Cassigerinella eocaenica Cordey 1968 from: Pearson, P.N.Olsson, R.K.Hemleben, C.Huber, B.T.Berggren, W.A. (2006): Atlas of Eocene Planktonic Foraminifera. p. 1-513 | . |
Notice: This catalogue page may contain unedited data.
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Species Cassigerinella eocaenica Cordey 1968 |
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| Diagnosis / Definition: |
Pearson et al. (2006):
DESCRIPTION.-
Type of wall: Finely perforate, monolamellar, surface smooth or my have minute pore mounds.
Test morphology: Test very small, outline subcircular to broadly elliptical; periphery lobate, initially subacute, later becoming subrounded; chambers in early growth stage are compactly arranged in a biserial planispire or low biserial trochospire, later biserially enrolled with the chamber arrangement alternating in the coiling plane, moderately inflated, 8-9 visible in external view, increasing gradually and uniformly in size; sutures distinct, depressed, curved; aperture a latero-marginal, extra-umbilical arch.
Size: Paratype diameter 0.11 mm, breadth 0.06 mm; maximum diameter 0.10-0.12 mm. |
| Discussion / Comments: |
Pearson et al. (2006):
DISTINGUISHING FEATURES.-
Differs from C. chipolensis and C. boudecensis by its smaller size, more compressed test, less inflation of the chambers, slower chamber size increase, and lower and broader aperture.
DISCUSSION.-
Although a number of authors (e.g. Blow, 1979; Li, 1986) considered C. eoceana Cordey as a junior synonym of C. winniana (Howe), SEM images of the holotype of C. winniana (PL. 16.4, Figs. 13-15) reveal that the test is lenticular in edge outline, on the side of the test shows a concentration of several large, blunt pustules in the umbilical region, and the aperture is a narrow, extraumbillical arched slit at the base of the final chamber, and is surrounded by a narrow lip. These features, and the biserially enrolled planspiral coiling mode (see Li, 1986 for explanation), suggest that winniana should be reassigned to the benthic foraminifer genus Cassidulina. Well preserved, previously unillustrated specimens that were identified by Liu and others (1997) as C. winniana from Zone E18 in the Atlantic City (New Jersey) borehole samples (Liu, pers. comm., 1990) show strong similarity to the C. winniana holotype except for the presence of large, blunt pustules on both sides, rather than one side of the test (Pl. 16.4, Figs. 16, 17). These specimens are now considered as Cassidulina winniana.
Rather than having a simple planispire with uniserial chamber coiling in the initial whorl, as suggested by Cordey's (1968) original type illustrations and species description. Li's (1986, fig. 6c) reillustration of C. eocaenica holotype revealed that its early growth stage is characterized by compactly arranged biserial chambers that coil along a planispire or low trochospire. This coiling mode was more clearly demonstrated by Li and McGowran's (1996, pl. 1, figs. 1-7) SEM images of specimens where they illustrated specimens designated as C. winniana (here considered as C. eocaenica) from lower Oligocene borehole samples in southern Australia. Two of these specimens are here re-illustrated (Pl. 16.4, Figs. 20, 21). A specimen considered by Li and McGowran (1996, pl. 1, fig. 8) as transitional between C. eocaenica and C. chipolensis is also re-illustrated (Pl. 10.4, Fig. 22).
PHYLOGENETIC RELATIONSHIPS.-
Uncertain. Li and McGowran (1996) postulated that C. eocaenica (~ their C. winniana) was derived from Pseudohastigerina micra, but we consider this unlikely because of the smaller pore size, monolamellar rather than bilamellar wall, and planspiral to biserially enrolled coiling mode in C. eocaenica. The microperforate wall and occasional presence of pore mounds suggest a possible phylogenetic link with the Guembelitriidae, but no guembelitriid species have been recorded near the first occurrence of C. eocaenica (Fig. 16.1). Alternatively, the restricted
occurrence of C. eocaenica to neritic environments and
its unusual shell morphology suggest that the ancestor
of this taxon may have been a benthic species.
