Alabamina obtusa
Alabamina obtusa
Common name
Foraminifer
Fossil group
Foraminifera
Order
Rotaliida
Family
Alabaminidae
Genus
Alabamina
Taxonomic status
Accepted
Geological age
Ypresian
Summary
Alabamina obtusa was a small benthic rotaliid foraminifer with a low trochospiral calcitic test. It occupied the microscopic sea-floor community and fed by extending pseudopodia to collect bacteria and fine detrital particles.
The organism itself was a single cell, but the fossil is its microscopic test. In the 2026 Hampshire Basin study this taxon occurs within the London Clay Formation assemblage used to construct the first foraminiferal zonation of the formation.
Quick Identification
Look for: a low, smooth trochospiral test with a rounded periphery, compact chambers and a planoconvex to weakly biconvex profile.
Diagnostic Features
- Test low trochospiral and compact.
- Profile planoconvex to weakly biconvex.
- Peripheral margin smoothly rounded and non-keeled.
- Chambers enlarge gradually with sutures visible but not deeply incised.
- Wall smooth, hyaline and finely perforate.
Fossil Details
Typical size
Microscopic; generally sub-millimetric.
Fossil material
Foraminiferal Test
Preservation
London Clay foraminiferal tests may be etched, crushed, stained or filled with matrix, and the 2026 study notes poorer preservation in parts of the succession. Fine apertural and sutural characters can disappear with corrosion; incomplete tests should be left at genus or higher rank.
Similar Species
Recorded Fossil Sites
No fossil-site occurrences have yet been recorded for this species.
References
- Hart, M. B.; Alex-Sanders, M. E. A.; Smart, C. W. (2026). Can the distribution of foraminifera locate the Early Eocene Climatic Optimum (EECO) and Middle Eocene Climatic Optimum (MECO) events in the Eocene succession of the Isle of Wight (UK)?. Journal of Micropalaeontology, 45(1), 315–334 View reference
Last Reviewed
20 August 2026
Reviewed by
Sam Harris