Catalog - Globorotaloides eovariabilis

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Globorotaloides eovariabilis

Citation: Globorotaloides eovariabilis Huber & Pearson, in Olsson et al. 2006

Type specimens: PLATE 5.4, FIGURES 1-17; Holotype (USNM 523429) and paratypes (USNM 523430a, 523430b)

Type sample (& lithostrat): DSDP 647A-50R-5, 101 cm

Type age (chronostrat): middle Eocene - calcareous nannofossil Zone NP16

Type locality: The holotype and paratype are from the middle Eocene of ODP Hole 647A (Sample 647A-50R-5, 101 cm) in the Labrador Basin, which was assigned to calcareous nannofossil Zone NP16 by Firth (1989). [Olsson et al. 2006]

Type repository: Washington; USNM

Type of wall: Normal perforate, coarsely cancellate, sacculifer-type wall texture, often with corroded interpore ridges resulting in a remnant wall texture consisting of distinct ‘rosettes’ around the pores.

Test morphology: Test outline lobate, subcircular in axial view, axial periphery rounded to very slightly compressed, biconvex, oval to egg-shaped in edge view; 3-3½whorls of slightly inflated chambers arranged in a flattened to slightly elevated trochospire; 14-15 chambers in adult tests, 4½-6 in the final whorl increasing moderately in size; umbilicus shallow to moderately deep and narrow; umbilical sutures moderately depressed, radial; spiral initially indistinct, later weakly depressed, radial; aperture a low umbilical- extraumbilical arch extending one-third towards peripheral margin, surrounded by a broad lip that extends into the umbilical area.

Holotype (USNM 523429) maximum diameter 0.18 mm, breadth 0.10 mm; paratype a (USNM 523430) maximum diameter 0.13 mm, breadth 0.80 mm; paratype b (USNM 523430) maximum diameter 0.15 m, breadth 0.93 mm.

Named as “dawn” variabilis because of its superficial resemblance to the much younger species Globorotaloides variabilis Bolli

Clavigerinella ?columbiana (Petters). McKeel and Lipps, 1975:258, pl.3: fig. 8a-c (partim; not pl. 4: fig. 6a, b =Parasubbotina eoclava Coxall, Huber, and Pearson) [lower middle Eocene, Elkton Siltstone, Coast Ranges, Oregon]. [Not Petters, 1954.]
?Globorotalia (Turborotalia) pseudoimitata Blow, 1979:1104-1105, pl. 101: figs. 1-3 [upper Paleocene Zone P5, DSDP Site 47, Shatsky Rise, northwest Pacific Ocean]; pl. 106: figs. 2-10; pl. 108: figs. 1-3 [lower Eocene Zone P6, Hole 20C, South Atlantic Ocean].
Globorotalia munda Jenkins.—Krasheninnikov and Basov, 1983:841 (partim), pl. 10: fig. 101 [lower Eocene, DSDP Site 511, Falkland Plateau, South Atlantic].[Not Jenkins, 1966.]
Globorotaloides aff. G. testarugosa Jenkins.—Stott and Kennett, 1990:560, pl. 7: fig. 11 [middle Eocene Zone AE4/5, ODP Hole 689B, Maud Rise, southern South Atlantic]. Huber, 1991:440, pl. 7: figs. 19, 20 [lower Oligocene, Zone AE9, ODP Hole 738B, Kerguelen Plateau, southern Indian Ocean]. [Not Jenkins, 1971.]
“Planorotalites” reissi (Loeblich and Tappan).—Huber, 1991:440, pl. 4: figs. 18-20 [lower Eocene Zone AE4/5, ODP Hole 738C, Kerguelen Plateau, southern Indian Ocean]. [Not Loeblich and Tappan, 1957.]
Globorotaloides aff. suteri Bolli.—Nocchi and others, 1991:268, pl. 4: figs. 4, 5 [lower middle Eocene Zone E8- E9, ODP Site 699, southern South Atlantic]. [Not Bolli, 1957b.]
Globorotaloides suteri Bolli.—Berggren, 1992:564, pl. 4: fig. 4 [upper Eocene G. suteri Zone ODP Hole 748B, Kerguelen Plateau, southern Indian Ocean]. [Not Bolli, 1957b.]
Globorotaloides sp. 1, Berggren, 1992: 568, pl. 4: fig. 11 [upper Eocene G. suteri Zone, ODP Hole 748B, Kerguelen Plateau, southern Indian Ocean].
Globorotaloides suteri Bolli.—Bolli, 1957:117, pl. 27, figs. 9a-c and 12a-b, G. suteri paratypes USNM P5655c and P5655d respectively [lower Oligocene, Globigerina ampliapertura Zone, Cipero Fm. Trinidad].—Jenkins and Orr, 1972:1106, pl. 36, figs. 10, 11 [lower Oligocene Pseudohastigerina barbadoensis Zone, DSDP Hole 77, eastern equatorial Pacific Ocean].—Poore and Brabb, 1977:260, pl. 1, figs. 11, 12 [lower Oligocene Zone P19-P20, San Lorenzo Fm., Rices Mudstone Member, Santa Cruz Mountains, California].—Krasheninnikov and Basov, 1983:840, pl. 8, figs. 1, 4 [upper Eocene, DSDP Hole 511, Falkland Plateau, South Atlantic Ocean].—Berggren, 1992:564, pl. 4, fig. 4 [upper Eocene Globorotaloides suteri Zone, ODP Hole 748B, Kerguelen Plateau, southern Indian Ocean]. [Not Bolli, 1957.]
Globorotaloides variabilis Bolli.—Kennett and Srinivasan, 1983:214, pl. 53, figs. 6-8 [upper Miocene Zone N16, DSDP Hole 289, Ontong Java Plateau, western equatorial Pacific Ocean]. [Not Bolli, 1957.]
Globorotalia munda Jenkins.—Krasheninnikov and Basov, 1983:841, pl. 10, fig. 11 [upper Eocene, DSDP Hole 511, Falkland Plateau, South Atlantic Ocean]. [Not Jenkins, 1965.]
Globorotaloides aff. G. testarugosa Jenkins.—Stott and Kennett, 1990:560, pl. 7, fig. 11 [middle Eocene Zone AE4/5, ODP Hole 689B, Maud Rise, sub-Antarctic South Atlantic Ocean].—Huber, 1991:440, pl. 7, figs. 19, 20 [lower Oligocene Zone AE9, ODP Hole 738B, Kerguelen Plateau, southern Indian Ocean]. [Not Jenkins, 1960.]
Globorotaloides sp. 1, Berggren, 1992:568, pl. 4, fig. 11 [upper Eocene Globorotaloides suteri Zone, ODP Hole 748B, Kerguelen Plateau, southern Indian Ocean].—Sexton and others, 2006:6, pl. 1, figs. 9, 10 [middle Eocene Zone E13, ODP Site 1052, Blake Nose, western North Atlantic Ocean].
Globorotaloides sp.—Li and others, 2003: pl. 1, fig. 17 [upper Eocene Zone P16, ODP Hole 1126D, Great Australian Bight].
Globorotaloides eovariabilis Huber and Pearson in Olsson and others, 2006a:79-83, pl. 5.4, figs. 1-3, 5-11 [middle Eocene Zone E10-E11, ODP Hole 647A, Labrador Sea], pl. 5.4, fig. 4 [middle Eocene Zone AE7, ODP Hole 690B, Maud Rise, southern Indian Ocean], pl. 5.4, figs. 12-17 [lower Eocene and lower Oligocene Zones AE2 and AO1, ODP Hole 738B, Kerguelen Plateau, southern Indian Ocean].—Pearson and Wade, 2009:206, pl. 5, fig. 7 [upper Oligocene Zone O6 (= O7), Cipero Fm., Trinidad]. [merged synonomy form Olsson 2006 & Coxall & Spezzaferri 2018]