STRATIGRAPHIC RANGE.-
Upper Eocene Zone
E13 to middle Oligocene Zone O4 according to Li
(1986). Blow (1979) illustrated metatypes (his pl. 51,
figs. 7,8) that were sent to him by W.G. Cordey from an
upper Eocene (~Zone P16) core drilled on Blake Plateau,
western North Atlantic. Li and McGowran (1996)
recorded C. winniana (=C. eocaenica) in southern
Australia from lower Oligocene Zone NP23 and
suggested, based on reports in the literature, that this
species ranged down to the Zone P14/P15 boundary (=
upper E13). McGowran and others (1992) reported the
last occurrence of C. eocaenica near the P21a/P21b
(=Zone 04/05) boundary in the St. Vincent Basin of
southern Australia. A specimen identified as
Cassigerinella sp. by Leckie and others (1993, pl. 7,
fig. 17), here considered synonymous with C. eocaenica,
was reported in Zone P18 (=Zone 01) at ODP Site 628
on Little Bahama Bank. Pre-Oligocene reports of C.
eocaenica require SEM verification of species
identification because of the easy confusion of this
species with Cassidulina winniana.
GEOGRAPHIC DISTRIBUTION.-
Originally
described by Cordey (1968) from an uppermost Eocene
core drilled on Blake Plateau. Also recorded from lower
Oligocene subsurface, outcrop samples of terrigenous
clastic sediments in southern Australia (Li and
McGowran, 1996) and pelagic carbonate sediments at
Little Bahama Bank in the North Atlantic Ocean (Leckie
and others, 1993).
STABLE ISOTOPE PALEOBIOLOGY.-
No data available. |
| Systematics: |
35
Ordo Foraminiferida
Superfamilia Globigerinaceae
Familia Cassigerinellidae
Genus Cassigerinella
Species Cassigerinella eocaenica
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| Synonym list: |
Pearson et al. (2006):
1968 Cassigerinella eocaenica Cordey. - Cordey : p.369 fig. 1a-c [Eocene, core hole drilled off northern Florida
on Blake Nose, western North Atlantic Ocean]
1979 Cassigerinella winniana Howe. - Blow : p. 1363-1304 pl. 51, fig. 6-8;
pl. 246, fig. 8-10 [Upper Eocene, Zone P16, deep-sea coreLamont A.,
southeast of Blake Plateau, North Atlantic Ocean;
metatypes from upper Eocene, JOIDES Hole Mo. 6,
Blake Plateau, North Atlantic Ocean; lower
Oligocene, Zone P18, DSDP Site 14, central South
Atl
1993 Cassigerinella sp. Quilty. - Leckie et al. : p.123 pl. 7; fig. 17 [loer Oligocene, Zone P18, ODP Hole 628A,
Little Bahama Bank, Atlantic Ocean]
1996 Cassigerinella winniana Howe. - Li & McGowran : p. 97-103 pl. 1; fig. 1-12 [lower Oligocene, Zone P23, Port Willunga Fm.,
Mount Gambier (SADME MBT-5) and Kingston
(WMC'507) boreholes, South Australia);
[Not Howe, 1939]
2006 Cassigerinella eocaenica Cordey. - Pearson et al. : p.482 pl. 16.4; fig. 18-22 (Pl. 16.4, Figs. 18, 19: new SEMs of paratype
of Cassigerinella eocaenica Cordey)
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| Was used in synonym list of: |
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| Specimen: |
Natural History Museum, London, Inventory number: P46838
Smithsonian Museum of Natural History, Washington, D.C., Inventory number: USNM 643514
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| References: |
Cordey,W.G.. (1968):
A new Eocene Cassigerinella from Florida . Paleontology Vol. 11(3) p. 368-370
Blow,W.H. (1979):
The Cainozoic Globigerinida. 3 Vols p. 1413 pp
Leckie,R.M.; Farnham,C.. and Schmidt,M.G.. (1993):
Oligocene planktonic foraminifer biostratigraphy of Hole 803D (Ontong Java Plateau) and Hole 628A (Little Bahama Bank), and comparison with the southern high latitudes.
In: Proceedings of the Ocean Drilling Program, Scientific Results: Ocean Drilling Program Vol. 130 Eds: Berger, W.H.Kroenke, L.W..and others p. 113-136
Li,Q. and McGowran,B. (1996):
The Planktonic foraminifer Cassigerinella winniana (Howe) from southern Australia; Comments on its lineage recognition . Revista Espanola de Micropaleontologia Vol. 28 p. 97-103
Pearson,P.N.; Olsson,R.K.; Hemleben,C.; Huber,B.T. and Berggren,W.A. (2006):
Atlas of Eocene Planktonic Foraminifera. p. 1-513
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