Discorbis chapmani

Discorbis chapmani

Bowen, 1954

Common name Foraminifer
Fossil group Foraminifera
Order Rotaliida
Family Discorbidae
Genus Discorbis
Taxonomic status Accepted
Geological age Ypresian
Recorded rarity by ageNot yet established
View age-specific evidence and explanation

There are no currently eligible, unambiguously age-indexed published Occurrences for this Species. This does not indicate absence or rarity.

These counts describe published LBPS Occurrence records with directly assigned, unambiguous geological-unit mappings—not specimen abundance. Records at restricted Localities and ambiguous or unsupported ages are excluded. Species-level age labels are not used as proof of an age-specific Occurrence.

Specimen-based rarity requires comparable, correctly identified physical fossils, geological provenance and publication permissions. It does not estimate your chance of finding a fossil or collecting access.

Quick Identification

Look for: a small discoidal to low trochospiral test with a flattened spiral side, more open umbilical side and a rounded lobulate margin.

Summary

Discorbis chapmani was a small benthic rotaliid foraminifer with a trochospiral calcitic test. It likely lived at the sediment-water interface or on small firm particles, using pseudopodia to graze bacteria and collect fine organic food.

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.

Diagnostic Features

  • Test low trochospiral and broadly discoidal.
  • Spiral side comparatively flat and shows successive whorls.
  • Umbilical side more inflated or open than the spiral side.
  • Final chambers produce a gently lobulate peripheral outline.
  • Aperture occurs near the umbilical margin of the final chamber.

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