Distinguishing features. Differs from Globorotaloides quadrocameratus n. sp. by having 41/2 to 6, rather than 4-41/2, final whorl chambers that are less inflated and increase more gradually in size; differs from Globorotaloides variabilis by its smaller size and less flat inner whorl.

Discussion. This form has been widely recognized at high latitude sites using various species names and open nomenclature. It is included in Globorotaloides because of its coarsely cancellate wall texture and low, sometimes flattened spiral coil. Specimens frequently exhibit corroded interpore ridges with a remnant surface texture consisting of a distinct rosette pattern (Pl. 5.4, Figs. 4, 13-15). A high latitude form from the lower Eocene of Site 690 (Maud Rise) that may be related to this species was designated by Stott and Kennett (1990, pl. 5, figs. 3-4) as “Tenuitella” reissi (Loeblich and Tappan). This morphotype has a similar coarsely reticulate wall texture but it is higher spired and the equatorial margin is more compressed.

Phylogenetic Relationships. Descended from Globorotaloides quadrocameratus n. sp. during the early Eocene. Intermediate morphologies can be found (e.g., Pl. 5.5, Figs. 13-15).

Stratigraphic Range. Lower Eocene-lower Oligocene, Zone E7 to Zone O1 at low latitudes, and Zone AE4-AO1 at high latitudes.

Geographic Distribution. Found at deep-sea sites in southern and northern high latitudes but not at middle or low latitudes.

References:

Coxall, H. K. & Spezzaferri, S. (2018). Taxonomy, biostratigraphy, and phylogeny of Oligocene Catapsydrax, Globorotaloides, and Protentelloides. In, Wade, B. S., Olsson, R. K., Pearson, P. N., Huber, B. T. & Berggren, W. A. (eds) Atlas of Oligocene Planktonic Foraminifera. Cushman Foundation for Foraminiferal Research, Special Publication . 46(Chap 4): 79-124. gs

Olsson, R. K., Pearson, P. N. & Huber, B. T. (2006c). Taxonomy, biostratigraphy, and phylogeny of Eocene Catapsydrax, Globorotaloides, Guembelitrioides, Paragloborotalia, Parasubbotina, and Pseudoglobigerinella n. gen. In, Pearson, P. N., Olsson, R. K., Hemleben, C., Huber, B. T. & Berggren, W. A. (eds) Atlas of Eocene Planktonic Foraminifera. Cushman Foundation for Foraminiferal Research, Special Publication . 41(Chap 5): 67-110. gs O

CATALOG OF ORIGINAL DESCRIPTIONS: Globorotaloides eovariabilis Huber & Pearson, in Olsson et al. 2006

Globorotaloides eovariabilis

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