Distribution

The Hildoceras bifrons species inhabited a shallow to deep oceanic nekton environment and are typically found in fine marine sediments. They are geographically distributed in:

  • England (Dorset, Somerset, Gloucestershire, Oxfordshire, Northamptonshire, Leicestershire, Lincolnshire and Yorkshire)
  • Europe
  • north Africa
  • Caucasus Mountains

Stratigraphically Hildoceras bifrons occurs in the Peronoceras fibulatum and Catacoeloceras crassum subzones of the H. bifrons zone, of the Lower Toarcian rocks.

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Glossary

Nekton is a free-swimming animals

Evolute and involute are geometrical terms relating to the shape of a curve

Lappets are spoon shaped extensions from the margin of the aperture

Arcuate is curved

Striae are fine lines of ornament

Ventro-lateral keels are ridges (keels) located on the sides of the venter

Tricarinate and bisulcate are two grooves separating the has three ridges (keels)of the venter.  

Venter is  the shell edge around the circumference