Globorotaloides eovariabilis


Classification: pf_cenozoic -> Globigerinidae -> Globorotaloides -> Globorotaloides eovariabilis
Sister taxa: G. atlanticus, G. stainforthi, G. eovariabilis, G. hexagonus, G. quadrocameratus, G. suteri, G. testarugosus, G. variabilis, G. sp.,

Taxonomy

Citation: Globorotaloides eovariabilis Huber & Pearson, in Olsson et al. 2006
Rank: Species
Basionym: Globorotaloides eovariabilis
Synonyms:
Taxonomic discussion:

Globorotaloides eovariabilis is a small but distinctive species that occurs frequently in the < 150 μm size fraction (although the holotype is slightly larger). It is long-ranging and most abundant in high latitude Eocene to early Oligocene or equatorial assemblages. It is possible that it is a junior synonym of G. hexagonus and the possibility that the Paleogene species had a spinose wall, whereas modern G. hexagonus does not (see discussion above). Eocene Globorotaloides eovariabilis usually does not have a bulla, however, we have observed in Oligocene populations from different localities (e.g., ODP Site 647, North Atlantic Ocean, and Site 1137, southern Indian Ocean) times when bullate and non-bullate forms co-occur (Plate 4.5, Figs. 11, 12). Removal or natural breakage of the bulla reveals the typical G. eovariabilis morphology beneath (Plate 4.5, Figs. 13). [Coxall & Spezzaferri 2018]

Catalog entries: Globorotaloides eovariabilis, Globorotalia (Turborotalia) pseudoimitata

Type images:

Distinguishing features: Test with 4½ to 6, final whorl chambers, increasing gradually in size.

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:

Globorotaloides eovariabilis differs from Globorotaloides quadrocameratus in having greater than 4 (typically 5 but up to 6½) final whorl chambers that are less inflated and increase more gradually in size; from Globorotaloides variabilis by its smaller size and more regular low trochospiral coiling and tendency for axial lateral compression and pinching of the periphery. It differs from Globorotaloides testarugosus in the more inflated chambers, lobate periphery, and curving of umbilical sutures and from Globorotaloides hexagonus, with which it intergrades, in the smaller size, slightly less inflated chambers and lower stratigraphic range (see discussion above). Where a central umbilical bulla occurs there is a single opening. [Coxall & Spezzaferri 2018]


Wall type: Normal perforate, coarsely cancellate, sacculifer-type wall texture, often with corroded interpore ridges resulting in a remnant wall texture consisting of distinct ‘rosettes’ around pores. Possibly spinose (modified from Olsson and others, 2006a). [Coxall & Spezzaferri 2018]

Test morphology: Test outline lobate, subcircular in axial view, axial periphery rounded to slightly compressed and pinched, biconvex, oval to egg-shaped in edge view; 3- 3½ whorls of slightly inflated chambers arranged in a flattened to slightly elevated trochospire; 14-15 chambers in adult tests, 4½-6½ in the final whorl increasing moderately in size; umbilicus shallow to moderately deep and narrow; umbilical sutures moderately depressed, curved, radial; spiral sutures initially indistinct, later weakly depressed, radial; aperture a low umbilical-extraumbilical arch extending one-third towards the peripheral margin, surrounded by a broad lip that extends into the umbilical area; tendency to develop an imperforate peripheral band in some Oligocene forms (modified from Olsson and others, 2006a). [Coxall & Spezzaferri 2018]

Size: 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 mm, breadth 0.93 mm. [Coxall & Spezzaferri 2018]

Character matrix

test outline:Lobatechamber arrangement:Trochospiraledge view:Equally biconvexaperture:Umbilical-extraumbilical
sp chamber shape:Globularcoiling axis:Lowperiphery:N/Aaperture border:Thick lip
umb chbr shape:Globularumbilicus:Narrowperiph margin shape:Broadly roundedaccessory apertures:None
spiral sutures:Weakly depressedumb depth:Shallowwall texture:Cancellateshell porosity:Macroperforate: >2.5µm
umbilical or test sutures:Moderately depressedfinal-whorl chambers:4.5-6.0 N.B. These characters are used for advanced search. N/A - not applicable

Biogeography and Palaeobiology


Geographic distribution: Global, including low and mid-latitudes. Can be common in southern and northern high latitudes. There may be an affinity with high productivity conditions. [Coxall & Spezzaferri 2018]

Isotope paleobiology: Globorotaloides eovariabilis exhibits relatively positive δ18O and negative δ13C compared to other species suggesting that it occupied a sub-thermocline planktonic habitat similar to Catapsydrax (Coxall, unpublished). [Coxall & Spezzaferri 2018]

Phylogenetic relations: Globorotaloides eovariabilis evolved from Globorotaloides quadrocameratus (Olsson and others, 2006a). [Coxall & Spezzaferri 2018]

Most likely ancestor: Globorotaloides quadrocameratus - at confidence level 4 (out of 5). Data source: Olsson et al. 2006, f5.1.
Likely descendants: Globorotaloides testarugosus; Globorotaloides variabilis;

Biostratigraphic distribution

Geological Range:
Notes: Lower Eocene (Olsson and others, 2006a) to upper Oligocene Zone O7 (Pearson and Wade, 2009), possibly extending into the lower Miocene (recorded as Globorotaloides permicrus at DSDP Sites 360, 26, 563 and 516, Spezzaferri, 1994), although difficult to determine because of the close similarities with G. hexagonus. The holotype and paratype are from the middle Eocene of ODP Hole 647A, southern Labrador Sea, which was assigned to calcareous nannofossil Zone NP16 by Firth (1989) and dated as 40.2 Ma on the revised Site 647 biomagnetochronology of Firth and others (2013). [Coxall & Spezzaferri 2018]
Last occurrence (top): within M1 zone (21.12-22.96Ma, top in Aquitanian stage). Data source: Coxall & Spezzaferri 2018
First occurrence (base): within E7 zone (45.72-50.20Ma, base in Ypresian stage). Data source: Olsson et al. 2006

