Euciphoceras regale

Euciphoceras regale

(J. Sowerby, 1822)

Common name Nautilus
Fossil group Molluscs
Order Nautilida
Family Nautilidae
Genus Euciphoceras
Taxonomic status Accepted
Geological age Ypresian

Representative Specimens

Selected reference specimens illustrating this species from different geological units and fossil sites.

Identification Examples

Choose a fossil site to view photographed reference specimens.

Summary

Euciphoceras regale was one of the largest chambered cephalopods in the London Clay sea. Its strongly coiled shell contained a series of buoyancy chambers, allowing the animal to remain suspended in the water and move by jet propulsion while the soft body occupied the final chamber.

As with living nautiloids, it was probably an opportunistic predator and scavenger feeding on crustaceans and other small marine animals as well as carrion. Large individuals approaching the size of a dinner plate would have been striking members of the early Eocene marine community.

Quick Identification

Look for: a very large, tightly involute nautilus with broad flattened flanks, a broad flattened to gently rounded venter and a robust subquadrate or trapezoidal whorl section.

Diagnostic Features

  • Shell is strongly involute, leaving only a very small umbilical region.
  • Whorls are broad and robust with comparatively flattened flanks.
  • Venter is broad rather than narrowly peaked.
  • Whorl section is characteristically subquadrate to trapezoidal.
  • Adult shell reaches a much larger diameter than most other London Clay molluscs.

Fossil Details

Typical size
About 140 mm; specimens approaching 200 mm are reported.
Fossil material
Shell, Internal Mould / Cast
Preservation
Aragonitic shell material is frequently dissolved, leaving large internal moulds. Weathering can remove the sutures and compression may distort the characteristic whorl section, so fragments without a clear cross-section are best identified more broadly.

Similar Species

Recorded Fossil Sites

Synonyms & Previous Names

Nautilus regalis; Eutrephoceras regalis

References

  • Edwards, F. E. (1849). A monograph of the Eocene Mollusca, or descriptions of shells from the older Tertiaries of England. Part I. Cephalopoda. Palaeontographical Society Monograph, 2, 1–56. Palaeontographical Society, London View reference
  • Hewitt, R. A. (2002). A review of the Early Eocene nautiloids of the London Clay Formation (upper division C to lowest division E) of south-east England, with particular reference to concretionary horizons and faunules in the offshore facies strata at Southend-on-Sea, Essex and in the adjacent cliffs of the Isle of Sheppey, Kent. Tertiary Research, 21(1–4), 39–50 View reference
Last Reviewed
15 August 2026 Reviewed by Sam Harris