Bolivinopsis adamsi

Bolivinopsis adamsi

(Lalicker, 1935)

Common name Foraminifer
Fossil group Foraminifera
Order Textulariida
Family Spiroplectamminidae
Genus Bolivinopsis
Taxonomic status Accepted
Geological age Ypresian

Summary

Bolivinopsis adamsi was an agglutinated benthic foraminifer that constructed its test by cementing sediment grains together. It lived on or within the London Clay sea floor and gathered fine organic material with pseudopodia; its abrupt appearance is important in the modern Hampshire Basin London Clay zonation.

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: an elongate agglutinated test with an early coiled stage followed by a flattened biserial series of chambers.

Diagnostic Features

  • Wall agglutinated, visibly composed of cemented sediment grains.
  • Early growth includes a small coiled or planispiral initial stage.
  • Later chambers become biserial, arranged in two alternating rows.
  • Test becomes elongate and compressed through adult growth.
  • Sutures between adult chambers are oblique and clearly expressed when preservation is good.

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