Plot of occurrence data:

Primary source for this page: Coxall & Spezzaferri 2018 - Olig Atlas chap.4 p.97; Olsson et al. 2006 - Eocene Atlas, chap. 5, p. 79

References:

Blow, W. H. (1979). The Cainozoic Globigerinida: A study of the morphology, taxonomy, evolutionary relationships and stratigraphical distribution of some Globigerinida (mainly Globigerinacea). E. J. Brill, Leiden. 2: 1-1413. gs

Bolli, H. M. (1957b). Planktonic foraminifera from the Oligocene-Miocene Cipero and Lengua formations of Trinidad, B.W.I. In, Loeblich, A. R. , Jr. , Tappan, H. , Beckmann, J. P. , Bolli, H. M. , Montanaro Gallitelli & E. Troelsen, J. C. (eds) Studies in Foraminifera. U.S. National Museum Bulletin. 215: 97-123. gs

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

Firth, J. V. (1989). Eocene and Oligocene calcareous nannofossils from the Labrador Sea, ODP Leg 105. Proceedings of the Ocean Drilling Program. Scientific Results. 105: 263-286. gs

Firth, J. V., Eldrett, J. S., Harding, I. C., Coxall, H. K. & Wade, B. S. (2013). Integrated biomagnetochronology for the Palaeogene of ODP Hole 647A: implications for correlating palaeoceanographic events from high to low latitudes, in Jovane, L., Herrero-Bervera, E., Hinnov, L.A., and Housen, B.A. (eds.), Magnetic Methods and the Timing of Geological Processes. Geological Society of London, Special Publications. 373: 29-78. gs

Huber, B. T. (1991c). Paleogene and Early Neogene Planktonic Foraminifer Biostratigraphy of Sites 738 and 744, Kerguelen Plateau (Southern Indian Ocean). Proceedings of the Ocean Drilling Program, Scientific Results. 119: 427-449. gs

Jenkins, D. G. & Orr, W. N. (1972). Planktonic foraminiferal biostratigraphy of the east equatorial Pacific--DSDP Leg 9. Initial Reports of the Deep Sea Drilling Project. 9: 1059-1193. gs

Jenkins, D. G. (1960). Planktonic foraminifera from the Lakes Entrance oil shaft, Victoria, Australia. Micropaleontology. 6: 345-371. gs

Jenkins, D. G. (1965b). 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. gs

Jenkins, D. G. (1966b). Planktonic foraminiferal zones and new taxa from the Danian to lower Miocene of New Zealand. New Zealand Journal of Geology and Geophysics. 8: 1088-1126. gs

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

Kennett, J. P. & Srinivasan, M. S. (1983). Neogene Planktonic Foraminifera. Hutchinson Ross Publishing Co., Stroudsburg, Pennsylvania. 1-265. gs

Krasheninnikov, V. A. & Basov, I. A. (1983). Stratigraphy of Cretaceous sediments of the Falkland Plateau based on planktonic foraminifers, Deep Sea Drilling Project, Leg 71. Initial Reports of the Deep Sea Drilling Project. 71: 789-820. gs

Li, Q., McGowran, B. & James, N. P. (2003b). Eocene–Oligocene planktonic forminiferal biostratigraphy of Sites 1126, 1130, 1132, and 1134, ODP Leg 182, Great Australian Bight. Proceedings of the Ocean Drilling Program, Scientific Results. 182: 1-28. gs

Loeblich, A. R. & Tappan, H. (1957b). Planktonic foraminifera of Paleocene and early Eocene Age from the Gulf and Atlantic coastal plains. In, Loeblich, A. R. , Jr. , Tappan, H. , Beckmann, J. P. , Bolli, H. M. , Montanaro Gallitelli, E. & Troelsen, J. C. (eds) Studies in Foraminifera. U.S. National Museum Bulletin. 215: 173-198. gs

McKeel, D. R. & Lipps, J. J. (1975). Eocene and Oligocene planktonic foraminifera from the Central and Southern Oregon Coast Range. Journal of Foraminiferal Research. 5(4): 249-269. gs

Natland, M. L. (1938). New Species of Foraminifera from off the West Coast of North America and from the Later Tertiary of the Los Angeles Basin. Bulletin of the Scripps Institute of Oceanography, Tech. Ser.. 4(5): 137-164. gs

Nocchi, M., Amici, E. & Premoli Silva, I. (1991). Planktonic foraminiferal biostratigraphy and paleoenvironmental interpretation of Paleogene faunas from the subantarctic transect, Leg 114. Proceedings of the Ocean Drilling Program, Scientific Results. 114: 233-273. 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

Pearson, P. N. & Wade, B. S. (2009). Taxonomy and stable isotope paleoecology of well-preserved planktonic foraminifera from the uppermost Oligocene of Trinidad. Journal of Foraminiferal Research. 39: 191-217. gs

Petters, V. (1954). Tertiary and Upper Cretaceous foraminifera from Colombia, S. A. Contributions from the Cushman Foundation for Foraminiferal Research. 5(1): 37-41. gs

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Stott, L. D. & Kennett, J. P. (1990). The Paleoceanographic and Paleoclimatic signature of the Cretaceous/Paleogene boundary in the Antarctic: Stable isotopic results from ODP Leg 113. Proceedings of the Ocean Drilling Program, Scientific Results. 113: 829-848. gs


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Globorotaloides eovariabilis compiled by the pforams@mikrotax project team viewed: 16-9-2019

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