having to invoke the plenary powers of International Commission for Zoological Nomenclature to suppress the lectotype of Pulvinulina crassata Cushman (inasmuch as the figures were still available), before a neotype could be erected from the syntypic series still remaining at the USNM, Blow (1979, p. 1012) recommended that crassatus should be considered nomen dubium non conservandum and the subsequently named spinulosa should be retained since
among the specimens in the syntypic series of crassatus there are individuals which conform to Cushman’s subsequent description of spinulosa. These arguments of Blow (1979) are rendered superfluous by the subsequent rediscovery of the crassatus lectotype.
Given the poor preservation of the types of crassatus and spinulosa (particularly the former), and their complex taxonomic histories, we have found it difficult to recommend clear guidelines for their discrimination that do not merely add to the taxonomic confusion. The most conservative solution is to follow Banner and Blow (1960) and Berggren (1977) in regarding crassatus as a senior synonym of spinulosa, while at the same time acknowledging that other solutions would be equally consistent with the known facts given the poor and probably broken condition of the crassatus lectotype.
Finally, mention needs to be made of Pulvinulina crassata var. densa Cushman 1925, also from the Moctezuma River in Mexico. This taxon has been variously recognized as a “morozovellid” (for example, as a more highly vaulted variant of crassatus) or an acarininid (similar to, and perhaps synonymous with, A. bullbrooki). Our new SEM illustrations of the holotype suggest that the former solution is more likely to be true. However, it is an atypical morphology for the middle Eocene, and we do not attempt to separate highly vaulted Morozovelloides from the more usual, biconvex morphologies in our taxonomy, hence it is held in questionable synonymy with crassatus. [Pearson & Berggren 2006]

Catalog entries: Pulvinulina crassata, Globorotalia hadii, Globorotalia spinulosa

Type images:

Distinguishing features: Test asymmetrically low-biconvex, sometimes nearly planoconvex; umbilicus closed to narrow

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.


Diagnostic characters: An asymmetrically low-biconvex test with closed or small, deep and narrow umbilicus, sometimes nearly planoconvex; differs from coronatus in lacking the strongy muricate circumumbilical ‘coronet’ and in having a closed to narrow umbilicus and from lehneri in its umbilico-convex test and thicker and more densely muricate keel and fewer chambers in the final whorl. [Pearson & Berggren 2006]

Character matrix

test outline:Subcircularchamber arrangement:Trochospiraledge view:Planoconvexaperture:Umbilical-extraumbilical
sp chamber shape:Inflatedcoiling axis:Lowperiphery:N/Aaperture border:N/A
umb chbr shape:Subtriangularumbilicus:Wideperiph margin shape:Subangularaccessory apertures:None
spiral sutures:Weakly depressedumb depth:N/Awall texture:Moderately muricateshell porosity:Finely Perforate: 1-2.5µm
umbilical or test sutures:Moderately depressedfinal-whorl chambers:5.0-6.0 N.B. These characters are used for advanced search. N/A - not applicable

Biogeography and Palaeobiology

Geographic distribution: Widely distributed in (sub)tropical regions of the world (see citations above); not recorded from the North Caucasus. [Pearson & Berggren 2006]
Aze et al. 2011 summary: Low latitudes; based on Pearson & Berggren (2006)

Isotope paleobiology: Oxygen and carbon isotopic ratios indicative of a shallow water, photosymbiotic habitat (Boersma and others, 1987, Pearson and others, 1993, 2001, Wade and others, 2001, Wade and Kroon, 2002; all recorded as Morozovella spinulosa). This interpretation is supported by the boron isotope data of Pearson and Palmer (1999) (also recorded as M. spinulosa). [Pearson & Berggren 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); Pearson et al. (1993, 2001a); Wade et al. (2001); Wade & Kroon (2002); Wade et al. (2008)

Phylogenetic relations: Morozovelloides crassatus evolved from M. bandyi and gave rise to M. coronatus. [Pearson & Berggren 2006]

Most likely ancestor: Morozovelloides bandyi - at confidence level 4 (out of 5). Data source: Pearson & Berggren 2006, f10.1.
Likely descendants: Morozovelloides coronatus;

Biostratigraphic distribution

Geological Range:
Notes: Zone E8-13 (middle Eocene; see Wade (2004) for data on the last occurrence).
[Pearson & Berggren 2006]
NB Given the problems with zones E7 and E8 disccussed by Wade et al. 2100 this range may need revising [JRY 2017] The LAD of Morozovelloides crassatus marks the base of zone E14 / top of E13 (Wade et al. 2011)
Last occurrence (top): at top of E13 zone (100% up, 38Ma, in Bartonian stage). Data source: zonal marker (Wade et al. 2011)
First occurrence (base): within E7b subzone (45.72-48.31Ma, base in Ypresian stage). Data source: Pearson & Berggren 2006, f10.1

Plot of occurrence data:

Primary source for this page: Pearson & Berggren 2006 - Eocene Atlas, chap. 10, p. 332


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Toumarkine, M. & Luterbacher, H. (1985). Paleocene and Eocene planktic foraminifera. In, Bolli, H. M. , Saunders, J. B. & Perch-Neilsen, K. (eds) Plankton Stratigraphy. Cambridge Univ. Press, Cambridge 87-154. gs :: ::

Wade, B. S. & Kroon, D. (2002). Middle Eocene regional climate instability: Evidence from the western North Atlantic. Geology. 30: 1011-1014. gs :: ::

Wade, B. S. (2004). Planktonic Foraminiferal biostratigraphy and mechanisms in the extinction of Morozovella in the Late Middle Eocene. Marine Micropaleontology. 51: 23-38. gs :: ::

Wade, B. S., Kroon, D. & Norris, R. D. (2001). Orbitally forced climate change in the Late Middle Eocene at Blake Nose (Leg 171B): Evidence From Stable Isotopes In Foraminifera. Geological Society of London, Special Publications. 183: 273-291. gs :: ::

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. gs :: ::


Morozovelloides crassatus compiled by the pforams@mikrotax project team viewed: 6-6-2020

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