Globorotaloides atlanticus forms part of the plexus of Oligocene bullate Globorotaloides. The most important diagnostic feature of this morphotype is the position of the bulla that extends from the umbilicus around to the equatorial margin. In this respect we view G. atlanticus as being transitional between G. stainforthi, where the bulla is umbilical, to Protentelloides spp., where the bulla forms on the equatorial margin. It is unclear whether or not Globorotaloides atlanticus and contemporaneous G. hexagonus and Protentelloides were spinose. The type material of G. atlanticus shows signs of dissolution and recrystallization, including contact dissolution around other biogenic sediment particles such as sponge spicules (linear impressions in Pl. 4.4, Figs. 1, 9 and 11). This obscures any evidence for or against spines. [Coxall & Spezzaferri 2018]
Catalog entries: Globorotaloides atlanticus
Type images:Distinguishing features:
Parent taxon (Globorotaloides): Trochospiral test, ovate to spherical chambers; final chamber often small/bulla-like; cancellate wall.
This taxon: Like G. stainforthi, but with an umbilical-to-equatorial bulla that extends around the peripheral margin, an equatorially directed primary aperture and more numerous chambers in the final whorl.
Morphology:
Wall type:
Size:
Character matrix
test outline: | Lobate | chamber arrangement: | Trochospiral | edge view: | Equally biconvex | aperture: | Umbilical-extraumbilical |
sp chamber shape: | Globular | coiling axis: | Very low | periphery: | N/A | aperture border: | Bulla |
umb chbr shape: | Globular | umbilicus: | Wide | periph margin shape: | Moderately rounded | accessory apertures: | Infralaminal |
spiral sutures: | Weakly depressed | umb depth: | Shallow | wall texture: | Cancellate | shell porosity: | Macroperforate: >2.5µm |
umbilical or test sutures: | Moderately depressed | final-whorl chambers: | 5-7 | N.B. These characters are used for advanced search. N/A - not applicable |
Geographic distribution
Isotope paleobiology
Phylogenetic relations
Most likely ancestor: Globorotaloides stainforthi - at confidence level 3 (out of 5). Data source: Coxall & Spezzaferri 2018.
Likely descendants: Protentelloides primitivus;
plot with descendants
Geological Range:
Notes: The range of G. atlanticus has been determined at equatorial Atlantic Ocean DSDP Site 354 and ODP Site 667 as upper Oligocene Zone O7 to lower Miocene Zone M3. This is supported by more sporadic occurrences at South Atlantic Ocean DSDP Site 526 and rare appearances at equatorial Indian Ocean Site 709. These limits are based on the biostratigraphies of Spezzaferri (1994) and new observations made during this study. Globorotaloides atlanticus appears to be most common in O7, where all the examples shown on Plate 4.4 are from. [Coxall & Spezzaferri 2018]
Last occurrence (top): within M3 zone (17.54-19.30Ma, top in Burdigalian stage). Data source: Coxall & Spezzaferri 2018
First occurrence (base): within O7 zone (22.96-25.21Ma, base in Chattian stage). Data source: Coxall & Spezzaferri 2018
Plot of occurrence data:
Primary source for this page: Coxall & Spezzaferri 2018 - Olig Atlas chap.4 p.93
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 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 Quilty, P. G. (1976). Planktonic foraminifera DSDP Leg 34, Nazca Plate. Initial Reports of the Deep Sea Drilling Project. 34: 629-703. gs O Spezzaferri, S. (1994). Planktonic foraminiferal biostratigraphy and taxonomy of the Oligocene and lower Miocene in the oceanic record. An overview. Palaeontographia Italica. 81: 1-187. gs Spezzaferri, S. (1995). Planktonic foraminiferal paleoclimatic implications across the Oligocene-Miocene transition in the oceanic record (Atlantic, Indian, and South Pacific). Palaeogeography Palaeoclimatology Palaeoecology. 114: 43-74. gsReferences:
Globorotaloides atlanticus compiled by the pforams@mikrotax project team viewed: 10-11-2024
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